JPS6156588A - Cable television system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates generally to cable television systems and, more particularly, to converting a portion of a cable network's television signal into a television signal that is supplied to a subscriber's television set. It concerns a cable television system in which the converter is located outside the subscriber's premises.

Conventional technology A converter for converting a portion of the cable television signal that the subscriber is trying to receive into a signal suitable for feeding into a television receiver.

There is increasing interest in cable television systems that are located outside of a subscriber's building, such as on or near utility poles. The reasons for placing the converter outside the building in this manner include unauthorized adjustment of the converter, accidental or intentional abuse of the converter, or.

This is to reduce the risk of damaging the converter.

Problems that the invention seeks to solve On the other hand, placing the converter outside the subscriber's building increases the complexity of the system since it must include equipment to allow the subscriber to remotely control the converter. At the same time, the cost increases. For this,
The development of outdoor converter cable television systems has been hindered.

Means for Solving the Problems 1. It is therefore an object of the invention to improve, simplify and reduce the cost of outdoor converter cable television systems. 6. This and other objects of the invention are 1. In accordance with the principles of the present invention, by providing a cable television system and method in which the outdoor converters of a number of adjacent subscribers are at least partially controlled by a common signal processing circuit associated with the converters. achieved.

Preferably, this common signal processing circuit and all associated converters are located in a common facility, such as a housing mounted on or near a utility pole in the vicinity of the subscriber's premises.

This device is hereinafter referred to as an external control unit or rEC.
It is called UJ. This external control unit.

Preferably, there is only a single tap for each network cable used.

The signals derived from this tap are distributed appropriately to the various components of the external control unit. A drop cable extends from this external control unit to each subscriber's building.

Inside the subscriber's premises, this drop cable is connected to a subscriber processing unit, or rsPUJ, which is typically located near the subscriber's television set. This subscriber processing unit supplies drop cable television signals to the television set and sends subscriber generated control signals to the drop cable and back to the external control unit. Provides control signals to drop cables for transmission back to other devices located within the subscriber's premises, such as burglar alarms, fire alarms, or other alarm devices, or to an external control unit. Monitoring devices that can be used can also be connected to the drop cable.

The external control unit processes the control signals generated by all relevant subscribers and, if appropriate, satisfies the service requests indicated by these control signals.

In particular, a common signal processing circuit included in the external control unit is used as extensively as possible to process the control signals generated by the subscribers, and an individual external control circuit must be provided for each subscriber. The amount of circuitry in the unit is considered to be minimal.

The external control unit can also receive and respond to control signals from a so-called "head end" of the cable network. for example.

These control signals include channel grant data that identifies which channels of the cable network are permitted to be received and viewed by a particular subscriber. The control signals generated by these head ends are preferably transmitted via a cable network, again using as extensively as possible the common signal processing circuitry contained in each external control unit. signals are processed. Since each external control unit typically serves a large number of subscribers, all these subscribers are addressed from the head end by control signals addressed to the external control unit rather than to each individual subscriber. can be affected. This greatly facilitates control of the system from the head end.

Further features, properties and various advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings.

Example ■Supervisor of the five Kaiten animals in the 1st ward! As shown in the embodiment of FIG. 1, the cable television system 10 of the present invention includes a head end device 12, a cable network 14, and a cable network 12, typically connected to each other and in a remote location from the head end device 12. Multiple external control units EC connected to network 14
UI, ECU2, etc., drop cable DROPI,
It comprises a plurality of subscriber premises 5UBI, 5UB2°, etc., each connected to an associated external control unit by a DROP2, etc. In the particular embodiment shown, each external control unit can connect to six subscribers, but this number is arbitrary and the maximum number of subscribers per external control unit is six. It may be more or less than.

Head end equipment 12 typically includes one or more television signal information sources, such as a common satellite antenna 20. A general satellite receiver has an antenna 20
separates the television signal information received via the baseband television signal into a plurality of baseband television signals, each representing one baseband television channel. A typical modulator 24 is used for each fundamental frequency channel or "physical" cable channel being distributed over the cable network 14.
Each of these television signals is modulated to shift the +F channel. Further baseband television signals or other signals (e.g., television signals from a studio camera or video recorder, FM audio signals, etc.) are transmitted to the modulator 24 via cables 26, 28, etc.
can also be supplied and shifted by this modulator for a given physical cable channel.

All output signals of the modulator 24 are sent to a general combiner 30 which combines these signals and feeds them via another general combiner 32 to the cable network 14. 32 is.

It also adds control and data signals to the signals sent to cable network 14. These control and data signals are of two types:

(1) so-called "forward" data signals representing information generated by the head end equipment 12 to control external control units in the network; and (2) typically included in the FM band and not Forward High Data Rate Channel (HDR), which allows cable networks to be used for purposes such as distributing television signal data (e.g., general purpose computer programs and data) to subscribers.
C) signal. This forward HD RC signal is typically F
M band, the term rFMFM audio signal as used herein shall also include forward HDRC signals if such signals are used in the system6. In addition to adding directional data and forward HDRC signals, combiner 32 also adds directional data and forward HDRC signals from cable network 14 to modem 34.
A so-called "reverse data" signal is also provided in the opposite direction.

This reverse data signal is a control signal generated by an external control unit as described below, which is
It is sent to head end equipment 12 and used to control the cable television network.

In the embodiment shown, four channels may be used for this reverse data communication.

Modem 34 converts (modulates) forward data signals generated by central control computer (CCC) 36 into signals suitable for transmission to cable network 14 and which receives signals from cable network 14 . The reverse direction data signal is sent to the central control computer 3.
The signal is converted (demodulated) into a signal suitable for processing in step 6.

The 1 combiner 32 also extracts the reverse direction HDCR signal from the signal of the cable network 14.

This signal allows the cable network to be used for purposes such as transmitting non-television signal data (eg, fire alarm signals and burglar alarm signals) from subscribers to a central location such as head end 12. This reverse HDRC: signal is typically in a different frequency band than all other frequency bands used in the system (e.g.
25MHz). The use of the reverse HDRC frequency band in the present invention allows direct two-way communication between the head end and the subscriber and eliminates the problems inherent in conventional two-way CATV systems. Problems with noise and other signal degradation that may affect other communication signals on the CATV cable can be minimized.

Each external control unit is equipped with a general signal connection device 50, which feeds the signals appearing on the cable network 14 into the circuitry of the external control unit.
The reverse data generated by the external control unit and the reverse HDCR signal generated by the associated subscriber are fed to the cable net leak 14 . Each external control unit typically.

It is located outside the premises of the subscriber affected by this. Typically, all circuits of an external control unit are located in a common housing that is attached to a utility pole or other suitable structure in the vicinity of the subscriber's premises served by the external control unit.

The signal connection device 50 is connected to a general splitting-combining circuit m52. This splitting-combining network 52 distributes the signals received from the cable network 14 to a plurality of subscriber units SU1, SU2, etc. within the external control unit, each subscriber being acted upon by the external control unit. Each subscriber unit is combined. Each subscriber unit includes further equipment, described in detail below, in which each subscriber unit acts as a digitally controlled converter to convert the subscriber's television receiver into a conventional cable network system. Suffice it to say that it performs the television signal frequency conversion function performed by a nearby converter.

Furthermore, the division-composition network 52 is connected to the cable network 1
The signals received from 4 are also distributed to analog unit 54, which will be described in detail below. Generally, analog unit 54
separates FM voice signals and forward data signals from other signals received from cable network 14. Analog unit 54 provides FM audio signals to each subscriber unit for transmission to the subscriber. The analog unit 54 also demodulates the forward data signal and supplies the resulting data signal to the digital unit 55. Analog unit 54 Hayashi, reverse HDRC received from subscriber unit
The signals are provided to split-combiner circuit #J52, which provides these reverse HDRC signals to signal connection device 50 and thus to cable network 14.

Split-combining network 52 also provides reverse data signals from communications unit 56 to signal connection device 50 . In addition, as described in more detail below, if a so-called "slave" external control unit (not shown in FIG. 1) is combined with a "master" external control unit,
A split-combining network 52 connects a lead 58 between the signal connection device 50 and the split-combining network of the slave external connection unit.
transmits signals in both directions.

As mentioned above, each subscriber unit receives all cable network signals from one split-combiner network 52. In response to control signals received from digital unit 55, each subscriber unit (1) selects from the cable network signal a portion of the signal representing the television channel that the subscriber wishes to view; 2
) This signal portion is converted into a television signal of a predetermined channel (for example, channel 3) to which the subscriber's television receiver 90 is tuned. This television signal is
Do07 cable/l/ combined with subscriber unit
Sent to DROPI, DROP2, etc. These drop cables extend from the subscriber unit to the associated subscriber building 5UB1.5QB2, etc.

Each subscriber unit also has analog units 54 through F
It also receives the M audio signal and combines this signal with the television signal supplied to the subscriber's drop cable.

Each external control unit transmits the i! (in particular, the subscriber processing unit 5PU of the subscriber concerned). Also, when a subscriber operates his subscriber processing unit to select a television channel, the subscriber processing unit transmits a VLF data signal representative of the desired channel selection via the drop cable to the external control unit.

Each subscriber unit provides these VLF data signals in both directions between that subscriber's drop cable and communication unit 56, which
It is equipped with a modem for exchanging data signals with the digital unit 55.

Each subscriber unit also provides a reverse HDRC signal to analog unit 54 from its subscriber drop cable.

The power required to operate each external control unit is provided by the subscriber served by that external control unit. Each subscriber has a subscriber processing unit that provides an alternating current (AC) power signal to the drop cable. The subscriber unit sends this power signal to a common power supply unit 60 in the external control unit. This common power supply unit 60 combines all power signals sent to it and derives from this combined signal the currents and voltages required to energize the various components of the external control unit. In this way, all subscribers served by the external control unit share in the power requirements of the external control unit. In case of a typical AC power outage, the common power supply unit 60 sends a control signal to the digital unit 55, which shuts down the digital unit so that no important data is lost.

Digital unit 55 controls the operation of the external control unit. The digital unit 55 is the analog unit 5
It receives and processes the forward data sent via 4. Digital unit 55 also generates reverse data and provides this data to communication unit 56 for transmission to head end 12. The digital unit 55 is
It receives and processes demodulated VLF signals sent via communication unit 56 from all subscriber units of the external control unit. Furthermore, the digital unit 55 has 1
Other signals are also generated which are transmitted back to the subscriber via the communication unit 56 and the subscriber unit.

The digital unit 55 also controls various functions of the subscriber unit, for example when the subscriber is attempting to view a particular television channel.

The digital unit 55 receives the VLF signal indicating the desired channel selection generated by the subscriber and determines whether the subscriber is authorized to receive that channel based on channel grant data previously provided by the head end 12. and, if the subscriber is authorized to receive the desired channel, controls the subscriber unit to provide the signal of the desired channel to the subscriber's drop cable.

Each subscriber has at least one subscriber processing unit;
It has at least one conventional television receiver 90 connected to the subscriber processing unit and a conventional remote control unit (RCU) for remotely controlling the subscriber processing unit by infrared or other signals. Whether or not to have this remote control unit is optional. The subscriber processing unit is connected to the drop cable and provides the received drop cable signal to the television set 90. The received drop cable signal may be sent to the subscriber's (optional) FM audio receiver BE (not shown) or to the subscriber's (optional) forward HDRC-enabled equipment (not shown). The subscriber processing unit may include a conventional keyboard (not shown in FIG. 1) that allows the subscriber to enter data himself, such as the number of the television channel he wishes to receive. are doing. Alternatively, this data can also be entered by the subscriber's remote control unit RCU. The subscriber processing unit converts the data input by the subscriber into a VLF data signal, which signal is
It is sent to the external control unit via the subscriber's drop cable.

The subscriber processing unit also typically includes a data display element, such as a seven element light emitting diode (LED) display. These display elements are controlled by VLF data sent from the external control unit to the subscriber processing unit. Additionally, the subscriber processing unit provides the reverse HDRC signal generated by the subscriber to the drop cable.

Table A below schematically shows the carrier signal frequency allocation in the present embodiment of the invention.

1 person, Wataru Toyosei Approximately 5 stars Wataru supervisor 1, AC power 60Hz 2, VL
F data (ECU 5PU) 430KHz3
, VLF data (SPU and ECU) 468K
Hz4, reverse data a, channel 0 19.125MHz
b, Channel 1 19.375MHz
C0 channel 2 19.625MHzd
, Channel 3 19.875KHz5
, Reverse HDRC data 25MHz6, TV: a :/ 50-88MHz
108-450MHz 7, FM audio 88-188-1
08 Forward II D Contains RC Data) 8, Forward Data 104M) Iz It will be understood that the frequencies shown in Table A are for illustration purposes only and that other frequencies may be used if required. For convenience, the television signal and FM audio signal (items 6 and 7 of Table A) sent over cable network 14 are collectively referred to hereinafter as the CATV signal.

Although cable network 14 has only one feeder cable in the embodiment shown in FIG. , two feeder cables may be used.1 For example, if two cables are provided, elements such as 24, 30, 32, 50 and 52 may be substantially connected to act on the second cable. Split into two. Each subscriber unit receives a CATV input signal from each cable. To select between the two cables, each subscriber unit is also equipped with a switch controlled by the digital unit 55 for switching between the two supply cable signals. This will be explained in detail below for subscriber units. In the case of a multi-cable system, the FM audio signal, reverse HDRC signal, forward data and reverse data signals are preferably transmitted by only one cable, referred to as the main cable, comprising other cable associated equipment. It can be simplified to some extent. Therefore, elements such as 34, 36, 54, 55, 56, and 60 do not need to be duplicated or significantly modified to form a multi-cable system.

It is also conceivable that each subscriber has two or more television receivers 90. Such additional television receivers can be attached to one subscriber processing unit, in which case all television receivers receive the same television signal. Alternatively, such additional television receiver is subjected to the action of a second subscriber processing unit,
It may also be arranged for a subscriber to select and receive two separate television channels simultaneously. If a subscriber has two subscriber processing units, both subscriber processing units can be connected to one drop cable. In this case, one subscriber processing unit is configured as an rmaster'' subscriber processing unit and the other as a ``slave'' subscriber processing unit. In the external control unit, a subscriber with master and slave subscriber processing units is serviced by two subscriber units. Each subscriber unit is
combined into separate subscriber processing units. The signals from the N subscriber units are multiplexed onto one drop cable. The television signal from the first or "primary" subscriber unit is converted by the subscriber unit to a first or lower drop cable channel and provided to the drop cable. the other, i.e.
The television signal from the secondary subscriber unit is
ie converted into a high drop cable channel and fed into a drop cable. Associated with each subscriber processing unit is a television set.

Each one is tuned to one of the two drop cable channels.

Each subscriber thus has at least one main subscriber unit associated with a master subscriber processing unit in the external control unit. If the subscriber has two subscriber processing units, the external control unit also has a secondary subscriber unit associated with the slave subscriber processing unit. In any case, in the particular embodiment shown here, the total number of subscriber units that can be included in the external control unit is six.

If it is necessary to add more subscribers to the location of the external control unit operating at full capacity, a second or "slave" external control unit containing six additional subscriber units can be added to the above. It can be connected via lead 58 to the split-combining network 52 of a "master" external control unit as described above. In this way, subscribers can be added without the need for interrupting the insertion of additional signal connection devices 50 into the cable network 14.

2. Subscriber Unit FIG. 2 shows in detail a typical subscriber unit SUI. Cable network signals from the zero split-to-combine network 52 (FIG. 1) are connected to the input terminals and any switching device 102. The signal is then sent to a general converter tuner 100. If the system has two cables instead of one cable as shown in Figure 1, each subscriber unit has two input terminals connected to each of the two cables. have Switching device 11
02 is 1 Tateishi Electric Co., Ltd. (OMRON), Tokyo, Japan
includes a common RF switching relay, such as part number G4Y-152P available from
00. Switching device 102 controls one or the other C by a common transistor switch (part of switching device 21f 102) in response to the state of the Q3 output appearing on bin 7 of common address latch 140.
Controlled to select signals from the ATV feeder cable.

Converter tuner 100 and general frequency synthesizer 10
4, crystal 106, capacitor 108゜110.112
．． 114.116.118, 120, resistance 122.12
4.126.128 and a circuit including transistors 130.132 select the portion of the cable television signal that the subscriber wishes to receive, and this signal portion is to which the subscriber's television receiver 90 is tuned. channel television signal and this signal is applied via a conventional FM adder 180, directional coupler 182 and capacitor 184 to the drop cable output terminal of the subscriber unit. In one embodiment shown herein, converter tuner 100 is part number CvA213A (Channel 3) or CVA215 available from Toshiba Corporation of Tokyo, Japan (hereinafter referred to as Toshiba).
A (Channel 5) or equivalent, which converts the CATV signal to the same or other channel or frequency.The frequency synthesizer 104 is Toshiba part number TD6352P or equivalent. .

The converter circuit operates as follows: The zero frequency synthesizer 104 outputs a 10-bit main channel conversion coefficient (MCCC) and a 5-bit "swallow" conversion coefficient (SCC) via its data input leads. receive. The bits of these two coefficients, collectively referred to as the main-swallow (MS) coefficients, are shifted into frequency synthesizer 104 at a clock rate established by its clock input. All bits of MS coefficients are passed to frequency synthesizer 1
When shifted to 04, these are 0 then 1 latched into the combiner in response to a signal sent to the load input terminal.
Frequency synthesizer 104 uses the MS coefficients in a known manner to determine (1) the voltage-controlled local oscillator (LOG) of converter tuner 100;

(2) perform a phase detection comparison of this reduced LOG, OSC, signal frequency with a reference oscillator (OSC,) signal frequency provided in part by crystal 106, and ( 3) 0 that generates an error signal on the phase detection output (P/D 0UT) terminal
The error signal generated by frequency synthesizer 104 is
It is used to control the voltage controlled oscillator of the converter tuner 100, from which the demodulated signal frequency required to convert the desired cable channel to the channel to which the subscriber's television receiver 90 is tuned is derived. Allow it to occur.

Addressable latch 140, which is a Toshiba part number TC40H259 or equivalent device, receives control and data signals from digital unit 55, stores this data, and outputs it to frequency synthesizer 104. In particular, addressable latch 140 receives data via its data input leads and processes this data based on function control signals sent to its A, B, and C input leads. The addressable latches of a particular subscriber unit are selected and enabled by appropriate signals applied to the not enable (NEA) input terminal. (
In general, the logical polarities and signal names of the signals shown in the accompanying drawings are as follows:
Ignored here. Thus, for example, although the signal appearing on pin 14 of addressable latch 140 is actually a negative enable signal, this signal is referred to herein as function name rNE, regardless of its logical polarity.
) Resistors 142-147, designated AJ, are pull-up resistors typically associated with selected inputs and outputs of addressable latch 140.

Addressable latch 140 also monitors whether the subscriber is providing the necessary shared AC power to operate the external control unit. This function is performed in response to a signal applied to the clear (CL) input terminal of addressable latch 140. Addressable latch 140 if the subscriber is not supplying AC power to the external control unit via its drop cable.
(7) Q4 output amount is resistor 150-152, transistor 153-155, diode 156, inductor 1
58 and capacitor 159 to cut off power to the converter tuner 100. This prevents subscribers who are not supplying AC power to the external control unit from receiving television signals from the external control unit. The Q5 output of addressable latch 140 also indicates whether the subscriber is providing AC power. This Q5 output amount is sent to the power detection output terminal of the subscriber unit, and is sent to the digital unit 55.
used by

Each main subscriber unit, eg, SUI, has a power supply section that includes a filter inductor 160, diodes 161-163, capacitors 164-167, and resistors 168-169. Inductor 160 has VLF and C
Block ATV signals. Diodes 161 and 162 generate half-wave rectified power signals (+ and -), respectively, from the 60 volt or less AC power signal of the drop cable.

These tens and - signals are connected and summed with other tens and - signals from other subscribers and subscriber units (i.e., 5U2-5U6) of the external control unit, respectively. The summed power signal is then sent to one circuit element 163 and 167 which is then sent to a common electric circuit 60, which will be described in detail below.
-169 constitutes another half-wave rectifier circuit, which produces a DC output signal (clamped to about +5V by diode 157) as long as the subscriber in question supplies AC power via the drop cable. This DC output signal is routed through voltage divider resistors 170-171 to the CL input terminal of addressable latch 140 for purposes described below.

