JPH08294107A - Television common viewing system - Google Patents

Abstract

PURPOSE: To attain ciphering control of an optional channel such as an optional floor from other location such as a supervisor's room. CONSTITUTION: A head end device 1 for television common viewing rebroadcast receives a video signal carrier from various signal sources or the like by a television receiver 2, converts the frequency and a mixer 3 mixes the frequency and the frequency is distributed to each floor by one trunk cable C1. A control signal from a ciphering central controller 4 is sent on the same trunk line cable C1 by a frequency different from the video signal carrier. A distributer 5 is arranged to a location corresponding to each floor of the trunk line cable and the signal is delivered to each room via a branch cable C2 and distributed to a television receiver 8 by a distributer 7 of each room. A ciphering control terminal equipment 6 comprising a trap filter or the like is installed to a branch point of the branch cable and a ciphering central controller 4 selects an optional channel of an optional floor and a specific channel of a specific floor is ciphered by inserting the trap filter of the ciphering control terminal equipment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television co-listening system which can be used in a complex building or the like used by a plurality of companies and which can control confidential talk from a distant place.

[0002]

2. Description of the Related Art As a conventional encryption technique, there is a technique of inserting a scrambler circuit in a head end device on the television co-listening retransmission side to make a specific channel confidential. However, this method has a problem in that the target of the secret story is fixed and the secret story control of any channel on any floor cannot be performed.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and makes it possible to secretly control an arbitrary channel such as an arbitrary floor from another place such as a control room. is there.

[0004]

A control means for inserting or not inserting a trap filter and a trap filter at a branching destination of each distribution cable, and a centralized control means capable of controlling the control means from another distant specific place. By providing whether or not each trap filter is inserted from a specific place, confidential channel control such as confidentializing or desecuring any channel at any branch destination is performed.

A control signal from a specific location of the centralized control means to each trap filter is transmitted by being frequency-separated from a television signal and superposed on a distribution cable.

The transmission of the control signal from a specific location of the centralized control means to each trap filter is a PSK (pulse shift keying) signal modulated with a digital signal.

Control of whether to insert the trap filter is performed by switching the electromagnetic relay.

Control of whether to insert the trap filter is performed by changing the bias voltage of the switching diode.

The trap filter is composed of a variable capacitance diode and a coil. Whether or not to insert each trap filter is controlled by changing the polarity of the bias voltage of the variable capacitance diode.

A remote control means for the attenuation frequency of the trap filter is provided, and the same trap filter switches and controls the confidential channels.

The trap filter is composed of a variable capacitance diode whose capacitance changes with an applied voltage and a coil, and digitizes and transmits the voltage corresponding to the applied voltage of the variable capacitance diode which gives an attenuation frequency from a specific location to transmit a secret channel. Switch.

The secret control terminal including a trap filter also serves as a booster for the television signal.

[0013]

The trap filter and the control means for inserting the trap filter at the branching destination of each distribution cable, and the centralized control means for controlling the control means from another specific place are provided. By controlling whether to insert or not, and by performing confidential control such as confidentializing or desecuring any channel at any branch destination, only the necessary channel at a specific place can be secured from a distant place. It becomes possible.

The control signal from a specific location of the centralized control means to each trap filter is transmitted by superposing it on the distribution cable by frequency-separating the television signal and superimposing it, so that a low power consumption and high quality can be achieved without providing a separate transmission line. Various transmission means can be obtained.

The control signal can be transmitted efficiently by using a PSK (pulse shift keying) signal modulated by a digital signal to transmit the control signal from a specific location of the centralized control means to each trap filter.

The control as to whether or not to insert the trap filter is performed by switching the electromagnetic relays to provide a simple confidential channel control means for a plurality of channels.

Control of whether or not to insert the trap filter is performed by changing the bias voltage of the switching diode, whereby a highly reliable and long-life secret control means for a plurality of channels can be obtained.

The trap filter is composed of a variable capacitance diode and a coil, and whether or not each trap filter is inserted is controlled by changing the polarity of the bias voltage of the variable capacitance diode. The secret control means of can be obtained.

By providing the remote control means for the attenuation frequency of the trap filter and switching and controlling the confidential channels with the same trap filter, a small number of trap filters can deal with the confidential control of all channels.

The trap filter is composed of a variable capacitance diode whose capacitance changes with applied voltage and a coil, and digitizes and transmits the voltage corresponding to the applied voltage of the variable capacitance diode which gives an attenuation frequency from a specific location to transmit the secret channel. By switching, reliable channel switching means can be obtained.

The secret-talk control terminal including a trap filter and the like also serves as a booster for the television signal, so that the amplifier necessary for compensating the insertion loss of the trap filter also serves as a booster, which is economical.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A television co-listening system according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram of a television co-listening system according to the present invention. In the television co-listening rebroadcast headend device 1 installed in the management room of the complex building, the television receiver 2 receives the video signal carrier from various television signal sources such as CS, BS, and terrestrial waves. Frequency conversion, mixing with mixer 3 and one main cable C1
Will be delivered to each floor. On the other hand, the control signal from the confidential talk centralized controller 4 is transmitted on the same main line cable C1 by the mixer 3 on a frequency different from the video signal carrier. The distributors 5, 5, ... Are arranged at locations corresponding to the respective floors of the main cable, and distributed to each room on each floor by the branch cable C2 on each floor. There are distributors 7, 7, ... In each room, and distribute