DC outputs generated by elements 163 and 167-169 if a secondary subscriber unit (e.g. 5U2) is associated with the SUl and the subscriber can select and receive two multiplexed channels via a drop cable. The signal is also sent to the secondary subscriber unit via a resistor 172 on the primary subscriber unit and a jumper 173 on the secondary subscriber unit. Jumper 173 is connected entirely to the secondary subscriber unit only. Power supply element 160-
169 is removed from the secondary subscriber unit, as is capacitor 184. Further, in the sub-subscriber unit, terminals corresponding to the drop cable terminals in FIG. 2 are connected to the FM input and reverse direction HDRC output terminals of the main subscriber unit.

The secondary subscriber unit then selects one television channel, adds the FM signal to the first television channel signal, and transmits the resulting signal to the F of the primary subscriber unit.
M input and reverse HDRC output terminal. The primary subscriber unit selects the second television channel, adds this signal to the signal received from the secondary subscriber unit, and supplies the resulting signal to the subscriber's drop cable.

In this way, each subscriber can receive two television channels multiplexed onto a single drop cable. As mentioned above, each subscriber's television set is tuned to view one or the other of the two channels of the drop cable. Other differences between primary subscriber units and secondary subscriber units are:

(1) the use of separate local oscillator frequencies so that the primary and secondary subscriber units output selected cable channels to separate drop cable channels; and (2) redundant VLF input/output. , etc. have been removed from the secondary subscriber unit.

Other elements included in the subscriber unit are (1) +27v
An inductor 190 to prevent high frequency signals from entering the power supply line, and a capacitor 192 and a resistor 1 to remove high frequency ripples from the +27V power supply line.
94; and (2) a VLF input/
Capacitor 19 connected between the output lead and ground
6. Directional coupler 182 transmits VLF signals in both directions between the drop cable and the VLF input/output terminal.

(2) Analog unit As shown in FIG. 3, the analog unit 54 includes a bandpass filter 200 for extracting the FM audio (approximately 88-108 MHz) signal and forward data (104 MHz±100 KHz) signal from the cable signal. ing. The FM signal is passed through the input/output coupling network 202 to the FM small output and reverse direction HDR of the analog unit 54.
Sent to the C input terminal. Each FM of analog unit 54
The output and reverse human HDRC terminals are connected to the FM input and reverse HDRC output terminals of each subscriber unit.

Input/output coupling network 2o2. The band pass filter 204 and the low pass filter 206 connect the FM low output and reverse direction manual HDRC terminal to the cable signal terminal.
Transmits an RC signal (25MHz±0.5MHz). Accordingly, filters 204 and 206 pass the reverse HDRC signals to subscriber buildings 5UB1.5UB2. etc. (Fig. 1) through the cable network 14 through the external control unit.
This creates a data signal path for direct communication between the subscriber and the head end 12 via the cable network 14. However,
Filters 204 and 206 prevent other signals from being sent directly to cable network 14 from subscriber and drop cables. In particular, filters 204 and 2
06 prevents signals such as citizen band or other two-way radio signals from entering the cable network 14 and interfering with or degrading the characteristics of reverse data signals sent from the external control unit to the head end 12. to prevent In contrast, traditional two-way cable television systems suffer from such interference due to various points such as poor or loose drop cable connections, dirty or corroded connections, and even cracks in the cable shield. Signals will typically be featured. Therefore, in the CATV system of the present invention, HDRC channels and elements 204 and 206
The use of a cable network 14 improves reliability between the subscriber and the head end 12 by isolating the cable network 14 and the reverse data sent therefrom from interfering signals picked up by multiple drop cable connections. Direct, high-speed, two-way communication is possible.

A general bandpass filter 210 extracts a forward data signal from the output signal of the bandpass filter 200.
The forward data output signal of the bandpass filter 210 is
Sent to Mixa 212.

It is mixed with the 108.5 MHz output signal of local oscillator 214. The resulting 4.5 MHz output signal is amplified by a general intermediate frequency amplifier 216 and sent to a general detector 220. The detector 220 converts a frequency modulated (FM) forward data signal to a baseband forward data signal, which is transmitted to the analog unit 54.
is sent to the forward direction data output terminal of the digital unit 5.
5.

■One communication unit 56 is shown in detail in FIG. The communication unit 56 is controlled by the digital unit 55 and includes (1) communication of reverse data from the external control unit to the CCC of the head/processor board 12, and (2) communication of the external rrIJ.
Facilitates communication of VLF data to and from each subscriber processing unit associated with the control unit.

To communicate information from the external control unit to the head end 12, the communication unit 56 includes a reverse channel selector 300, a conventional modulator 330, and a conventional bandpass filter 332. Channel selector 300, upon command from digital unit 55, selects one of four available reverse channels for communicating external control unit reverse data to head end 12. 2-bit reverse channel selection signals (REV, CH, A and REV, CH.

B) is a digital unit 55 and a general binary decoder 3
Sent to 02. The combination of bits appearing at the A and B inputs of decoder 302 (i.e., oo.

Of, 10 or 11), the decoder 3°2 of 4
One of the two outputs will be at a low level and all other outputs will be at a high level. The outputs of the decoders 302 are each 4
Two crystal controlled oscillators 304, 306, 308 and 310
is connected to each of the four oscillators to activate one of these four oscillators. Each oscillator 304, 306, 308 and 310
are tuned to oscillate at separate frequencies corresponding to one of the four channel frequencies available for reverse data communication. In the embodiment shown, the oscillator 304.3
06.308 and 310 are each 19.126MHz
, 19.375MHz, 19°625MHz and 19.
Operates at 875MHz.

Of course, it will be apparent that other frequencies and other numbers of reverse channels may be used if desired.

The output of the particular oscillator selected by decoder 302 is sent as a carrier frequency to modulator 330 and modulated by the reverse data to be sent to head end 12. Modulator 330 is a general modulator for modulating a digital signal onto an analog carrier. In certain embodiments.

Modulator 330 uses binary phase shift keying (BPSK).
A modulator manufactured by, for example, Motorola Corporation of Phoenix, Alisina, USA.

Part number MC1 available from Motorola
It is 496. Data is modulated to be sent over each reverse channel at a data rate of 50 Kbps.

Further, the channel selector 300 is a general logic circuit 30.
5 (e.g., comprised of common Nord and Nant gates), the circuitry receives digital reverse data from the digital unit 55 and allows it to be transmitted to the head end 12; It receives a request to send (RTS) signal from the digital unit 55 and supplies a clear to send (CTS) signal to the digital unit 55. When digital unit 55 is not transmitting data to head end 12, digital unit 55 maintains the RTS lead to logic circuit 305 in a logic "0" state. This causes the logic circuit 305 to control the current limiting resistor 3
07 to transistor 309 to short the outputs of oscillators 1 304, 308, 308 and 310 to ground and prevent carriers from being sent to modulator 330. Additionally, logic circuit 305 (1) maintains the CTS lead in a logic "1" state to inform digital unit S5 that data transmission is not cleared;
(2) disabling transmission of data signals to modulator 330; When the digital unit 55 intends to send data to the head end 12, it raises the level of the RTS read.

This causes the logic circuit 305 to, after a short delay, (1
) removing the signal from transistor 309 so that the carrier signal can be sent to modulator 330;
Set the logic state of the read to "0" to inform the digital unit 55 that the data transmission is cleared, and (
3) Enable the data signal to be transmitted to the modulator 330. Digital signal 1-55 indicates that the CTS lead is logic “0”.
” data can only be sent while in this state.

Modulator 330 modulates the carrier signal appearing on its carrier input line with the reverse data appearing on its data input line. The output of modulator 330 is a modulated signal with a selected one of four carrier frequencies that is sent to bandpass filter 332. The bandpass filter 332 has a passband of I MHz centered around 19.5MHz. Bandpass filter 3
The output of 32 is the reverse channel output, which is
to split-combiner network 52 (FIG. 1).

It is sent to head end 12 via cable network 14 .

External control unit and associated each subscriber 5U
B1.5UB2, etc., the communication unit 56 connects the subscriber address lines A, B1.5UB2, etc.
Based on the binary code appearing at B and C the first input/
A bidirectional multiplexer 350 is included to connect the output line to any one of the plurality of second input/output lines.

Subscriber address lines A, B and C are connected to digital unit 55 so that digital unit 55
can selectively connect any one of the plurality of second input/output lines to the first input/output line. In the preferred embodiment, multiplexer 350 is a 1-to-8 multiplexer, such as Toshiba part number TC40518P, which has eight secondary input/output lines, only six of which are used. (one for each of up to six subscriber units).

Each of the second input/output lines is connected to each subscriber unit S.
U1. SU2, etc. (see Figure 1) (7) Connected to the VLF input/output terminal. By applying various code combinations to address lines A, B and C (i.e. 000
, OOl, 010.011.100 or 101), the digital unit 55 is.

To allow certain subscribers to communicate with external control units,
Specific drop cables can be selected.

A multiplexer 35 for receiving communications from subscribers.
0 first power/output line is a DC blocking capacitor 33
6 to the input of a very low frequency (VLF) demodulator 340. The VLF demodulator 340 receives VLF modulated analog signals from the subscriber processing unit at a data rate of 1200 bps (or other convenient rate), demodulates these signals, and processes them in the digital unit 55. Forms serial digital data for.

In one embodiment, the VLF signal received from the subscriber processing unit has a carrier frequency of 468 KHz.
is an on/off amplitude shift keying (ASK) modulation signal. A logical "1" (mark) is represented by 100% carrier, and a logical rOJ (space) is represented by 0% carrier. The demodulator 340 is a general parallel-tuned LC
circuit 342, which has a frequency 46 at its input.
The output of one circuit 342, which is tuned to produce an output in response to receiving a signal of 8 KH2, is also 46
Surface acoustic wave (SAW) filter 34 tuned to 8KHz
Sent to 4. The output of this SAW filter 344 is connected to a general amplifier 346, which generates mark and space data outputs in response to the presence or absence of carrier. This data output is sent to digital unit 55 and processed as data received from the subscriber processing unit.

In order to communicate from the external control unit to the subscriber processing unit, data from the digital unit 55 is transferred to the VLF.
In one embodiment, the VLF modulator 320 is connected to the digital unit 55.
to form an on/off ASK analog VLF signal with a carrier frequency of 430 KHz. Data from digital unit 5S turns transistor 327 on and off (via current limiting resistor 328). Transistor 327 then controls the on and off operation of FET transistor switch 324 via resistors 325 and 326. A 430 KHz carrier signal generated by a common crystal controlled oscillator 322 is sent to the base of a transistor 360, which indicates that the carrier signal appearing at its collector is 1806 kHz relative to the carrier signal appearing at its emitter.
Connected to be shifted. The collector carrier signal is turned on and off by transistor switch 324 based on the VLF data to be sent to the subscriber processing unit. This switched carrier signal is.

It is routed through resistor 334 to a first power/output line of multiplexer 350 for transmission to one of a plurality of subscriber processing units. The continuous carrier signal appearing at the emitter of transistor 360 is sent to all second input/output lines of multiplexer 350 via transistor 370 and resistors 381-386. In this way, all second power/output lines of multiplexer 350 are fed a constant 430 KHz carrier, but the carrier appearing on one of these lines is connected to transistor switch 32.
This is not the case when the signal is canceled by the carrier switched by 4.

(2) Digital unit As shown in FIG. 5, the digital unit 55 is composed of two main parts. These are (1) a signal processing section 55a (FIGS. 5a to 5f) and (2) a memory section 55b (FIGS. 5g to 51). These two parts of the digital unit 55 are interconnected by terminals represented by rectangles numbered 01-40. For example, the terminal numbered 01 in Figure 5f corresponds to the corresponding terminal in Figure 5g. Connected to the numbered terminal.

The digital unit 55 includes a general purpose synchronous or asynchronous receiver/transmitter (USART) 400;
This is, for example, part number 8274 available from Intel Corporation (hereinafter referred to as Intel) of Santa Clara, California, USA. The USART 400 converts the HDLC format serial application data received from the head end 12 into parallel data for processing by other parts of the digital unit 55. Also, USART4
'OO converts parallel reverse data generated by other elements of the digital unit into serial data in HDLC format for transmission back to the head end 12. US
How does ART400 work?

Fifth, facilitated by a gate array 402, shown in detail in Figures
Non-return-to-zero inversion sent from 2 to forward data read (
The gate array 402 performs various functions such as converting forward data (NRZI) to non-return-to-zero (NRZ) r-receive data on the RXD lead, and converts NRZ "transmit" data on the TXD lead to reverse data read. NRZ
I Convert to reverse direction data.

The USART 400 and gate array 402 handle interrupts (
INT) read, clock (CLK) read, RXC
Read, TXC read, read (RD) read,
Also interconnected by write (WR) read and reset (RES) leads. INT signal is USA
It is generated by RT 400, inverted by gate array 402, and sent to the INTO terminal of microprocessor 420. This signal is used to inform microprocessor 420 that an event of interest to USART 400 has occurred (eg, a character has been received or transmitted via a forward or reverse data read). The CLK3 output signal of gate array 402 is derived from the CLKOUT output signal of microprocessor 420.

Specifically, the 6 MHz CLKOUT signal is divided by two by gate array 402 and a 3 MHz CLK3 output signal is generated and sent to USART 400. The RXC output signal of gate array 402 is a clock signal derived by gate array 402 from the NRZI forward data signal. The TXC input signal of gate array 402 is a clock signal generated by microprocessor 420, which controls the data rate at which reverse data is sent back to head end 12. RD and W
The R times signal source is the microprocessor 420.

These signals each enable other devices within digital unit 55 to output data for reading by microprocessor 420, or other devices within digital unit 55 may output data from microprocessor 420. to be entered. The ultimate source of the reset or RES signal is power detection circuit 480. The power detection input terminal of the digital unit 55 is connected to the reset output terminal of a common power supply unit 60 (FIG. 6).

Power detection circuit 480 generates an output signal that resets microprocessor 420 when power is restored after a power outage. Microprocessor 420.

A reset output signal is generated in response to the RES input signal, which is sent to the reset input terminal of gate array 402. The gate array 402 is USART400.
Microcomputer 450 and hexadecimal inversion buffer 4
An inverted reset signal is supplied to 65.

Gate array 402 is shown in detail in Figures 5-55. Fifth, in the figure, reference numeral 250 indicates a typical input buffer, reference numeral 252 indicates a typical AND gate, reference numeral 254 indicates a typical Nants gate, and reference numeral 256 indicates a typical Nants gate. Reference numeral 258 indicates a typical J-type flip-flop, reference numeral 260 indicates a typical OR gate, and reference numeral 262 indicates a typical output flip-flop. show. In figure 5s, reference number 264
Table B below shows the pin numbers of the gate array 102 shown in FIG.
It shows the correlation with the lead display used in the s-diagram.

艮l Fig. 5C Fifth ~5s5sλ flea beans
-Shinibentachijo I l
Nl 2 REST 3 lNlO 4lN3 5 1N4 6 lN5 7 lN6 8 lN7 9 lN8 10 lN9 11 lN11 12 1N12 13 +
--14 GND15
lN1316
0TIO170T9 18 0T819
0T720
0T621
0T522 0T
423 0T324
0T225
0TI26
0T1227
0T1128 VC
Furthermore, the lead labeled EX in Figures 5 to 53 is connected to the lead similarly labeled in Figures 5 to 53. For example, the output labeled EX4 in Figure 5m The lead is connected to the input lead labeled EX4 in the 51st factor. The detailed operation of the gate array circuit shown in FIGS. Dew.

USART 400 sends a request to send (RTS or DTRA)
has a lead by which the USART interrogates the communications unit 56 to see if it is ready to send reverse data to the head end 12 .

When the communication unit 56 is ready to transmit reverse data, it sends the appropriate signal to the USART 400 via a clear to send (CTS or CTSA) lead. USART 400 selects the reverse data channel to be used by signals on Reverse Data Channel Selection A and B (RTSA and RTSB) leads, which are also connected to communication unit 56 .

The pull-up resistor network 404-407 connects the +5v power supply circuit 414 with CTS, RTSA, RTSB, RTS,
Connected in a conventional manner between interrupts, forward data and reverse reads.

Also connected to the TXDB and RXDB leads (not used). Power supply circuit 414 is generally configured to provide noise protection for the +5v power signal used through digital unit 55. V of USART400
The CC terminal is connected to +5 in parallel with capacitors 408 and 409.
V power supply 414 is also commonly connected. Gate array 4
Similarly, the VCC terminal of 02 is connected to capacitors 410 and 411.
is connected in parallel to the +5V power supply. The 5YNCA terminal of USART 400 is clamped to the +5V power supply via resistor 412. USART400 PRl, CDA and G
ROUND (GND) With lead.

The GROUND (GND) leads of gate array 402 are all grounded.

USART 400 provides parallel forward data to the data bus of digital unit 55 via terminal Do-D7. Also, the USART400 connects the data bus to the terminal Do-
Receives parallel reverse direction data via D7. The data bus includes USART 400, microprocessor 420, latches 430 and 432, and multiplexers 440 and 442.
, microcomputer 450 and memory unit 47
5. Distribute the data among 5. Pull-up resistor network 4
13 is connected in a conventional manner between the +5V power supply and the data bus lead.

Microprocessor 420, which may be a conventional microprocessor such as an Intel part number 80186, is responsible for (1) communicating with head end 12, (2) processing subscriber requests (e.g., channel selection), and (3) microcomputer processing. 450. In addition to connecting to the data bus, microprocessor 420
DRQI, INTAO, DRQOlAl, A2, PCS
USART via O, T10UT and TOOUT leads
Communicate with 400. When USART 400 is to read data directly from memory portion 55b of digital unit 55, it requests direct memory access (DMA) for reading by providing a DRQI signal to microprocessor 420. microprocessor 42
0 is determined by the INTAO output signal as described above.
The reception of the INTO signal from the RT 400 via the gate array 402 is confirmed. When USART 400 is to write data directly to memory portion 55b of digital unit 55, it requests direct memory access (DMA) for writing by providing a DRQO signal to microprocessor 420. microprocessor 420
The A1 output signal of the U
Sent to SART400. microprocessor 420
The A2 output signal of is the USA selected by the A1 signal.
Two register formats of the register set in RT (
That is, it is sent to either control C or data D). The PCSO (programmable chip select 0) output signal of microprocessor 420 is used to select USART 400 to read data (RD) or write data (WR) to microprocessor 420. TOOUT of microprocessor 420
The output signal is a timer signal that controls the rate at which forward and reverse data is transmitted.

The Tl0UT output signal of microprocessor 420 is T
Similar to the OOUT output signal, but controls the data rate of unused channels TXDB/RXDB.

Also, the microprocessor 420 has its T.

OUT, PCS2, PC34, BHE, INTOLRE
SET, CLOCK 0UT (C:LKOUT), R
It communicates with the gate array 402 via the EAD (RD) and WRITE (WT) leads. microprocessor 4
The TOOUT output signal of 20 is as described above. PC82 and PC34 (programmable chip selections 2 and 4) of microprocessor 420 are
It is similar to a signal.

The BHE (byte high enable) output signal of microprocessor 420 enables the 16-bit data bus to be used as an 8-bit data bus.

The INTO input signal of microprocessor 420 is
ART 400 and gate array 402 are described above. Microprocessor 420 RESET, CLK
The OUT, RD and WR output signals were also described above.

Microprocessor 420 provides data and address signal information to the data bus, and A
Such information is received via DO-AD15 read. Microprocessor 420 communicates directly with microcomputer 450 via INTI, INT3 and PC8L leads. Microprocessor 420 is UPPE
RCHIP 5ELECT (UO3), MIDDL
E CHIP 5ELECT (MC5O) and L
Provides yet another control signal to the memory unit 475 via the OVERCHIP 5ELECT (LC5) read. The operating frequency of microprocessor 420 is established in the conventional manner by a circuit including crystal 421 and capacitors 422 and 423. VCC, TOIN, TI
IN, 5RDY and ARDY leads are capacitor 4
24 and 425 in parallel to a +5V power supply. T.E.
ST, GROUND (GND), NMI and HOL
DIJ-D is grounded. As mentioned above, the RES@ child of the microprocessor 420 has a power detection circuit (
(including resistors 481-486, inductor 487, transistors 488-489, Zener diode 490, diode 491, and capacitor 492) to the power detection input terminal of digital unit 55. This power detection terminal is connected to the reset output terminal of the common power supply 60, and is used to detect a power outage of the AC power supply. When AC power is restored after a power outage, power detection circuit 480 holds processor 420 in a reset state until sufficient time has elapsed for the microprocessor to properly reinitialize itself. Therefore, the output signal of power detection circuit 480 is connected to the reset (RES) terminal of microprocessor 420 in parallel with capacitor 426.

Latches 430 and 432 are connected to microprocessor 420.
is used to store address signal information generated by the terminals ADO-AD15.

Associated data signals are transmitted or received via these same microprocessor terminals.

The IQ-8Q output leads of latches 430 and 432 together constitute an address bus that is connected to memory unit 475. Six latches 430 and 432 are generated by microprocessor 420 and It is enabled by an address latch enable (ALE) signal sent to the G input terminal. A voltage (+5 V) is applied to the VCC input terminal of each latch 430 and 432 in parallel with capacitors 434-436. The QC terminals of both latches are grounded.

Multiplexers 440 and 442 serve as an interface between 16 manually positionable switches 444 that address external control units, and microprocessor 420 transfers the information represented by these switches 444 into two successive 8-bit bytes. It can be read as A signal (SEL) selecting multiplexers 440 and 442 is sent from latch 432. These multiplexers connect their O
It is advanced or stepped by a signal sent to the C terminal. A voltage (+5V) is supplied to the VCC terminals of multiplexers 440 and 442 in parallel with capacitors 445-447. Pull-up resistor circuit [448-449 is
It is typically connected between the +5v power supply and the data input lead of the multiplexer.

Microcomputer 450, which is a general microcomputer such as Intel part number 8472, is (1
) control communication with the subscriber via the drop cable; (2) control the tuner/converter within the subscriber unit; and (3) communicate with the microprocessor 420. microcomputer 4
50 is connected to the data bus via its Do-07 lead. VDD of microcomputer 450.

VCC and SS leads are capacitors 451 and 542
is connected in parallel to the +5V power supply. The AO leads are connected to the SEL input terminals of multiplexers 440 and 442. P25, P24 and CS leads are connected directly to microprocessor 420 as described above. RESE
T, WRITE (WR), READ (RD), XTA
L2, XTALL and T1 leads are connected to gate array 40
Connected to 2. Also, the RD read is from memory unit 5.
5 b d is also connected. The signals on the XTAL1 and XTAL2 leads determine the operating frequency of the microcomputer 450. A pull up resistor network 453 is connected between these leads and the +5v power supply.

P2O-P23 and PR of microcomputer 450
The OG terminal is connected to a common input/output spanner 454, which is Intel part number TMP82C43P.

This expander 454 allows a small number of input/output terminals of the microcomputer to be connected to a larger number of input/output leads. Microcomputer 450 E
The A and vSS leads are grounded. In this configuration, the P17 lead of the microcomputer 45'O is connected to the +5■ power supply via the pull-up resistor 455.
Grounded via manual switch 456.

Microcomputer 450 receives VLF data from communication unit 56 via its TO read. P16
Lead is not used, six subscriber selection signals are generated by microcomputer 450, and lead PIO
- Sent to P15. Each of these signals is sent to each of the six subscriber units of this external control unit to select one or more subscriber units to be responsive to the data and function selection signals described above. Read TO and PIO-PI3 signals are general buffer and pull signals.
Through up resistor network 457, this network is also connected to the +5V power supply.

A +5V power supply is connected to input/output spanner 454 in parallel with capacitors 458 and 459. Chip select (CS) and ground (GND) leads are grounded. The signal on lead P43 is sent to the microcomputer 45.
For example, this data signal is the MS coefficient used by the subscriber unit as described above for the subscriber unit. Lead P40-P
Signals 42 are three function selection signals,
These are sent to the subscriber unit to control the processing of the data signals. P2O-P63, P2O and P
The 71 lead signals are each six power detection signals generated by the subscriber unit as described above. As mentioned above, each of these signals indicates whether the subscriber in question is providing its share of the total power required for operation of the external control unit. The signal on the P53 lead is the VLF data signal to be sent from the external control unit via the communication unit 56 to the selected subscriber processing unit. The P2O-P52 lead signals are also sent to communications unit 56, and these signals are used to control multiplexer 350 to select the subscriber processing unit to transmit or receive VLF data. Lead P40-
P43, P2O-P53. P2O-P63 and P2O-
The P71 signal is sent to a common buffer and pull up or clamp resistor circuit l2I460.

Leads P72 and P73 are connected to manual switches 461 and 4.
They are each grounded through 62 and connected to the +5■ power supply through a pull-up resistor circuit 1463. Switches 461 and 462 allow the system's external control unit to group up to four different addressable banks.

The backup power supply 464 operates when the AC power supply is completely cut off, and operates to store important parts of the memory unit 55b.
That is, data included in the portion of the memory unit selected by the lower chip select (LC5) signal is prevented from being lost. The backup power supply is a common hex inverting buffer 465° resistor 466-469. capacitor 47
0-472, 6 buffer 465 with diode 473 and inductor 474 is Toshiba part number TC4.
0H368P or similar equipment. Backup power is actually derived from capacitor 471, which has a relatively large storage capacity.

While the AC power supply is on, the capacitor 471 is +5°7V.
It is charged from a power source through a circuit including elements 468, 469 and 472-474. During AC power outage (buffer 46
capacitor 471 provides +5v backup power to energize buffer 465 and generate the LCS signal, which is selected by the LSC signal. +5Vffi power is applied to the memory 22 bit 475 section.

Memory unit 55b includes two common 16-byte read-only memories (ROMs) 476 and 477 that store operational program instructions for microprocessor 420. R.O.
M476 and 477 are each Intel part number 27
128 or equivalent. memory unit 5
6b also includes six common 8-byte random access memories (RAM) 493-498, which store data necessary to control the external control unit. Each of RAM493-498.

Toshiba part number TC5565PL-15 or equivalent. The connections between the various elements of the memory unit 55b and other parts of the digital unit 55, as well as the connections between the elements of the memory unit, are done in a completely conventional manner and will be readily apparent to those skilled in the art. UO3, MC5O
The LC5 and LC5 signals extend the 16-bit address information so that more memory can be used than can be accessed with 16 bits alone. Upper bank select (BKU) and lower bank select (BKL) signals generated by gate array 402 can be used in conjunction with jumper circuitry 478 to vary the relative amounts of ROM and RAM as desired. The RAMs 495 and 496 are memory units that are powered by the backup power supply 464 in the event of a power outage of the AC power supply as described above.

■In order to reduce the amount of power that must be supplied by the operator of the shared CATV system, the power required to operate each external control unit is supplied from the subscriber operated by that external control unit. be done. This is accomplished by configuring each master subscriber processing unit to provide a 60 volt AC power signal to its associated drop cable. As mentioned above, the AC power signal from each subscriber is converted into a half-wave rectified DC power signal by each subscriber unit.

These two signals are added together to form a common power supply unit 6.
Sent to 0.

FIG. 6 shows the common power supply unit 60 in detail. As shown in FIG. 6, the combined power obtained from the subscriber units is sent to a filter/smoothing circuit 510. The filter/smoothing circuit 510 includes a plurality of filter capacitors 514 and 516 to further remove AC ripple from the input power. A pair of series inductors 512 are connected to the CATV
Or remove the VLF communication signal.

The output of filter/smoothing circuit 510 is a well-filtered but unregulated DC voltage. This DC voltage output is sent to the input of a general switching power supply 520. Switching power supply 520 includes a step-down transformer 522 that generates three alternating current signals as outputs. These AC power signals are passed through rectifier diodes 532
, 534 and 536, respectively. The outputs of these diodes 532, 534 and 536 are connected to capacitors 543, 545 and 547 and inductor 5.
42, 544 and 546. The outputs of the capacitor/inductor smoothing/filter circuits are sent as inputs to common voltage regulation circuits 530, 540, and 550, respectively. Voltage adjustment circuit 530, 540
and 550 are the voltages appearing at their inputs, respectively.

Adjust to DC voltage levels of 27 volts, 12 volts and 5 volts. Each of these output voltages is connected to an output capacitor 5
70, 572 and 574.

A fourth regulated output of 5.7 volts is connected to a series pass transistor 560, a diode 562 and a Zener diode 56.
It is obtained from a circuit consisting of 4. The output signal of inductor 546 is:

This reset signal is also used as a reset signal to indicate a power outage of the AC power supply.
It is sent to the power detection input terminal of 5.

The regulated DC output voltage of the common power supply 60 is used to energize the circuitry of the external control unit. Accordingly, +5V, +12V and +27V signals are sent from the common power supply 60 to each subscriber unit (FIG. 2), as well as to the analog unit 54 (FIG. 3) and communication unit 56.
(FIG. 4) and the digital unit 55 (FIG. 5).

In order for each subscriber unit to have an equal share of the power supply operating its associated external control unit, each subscriber unit, as described above, will not be able to receive AC power from its associated drop cable. It has a power detection circuit that turns off the unit.

■Single entry The ring unit subscriber processing unit (SPU) is located within the subscriber's building. Each subscriber processing unit handles (1) channel tuning requests and paid viewing requests;

(2) accept and transmit subscriber input requests such as parent-child control requests and other functions typically associated with television viewers to the external control unit; and (2) receive data and commands from the external control unit to the subscriber. It is designed to display information and control the on and off operation of the subscriber's television set. Additionally, each subscriber processing unit serves as a data entry terminal to accept viewer responses, telephone shopping, and other occasional two-way communications. FIG. 7 shows a typical master subscriber processing unit in detail.

As shown in FIG. 7, a typical master subscriber processing unit is connected to the subscriber's 120V AC power source via a plug 761. Transformer 762 steps down this power supply for use by the subscriber processing unit. A general rectifier and smoothing network 760 rectifies the AC power and provides it to a general voltage regulation circuit 764 . Voltage regulation circuit 764 provides as an output (+) all DC 11 voltages necessary to operate the circuits of the subscriber processing unit.

In addition to providing AC power to the rectifier/filter 760, transformer 762 outputs 60V, 60H2 AC power to the drop cable connecting the subscriber processing unit to its associated external control unit. Sent. To this end, transformer 762 includes a separate secondary winding connected to capacitor 761 and inductor 763. The inductor 763 is used for relatively high frequency CATV, VL
A high impedance is provided for F and reverse HDRC signals, but a low impedance is provided for a low AC power signal of one frequency. The AC power signal is taken from inductor 763 and sent to terminal 767 to which the drop cable is connected. Each subscriber thus supplies, via a master subscriber processing unit located in the subscriber's premises, its share of the total power required to operate the external control unit to which this subscriber processing unit is connected. If the subscriber processing unit of FIG. 7 is a slave subscriber processing unit, inductor 763 is removed so that only the master subscriber processing unit powers the drop cable.

The drop cable terminal 767 is also connected to one terminal of a general directional coupler 778 via a capacitor 765. The capacitor 765 provides a high impedance for a 60Hz AC power signal, but a high impedance for a 60Hz AC power signal (?:
Provides low impedance for ATV, VLF and reverse HDRC signals. Another terminal of the directional coupler 778 is connected via a combiner 779 to a terminal (TV), which includes the subscriber's television set 90 (FIG. 1), any FM audio receiving device, and any A forward HDRC utilization device is attached. In this way, the CATV signal (television signal, FM
0 combiner 779 sends the reverse HDRC signals to devices that use these signals.
Add DRC signal and feed to drop cable. In the preferred embodiment shown herein, the subscriber's television set, F
The M voice receiving device and the HDRC device are connected to the drop cable via a connection to the subscriber processing unit, but of course such devices can be connected to the subscriber processing unit by using common directional couplers and capacitors. It will be clear that it may be connected to a drop cable without being directly connected to. Thus, the present invention provides a subscriber with significant flexibility in being able to locate the subscriber processing unit, subscriber's television set, and other equipment at various locations within the subscriber's premises.

Directional coupler 77 connected to TV and FM audio terminals
The terminal 8 is also connected to the input of a general VLF demodulator 770. Demodulator 770 receives signals (including CATV and VLF communication signals) sent from an external control unit. As already mentioned for the embodiment of the external control unit, the VL from the external control unit to the subscriber processing unit
The F communication signal is ASK with a carrier frequency of 430KHz.
It is a modulated signal. This carrier signal is always on except when data is being transmitted. Demodulator 770 demodulates the VLF signal from the external control unit to the subscriber processing unit to generate serial digital data as output. This is accomplished in one embodiment by a parallel tuned LC circuit 776 tuned to 430 KHz. A general amplifier/filter circuit 774, which in one embodiment uses a surface acoustic wave (SAW) filter as a filter element, receives the output of one circuit 776 and receives a
It generates an output only when a KHz carrier is detected. The output from circuit 774 is sent to operational amplifier 772, which generates a high or low level output in response to the presence or absence of a signal from amplifier/filter 774, respectively. Thus, operational amplifier 772 produces a digital data output representing the information sent by the VLF signal from the external control unit to the subscriber processing unit.

The digital data output of demodulator 770 is sent to data input lines and interrupt input lines of general microcomputer 700. Microcomputer 700 is a suitable commercially available microprocessor or microcomputer, such as Toshiba part number TMP4740F, which is a 4-bit microcomputer with 4 bytes of onboard ROM and 256 bytes of onboard RAM memory. be. A list of objects and source code computer programs suitable for controlling the operation of this microcomputer 700 that are obvious to those skilled in the art include:
As shown in Reference Material 1 attached to the application.

The microcomputer 700 uses the data received from the external control unit to display a general 7-element display device 71.
Display information on 0. In one embodiment, the display device 710 includes, for example, two channels representing the television channels to which the subscriber unit of the external control unit is tuned.
Can display 0-decimal numbers. Microcomputer 700 drives display device 710 in a conventional manner by multiplexing display data onto a common seven line bus B1 and alternately enabling two return lines A and B. The resistance pack 712 is.

It includes seven resistors, each resistor being in series with a line of bus B1 to limit the current of one display device 710.

The microcomputer 700 also uses the data received from the external control unit to illuminate a so-called order event lamp. In one embodiment, the order event lamp is a conventional light emitting diode (LED) 7 connected to the microcomputer 700 via a current limiting resistor 792.
It is 90.

As discussed in more detail below, this order event light is used to notify subscribers that they are viewing programming for which they will be charged an additional fee.

Another circuit element controlled by microcomputer 700 is television power relay 791. The television power relay 791 is a normally open relay that controls the supply of 120V AC power to the power outlet 793 into which the television receiver 90 is inserted. This relay 791 is controlled on and off in response to commands from an external control unit.

Also connected to the microcomputer 700 is, for example, a keyboard 720 used by the subscriber when inputting a channel selection request.

In one embodiment, a keyboard 720.

This is a general membrane matrix keyboard with 4 columns and 4 rows.

A common bus B2 with eight lines connects the matrix outputs of the keyboard to the corresponding inputs of the microcomputer 700 via resistor packs 722. In addition to the keyboard 720, an optional remote control unit (RC:U
) allows the subscriber to remotely input data to the subscriber processing unit (FIG. 1). Such an RCU may be of any type and may or may not be hardwired; in one embodiment, the RCU may provide subscriber processing by transmitting coded infrared radiation. A common wireless device that communicates with the unit. In the subscriber processing unit,
A conventional remote control receiver 730 with an infrared sensitive photodiode receives these coded signals and converts them to serial digital data. This data is sent to the microcomputer 700. The microcomputer 700 uses the VLF modulator 74
0 to communicate the channels entered by the subscriber and other requests to the external control unit. Based on the digital data above, the current limiting resistor 78
Transistor 742 is turned on and off via 0
This transistor 742 then connects the resistor 743.7.
45. FET transistor 74 via 747 and 749
6 is turned on and off. FET)-Langistav 4
6 controls the output of the 468 KHz oscillator 744, which is always active, on and off to perform ASK modulation on the 468 KHz signal. SAW filter 748 performs bandpass limiting on the modulated output of modulator 740.
The output of 8 is connected to transistor 750 and resistors 752-75.
It is sent to an emitter follower circuit consisting of 5. Capacitor 751 blocks DC voltage. The output of the emitter follower circuit is sent to a terminal of a directional coupler 778 via a capacitor 757 and a resistor 756. The VLF modulated signal is
It is then routed from directional coupler 778 to a drop cable and via a communication channel from the subscriber processing unit to the external control unit to the external control unit.

To enable each of the plurality of subscriber processing units (i.e., a master subscriber processing unit and one or more slave subscriber processing units) connected to the drop cable, each subscriber processing unit has a It is given a unique address when it is installed in a person's building. This is done by placing the appropriate jumper wires on jumper block 782. jumper block 7
82 has two jumper connections, each of which has two jumper connections.
It represents one bit of a bit address. By suitably jumpering the terminals of jumper block 782, each subscriber processing unit attached to the external control unit can be assigned one of four separate addresses. Furthermore, based on whether switch 780 is open or closed, it identifies the subscriber processing unit as a master subscriber processing unit associated with the main subscriber unit of the external control unit, or
Serves to identify the external control unit as a slave subscriber processing unit associated with the secondary subscriber unit. Typically, the master subscriber processing unit is designated with binary address 00 in jumper block 782 and the slave subscriber processing unit is designated with address 01.10 or 11 in jumper block 782.

Communication between the external control unit and the associated subscriber processing unit is via separate transmit and receive channels;
This is done via a drop cable. As mentioned above,
The first channel, ie.

The channel from the external control unit to the subscriber processing unit is the LF channel with a carrier frequency of 468 KHz. Both channels transmit data at a rate of 1200 bps, although other suitable data rates may be used. . Each subscriber processing unit associated with the external control unit transmits data to the external control unit via a common channel from the subscriber processing unit to the external control unit. Similarly, the external control unit transmits data to each respective subscriber processing unit via a common channel from the external control unit to the subscriber processing unit.

2. Head End The elements 34 and 36 of the head end 12 are shown in detail in FIG. The forward and reverse data signals of cable network 14 are routed to combiner 8 by combiner 32.
The 0-to-0 combiner 800 sends the forward data signal from the modulator 810 of the modem 34 to the combiner 32 and provides the reverse data signal from the combiner 32 to the demodulator 840 of the modem.

The central control computer 36, which may be a conventional suitable computer such as an Intel 330 computer, includes a conventional main central processing unit (CPU) 880, a conventional main memory 882 . It is equipped with a general output buffer unit 884 and four general master cover sofa units 886-889. These elements 880, 882, 884 and 88
6-889 are commonly interconnected by a communications bus 890. Buffer units 884 and 886-889
unit 884, depending on the data rate and operating speed of unit 884.
and 886-889 functions can be combined into a small number of buffer units. Main CPU 880 includes or is connected to common input/output devices (not shown) used by an operator of the system to control the system.

Each of buffer units 884 and 886-889 is
It includes a general high level data link (HDLC) control section, a general CPU section and a general memory section. The HDLC control section of the output buffer unit 884 is controlled by the main CPU 88.
Parallel forward method data set by 0 to serial NR
Convert to ZI forward data signal. This forward data signal is.

General EIA R84 in modulator 810 of modem 34
22 interface device 812. This interface device 812 provides forward data signals to a general TTL buffer 814 . This TTL buffer 814 transfers forward data to the PIN diode switch 8.
Supply to 16.

This diode switch operates based on the data signal sent to 103.9. MHz oscillator 818 and 104.1MH
The frequency modulated forward data signal is frequency modulated by switching back and forth between the z oscillator 820 and the 1 surface acoustic wave bandpass filter 82.
2 is sent to 1, then sent to combiner 800, and is sent to combiner 3.
2 to the cable network 14.

The elements that receive, demodulate, and process the reverse data signal are described below.One frequency is 19.125 MH.
z, 19.375MHz, 19°625MHz and 19
．． Recall that there are four reverse data channels at 875 MHz and the reverse data is in the NRZI protocol, all these reverse data signals pass through a common bandpass filter 842 and a common preamplifier 844. sent after. The output signal of preamplifier 844 is sent to four similar demodulation circuit paths, one of which is shown in FIG.
Only one is shown. Each of these circuit paths demodulates the reverse data signal on each reverse data channel.

In each of the above circuit paths, the reverse data signal is
The mixer 850 determines that the signal frequency of the reverse data channel minus the local oscillation frequency is io, 7M.
a local oscillator 8 with a frequency selected to be Hz;
It is mixed with the output signal of 52. Therefore, mixer 850 shifts the reverse data channel signal to 10.7 MHz. The output signal of mixer 850 is sent to a bandpass filter 854, which has a 10°7 M
Remove all signals except the Hz modulation signal.

The output signal of bandpass filter 854 is sent to a conventional intermediate frequency (IF) amplifier 856. This IF amplifier 856 is facilitated by a general carrier detection device 858, which carrier detection device? ! , 10.7MH
When the z signal is detected, the request to send (RTS) output signal is sent to the general EIA R5422 interface device 86.
Supply to 6.

A typical Costas loop device 860 converts the 10.7 MHz data signal to a baseband data signal.

This is sent to interface device 866.

This baseband data signal is also sent to program logic array 862, which array combines this data signal with
Using the high frequency output signal of the oscillator 864, the NRZ
A clock signal pulse is generated during each bit interval of the I data signal. This clock signal is also sent to interface device 866.

Interface device 866 provides carrier detect signals, clock signals, and NRZI data signals to the input buffer devices 886-889.

The HDLC controller of this buffer unit converts the serial NRZI data into parallel data suitable for further processing by the central control computer 36.

The microprocessor 420 (hereinafter also referred to as "data processor") of the 6-' unit is responsible for controlling all operations of the external control unit, including the head end 12
communication with the CCC, initiation, execution and coordination of various operations within the external control unit, and communication with the subscriber processing unit.

The data processor is assisted in its functionality by a microcomputer 450 (hereinafter referred to as the "drop processor"). The drop processor is responsible for transmitting messages generated by the data processor to the subscriber processing unit and for transmitting a message generated by the subscriber processing unit to the data processor; The external control unit controls various functions associated with the subscriber unit based on commands from the data processor. The data processor and drop processor
The operation of communicating with the CCC of head end 12 and its subscriber processing unit to perform and control various functions of the external control unit will now be described.

The communication protocol between the external control unit and the associated subscriber processing unit includes channel selection and control from any of the multiple subscriber processing units (both master and slave) associated with up to six drop cables. ,
Paid viewing request.

It must be able to quickly detect and respond to requests issued by other subscribers. Furthermore, the communication protocol must be able to detect requests that occur rarely.

Communication access to the external control unit is provided by the digital unit 55 of the external control unit in order to quickly respond to and process requests of the subscriber processing unit originating from the subscriber.
is controlled using a two-level polling mechanism. The first level, termed "drop polling," has a subscriber processing unit that very quickly polls or senses each drop associated with the external control unit and requests processing (i.e., the external control unit (with information to be sent to) can be identified. Drop polling is relatively slow (in one embodiment,
1200 bps) without sending or receiving data over an external control unit/subscriber processing unit data link.

Once a particular drop has been identified by the external control unit as requesting processing, the external control unit will issue an "equipment A second level of polling, referred to as "polling", is used to differentiate between subscriber processing units, in this case using one communication link;
Specifically addresses each subscriber processing unit connected to the drop and determines which subscriber processing unit is requesting processing. The external control unit maintains in memory a map of each drop and a map of each device in each drop. The data in each map is in a predetermined order to optimize response time and to give priority to the constituent subscriber processing units.

Drop Polling Drop polling is controlled by a microcomputer 450 included in the digital unit 55 (FIG. 5e) of the external control unit and a multiplexer 350 included in the communication unit 56 (FIG. 4). When the subscriber processing unit requests processing (for example, when a subscriber enters a channel request into the subscriber processing unit's keyboard), the subscriber processing unit's microcomputer 700 sends the VLF modulator 740 to 468
A KHz carrier signal is sent to an external control unit.

This continuous carrier signal is called “cry J
Also referred to as a "processing request" signal.

In the external control unit, the microcomputer 4
50 is the multiplexer address lines A, B and C (
4) to the multiplexer 350 and the VLF modulator 320 and demodulator 340 of the external control unit.
is selectively connected to a particular one of the six drops. Once connected to the drop via the multiplexer 350, the digital unit 55 of the external control unit checks whether there is a carrier signal (processing request) on the drop.

The presence of a carrier signal on a drop and detected by the external control unit is interpreted by the external control unit as a request for processing by a subscriber processing unit connected to the drop. If no carrier signal is detected on the drop, the external control unit interprets that the subscriber processing unit connected to the drop has not issued a processing request. In this latter case, the external control unit selects (via multiplexer 350) another drop in the predetermined sequence and checks for the presence of a carrier in this drop. If the carrier is present, a subscriber processing unit attached to the drop has issued a processing request.

Note that a subscriber processing unit attached to multiple drops can issue a processing request simply by transmitting a carrier on the drop cable communication channel from the subscriber processing unit to the external control unit. The subscriber processing unit does not need to send data or special commands to the external control unit for processing and can perform very rapid polling. In order not to interfere with communications already taking place on the drop, each subscriber processing unit connected to the drop constantly monitors the channel from the external control unit to the subscriber processing unit for the presence of data. The subscriber processing unit activates the carrier and issues a processing request only after detecting a continuous mark state for a predetermined number (e.g., 12) of bit times on the channel from the external control unit to the subscriber processing unit. I can do it.

Device Polling A Device polling is also controlled by the microcomputer 450 of the external control unit.

As mentioned above, if more than one subscriber processing unit is attached to a drop in which a processing request is detected, the external control unit polls the subscriber processing units on the drop individually and determines which subscriber Polling of the device must be performed by the external control unit to determine whether the subscriber processing unit has requested communication with the external control unit, regardless of which subscriber processing unit on the drop first made the request for processing. This is done in an established predetermined order.

The external control unit starts polling the device by sending conditional polling commands to one selected drop. All subscriber processing units and other devices connected to one selected drop accept these commands. sensing and stopping operation (ie carrier transmission) on the link from the subscriber processing unit to the external control unit.

The particular subscriber processing unit being polled will respond to the external control unit with a single mark pit if it has not issued a processing request. If the polled subscriber processing unit is issuing a processing request,
This subscriber processing unit responds by sending confirmation information (space bit) after the data to the external control unit.

Communication of messages between the external control unit and the associated subscriber processing unit is asynchronous with uniform bit timing and non-uniform intermediate character timing. The link from the external control unit to the subscriber processing unit completely controls the data transfer on the link from the subscriber processing unit to the external control unit. Each character sent by the external control unit to the subscriber processing unit is accompanied by a 1-bit confirmation/no-acknowledgment (ACK/NAK).
) confirmed by the subscriber processing unit by handshake. This bit is also used in response to polling, as described above. Each character is preceded by at least one bit time of mark state. The first bit in which a character is started by a mark/space transition forming the start bit in the space state is the message framing bit, and then the eight data bits (R first transmitted low order bits).

followed by a parity bit and a mark state of at least 1 bit time indicating the end, the mark state of this end bit time is 1
It also serves as leading information for the next character.

Framing of Characters Framing of characters is performed by the subscriber processing unit.
After consecutive mark states for at least a predetermined number (e.g. 12) of bit times, the mark/mark constituting the start bit is
Continuation of space transitions.

is established by sensing in the link from the external control unit to the subscriber processing unit. If the subscriber processing unit loses character framing, the command will not be acknowledged until character framing is re-established by the external control unit. A given drop can be given a periodic opportunity to re-establish.

Message framing subscriber processing unit uses message characters (data)
How to decode the message is determined by the state (mark or space) of the message framing pit. The start of a message is indicated by the space state (logic 0) of the message framing pit. A logic 0 message framing pit means that the data field (8 bits) represents a command that must be interpreted by all subscriber processing units on the drop. On the other hand, if the message framing pit is in the marked state (logic 1), the data field is interpreted as containing information following the previous command.

Any number of message characters may occur between command bytes. Incorporating message framing pits adds 1711 overhead to each message character, but increases framing integrity and can increase throughput for long data streams. Without message framing pits, long data streams to and from the subscriber processing unit may be truncated or not transmitted. , since it is necessary for the external control unit to be able to rapidly poll and process up to six drops, possibly each having multiple subscriber processing units. By using message framing pits, an external control unit can perform drop polling or interpolate between character transfers to a particular subscriber processing unit on a particular drop. It may also serve other subscriber processing units above.

ACK/NAK and Polling: The bit time immediately following the answer parity pit is used as the AC:NAK window in the link from the subscriber processing unit to the external control unit. Each character sent by the external control unit.

During this ACK/NAKg it is acknowledged by the subscriber processing unit. This ACK/NAK window is also used to respond to polling in a special way.

The subscriber processing unit responds to the external control unit in the following manner during the ACK/NAK window. Upon receiving the start bit of the initial message, all subscriber processing units connected to the drop turn off the carrier on the link from the subscriber processing unit to the external control unit. Upon receiving a message framing bit, all subscriber processing units input data bits (representing commands) and check for the presence of their address if the bit is a space.

If the message framing bit is a mark, only subscriber processing units on already addressed drops input data bits.

Upon receiving the last data bit, the addressed subscriber processing unit turns on its carrier on the link from the subscriber processing unit to the external control unit. When receiving a parity bit.

If the parity pit indicates a transmission error, the subscriber processing unit keeps its carrier on during the next bit time as a NAK signal to the external control unit, the parity pit indicates proper transmission. If so, the subscriber processing unit turns off its carrier and keeps it off as an ACK signal to the external control unit during the primary bit time.

If the data is properly transmitted and polled, the polled subscriber processing unit, after receiving the parity pit, turns off its carrier by sending a start bit of the information that it must send to the external control unit. do.

Otherwise, the carrier is kept on during the ACK/NAK window. One bit time after receiving the parity pit (i.e., after the A(1, to/NAK window).

All subscriber processing units turn off their carriers and prepare for another transmission with the external control unit.

B.-'UNI-TO The communications from the Data Processor to the Drop Processor are in the form of various lengths representing commands to be executed by the Drop Processor. Execution of a data processor's commands by a drop processor typically follows a handshake sequence, which requires the drop processor to send a command response back to the data processor. This command response may be a single-byte acknowledgment, or it may be a multi-byte response if the data processor's command requires the return of data, but the data processor's command Therefore, if the drop processor needs to send a message to a device attached to the drop cable, no command response is required, as discussed below.

In addition to command responses, information is sent from the drop processor to the data processor without any commands being generated by the data processor. Such transfer occurs when a device attached to the drop cable sends a processing request to an external control unit, as described in more detail below. In such a case, the drop processor reads data from the device issuing the processing request and provides information as an extra data response to the data processor.

Table C below shows the data processor/drop processor communication commands used in one embodiment of the present invention. Commands marked with a circle are sent from the drop processor. Other commands are sent from the data processor.

1 iriyu 3shi” 辷U MENU) 堡-11 00
Reset Drop Processor 01 Power Detection and Read Bank Address 03 Change Tuner Frequency (Channel Selection) 04 Send Message to Attached Device 05 Turn Converter On/Off and Select Cable A or Cable B 07 Drop Pole Sequence Definition 08 Drop Pole Sequence Definition 84 Extra Data Responses from Attached Devices Briefly, the commands shown in Table C work as follows.

Command OO: This is a one-byte command message used by the data processor to reset the drop processor and initialize its registers and pointers. All polling effects are blocked. The Drop Processor acknowledges receipt of this command by sending a single command response byte equal to 00 back to the Data Processor.

Command 01: This is used by the data processor to send subscriber units SU1. This is a one-byte command message that causes the drop processor to read the state of the six power detection lines (POWERDET, FIG. 2) from SU2, etc., and the bank to which the address of the external control unit is specified. The response sent by the drop processor to this command is 2 bytes. 1st
The byte is an echo of the command byte (01). The second byte is a data byte that specifies the state of each power detection line and the bank address of the external control unit.

For each of the six subscriber unit power sense lines:
Corresponding bits 0-5 of the response byte are each set to 1 or O based on whether the drop cable is powered by the subscriber connected to that subscriber unit. Bits 6 and 7 of the response data byte.

Indicates which of the four banks the address of the external control unit is assigned to.

Command 03: This is a 4-byte command message used by the data processor to cause the drop processor to tune the six relevant subscriber units of the external control unit to the specified physical channel.

The first byte is a command byte (03), and the next is 3 bytes of data. The first byte specifies in bits 0-2 which of the six subscriber units should be tuned. The next two bytes specify the two MS numbers mentioned above, which are needed by the subscriber unit's tuner/converter circuitry to tune to a particular physical television channel. The drop processor sends a two-byte command response to the data processor when it receives a command that is an echo of the first two bytes of the command message.

Command 04: This command message (hereinafter referred to as “o4
``command'') is used by the data processor to cause the drop processor to send the addressed message to the device attached to the drop cable. In one embodiment, the apparatus includes:
It may be a subscriber processing unit with an address equal to 2.3.4 or 5, or it may be any other type of device that can be attached to a drop cable and communicate with an external control unit. , such other devices include, for example, medical monitoring devices, fire alarms, smoke alarms, burglar alarms, and the like.

Such other devices have addresses equal to 0.1.6 or 7.

The 04 command message to the drop processor contains at least four bytes as follows: (1) 1st byte; command code (04).

(2) Second byte; drop number (bits 0-2) and device address from O-7 (bits 1-3-7).

(3) Third byte: Number of bytes included in the message.

(4) Fourth byte: Device command, following the device command byte, there is one or more data bytes. A device command and data bytes constitute a message. The device command byte consists of a 3-bit device address (bits 0-2
) and a 5-bit function code (bits 3-7
).

Function codes are used to direct specific operations of the addressed device. The table below shows the function codes used to control the operation of a subscriber processing unit or device in one embodiment of the invention.

Read the internal state of 00 External response message Return to control unit.

01 Turns the order event lamp on or off.

02 Set the order event lamp to flash or non-flash mode.

03 Enable or disable data entry to the device.

04 Enable or disable data output from the device.

05 Turn the TV power relay on or off.

06　　　　　　　　　　Make the display blank.

07 Set the display device to flash or non-flash mode.

08 Display characters on the rightmost part of the display device.

09 04 Sends the number of characters specified by the byte count of the command message to the external control unit.

OA Displays characters in a designated area of the display device.

OB Conditional polling that identifies the device issuing the processing request. The device sends the data back.

For device messages that require the device to send a response back to the external control unit (e.g. in response to function code 00.09 or OB), the command response (r04 response) is dropped. from the processor back to the data processor. This response is 3
A response header of bytes followed by one or more data bytes. The response header consists of (1) the command response code (hex04) in the first byte, and (2
) in the second byte, an echo of the drop and device address originally sent by the data processor, and (3
) The third byte contains the number of bytes of data in the response message. Assuming there are no transmission errors, the response header is followed by one or more response data bytes.

For example, the data byte of an error-free o4 response to a one-condition poll identifies the key pressed by the subscriber. Or
In the case of an error-free 04 response to a status request message, the data byte specifies the following abuse status 1 by its bit settings: The device is a master or slave subscriber processing unit (bit 7), the order event light flashes (bit 5), the order event light is on (bit 4), the TV power relay is on (bit 3) ), the latest power up (bit 2
), is the latest key suppression (bit 1).

If a new character is available (bit O) and a transmission error occurs, the byte count will be OO. In this case, a single data byte follows the byte count and specifies the error code.

The error code may be 01 (indicating a transmission (parity) error from the external control unit to the device), 02 (indicating a transmission (parity) error from the device to the external control unit), or 03 (indicating an invalid device response). ), the error code is sent to the data processor only after five consecutive link transmission errors occur.

Command 05: This command is used by the data processor to turn a particular subscriber unit on or off.

In the case of a two-cable system, this would allow the subscriber unit to select either cable A or cable B. The command message contains two bytes. The first byte is the command code byte (hex05), the second byte (1) specifies the subscriber unit (bits 0-2), (2) specifies the selected cable (bit 6 specifies cable A or (3) 2 bytes specifying whether the subscriber unit is on or off (bit 7 is set to 0 or 1, respectively); Command responses are sent back to the data processor by the drop processor. The first byte is an echo of the command byte (05). The second byte contains the subscriber unit address contained in the command message, bits 0-
Included in 2.

Command 07: This command is used by the data processor to load the drop poll map into the drop processor and define the drop poll sequence.

This command message contains 5 bytes.

The first byte is a command code byte (hex.

7), bytes 2 to 4 define the drop bowling sequence. Each of these bytes is divided into two nibbles, 4 bits per nibble. The value of each nibble is set from O-5 to specify a particular drop in each nibble. Drops are polled sequentially in the order specified by the nibbles received by the drop processor from the data processor. The value of hexF in the nibble indicates the end of the polling map. If all nibbles contain hexF, drop polling is disabled. The fifth byte is 6
F is included in the upper nibble to indicate the end of the polling map for one drop. A one byte command response (07) is sent by the drop processor to the data processor forming an echo of the command code byte.

This command is used by the data processor to load the device polling map into the drop processor to define the device polling sequence.

This command message contains the first
byte is the command byte (hex08), the second
Part-time job.

Bits 0-2 specify drop. Part-time job 3 to 6
specifies a device address in each of the eight nibbles. The devices at a specified drop are polled sequentially in the order specified by the device address nibbles received by the drop processor from the data processor. The value of hexF in the nibble indicates the end of the device poll map. All inputs to the device polling map are he
If set to xF, device polling is disabled. The seventh byte contains F in its upper nibble, which indicates the end of the device polling map for eight devices. A two-byte command response is sent by the drop processor to the data processor, forming an echo of the first two bytes of the data processor's command message.

Command 84: This command (hereinafter referred to as "84 command")
) is sent from the drop processor to the data processor to indicate that the drop processor has received extra data from a device attached to the drop cable. This 84 command is a command used by the drop processor to send to the data processor data received from the device that issued the processing request to the external control unit (for example, the subscriber can inputting a channel selection request), this command message contains at least four bytes, the first byte being the command code (he
The second byte, containing the drop address (bits 0-2) and the device address (bits 3-7), identifies the particular drop and device issuing the extra data response. The third byte specifies the number of data bytes sent by the device.

Furthermore, the fourth byte is a data byte. If the byte count is 00, an error has occurred. In such cases, a further byte follows the data count byte and specifies the error code. Error code 01 indicates that the transmission from the external control unit to the subscriber processing unit (
Error code 02 indicates a transmission (parity) error from the subscriber processing unit to the external control unit.

C. Drop Processor Figures 9a-b are flowcharts of computer programs used in one embodiment of the invention to control the operation of the drop processor. A list of objects and source code computer programs for controlling the operation of the drop processor according to the flowcharts of FIGS. 9a-b, as will be readily understood by those skilled in the art, is provided in Reference No. 2 attached to the application. shows.

The program that controls the drop processor consists of a main routine (Figure 9a) and a timer interrupt routine (Figure 9b).
Each of these two routines operates independently of each other. The main routine is periodically interrupted in a conventional manner by a timer interrupt routine after a predetermined period of time determined by the expiration of the interrupt timer. The functions of the drop processor's main routine are to (1) receive data from the timer interrupt routine (e.g., a message from the subscriber processing unit to the external control unit) and send it to the data processor; and (2) receive data from the data processor. data to the timer interrupt routine and finally to the subscriber processing unit. The functions of the timer interrupt routine are to (1) perform drop and device polling, (2) communicate messages to and from the subscriber processing unit attached to the drop, and (3) communicate signals to and from the subscriber unit. It is something to do.

1. Main Routine As shown in FIG. 9a, the program flow of the main routine begins at step 901, where various buffers, counters, flags, and ports are initialized.

Also, in step 901, drop polling and device polling are initiated and register R5 (described in detail below) is set to three. Steps 902 and 903
Well then.

The address to jump to the timer interrupt routine is set and one interrupt timer is activated.

When the program flow reaches step 904, initialization ends. In step 904, the main routine queries the state of the input buffer full (IBF) flag. This flag is associated with the drop processor buffer that receives data sent from the data processor to the drop processor. This IBF flag is
Indicating that the input buffer is full, program flow continues to step 905, otherwise
If so, the program flow branches to step 906.

First, assuming the IBF buffer is not full, the program proceeds to step 906 where the drop processor checks the buffer (84 buffer) and the device attached to the drop receives extra data responses (i.e., 84 commands). Determine whether you have sent the . If so, the program proceeds to step 907 and sends an 84 command to the data processor. Otherwise, the program proceeds to step 908 and the drop processor determines whether the device sent an 04 response.

If no, the program proceeds to step 904 and checks the IBF flag again as described above.

If yes, the program proceeds to step 909 and sends a 04 response to the data processor. From step 909 (or from this step if the program has proceeded to step 907), the program proceeds to step 904.

In step 904, if the IBF flag indicates that the input buffer is currently full, the program proceeds to step 905 where the contents of the buffer are entered and the IBF flag is cleared. The process proceeds to step 910, where the drop processor determines what type of command (described above) was included in the message sent by the data processor. Based on the command, the program branches in one of three directions from step 910.

branch out

If command 00 (reset) is sent, program flow continues to step 920 where the drop processor outputs an OO command response message to the data processor via the associated output buffer. Flow proceeds to step 901 where the drop processor is reinitialized as described above.

In step 910, commands 00, 03.05.
If 07 or 08 is sent by the data processor, program flow proceeds to step 911 where the drop processor processes the particular command as described above.

Proceeding to step 912, the drop processor sends the appropriate command response to the data processor.

From step 912, the program flow continues to step 90.
Proceed to step 4.

Further, if it is determined in step 910 that the 04 command message was sent by the data processor, program flow branches to step 913. In step 913, the main routine interrogates a flag indicating the status (empty or full) of the "04 buffer" associated with the drop processor. This 04 buffer contains data to be sent by the drop processor to devices attached to the drop. 04
If the buffer is empty, the program executes step 914.
Otherwise, the program branches to step 915
Branch to.

When the program advances from step 913 to step 914 (ie, the 04 buffer is empty).

Step 914 sends the data received from the data processor to the 04 buffer. Program flow then proceeds to step 917 where register R5 is checked. If the contents of register R5 are not zero, the program branches to step 919 and the contents of register R5 is decremented by one. Otherwise, the program (
1) Proceeding to step 918, the contents of register R5 are initialized to the value 3 and incremented by one; and (2) Proceeding to step 919, the contents of register R5 are decremented by one. From step 919, the program flow is as follows:
Proceeding to step 904, the input buffer is checked again.

Now, referring to step 913, if the 04 buffer is not empty, the program branches to step 915. In step 915, the main routine executes 0
4 buffer contains an 04 response from the attached device. If yes, the program branches to step 916 and sends this 04 response data to the data processor. From step 916, the program advances to Steadub 914 and inputs the data received from the data processor. On the other hand, if the determination at step 915 is no, the program proceeds to step 921;
The contents of register R5 are checked. If the contents of register R5 are not 0, the program proceeds to step 913.
The status of the 04 buffer (empty or full) is asked again.

Otherwise, the program proceeds from step 921 to step 922, where the status of the 84 buffer is checked. If the 84 buffer is empty, the program immediately proceeds to step 913. However, if the 84 buffer contains data at step 922, the program (1) proceeds to step 923 and stores the data at 84 buffers.
4 command to the data processor and (2) proceed to step 924 to reset the R5 register to count 30.The program then proceeds to step 913.

2. Timer Interrupt Routine A flow chart of the timer interrupt routine is shown in Figure 9b. As shown in FIG. 9b, the timer interrupt routine starts at step 950 where the drop and device map is initialized and various flags and buffers are cleared.Then the program continues to step 951. Then, via multiplexer 350 (FIG. 4), it is determined whether a processing request exists in the drop to which the drop processor is connected (yes or no).

First, assuming no processing request is detected in step 951, the program branches to step 966 where the 04 buffer is checked and the drop processor receives the 04 command from the data processor for transmission to the device connected to the drop cable. It is determined whether the person has received the

If not, the program proceeds to step 96o and the drop poll map pointer is updated. If this pointer does not indicate the end of the drop map, the drop map pointer is incremented in step 965, the device map pointer is initialized to the start of the device map, and the process continues to step 951 to process another drop. Check to see if there are any requests. on the other hand,
If it is determined in step 960 that the drop pointer points to the end point of the drop map, then
The program proceeds to step 961, where the drop map pointer is set to the starting point of the drop map, and then 1. Proceed to step 962 and then proceed to step 951 as described above.

Returning to step 966, if the 04 buffer contains an 04 command to be sent to the device, step 9
After flag (1) is set at 67, the program proceeds to step 973, where the drop processor sends the 04 command message to the appropriate device.

If an error occurs, the program proceeds to step 97
Branch to 2. If the number of errors that have occurred is less than 5, the program proceeds from step 972 to step 973 and the 04 command is retransmitted. However, the fifth
In case of the second error, the program executes step 97
2 branches to step 975, where a 04 response containing the appropriate error code is sent from the drop processor to the data processor, as described above. From step 975 if an error occurs, or from step 974 if no error occurs, the program advances to step 976, where the state of the "1" flag is checked. Since the program has proceeded from step 967, the "1" flag has already been set. Accordingly, the program proceeds from step 976 to step 960, where the drop map pointer is incremented or initialized as described above.

Now, assuming that a processing request was detected at step 951, the program proceeds to step 952 where a conditional poll command (described above) is sent to the drop where the processing request was detected. In step 953, the drop processor determines whether an ACK or NACK is returned in response to the poll. First, assuming a NACK is returned, the program proceeds to step 968.
A branch is made to determine if a transmission error occurred; if yes, the program proceeds to step 969 and an appropriate error code is sent back to the data processor. Otherwise, the program proceeds to step 970 and determines whether an 04 command was received from the data processor to send to the device. If yes, the program proceeds to step 973 and the 04 command is sent as described above. Otherwise, the program proceeds to step 959 and determines whether the device map pointer is at the end of the device ball map. If this pointer is not at the end of the device map, the device map pointer is incremented in step 963 and a conditional poll command for the next device is sent in step 952. If, on the other hand, the end of the device map is reached, the program proceeds from step 959 to step 960, where the drop map pointer and loop are advanced as described above.

Now, if an ACK is detected in step 953 (indicating that the polled device should send an extra data response to the external control unit), the program proceeds to step 954 and returns the extra data. is input. Steps 955, 956 and 964 are as described above for steps 972, 974 and 975.
Determine whether five transmission errors have occurred. If five errors occur, the appropriate error code is sent to the data processor at step 964. From step 964 or step 955.

The program proceeds to step 957 with an Outbound Sofa Full (OBF) that indicates to the data processor whether the drop processor's Outbound Sofa is full or empty.
Flags are checked. If the buffer is empty, the program proceeds to step 958, where the extra data is sent as an 84 command to the data processor via the output buffer of the drop processor.The program then proceeds to step 958.

Proceeding to step 959, the drop and device map pointers are updated, or alternatively, as described above.

If the output buffer is full at step 957, the program proceeds to step 971 where it is determined whether the data processor has sent an 04 command to the drop processor for the device attached to the drop cable. In step 971, if the 04 command has not been sent, the program proceeds to step 957, whereas if the 04 command has been sent, the program proceeds to step 973, and the 04 command is sent as described above. Ru. In step 976, since the "1" flag is not set at this time, the program returns to step 957.

A central control computer (CC) located at the head end 12
C) and a plurality of external control units connected to the cable network 14, typical data message formats used in one embodiment of the invention are shown in FIGS. The diagram is described below.

The basic message format for data communication in the forward direction (ie, from the central control computer to the external control unit) is shown in Figure 10a. As shown in Figure 10a, each message is of a predetermined format and contains a flag byte (FLAG) and two addresses (ADDR) specifying the address of the external control unit.
ESS) byte and byte count (BYTE C0
UNT) byte (N) and command (COMMAND)
data (CMD), multiple data (DATA) bytes, and two cyclic redundancy checks (CYCLICR).
EDUNDANCY CHECK) byte (CRC)
and another flag (FLAG) byte. Each byte consists of 8 bits.

Flag bytes identify the beginning and end of a message.

Each flag byte has a unique bit pattern (01111
110). At the end of a message, if there are no more messages to send by the central control computer, the central control computer repeatedly sends a flag byte to maintain synchronization on the communication link. Otherwise, the mass flag byte serves as the start flag byte for the next message.

The two address bytes typically specify the address of a particular external control unit from 00°1 (hex) to FFFE (hex). By addressing the external control unit using two address bytes in this manner, the central control computer can uniquely address a message to a particular one of the 65,534 external control units. can. The first address byte (ADH) specifies the upper part of the address;
The byte (ADL) specifies the lower part of the address. The two addresses have specific meanings.

Address FFFF (hex) is the global or broadcast address. All external control units.

Respond to messages containing broadcast addresses. address 0
000 is the "mask" address, discussed in detail below.

The byte count byte (N) specifies the number of subsequent bytes in the message. However, the CRC and FLAG bytes are excluded. After the byte count byte, there is a command byte (CMD). As detailed below, the command byte determines the format of the message being sent and how to decode the subsequent data bytes. Specify whether to do so.

The CRC bytes (CRH and CRL) are two bytes that form a common 16-bit CRC number. These 2
The two bytes are derived from a mathematical operation on all bits before the CRC byte (excluding the FLAG bit),
It is used to check whether messages are correctly sent and received by the external control unit. The derivation of the CRC byte is performed by international standards such as CCITT.
It is based on standards published by the Standards Organization.

By using address 0000 (mask address) a message can be sent to a specific external control unit or group of external control units. The basic format of the message with address 0000 is the first
Figure 0b shows nine. As shown in Figure LOb,
A message with a mask address equal to oooo differs from the basic message (Figure 10a) by the inclusion of four additional bytes after the address byte. These 4 bytes are 2 masks (MASK)
bytes (MH and ML) followed by two references (R
EFERENCE) bytes (RH and RL), o
An external control unit receiving a message with an ooo mask address ANDs its own address with the value of the mask byte. If the result of this logical operation is equal to the value indicated by the reference byte.

The external control unit recognizes and responds to messages addressed to it. Otherwise, the external control unit ignores this message.

As will be readily apparent to those skilled in the art, by using a mask address in this way, a single message can be sent to one or a selected group of external control units. For example, if the mask byte is 0001. If yes and the reference byte is also 0001, all external control units with odd addresses will respond to the message. on the other hand.

If the reference byte changes to 0000, all external control units with even addresses respond to the message.

The basic message format in the reverse direction (ie, from the external control unit to the central control computer) is shown in FIG. 11, which is similar to the format for forward communication shown in FIG. 10a.

Similar. Therefore, the unique flag (Ol 1111
10) Bytes are used to identify the start and end of the message. Following the start flag byte are two address bytes, which specify the address of the particular external control unit to which the message is to be sent. Following this,
Byte count byte (N) and command byte (CM
D) and data byte. As mentioned above, after the last data byte, there are two commonly derived CRs.
There is a C by 1-.

12-17 illustrate a number of typical messages sent between the central control computer and the external control unit in one embodiment of the invention.

The formats of the messages shown in FIGS. 12 through 17 are determined based on the basic message formats shown in FIGS. 10 through 11.

FIG. 12 shows a WRITE message sent from the central control computer to the external control unit. This write message is used to write a program or data to one or more external control units starting from a specific address in the external control unit's memory. By using write messages in this manner, the operator of the cable system can add new functionality, accommodate external control units, or modify existing ones. Therefore, the operation of the cable system can be easily facilitated or modified without replacing or modifying the hardware of the external control unit or subscriber processing unit.

The written messages are used to implement various functions of the external control unit. For example, the written messages are used to specify which television channels each concerned subscriber is allowed to watch, the channel permissions of the external control unit. Maps can be downloaded. In one embodiment, this channel grant map consists of a series of 128 bytes of data stored in the memory of the external control unit, each byte being associated with each of 128 so-called logical channels. A @control channel is a channel to which a subscriber makes a request by inputting a channel number into a subscriber processing unit. Each of the first six bits of each byte of the channel grant map is associated with each of the six subscriber units. Each bit is set to ``1'' or ``0'' based on that bit and whether the subscriber associated with the subscriber unit is authorized to view the television channel associated with that byte. To send the channel authorization map to the external control unit, a write command is used to specify the starting address of the map in the memory of the external control unit and 128 bytes of logical channel data. By sending a new channel grant map or a channel grant map for replacement using a write command, the cable operator can determine, for example, whether the subscriber is paying the bill, whether the subscriber is viewing an increase or decrease in the number of channels the subscriber is viewing, etc. whether you are requesting

Based on this, it is possible to add or reduce channels that a specific subscriber is allowed to view.

As another example, a write command can be used to send to the external control unit a so-called channelization map specifying the correlation between logical channels and physical channels. As mentioned above, a physical channel is a CA
A channel on a TV feeder cable to which a converter/tuner in a subscriber unit is tuned in response to a subscriber's viewing request for a particular logical channel. and physical channel 52, logical channel 9 and physical channel 15, and so on. In one embodiment, where there is one feeder cable, the channelization map for each external control unit contains 128 bytes of data (for a two-cable system, the channelization map contains 256 bytes of data). ), this data is sorted into pairs, with each byte being combined into each of the 64 (128 in the case of a two-cable system) logical channels. Thus, the first pair of bytes is associated with logical channel 0, the second pair of bytes is associated with logical channel 1,' and so on. Bytes everywhere specify the two MS numbers mentioned above, and these are the tuning information needed by each subscriber unit's converter/tuner to tune to a particular physical channel. By changing the value of the MS number in the channelization map using write messages, the central control computer dynamically (i.e.
(at a given date and time). This allows cable system operators to send television programming to physical cable channels that are available to subscribers while still allowing them to send television programs to physical cable channels that are available to them.

By selecting the same physical channel, you can always watch the program. This is important if there is a lot of noise on a particular physical channel, reducing the quality of the television signal. In such a case,
The system operator may send a new channelization map to redefine the physical channel/logical channel correlation to relate the lower noise physical channels to the logical channels and transmit the program on the lower noise channels. I can do it. However, the subscriber can still access the channel carrying the program he wishes to view by entering the same logical channel number into the subscriber processing unit.

As shown in Figure 12, a write message typically includes two address bytes (ADH and ADL) that specify the particular external control unit to which the message is sent, and a byte count byte (N) that specifies the number of subsequent bytes in the message. ). The next thing that appears is h
Command byte equal to exFc (11111100). This command byte identifies the message as a write message. After the command byte is a data count byte (NN).

This specifies the number of data bytes contained in the write message to be written to the memory of the external control unit. The next two bytes (MDL and MDH) are
A specific external control unit memory address at which to start a write operation is specified in the lower part and upper part, respectively.

Finally follows the data byte NN to be written to the memory of the external control unit.

Another message sent from the central control computer to the external control unit is the readout (R) shown in Figure 13a.
EAD) message. This read message allows the central control computer to obtain one or more data bytes from the external control unit starting from a particular address in the external control unit's memory. Read messages are used for various purposes. For example, read messages are used to determine which subscribers are allowed to view which channels, which subscribers should be charged for viewing pay-per-view programs, etc.

The read messages are also used to examine various portions of the external control unit's data or program memory to diagnose faults or defects in the external control unit.

As shown in Figure 13a, the read message includes normal address (ADL and ADH) bytes and byte count (N) bytes. After these bytes there is a command by 1~, which is hexF8, F9-F
A or FB (11111000, 11111001, 1
1111010 or 111110.11).

Each command byte F8 to FB indicates that the message is a read message; however, each command byte is routed via which of the four available reverse channels to the external control unit, depending on the value of the two least significant bits. Specifies whether data should be sent back to the central control computer. Therefore.

Command byte F8. F9. FA and FB are connected to reverse channels 00. Of.

Specifies that the data should be sent back to the central control computer via 02 and 03, respectively. The command byte is followed by (1) a data count byte (NN) that specifies how many data bytes are to be sent back to the central control computer, and (2) the memory of the external control unit where the data read operation should be initiated. Two memory address bytes (MADL
and MADH).

In response to the read message, the external control unit:
The message shown in Figure 13b is sent back to the central control computer via a designated reverse channel. The message of Figure 13b contains the data required by the read message. The returned data comprises the usual address and byte count bytes followed by a command byte, which is set to the value of the read command in response to the returned message. Following this is the data count byte (NN), which specifies the number of bytes of data to be returned, the NN bytes of data requested by the read message.

Yet another message sent from the central control computer to the external control unit is the ECHOBACK message shown in FIG. This echo back message causes the addressed external control unit to send back to the central control computer, via the designated reverse channel, the same message that it received. This echoback message can also be used to test cable networks for signal degradation and transmission errors.
It is also possible to search for inactive external control units.

As shown in FIG. 14, the echo back message includes normal address (ADL and ADH) bytes and byte count (N) bytes. Next is the command byte, which consists of hexFo, Fl,
F2 or F3 (11110000, 11110001%
1111001o or 11110011). As described above for read messages, the last two bits of the command byte specify which of the four reverse channels the external control unit should echo back the central control computer's message. Following the command byte, there is a data count byte (NN), followed by a NN data byte.

In response to receiving an echoback message, the addressed external control unit transmits the message back to the central control computer via a designated reverse channel as shown in Figure 14b. Regardless of how the message is addressed to the external control unit (i.e., whether using a global address, a mask address, or a specific address), the external control unit's message , contains the unique address of the responding external control unit in the ADH and ADL bytes, followed by a byte count byte (N). Thereafter, the returned message (assuming no transmission errors) will be the same as the message originally sent by the central control computer.

Yet another message sent from the central control computer to the external control unit is the forced tuning (FO) shown in FIG.
RCE TUNE) message. This message is used by the addressed external control unit to force the associated drop to tune to either channel. Such forced tuning is, for example, C
All subscriber television sets connected to the ATV system.

It is used to tune into a channel that communicates orders and news to subscribers during civil emergencies.

The message is also used to automatically tune the subscriber's television set to the channel broadcasting the pay-per-view program (eg, boxing) that the subscriber desires to view at the appropriate date and time.

As shown in Figure 15, a typical force tune message contains the normal address (ADL and ADH) bytes and byte count (N) bytes. The command (CMD) byte is made equal to haxF4 (11110100) and the data count byte (NN) is made equal to 2, then the subscriber unit (SU) byte is specified to be forced to tune. subscriber unit. In one embodiment, the SU byte specifies any one converter using the three least significant bits of the byte. This requires sending a forced tuning message for each converter that is to be forced tuned. Alternatively, each bit of the SU byte is associated with each of the six converters so that one message to the external control unit can force the tuning of two or more converters associated with this external control unit.

Finally, the logical channel (LC) byte specifies the number of logical channels to which a given converter is forced to tune. If the SU byte is combined into two or more converters, one for each converter to be forced tuned.
There are multiple LC bytes.

A further series of messages sent from the central control computer to the external control unit is the Send Funk Scene (S
END FUNCTION) message. These messages are used to cause so-called transmission function data stored by the external control unit from the subscriber in question to be transmitted back from the external control unit to the central control computer. For example, the transmit function data may be entered into the subscriber processing unit by the subscriber in response to a request for such data from a central control computer located at the head end 12. represents voting data or shopping data entered by subscribers in connection with viewer selection and home shopping services. In one embodiment, each external control unit maintains in memory a plurality of so-called transmit function bytes arranged in pairs. Each part of the transmit function byte is associated with each of up to six subscribers. The first byte specifies the subscriber to which the byte pair is combined. The second byte contains the transmit function data. In addition to these byte pairs, the external control unit maintains in memory a transmit function count byte that specifies the number of transmit function bytes contained in its memory. If the memory of the external control unit does not contain transmit function data (eg, no subscriber has entered transmit function data), the value of the transmit function count byte is zero.

In one embodiment of the invention, there are six transmit function messages. These messages are the 16th
Shown in Figures a-16c.

The first message is the transmit function enable message shown in Figure 16a. In addition to the normal address and byte count bytes, this message includes a command byte equal to hex80, a data count byte (NN) , a single data byte (S
U).

Each bit O-5 of the (SU) byte is combined into each of the six SUs. The transmit function enable message is used by the central control computer to
The transmit function of an external control unit is enabled or disabled for the particular subscriber unit SU associated with that external control unit. The transmit function for a particular subscriber unit is enabled or disabled, respectively, depending on whether the bit in the SU byte associated with that subscriber unit is set to '1' or rOJ. .

The second message is the transmit function clear message shown in Figure 16b. This message is
he: Contains a command byte equal to c81 and a data count byte (NN) equal to 0. In response to receiving this message, the addressed subscriber control unit clears the transmit function data in its memory.

The third message is the send function data message shown in Figure 16c. This message is
hex84-85.86 or 87 (10000100
,10000101,10000110 or 10000
111). Upon receiving this message, the addressed external control unit will only send (
It sends the transmit function data in its memory (determined by the value of the external control unit's transmit function count byte) back to the central control computer. As described above for read messages, the data is read by the external control unit via the reverse channel (00, 01, 02 or 03) specified by the value of the two least significant bits of the command byte of the transmit function data message. will be returned. In response to the transmitted function data message, the external control unit:
transmitting a message containing one or more pairs of data bytes to a central control computer;

Each pair of data bytes above is associated with a separate subscriber unit. The first byte at each location is the subscriber unit (0
to 5), and the second byte is the transmit data for that subscriber unit.

Yet another message that can be used to send from the central control computer to the external control unit is a pay-per-view message. This message is.

It is used to (1) force the subscriber unit to tune to a pay-per-view event requested by the subscriber, and (2) power up the subscriber's television set via the subscriber processing unit's power relay.

A pay-per-view message used in one embodiment of the invention is shown in FIG. 17 and includes a command byte equal to hex88.

This is followed by a data count byte (NN).

The program number (PN) byte specifies the so-called program number (described in detail below) associated with the message. lastly,
The two MS bytes specify the MS number mentioned above. This is required to tune the converter/tuner circuit included in the subscriber unit to the particular physical channel broadcasting the pay-per-view event specified by the program number byte.

In one embodiment of the invention, pay-per-view messages operate as follows. Each external control unit includes event viewing bytes in its memory.

Each of bits 0-5 of this byte is associated with each of up to six subscriber units. When a subscriber tunes into a pay-per-view event, the bit in the event-view byte associated with the subscriber unit tuned to the pay-per-view event is set to "1." This bit is.

It is reset to [0] when the subscriber unit is tuned to a channel not associated with a pay-per-view event, or when the subscriber turns off the television set via the subscriber processing unit. This event viewing byte is used to control timer increments, as described below.

In addition, each external control unit has in its memory a program event map consisting of 128 pairs of bytes. Each pair of bytes in this map is associated with each of the 128 program numbers. Each program number is associated with a separate pay-per-view program event.

Thus, the first pair of bytes in the one program event map is associated with one program number, event 0, the second pair is associated with one program number, event 1, and so on. The byte pair contains the MS number sent by the potential viewing message.

In addition to the program event map, each external control unit contains one program authorization map in its memory.

This map contains 768 bytes organized into 6 groups of 128 bytes per group. 1
Each group of 28 bytes is associated with a separate subscriber unit, and each byte of each group is associated with each one of the 128 pay-per-view events.

If a subscriber associated with a particular subscriber unit is allowed to view a pay program and requests viewing of a particular pay program via a subscriber processing unit, the bytes associated with this program and the subscriber unit are The three least significant bits are set to the address of the subscriber processing unit from which the pay-per-view request was received. The five most significant bits of the byte (initially each 0) are used as a preview timer, described below.

To order a desired pay-per-view event, the subscriber enters the program number associated with the pay-per-view event into the keyboard of the subscriber processing unit. If the subscriber is permitted to view pay-per-view events.

The address of the subscriber processing unit receiving the request is placed in the appropriate byte of the program authorization map as described above. When an event begins, the central control computer sends a pay-per-view message specifying the program number and the MS tuning data needed by the subscriber unit's converter/tuner to tune to that program. If a subscriber requests viewing of a pay-per-view program specified in a pay-per-view message, the external control unit forces the subscriber unit associated with the subscriber to tune to a channel broadcasting the pay-per-view event. . Further, the external control unit sends a command to the subscriber processing unit so that the subscriber processing unit (1) flashes its event order LED;
indicating that the subscriber is viewing a pay-per-view event during the preview hour; and (2) turning on a relay in the subscriber processing unit to provide power to the subscriber's television set. Thus, at the appropriate date and time, the external control unit turns on the subscriber's television set and forces it to tune to the requested pay-per-view event. In addition, the external control unit is
Starts operation of the preview one hour timer. During this preview hour, subscribers can view pay-per-view events for free.

If the subscriber watches a pay-per-view program for more than a predetermined number of minutes, the preview timer expires and the external control unit sends a command to the subscriber processing unit to continuously turn on the event order LED. lights up to indicate that the subscriber will be charged for viewing the event.

The preview timer operates as follows.

When the pay-per-view event timer expires, the external control unit checks the state of the bit flag in the event-view byte. If the bit associated with the subscriber unit is set to '1', then the preview timer bit associated with the subscriber unit and the program to which it is tuned (as described above) is set to '1'. Each of the five bits of the preview timer in the one program permission map represents a portion (ie, 115) of one preview hour. Whenever the pay-per-view event timer expires, another bit of the five bits of the appropriate preview timer is set by the external control unit if the corresponding bit of the event-view byte is set to '1'. Ru. Preview timer 5
If all bits are set, one hour of preview is exceeded and the subscriber will be charged for the pay-per-view event.

The central control computer uses the read messages to periodically collect preview timer information contained in the program authorization map to determine which subscribers should be charged for viewing which paid events.

Although a number of messages have been described in detail for embodiments of the present invention, the message format used in the present invention may also include a number of other messages sent between the central control computer and the external control unit. It will be obvious to those skilled in the art, and it will also be obvious to those skilled in the art that the basic format of the central control computer/external control unit messages can be varied.

E. DATA PROCESSOR OPERATION Regarding an embodiment of the present invention using the message formats and messages shown in FIGS. 10 to 17,
The operation of the data processor will be explained below. A list of source and object code computer programs apparent to those skilled in the art for controlling the operation of a data processor is as set forth in Reference No. 3 attached to the application.

Figure 18a shows the complete program operation of the data processor. As shown in Figure 18a, the data received from the central control computer is transferred to the digital unit 55 (
The data is stored in the FIFO receive buffer 1001 by the USART 400 (FIG. 5). This buffer is 256x
It is configured as a 4-byte buffer and can hold up to four 256-byte central control computer messages at one time. A buffer counter associated with the data processor points to the next empty buffer in the FIFO. The other two buffers shown in Figure 18a are FIF
O output buffer 1002.

FIFO Input Coverer Buffer 1003° Data received by the data processor from the drop processor is placed in the output buffer 1002. Similarly, data sent from the data processor to the drop processor is sent to the FIFO buffer 1003. Each of these buffers contains 256 bytes and buffers up to 25 10 byte messages. A buffer counter associated with each buffer points to the next empty buffer. The data processor receives data from the FIFO buffers 1001 and 1002 and operates based on this data (shown at 1004 in FIG. 18a), and transfers the data to the FIFO
0 buffer 1003 or to the central control computer.

FIG. 18b determines by the data processor whether a message has been received from the central control computer;
If so, is a flowchart of a routine that determines whether the message is for an external control unit. The routine of FIG. 18b causes the data processor to send an message to the USART 400 (FIG. 5) to indicate that a message has been received from the central control computer.
Called when interrupted by.

The routine of FIG. 18b begins at step 1021;
Further input from the USART 400 is inhibited and the CRC byte of the received message is used to determine if a transmission error has occurred.

If an error occurs, the routine returns to step 1028.
The input from USART 400 is re-enabled. After step 1028.

The interrupt service routine proceeds to step 1029;
Return to the calling program.

Alternatively, if in step 1021 no transmission errors have occurred, the routine proceeds to step 1022 where the data processor checks the address byte of the received message.

If the address byte matches the address of the external control unit, the routine continues with step 1027^ -F
The buffer counter associated with IFO buffer yi001 (FIG. 18a) is incremented by 1. The routine then proceeds to step 1028 where the USA
RT400 is enabled. Since the value of the buffer 7 counter is incremented in step 1027, +USA
Central control computer messages subsequently received by RT 400 are written to the primary buffer.

It is not written over the contents of the buffer containing the central control computer messages that have already been received.

Returning to step 1022, if the address byte of the received message does not match the address of the external control unit, the routine branches to step 1024 and determines whether there is a global or broadcast address (F F F F in hexadecimal). The address byte is checked against. If this address is present, the message is to an external control unit and the routine proceeds to step 1027 as described above; otherwise, the routine continues.

Proceeding to step 1025, the data processor checks for a mask address (OOOO in hexadecimal) in the central control computer's message. If this address does not exist, the message is not for an external control unit and the routine continues in step 1.
Branches to 028.

Otherwise, the routine continues to step 1026;
A masking operation is performed as described above.

The routine then branches to step 1027 or step 1028, depending on whether the mask operation performed in step 1026 indicates that the message is for an external control unit.

The operation program of the data processor, No. 18 c-1
The 8h diagram will be explained below. This program consists of two main parts:

(1) a main routine; and (2) an application program for performing various functions within the external control unit; the main routine branches to one or another application program based on the task to be performed. It is a task-guided program. The application program performs its tasks (eg, enters data from the keys of the subscriber processing unit, such as subscriber-entered channel requests, pay-per-view requests, transmit function data, etc.) and returns to the main routine. Because of the need to service multiple subscriber processing units connected to multiple drop cables, an application program may
Sometimes it is necessary to return to the main routine1
For example, if a subscriber enters a request for a two-digit channel on the keyboard of a subscriber processing unit, the application program associated with this function will enter the first digit, return to the main routine, and then enters the second digit.

In this case, the application program sets the timeout value in the time table and the jump address in the jump address table before returning to the main routine. As discussed in more detail below, this timeout value and jump address value allow the main routine to jump back to the application program at the appropriate time and continue operating from the point it left the application program.

FIG. 18c is a flowchart generally illustrating the operation of the main routine. As shown in Figure 18c, the main routine begins at step 1005 when the external control unit is powered on.

In step 1005, the data processor
The program then proceeds to step 1006 where the data processor initializes the USART 400. In step 1007, data processor 420 checks whether its backup memory requires initialization. If so, the program proceeds to step 1008 and initializes the backup memory. Otherwise, the back-up in step 1008
After up memory initialization is complete, the program proceeds to step 1009 where other memory locations are initialized. Generally, in steps 1008 and 1009, items such as channel permission map, channelization map, parentage control codes, program event map, program permission map, etc. are initialized. Steps 1010, 1011 and 1
At 012, the data processor initializes the drop and device polling maps and pointers.

After initialization, the drop processor enters the main loop. The main loop is shown in the flowchart of Figure 18d. As shown in FIG. 18d, the data processor determines whether any of four events occur in the main loop: (1) whether the data processor receives a message from the central control computer (step 1013); (2) whether the 100/64 millisecond paid viewing event timer has expired (step 101);
4) sequentially determining whether the drop processor's output sofa contains data for the data processor (step 1015) and (4) whether the pay-per-view event timer has expired (step 1016); If any of the following events occurs, the data processor branches to the appropriate operation routine at the appropriate step 1013, 1014, 1015, or 1016. These are shown in Figure 18d for operation 1. They are shown as action 2, action 3 and action 4, respectively. If the above event does not occur, the program proceeds to the next numbered step in FIG. 18d. After step 1016, or after the operational routine, program flow proceeds to step 1o13.

The operating routine of FIG. 18d will now be described with reference to FIGS. 18e-18h.

The main routine is Step 1013 (Fig. 18d)
If the program detects that a message addressed to the external control unit has been received from the central control unit, the program branches to the Operation 1 routine shown in FIG. 18e to respond to the central control computer's message.

The Operation 1 routine begins in step 1013, where the data processor loads the central control computer's message from buffer 1001 (FIG. 18a) into work memory. The program then proceeds to step 1031 where the command byte of the central control computer message is checked to determine what action the data processor should take.

In step E031, if the command byte of the message from the central control computer is hexFO-F3 (echo back), the program
Step 032 returns (echoes) the received message to the central control computer. After sending the message,
The program proceeds to step 1041 and returns to the main loop as described above.

In step 1031, the command byte is hexF
c (write), the program proceeds to step 1033 and stores the data contained in the write message in a memory location of the external control unit. From step 1033, the program proceeds to step 1034 and returns to the main loop as described above.

In step 1031, the command byte is hsxF
8-FB (read), the program proceeds to step 1035 and transmits data from the memory of the external control unit specified in the write message to the central control computer.

From step 1035, the program proceeds to step 104
3 and return to the main loop as described above.

In step 1031, the command byte is hexF
4 (Forced Tune), the program proceeds to step 1037 where the converter of the specified subscriber unit is tuned to the specified channel and the 7-element display of the subscriber processing unit forces the subscriber unit to tune. and the power relay of the subscriber processing unit associated with that subscriber unit is activated to turn on the subscriber's television set.The program then proceeds to step 1038. , returns to the main loop as described above.

In step 1031, the command byte is hex8
0 (send function enable) or hsx81 (send function clear), the program proceeds to step 1039 to enable/disable the send function of the subscriber processing unit, respectively. or 6 step 103, which either proceeds to step 1042 and clears the transmit function data buffer of the external control unit.
From either step 9 or 1042, the program proceeds to step 1040 or step 1043, respectively, and returns to the main loop as described above.

In step 1031, the command byte is hex8
4-87 (transmit function data), the program proceeds to step 1044 where the data processor checks the value of the transmit function data count byte and the external control unit determines the transmit function data to be sent back to the central control computer. It is determined whether it has data. If the external control unit does not have transmit function data, the program branches from step 1044 to step 1047 and returns to the main loop as described above.

Otherwise, the program proceeds to step 1045 where the external control unit's transmit function data is sent to the central control computer.

The program proceeds to step 1046 and returns to the main loop as described above.

Finally, in step 1031, if the command byte is hex88 (pay-per-view), the program branches to step 1048, where the MS tuning data contained in the pay-per-view message is stored in the program event map of the external control unit. Ru.

The program then proceeds to step 1o49, where the data processor checks the program authorization map to determine whether the first subscriber has ordered a pay-per-view program to be viewed by the subscriber. If the subscriber is requesting to view a pay-per-view event, the program returns to step 1050.
, the subscriber unit associated with that subscriber is tuned to the pay-per-view program, the associated 5-minute preview timer is started, and the subscriber processing unit's event order L
The ED is set to flash and the subscriber processing unit's power relay is activated to turn on the subscriber's television set.The program then proceeds to step 1051 to provide each of up to six subscribers with In contrast, the program is caused to return to step 1049. After processing all subscribers, the program proceeds from step 1051 to step 1052 and returns to the main loop as described above.

The main routine is step 1014 (Figure 18d)
If the expiration of the 100/64 second timer is detected, the program branches to the operation 2 routine shown in FIG. 18f. This action 2 routine operates to transfer control of the data processor to one of a plurality of application programs. As previously discussed, the application program performs the desired actions (e.g., Channel selection, paid viewing,
parent-child control), activate the power relay of the subscriber processing unit, or activate the order event LE of the subscriber processing unit.
Activate (flushing or non-flashing) or deactivate D, clear the subscriber processing unit's seven-element display, or send data (e.g., program or channel information) to the subscriber processing unit's display. It performs various functions such as sending.

The Operation 2 program works as follows: the data processor sends a plurality of 2
A time table with byte input is maintained in memory. In one embodiment, this time table includes 6
4 inputs (0-63), but in the embodiment shown there are no more than 6 drops and no more than 8 devices on each drop associated with each external control unit ( up to 4 subscriber processing units and up to 4 other devices). The inputs of the time table are arranged sequentially by drop and device such that inputs 0-7 are combined into the device with address O-7 in drop O, and inputs 8-15 are combined with the device with address O-7 in drop 1. It is combined with , and is considered to be the first prize. As mentioned above, the one time table entry is set by various application programs as the timeout value before the application program returns to the main routine.

When entering the operation 2 routine, the time table pointer CI)
is 0-6 based on the value of the time table counter (J)
It is set to a value of 3 (step 1060). Then,
The routine proceeds to step 1061 and uses the ■ pointer to read the Ith entry (associated with a particular device on a particular drop, as described above) from the time table. If the value of this input is hexFFFF (indicating that the timer is off), the routine branches to step 1066, where the time table counter J is incremented by 1 and the next step in the Operation 2 routine occurs. It is prepared as follows. If the input is other than hexFFFF, the routine continues to step 1062 and the time table input is decreased by one. After this decrement, if the time table value is not zero (step 1063), the routine branches to step 1066 and the J counter is incremented as described above.

On the other hand, if the timer input is 0, the timer expires and the routine proceeds to step 1064 where a 0 is placed in the memory location (key code) and the jump table is interrogated using the value of the pointer. Ru. This jump table is a table held in the memory of the external control unit and has the same structure as the time table. However, jump table entries specify memory locations in an application program to which the program should jump. These values point to the start of the application program or, if the application program returns to the main routine before completing its task, points within the application program. Based on the inputs contained in the jump table, the Operation 2 routine proceeds to step 1065 where the routine jumps to the point in the application program (APL) specified in the jump table. When the application program returns to the Operation 2 routine, the Operation 2 routine proceeds to step 1066 and the J counter is incremented as described above. The routine then proceeds to step 1067 and returns to the main loop.

The main routine is step 1015 (Figure 18d)
In , the drop processor has data for the data processor! ¥! If I is disconnected, the program branches to the operation 3 routine shown in FIG. 18d. This Operation 3 routine serves to appropriately respond to data received from the drop processor, such data including the 84 command (extra data response) and the 04 response received from the subscriber processing unit.

As shown in FIG. 18g, the operation 3 routine is as follows.

First, in step 1070, it is determined what type of message will be sent from the drop processor.

If this message is a 01.03.05, o7 or 08 command response (described above), no action is required and the action 3 routine proceeds to step 1083 and returns to the main routine as described above. Return. 18th g
In the flowchart in the figure, 01, 03.05.0
Although no action is taken in the case of a 7 or 08 command response, it will be apparent to those skilled in the art that the program flow can easily be modified in various ways so that the data processor responds to any or all of these command responses. For example, in an 01 response, the program can be modified so that when the data processor detects that no power is being received from a particular drop, it informs the system operator of this.

In step 1070, if an 84 command is detected, the action 3 program branches to step 1072 to determine if an error has occurred. If [Jesus]
If so, the program branches to step 1073 where a device error counter is incremented in an error action subroutine.

If the counter reaches a predetermined value (eg, 2), the error subroutine reinitializes the pointer and jump table entries associated with the subscriber processing unit or device sending the 84 command. The program then branches to step 1083 and returns to the main loop as described above. On the other hand, if no error is detected in step 1072, the program:
(1) Go to step 1074 and set the jump pointer table, or (2) Go to step 1075 and put the received data in the memory location (key code).
, (3) Proceeding to step 1076, the program jumps to the appropriate application program (APL) using the jump table. When the application program returns to the operation 3 routine, the operation 3 routine proceeds to step 1083 and returns to the main loop.

Furthermore, if a 04 response is detected in step 1070, the operation 3 routine proceeds to step 1071, where a transmission error is checked.

If an error has occurred, the routine returns to step 1.
Branch to o73. Otherwise, the routine proceeds to step 1077 where the data processor determines whether the 04 response is a status response.

If the 04 response is not a status response, the program branches from step 1077 to step 1083 and returns to the main loop as described above. Otherwise, the program branches to step 1078. This step 10
At 78, if the status response indicates that a key on the device keyboard was recently pressed, the routine branches to steps 1080, 1081, and 1082.

Responsive to key depression as described for steps 1074-1076. If the status response indicates that the key has not been pressed recently, the program proceeds from step 1078 to step 1079, where the status byte is checked to determine the state of bit 7. As mentioned above, bit 7 indicates whether the responder is a master or slave subscriber processing unit, based on the setting of the subscriber processing unit's switch 780 (FIG. 7), and thus , indicates which converter (primary or secondary) the subscriber processing unit has designated. After step 1079, the program executes step 1
The process advances to 083 and returns to the main loop as described above.

In addition, if the main routine determines in step 1016 (Figure 18d) that the pay-per-view timer has expired, the program performs action 4 shown in Figure 18h.
Branch to routine. This routine includes step 109
1 and determines for each subscriber whether the subscriber is watching a pay-per-view program. In step 1091, if the subscriber is not watching a pay-per-view program, the routine branches to step 1096 and further continues in step 10.
Returning to step 91, the above determination is made for the next subscriber. In step 1091, if the subscriber is viewing a pay-per-view event, the routine proceeds to step 1092 and checks the 5-bit preview timer in the appropriate byte of the one-program permission map. If the value of the byte is greater than or equal to F8, and the upper five bits of the byte (i.e., timer bits) are all set to 1, indicating that one hour of previewing has elapsed, the program executes step 1.
Branch to 096. However, the value of the byte is hexF8
If at least one of bits 3-7 of the byte is equal to O and indicates that no preview time has elapsed, the program returns to step 1093.
The routine then proceeds to step 1, where the 5 minute timer is incremented by setting the timer bit to 1.
Proceeding to 094, the value of the byte is checked again. If all five timer bits are set to "1",
One preview hour has elapsed and the program proceeds to step 1095 to display the order event LED on the subscriber processing unit.
remains lit and the subscriber is billed for pay-per-view events. Otherwise, the program branches to step 1096. This step 1096
The routine then proceeds to step 1091 and checks for each subscriber whether they are viewing a pay-per-view event. After it is determined for each subscriber whether the subscriber is viewing a pay-per-view event in step 1096, the routine continues to step 1097 and returns to the main loop as described above.

F. Polling and Handling In the above system, the external control unit only polls when it receives a message from the central control computer that requires a return message (e.g. a message such as a read, echo back or send function data). , sends a message to a central control computer.

Otherwise, the external control unit will not send messages to the central control computer.

Thus, in the system described above, the external control unit is configured to provide critical information (e.g. information from a subscriber requesting additional processing or information from a medical monitoring device attached to the drop cable of the external control unit). Although it can be sent to the central control computer, it is not possible to inform the central control computer of this fact. Also, when the external control unit of the above system receives a message from the central control computer, it usually does not inform the central control computer of this, so that the message requesting a response (e.g. read) is not addressed to the external control unit. The central control computer has no knowledge of the inoperative state of the external control unit or of the transmission link until the response message is sent and this response message is not received by the central control computer.

A polling and handshake communication protocol is used to enable the external control unit to send critical information to the central control computer in a timely manner, as well as to check that the external control unit is working. In view of the fact that a very large number of external control units (up to 65°536 for each of up to 4 banks) can be connected to the cable network of the invention, the polling and handing of one individual external control unit is essential in the design of such a protocol. It is important to minimize the time required for shaking.

The invention therefore provides a handshaking machine M1 which notifies the central control computer of an inactive external control unit and which does not require the transmission of relatively long format messages. In addition to this, the present invention can notify the central control computer that the external control unit has information for the central control computer, and the external control unit can respond to receiving a polling message by To provide a polling mechanism that does not require sending information messages to a central control computer.

This polling mechanism allows the central control computer to
Information can be collected from the external control unit via two independently operating mechanisms. A first or "general" polling store allows the central control computer to poll each external control unit to determine whether the external control unit has information to send to the central control computer. I can do it. This general polling mechanism can detect within 20 seconds all properly operating external control units requesting processing.

A second; ie, "priority" polling mechanism is capable of detecting within 20 milliseconds any external control unit that has so-called priority information about the central control computer. In the case of both of these polling mechanisms, prior to polling, a response is sent by the central control computer to identify and obtain responses from only those external control units that have information within a predetermined importance level or limit. level” is established. The information level is
For example, based on the value of information or on information timing.

1. Message Format The polling and handshake protocol is described below for an alternative basic message format than that shown in FIGS. 10-11 and described above.

This alternative basic message format is shown in FIGS. 19-20.

FIG. 19 shows another basic message format for data communication in the forward direction (ie, from the central control computer to the external control unit). Each message is of a predetermined format and includes a flag byte, a send control (SEND CNTL) byte, several data bytes, and two cyclic redundancy checks (CRC).
) byte and another flag byte. Each byte consists of 8 bits. The flags and CRC bytes are the same as the flags and CRC bytes described above and serve similar functions.

The 5 END CNTL bytes of the message of Figure 19 are used to define any of 256 unique commands. As detailed below, 5END C
NTL commands allow the external control unit to send information back to the central control computer or otherwise allow the external control unit to perform specified operations.

Data bytes consist of 0 to 255 bytes per message. The 5END CNTL byte specifies how the external control unit decodes the data byte. If a message should be sent to a specific external control unit.

The first two data bytes typically specify the address of the external control unit from O-65536. The first address byte (ADL) specifies the lower part of the address and the second byte (ADH) specifies the upper byte part. Also, typically.

The third data byte of a message addressed to a particular external control unit is the control (CTL) byte. This CTL byte specifies which external control unit drops the message to, the particular reverse channel the external control unit should use to respond to the central control computer, and so on.

Another basic message format for the reverse direction (ie, from the external control unit to the central processing computer) is shown in FIG. 20, which is similar to the format for forward communication. Therefore, the flag byte is used to identify the beginning and end of a message. This first flag byte is followed by a receive control (RE)
CCNTL) byte. This RECCNTL byte need not be the same as the 5END CNTL byte and specifies how the central control computer will Mrl the next data byte contained in the message. The last data byte is followed by the two CRC bytes described above.

In addition to the basic messages mentioned above, certain external control unit poll response bytes are used. These poll response bytes consist of one or two byte times of the carrier from the external control unit. As discussed below, these poll response bytes are used as a handshake in response to poll and information messages sent from the central control computer.

2. General Level Polling Protocol The first polling method is the so-called General Level Request (GLR) polling. Using this mechanism, a ball message is sequentially addressed to each external control unit in the system, and whether the external control unit requests processing (i.e. whether the external control unit has information for the central control computer) Please) be judged. Prior to polling, the central control computer establishes the "level" at which the external control unit will respond to the poll. Once the central control unit establishes the polling level, the external control unit (a) issues a processing request and (
b) has information to be sent to Head Ezod 12;
The external control unit responds to the GLR poll only if that level is less than or equal to (ie, more significant) the level currently established by the central control computer. When an addressed external control unit receives a GLR poll, it responds by sending one or two general poll responses (GPR) to the central control computer. Each GPR byte corresponds to one byte time of the carrier from the external control unit, i.e. 1111111
Consists of 1. If the central control computer does not detect a GPR byte from a polled external control unit within a predetermined period of time (e.g., 350 microseconds), the central control computer marks the external control unit as inactive. I reckon. After a predetermined number of unsuccessful attempts to communicate to the external control unit (eg, five), the central control computer prints an appropriate error message to the headend operator.

If the addressed external control unit sends a single GPR byte to the central control computer in response to a GLR poll, the central control computer must be able to detect whether the external control unit is active and has not issued a processing request. It is interpreted as. The central control computer then polls the external control unit with the next address. However, if the external control unit does not return two GPR bytes, the central control computer interprets the response as a processing request from one active external control unit. Using GLR polling, the central control computer periodically processes all external control units in one operation and creates a processing request table in memory. The central control computer then uses this table and uses the priority information request message described below to determine whether the external i? Selectively retrieve information from i-control units only. At a forward data transmission rate of 200 Kbps, a complete general poll request cycle for 65,536 external control units typically takes less than 20 seconds.

GLR polling is performed by the central control computer as follows. First, the central control computer sends a general level request threshold (GLRT) message. A typical GLRT message is shown in Figure 21a based on the basic message format of Figure 19.
As shown in the figure. The GLRT message has 5 END CNTL bytes equal to 08, which is used by the central control computer to
A response threshold for GLR polling is established. This response threshold is established by the Level (LVL) byte contained within the GLRT message. The first two bits of the CTL byte of the GLRT message specify how the external control unit should decode the LVL byte. If the first two bits of the CTL byte are '01', this means that the external control unit will send the next polling message only if the level of information in the external control unit is equal to the level indicated by the LVL byte. (i.e., with two GPR bytes). C
If the first two bits of the TL byte are '10', the external control unit should reliably respond to the polling message if the level of information to be sent to the central control computer is below the LVL level. It turns out.

After sending the GLRT message and establishing the polling level, the central control computer.

Send one or more General Level Request Polling (GLRP) messages. A typical GLRP message is the first
21b based on the basic message format of Figure 9.
As shown in the figure. As shown in Figure 21b, GL
The 5END C:NTL byte of the RP message is 0.
, 1.2 or 3. The 5ENDCNTL byte of the message indicates that the message is GLRP.
It indicates to the addressed external control unit that it is a message and also indicates through which reverse channel (0, 1, 2 or 3) the external control unit should send the GPR response byte. External control unit performs GLR on two GPR pies on designated reverse channels
When responding to P messages, this is done by the central control computer.

As described above, it is read as a processing request from an operating external control unit. If one GPR byte is returned, it is interpreted by the central control computer as a response from an active external control unit that has not issued a processing request.

If no GPR bytes are received, the central control computer considers the external control unit to be inactive.

3. Priority Polling Protocol The second or priority polling protocol method is:
This is so-called priority information window (PIW) polling. This second method gives the cable network a priority "window"
An external control unit that establishes a
In response to receiving a general poll request addressed to this unit, this is communicated to the head end via a predetermined priority processing request channel.

Priority polling is enabled by Priority Information Request Window Control (PIRWC) messages sent from a central control computer. This PIRWC message is shown in FIG. 22a based on the format of FIG. 19, and is used by the central control computer.

Sets the priority response threshold level for the external control unit. As shown in Figure 22a, P.I.
RWC message is 5END CNTL equal to 9
Has a part-time job. LV of this PIRWC message
The L byte specifies the priority response threshold level. The external control unit controls the LVL as determined by the value of the bits contained in the control (CTL) byte.
Decoding By1-. Bits 0 and 1 of the CTL byte are.

Should the external control unit respond if its level of information is equal to the value of the LVL byte?

Alternatively, it is specified whether a response should be made when the level of the information is less than or equal to the LVL value. Furthermore, bit 2 of the CTL byte specifies whether the PIW function of the external control unit should be turned on or off. Furthermore, C.T.L.
Bits 3 and 4 of the byte specify through which of the four reverse channels the external control unit should send the priority response back. In one embodiment, the values and functions of the bits in the CTL byte of the PIRWC message are shown in Table E below.

Eidan 0 1 The external control unit has an information level of L.
Respond to priority polling only if it is equal to the value of VL.

1 0 The external control unit has an information level of L.
It responds to priority polling only if it is less than or equal to the value of VL.

B2 Function 0 Sets the PIW of the external control unit to OFF.

1 Set the PIW of the external control unit to ON.

84 B3 Function 0 0 Return priority response via reverse channel 0.

0 1 Return priority response via reverse channel 1.

P I RWC: After a message is sent to an external control unit and received by this unit, an external control unit with priority information corresponding to the threshold level established by this PIRWC message receives a general level polling message. After that, the general polling response (G P
R) Send the byte to the central control computer. The central control computer connects G via the priority reverse channel.
Upon receipt of a PR byte (two or more responses from multiple external control units), the central control computer is informed that the external control unit has priority information to send (which external control unit (which the central control computer does not yet know), upon receiving such a priority response.

The central control computer sends a series of messages described below to disable the priority "window" and:
Find the external control unit issuing the priority poll response within 20 milliseconds.

Assuming that an external control unit is identified by the central control computer that is returning a priority response (or is issuing a processing request in response to said GLR poll), the central control computer Information is obtained from the identified external control unit by addressing an information request (PIR) message to the external control unit. PIR message is PIROlP
There are four, IR1, PIR2 and PIR3, which have 5 END CNTL bytes equal to 4.5.6 and 7, respectively (Figure 22b).

By means of the PIROlPIRI, PIR2 and PIR3 messages, the external control unit transmits its priority information via the reverse channel 0.1.2 or 3, respectively, to the central control computer. - In response to the PIR message, the addressed external control unit sends the priority information to the central control computer using a priority information request response (P I RR) message. This PIRR
The messages allow the external control unit to send to the central control computer either the numerical data value for each drop associated with it or any of 256 different messages.

A typical PI, RR message is shown in Figure 22c following the format of Figure 20.

As shown in Figure 22c, the PIRR message is
Contains RECCNTL bytes equal to 0. The level (LVL) byte indicates the threshold level specified in the priority information that the external control unit sends to the central control computer (LVL byte is based on information contained in previously sent PIRWC messages).

After this LVL byte is a control (CTL) byte (matching or numerically less than an already established level). This CTL byte specifies one or more drops associated with the priority information contained in the message by setting bit O-5. CT
Each bit position 0-5 of the L byte is associated with a different drop of the external control unit. For each drop for which the external control unit sends priority information, the external control unit sets the corresponding bit in the CTL byte to '1'. After the CTL byte, up to 6 bytes of data (Dn)
, and each byte represents a given or "cat" priority message.

or the end of the message is 1 normal CRC and FLAG representing the numerical value for each one of the 6 drops specified by the CTL byte and combined into the external control unit.
It's a part-time job.

Various divisions and definitions are used to establish different levels of priority information for the external control unit. For example, levels 0-7 may be obtained from medical monitoring equipment attached to the drop cable of the external control unit. medical information. Similarly, level 16-
23 is combined with the safety information obtained from the safety device attached to the drop of the external control unit. Lower levels, eg, levels 32-39, are used by the external control unit to inform the central control computer of syntax or other errors contained in central control computer messages received by the external control unit. Similarly, information such as external control unit status information, subscriber requests for additional processing, subscriber responses to interactive two-way communication, and other information may be combined with different priority levels.

Describes how a central control computer identifies an unknown external control unit that is responding to a priority processing request. The central control computer identifies an unknown external control unit that has priority information for Identification using classification methods. This binary classification method classifies a group of external control units with sequential addresses ranging from 0 to n as a first group address ranging from 0 to n/2, and a first group address ranging from 0 to n/2;
/ 2 + a second group address ranging from 1 to n.

The central control unit then sends a message to the first group to determine whether the external control units within this first group have priority information. If the first group includes an external control unit (as yet unknown) with priority information, the central control computer divides this first group into a third and fourth group as described above. , now sends a message towards a third group to determine whether an external control unit within this third group has priority information to send. If this third group includes an external control unit having priority order information, the central control unit divides this third group into a fifth and sixth group and repeats the above process. At the time of
5th, etc.) does not have priority information, each of the other groups (2nd, 4th, 61st, etc.) must contain an external control unit that has priority information. The central control computer then sends messages to the group and subdivides it repeatedly, eventually subdividing a group into one external control unit with priority information. As will be apparent to those skilled in the art, in the binary classification method described above, if there are 65,536 (2'') external control units, the number of iterations before searching for an external control unit with priority information is 16 times or less is sufficient.

The messages used by the central control computer in implementing this binary classification method in an embodiment of the invention are shown in Figures 23a-23d.

The central control computer uses the Binary Classification Initialization (BSI) message shown in Figure 23a.

Start searching for an unknown external control unit with priority information. BSI message is 5END equal to 10
(?: NTL byte, followed by two bytes (in the lower and upper parts) specifying the binary sorting upper address (BSHAL and BSHAH) and specifying the binary sorting lower address (BSLAL and BSLAH) (lower and in the upper part).The BSI message has two bytes.

The priority information is sent by the central control computer after receiving the GPR byte via the reverse channel. BSI messages are used by the central control computer to turn off windows of priority information and specify the upper address of a binary classification group, as well as specify the lower address of a binary classification group. No response to this BSI message is expected from any external control unit.

After binary classification is initiated by a BSI message, the central control computer sends a series of binary classification polling messages to search for external control units that have priority information to send. Each binary classification poll message turns off the priority information window and specifies the address range of the binary classification group. Upon receiving a binary classification polling message, an external control unit having priority information within the priority information threshold level and an address within the specified group address range will respond to the binary classification polling message already established by the central control computer. In one embodiment of the present invention, the three binary classification polling messages shown in Figures 23b-23d are used to transmit the GPR bytes to a central control computer via a priority information channel that identifies the binary classification group. A range is defined.

Figure 23b shows the binary classification polling top and bottom (BS
PHL) message. This message is
A boundary room is placed between the lower address and the upper address 2
Used by the central control computer to specify the hexadecimal classification group address range. A BSPHL message has 5 END CNTL bytes equal to 11. Following this 5END CNTL byte,
Two bytes specifying the binary classification high address (BSHAL and BSHAH) and the binary classification low address (BSHAL).
There are two bytes specifying the LAL and BSLAH). An external control unit having priority information within the priority information threshold level and addresses within the lower and upper group address ranges specified in the BSPHL message transmits the GPR byte over a reverse channel of priority information. by responding to a central control computer.

Figure 23c shows a binary sorted polling low level (BSPL) message. 5END CN equal to 12
BSPL messages with TL bytes are
Although it is similar to Message.

BSPL messages specify only binary classified subgroup addresses (BSLAL and BSLAH). This message is used by the central control computer to subdivide the group address range by changing only the lower addresses of the group range. Therefore, B
SPL allows a central control computer to separate a group address range without having to send both the lower and upper addresses of the address range.

An external control unit having priority information within the priority information threshold level and an address that is greater than or equal to the specified lower group address of the BSPL message and less than or equal to the already specified upper group address the central control computer by transmitting a GPR byte over the reverse channel.

Furthermore, FIG. 23d shows the binary classification polling top (BS
PH) indicates a message. This BSPH message contains 5 END CNTL bytes equal to 13. In this message, the two bytes are
Binary classification group upper address (BSHAL and BSH
AH). This message is also used similarly to the BSPL message to subdivide groups by changing only one (ie, upper) group address. An external control unit having priority information within the priority information threshold level and an address that is less than or equal to the group upper address of the BSPH message and greater than or equal to the already specified lower group address sends the reverse channel of the priority information. the central control computer by sending a GPR byte via the central control computer.

4.111 TR other than Σprocessing color polling request or status request? When transmitting information from the central control computer to the external control unit, an information protocol including a handshake sequence is used to provide positive feedback to the central control computer indicating that: That is, (a) the external control unit has received a message. (b) The syntax of the message is appropriate. (C) There are no transmission errors, (d
) External control unit is activated. This handshake sequence does not require sending long format messages and therefore minimizes the time required to handshake with the central control computer.

The handshake response to the information message is the General Polling Response Verification (GPRV), which is
If no GPRV is detected by the central control computer containing one or two l 1111111 J bytes, the central control computer interprets this as the external control unit is inactive. If one bit is received, the central control computer interprets that the message was not accepted by the external control unit. If two bytes are received.

The central control computer interprets the message as being received and processed without error by the external control unit. If a two-byte response is not received, the central control computer makes a predetermined number of attempts (eg, five) before logging the error and notifying the operator.

Although the invention has been described in terms of preferred embodiments thereof, it is understood that various modifications to the embodiments described herein will be apparent to those skilled in the art and are therefore intended to include all modifications that fall within the spirit and scope of the invention. All modifications and variations are intended to be included within the scope of the claims.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a cable television system constructed according to the present invention. FIG. 2 shows a typical subscriber unit (S) of the apparatus of FIG.
Schematic diagram showing U). FIG. 3 is a block diagram showing an analog unit of the device shown in FIG. 1, and FIG. 4 is a schematic block diagram showing a communication unit of the device shown in FIG. Figures 5a to 51 are block diagrams showing the digital unit of the apparatus of Figure 1 as a whole when arranged as shown in Figure 5j; 5 is a circuit diagram of the gate array shown in FIG.
Figures a through 5s are often collectively referred to as Figure 5, Figure 6 is a circuit diagram showing a common power supply unit of the equipment in Figure 1, and Figure 7 is a circuit diagram showing the subscriber processing of the equipment in Figure 1. The block diagram of the unit, FIG. 8, shows the central control computer (CC) of the apparatus of FIG.
C) and a block diagram of the modem; FIGS. 9a and 9b are flowcharts for controlling the flow of the program that controls the operation of the so-called drop processor of the external control unit; FIGS. 10a and 10b are block diagrams of the modem; FIG. 3 is a diagram illustrating the basic message format used in an embodiment of the invention for data communication <y in the forward direction towards an external control unit. FIG. 11 is a diagram illustrating the basic message format used in an embodiment of the invention to communicate data in the reverse direction from an external control unit to a central control computer. FIG. 12 to FIG. 17 show that in the embodiment of the present invention,
Figures 18a to 18h show various messages sent between the central control computer and the external control unit; Figures 18a to 18h show a program for controlling the operation of a so-called data processor of the external control unit in an embodiment of the invention; FIG. 19 is a diagram illustrating the basic message format used in another embodiment of the present invention to communicate data in the forward direction from the central control computer to the external control unit. Figure 20 shows the basic message format used in another embodiment of the invention for data communication in the reverse direction from an external control unit to a central control computer; The figure is a diagram illustrating messages sent between a central control computer and an external control unit in another embodiment of the invention. 10... Cable television system 12... Head end device 14... Cable network ECUI ECU2... External control unit 5UB1.
5UB2...Subscriber's building DROPI, DROP2・
...Drop cable 20...Satellite antenna 22...Satellite receiver 24...Modulator 32...Synthesizer 34...Modem 36...Central control computer (CCC) 50...
Signal connection device 52...Dividing and combining network 54...Analog unit 55...Digital unit 56...Communication unit 60...Common power supply unit 90...Television receiver 100...Converter Tuner 102...Switching device 104...Frequency synthesizer 14Q...Address latch

Claims (38)

[Claims] (1) A cable television system that provides selected television signals to a plurality of remotely located subscriber premises, the cable television system having a head end that generates the television signals and a plurality of remote terminals from the head end. a cable network for directing television signals to locations, each of said remote locations being adjacent to, but external to, each small set of subscriber buildings; comprising external control unit means at each of said remote locations for receiving a television signal from the cable network, and further connected to each external control unit means;
a plurality of drop cables for conducting selected portions of the television signal from the external control unit means to each of the subscriber premises associated with the external control unit means; subscriber equipment means connected to each drop cable for providing the drop cable with a first control signal representative of data to be transmitted to the external control unit means, at least one of the subscriber equipment means being connected to the external control unit means; subscriber processing unit means for enabling the subscriber to supply to the drop cable a first control signal containing channel data representative of the portion of the television signal that the subscriber wishes to select; It is combined,
processing a first control signal sent to all drop cables associated with the external control unit means; and processing a first control signal sent to all drop cables associated with the external control unit means; the first means for causing a portion of the drop cable to supply a portion of the drop cable;
The means is characterized in that it comprises a common signal processing circuit for at least partially processing the information represented by the first control signal sent to all drop cables associated with the external control unit means. cable television system. (2) associated with each external control unit means;
second means for providing a second control signal to each drop cable representing data to be transmitted to the subscriber premises; and a second means associated with each subscriber processing unit means;
Apparatus according to claim 1, further comprising third means for processing the control signal and for receiving and storing data indicated by the second control signal. (3) the subscriber processing unit means includes character display means, the second control signal sent to each drop cable includes character display data, and the subscriber processing unit means receives and stores the received and stored character display data; Claim (2) further comprising fourth means for controlling the character display means based on the character display data instructed by the second control signal in response to the second control signal. equipment. (4) The character display data indicated by the second control signal sent to each drop cable represents a selected portion of the television signal sent to that drop cable by external control unit means. The device described in paragraph (3). (5) fourth means associated with the head end for supplying a third control signal to the cable network representing data to be transmitted to the at least one external control unit means; 3. The apparatus of claim 2, further comprising fifth means for processing the third control signal and for receiving and storing data indicated by the third control signal. (6) associated with each external control unit means;
sixth means for supplying a fourth control signal to the cable network representative of data to be transmitted to the head end, the sixth means being associated with the head end for processing the fourth control signal and for transmitting data as directed by the fourth control signal; 3. A device as claimed in claim 2, further comprising seventh means for receiving and storing the data. (7) associated with each external control unit means;
sixth means for supplying a fourth control signal to the cable network representative of data to be transmitted to the head end, the sixth means being associated with the head end for processing the fourth control signal and for transmitting data as directed by the fourth control signal; 6. The apparatus as claimed in claim 5, further comprising seventh means for receiving and storing said data. (8) The fifth means associated with each external control unit means includes eighth means for generating address signal information uniquely identifying the external control unit means, and the third control signal is configured such that the third control signal The fifth means includes address signal data representative of at least one external control unit means to be transmitted and is associated with each external control unit means for transmitting received address signal data and address signal information associated therewith. Ninth means for comparing, the fifth means being directed by the third control signal if the received address signal data has a predetermined relationship to the address signal information associated therewith. 5. A device according to claim 5, wherein the device is adapted to store stored data. (9) said ninth means associated with each external control unit means causes said fifth means to transmit the data indicated by the third control signal if the received address signal data matches the address signal information associated therewith; Device according to claim 8, which enables storage. (10) said third control signal includes broadcast address signal data representative of all external control unit means, and said fifth means associated with each external control unit means comprises a tenth control signal for identifying broadcast address signal data; Claim 5 further comprises means for enabling the fifth means to store the data indicated by the third control signal if the received broadcast address signal data is verified. The device described. (11) said third control signal includes channel grant data representing a portion of the television signal from which at least one subscriber associated with said external control unit means is authorized to select; The related fifth means provides that the portion of the television signal is received over the drop cable only if the stored channel authorization data indicates that the subscriber associated with the drop cable is authorized to receive that portion of the television signal. Claim 5 further comprising eleven means for causing said external control unit means to supply to each said drop cable a portion of the television signal directed by said first control signal channel data. The device described. (12) The third control signal provides a link between each portion of the television signal that can be selected by the subscriber and the channel data indicated by the first control signal used to select each portion of the television signal. The fifth means includes channelization data representative of the desired correlation and is associated with each external control unit means responsive to the channelization data and directed by a first control signal channel data transmitted via the drop cable. Apparatus as claimed in claim 5, comprising twelfth means for causing the external control unit part to supply a correlated portion of the television signal obtained to each respective drop cable. (13) said third control signal includes forced tuning data representative of a portion of the television signal to be transmitted to the subscriber's premises; said fifth means associated with each external control unit means responsive to said forced tuning data; and thirteenth means for causing said external control unit means to supply said drop cable with a portion of said television signal indicated by said forced tuning data.
Equipment described in Section. (14) said second means associated with each external control unit means comprises fourteenth means for causing said second means to provide a second control signal to said drop cable in response to forced tuning data; The second control signal sent to each drop cable includes television on/off data, and the subscriber processing unit means is responsive to the second control signal to receive television reception based on the television on/off data. The apparatus according to claim 13, further comprising fifteen means for controlling on/off operation of the machine. (15) The fifth means associated with each external control unit means includes a sixteenth means for storing data at one or more storage addresses, and the third control signal is transmitted to the storage address of the external control unit means. , and associated with each external control unit means, the fifth means includes storage address data representative of the storage address data indicated by the third control signal. 9. Apparatus according to claim 8, further comprising seventeenth means for causing the sixteenth means to store data indicated by said second control signal. (16) said first control signal includes data representative of information to be transmitted from subscriber equipment means to a head end, said first means associated with each external control unit means being configured to eighteenth means for receiving and storing directed information, said third control signal comprising read data representing a request to transmit information stored in said eighteenth means to a head end; Said sixth means associated with control unit means are responsive to said third control signal such that said sixth means is capable of providing a fourth control signal to the cable network comprising data representative of said stored information. The apparatus according to claim (6), comprising nineteenth means for: (17) said first control signal includes data representative of information to be transmitted to a head end, said first means associated with each external control unit means transmitting information to all external control unit means associated with said external control unit means; a twentieth means for accumulating and storing information indicated by the first control signal sent to the drop cable; said third control signal transmitting the information accumulated and stored in said twentieth means to the head end; The sixth means is associated with the external control unit means for transmitting data representative of the accumulated and stored information in response to the transmitting function data of the third control signal. 7. Apparatus as claimed in claim 6, comprising twenty-first means for enabling said sixth means to supply a fourth control signal comprising a fourth control signal to the cable network. (18) The first control signal includes data representing a request to view a pay-view program event, and the third control signal includes a pay-view program event and a television signal corresponding to the pay-view program event. and said fifth means associated with each external control unit means includes pay-per-view program event data representative of a transmission with a portion of said third control signal. providing a portion of the television signal indicated by the third control signal to each such drop cable if the pay-per-view program event indicated by the control signal matches the pay-per-view program event request of the first control signal; An apparatus according to claim (5), comprising twenty-second means such as. (19) In a cable television system that transmits television signals from a head end to a plurality of remote locations via a cable network, and also transmits other signals between the head end and the plurality of remote locations, means at each remote location for receiving a television signal from a cable network, and further coupled to the head end, a first control signal representative of data to be transmitted to the at least one said receiving means. a first means for providing a signal to a cable network, wherein at least a portion of the first control signal is representative of a particular one of a plurality of reverse channel frequency bands; and second means for processing the first control signal and providing a second control signal to the cable network in one of a plurality of reverse channel frequency bands representing data to be transmitted to the head end. and wherein the second means, in response to the first control signal, provides a second control signal in a reverse channel frequency band indicated by the first control signal. (20) each remote location is adjacent to, but external to, each set of subscriber buildings, and the receiving means comprises external control unit means, and the cable television system further comprises: a plurality of drop cables connected to the control unit means, each drop cable transmitting a selected portion of the television signal from the external control unit means to each of the subscriber premises associated with the external control unit means; conduction and further connected to the drop cable in at least one subscriber premises to enable the subscriber to provide a third control signal to the drop cable representing a portion of the television signal that the subscriber wishes to select. subscriber processing unit means, and further for processing a third control signal coupled to each external control unit and sent to all drop cables associated with that external control unit; processing means for causing the external control unit means to supply to each such drop cable a portion of the television signal directed by the external control circuit means; Cable television system according to claim 19, comprising a common signal processing circuit for at least partially processing the information represented by the third control signal sent to the cable television system. (21) transmitting television signals from a head end to a plurality of remote locations via a cable network, as well as transmitting other signals between the head end and a plurality of remote locations, each remote location having a set of In a cable television system that is located adjacent to, but external to, a subscriber building, each remote location comprises addressable external control unit means for receiving television signals from the cable network. and further comprising a plurality of drop cables connected to each external control unit means, each drop cable transmitting a television signal from the external control unit means to each of the subscriber premises associated with the external control unit means. connected to each drop cable at the subscriber's premises, the subscriber transmits a first control signal to the drop cable representing the portion of the television signal to be selected by the subscriber. subscriber processing unit means for providing a subscriber processing unit, and further associated with each external control unit means;
processing a first control signal sent to all drop cables associated with the external control unit means; and processing a first control signal sent to every drop cable associated with the external control unit means; comprising first means for causing a portion of the signal to be supplied to each such drop cable, said first means being represented by a first control signal sent to all drop cables associated with said external control unit means; a common signal processing circuit for at least partially processing the information transmitted to the cable; second means for providing to the network, at least a portion of the second control signal representing an address of the external control unit means, and further associated with each external control unit means;
third means for processing the second control signal to receive and store data indicated by the second control signal when the second control signal is addressed to the external control unit means; combined with an external control unit means;
In response to said third means, said external control unit means said second
A cable television system comprising handshaking means for supplying a response signal indicating whether a control signal has been received without error to a cable network for transmission to a head end. (22) A cable television system that transmits television signals from a head end to multiple subscriber premises via a cable network, as well as transmitting other signals between the head end and multiple subscriber premises. a polling signal means associated with the head end for supplying a polling signal to the cable network, and further comprising external control unit means located at a plurality of remote locations, each location having a small assembly. adjacent to, but external to, a subscriber building, said external control unit means receiving television signals and polling signals from said cable network; a plurality of drop cables connected to each external control unit means for conducting selected portions of the television signal to each of the subscriber premises associated with the means; comprising subscriber processing unit means connected to the cable, the subscriber processing unit means enabling the subscriber to supply control signals to the drop cable representing information to be transmitted to the external control unit means; , said information including information indicative of the portion of the television signal that the subscriber wishes to select and information to be transmitted to the head end, and further associated with an external control unit, said external control unit means receives and stores information directed by control signals sent to all associated drop cables, and provides each drop cable with a portion of the television signal directed by television signal selection information received via that drop cable; and further associated with each external control unit means for processing the received polling signal and responsively causing said external control unit means to control the head end. A cable television system, characterized in that it comprises means for processing a polling signal for supplying a response signal to the cable network to transmit to the head end, indicating whether it has information to transmit. (23) The polling signal includes address signal data representing the external control unit means to which the polling signal is to be sent, and the polling signal processing means further includes address signal information uniquely identifying the external control unit means. the polling signal processing means compares the received address signal data with the address signal information, and when the received address signal data holds a predetermined relationship with the address signal information, the polling signal processing means receives the polling signal; 23. The cable television system according to claim 22, further comprising means for causing the cable television system to respond to a polling signal sent to the television. (24) The external control unit means is a head
means for associating a level of importance to the information to be transmitted to the head end, said polling signal means associated with the head end being indicative of the level at which said external control unit means should respond to the polling signal received; The polling signal processing means includes means for supplying response threshold level signal data to the cable network and is associated with each external control unit means so that the external control unit means receives the received threshold level signal data from the head. The external control unit means determines when the level of information to be sent to the head end has a predetermined relationship to the receive response threshold level signal data compared to the level of information to be sent to the head end. Claim (23) further comprising means for enabling the polling signal processing means to transmit to the head end a response signal indicating that the polling signal processing means has information to be transmitted to the head end. Cable television system as described. (25) The external control unit means is a head
means for associating a level of importance to the information to be transmitted to the end, said polling signal means associated with the head end being means for providing a signal to the cable network for establishing a priority information window in the cable network; , the priority information window signal includes priority response threshold level signal data representing a priority information level at which the external control unit means should respond to the polling signal; The external control unit means receives the priority information window signal and stores the priority response threshold level signal data, and the external control unit means receives the priority response threshold level signal data.
said external control unit means when the information to be transmitted to the head end has a predetermined relationship to the priority response threshold level signal data compared to the level of information to be transmitted to the head end; 24. A cable television system as claimed in claim 23, comprising means for causing said associated polling signal processing means to be responsive to received polling signals. (26) In a two-way cable television system in which television signals and other signals are transmitted over a cable network from a head end to addressable terminal equipment at a plurality of remote locations, the terminal equipment associated with the head end; first means for transmitting a polling signal to the addressable terminal device including an address of the addressable terminal device; second means associated with the terminal device for storing information and assigning a level of importance to the stored information; , a third means associated with the head end for transmitting a threshold level control signal to the terminal device representing a threshold level at which the terminal device should transmit information to the head end; fourth means for receiving the threshold level control signal and comparing the level of information stored in the terminal device with a threshold level indicated by the threshold level control signal; In response to a received polling signal addressed to a terminal device, the terminal device determines whether the terminal device is connected to the head end if said level of information has a predetermined relationship to a threshold level indicated by said threshold level control signal. and fifth means for transmitting a response signal to the head end indicating that the head end has information to transmit. (27) In a two-way cable television system in which television signals and other signals are transmitted over a cable network from a head end to addressable terminal equipment at a plurality of remote locations, first means for transmitting a polling signal to the addressable terminal device including an address of the addressable terminal device; second means associated with the terminal device for storing information and assigning a level of importance to the stored information; , a third means associated with the head end for transmitting a priority information control signal to the terminal device representing a priority threshold level at which the terminal device should transmit information to the head end; fourth means for receiving the priority information control signal and comparing the level of information stored in the terminal device with a priority threshold level indicated by the priority information control signal; 4 means, and in response to the received polling signal, the terminal device transmits the information to the head end if the level of information has a predetermined relationship to the priority threshold level indicated by the priority information control signal. a fifth sending a response signal to the head end indicating that it has information to send to the head end;
A two-way cable television system comprising means. (28) the priority information control signal includes data representative of a particular one of a plurality of reverse channels that can be used to transmit information from the terminal device to the head end, and the terminal device: Claim 27, further comprising sixth means for transmitting, in response to the priority information control signal, a response signal on a particular reverse channel indicated by the priority information control signal data. cable television system. (29) In a cable television system that transmits television signals from a head end to a plurality of remote locations over a cable network, each remote location being adjacent to a selected set of subscriber premises; External thereto, the system comprises external control unit means at each remote location for receiving television signals from the cable network, and further comprising a plurality of droplets connected to the at least one external control unit means. a cable, each drop cable conducting a selected portion of the television signal from the external control unit means to each of the subscriber premises associated with the external control unit means; subscriber equipment means connected to the external control unit means for providing a processing request signal to the drop cable indicative of a request to communicate with the external control unit means; sensing the presence of the processing request signal in a predetermined order in the cable;
A cable television system characterized in that it comprises drop polling means for enabling the external control unit means to rapidly search for drop cables from which the subscriber equipment means are issuing communication requests with the external control unit means. . (30) The cable television set according to claim 29, wherein the drop polling means comprises multiplexer means for selectively connecting the drop polling means to each drop cable connected to the external control unit means. john system. (31) responsive to drop polling means coupled to the external control unit means and sensing a processing request signal on the drop cable for providing a first control signal to the drop cable including data representative of an address of the subscriber equipment means; and address means associated with each subscriber equipment means for generating address signal information uniquely identifying the subscriber equipment means on the drop cable to which the subscriber equipment means is connected; transmitting means, associated with each subscriber equipment means, for supplying a second control signal to the drop cable representing data to be transmitted to the external control unit means; 1 control signal, compares the received address signaling data with the address signaling information, and if the received address signaling data has a predetermined relationship to the address signaling information, the subscriber equipment means is coupled to the subscriber equipment means; A cable television system according to claim 29, further comprising means for enabling said transmitting means to transmit a second control signal. (32) a plurality of subscriber device means are connected to the same drop cable, and the device polling means comprises means for providing a plurality of first control signals to the drop cable in a predetermined order;
32. The cable television system of claim 31, wherein each first control signal includes address data representing each subscriber device connected to the drop cable. (33) at least one of the subscriber equipment means is configured to enable the subscriber to communicate to the external control unit means a second control signal representing a portion of the television signal that the subscriber wishes to select; 33. A cable television system according to claim 32, wherein the cable television system is a subscriber processing unit means for providing a subscriber processing unit. (34) In a cable television system that provides selected television signals to a plurality of remotely located subscriber premises via a cable network, a head that transmits the television signals to the plurality of remote locations;
end means, each remote location being adjacent to, but external to, each sub-set of subscriber premises and further connected to the cable network at each remote location for receiving a television signal; external control unit means comprising a plurality of drop cables connected to each external control unit means, the external control unit means comprising a slave cable terminal to which a television signal is supplied from the cable network; Each drop cable conducts a selected portion of the television signal from the external control unit means to each of the subscriber premises associated with the external control unit means, and is further connected to each drop cable at the subscriber premises. and comprising subscriber processing unit means associated with each external control unit means for enabling the subscriber to supply the drop cable with a first control signal representative of a portion of the television signal that the subscriber wishes to select. processing a first control signal sent to all drop cables associated with the external control unit means and transmitting a portion of the television signal directed by the first control signal received via the drop cable to the external control unit; means for causing each said drop cable to receive information represented by a first control signal sent to all drop cables associated with said external control unit means. slave external control unit means including a common signal processing circuit for at least partially processing the slave external control unit means, and further connected to a slave cable terminal of one of the external control unit means,
A cable television system comprising slave external control unit means for supplying selected portions of the television signal to further subscriber processing unit means associated therewith. (35) In a cable television system that provides selected television signals to a plurality of remotely located subscriber premises via a cable network, a head that transmits the television signals to a plurality of remote locations;
an end means, each remote location being adjacent to, but external to, each sub-set of subscriber premises, further comprising an external control at each remote location for receiving a television signal from the cable network; unit means, and a plurality of drop cables connected to each external control unit means, each drop cable connecting a television from the external control unit means to each of the subscriber premises associated with the external control unit means. a first control signal connected to each drop cable at the subscriber's premises and representing a first portion of the television signal to be selected by the subscriber; a second portion of the television signal for selection by the subscriber, the second portion being connected to the drop cable in at least one subscriber premises and representing a second portion of the television signal to be selected by the subscriber; slave subscriber processing unit means for enabling the subscriber to provide control signals to the drop cable, and further comprising means associated with each external control unit means associated with the external control unit means. processing the first and second control signals sent to the drop cable;
causing the external control unit means to supply to each such drop cable in a first predetermined channel a portion of the television signal directed by a first control signal received via the drop cable; means for causing the drop cable associated with the slave subscriber processing unit means to supply, in a second predetermined channel, a portion of the television signal directed by the second control signal received via the slave subscriber processing unit means; the first means includes a common signal processing circuit for at least partially processing information represented by the first and second control signals sent to all drop cables associated with the external control unit means; A cable television system featuring (36) A cable television system providing selected television signals to a plurality of remotely located subscriber premises, comprising a head end for transmitting the television signals, and further comprising a plurality of cables connected in parallel. a cable network with each cable conducting a separate portion of the television signal from the head end means to a plurality of remote locations, each remote location being adjacent to a respective small set of subscriber buildings; external control unit means located at each remote location and connected to each of the plurality of cables to receive television signals from the cable network; a plurality of subscriber unit means associated with the unit means, each subscriber unit means receiving a selected number of television signals from the external control unit means to each of the subscriber premises associated with the external control unit means; and further connected to each drop cable at the subscriber's premises to provide the subscriber with a control signal representative of the portion of the television signal to be selected by the subscriber. subscriber processing unit means adapted to supply the cable and further associated with each subscriber unit means for selectively connecting each subscriber unit means to one of the plurality of cables of the cable network; cable selection means, further comprising: first means associated with each external control unit means for processing a first control signal sent to all drop cables associated with that external control unit means; first means for causing each subscriber unit means to supply to each such drop cable a portion of the television signal directed by a first control signal received via the drop cable; a common signal processing circuit for at least partially processing information represented by a first control signal sent to all drop cables associated with the control unit means, and further comprising a second signal processing circuit responsive to said first means. means, each cable selection means connecting its respective subscriber unit means to a cable carrying a portion of the television signal including the portion of the television signal indicated by the first control signal received via the drop cable; A cable television system characterized by comprising second means for causing. (37) In a cable television system that provides selected television signals to a plurality of remotely located subscriber premises via a cable network that includes a frequency band for reverse communication to a head end. The head that transmits the television signal
an end means, each remote location being adjacent to, but external to, each sub-set of subscriber premises, further comprising an external control at each remote location for receiving a television signal from the cable network; unit means, and further comprising a plurality of drop cables connected to each external control unit means, each drop cable connecting from the external control unit means to each of the subscriber premises associated with the external control unit means. a selected portion of the television signal at the subscriber's premises;
and subscriber processing unit means for enabling the subscriber to provide a first control signal to the drop cable for transmission to the drop cable; first means for processing a first control signal sent to all drop cables associated with the external control unit means to control the television signal as directed by the first control signal received via the drop cable; first means for causing the external control unit means to supply a portion to each such drop cable and for transmitting to the head end a signal comprising subscriber data indicated by the first control signal; The first means includes a common signal processing circuit for at least partially processing the information represented by the first control signal sent to all drop cables associated with the external control unit means; second means connected to each drop cable in the subscriber's premises for enabling the subscriber to provide the drop cable with a second control signal containing data to be transmitted from the subscriber's premises to the head end; and further coupled to each external control unit means and connected to each drop cable and cable network for transmitting a second control signal in a frequency band comprising a portion of the total frequency band available in the cable network for reverse communication. third means are provided to enable direct transmission to the head end via the external control unit means and to minimize the ingress of signals through the cable network from the drop cable that would interfere with the transmitted subscriber data signals. A cable television system characterized by: (38) The device according to claim 37, wherein the third means comprises a bandpass filter.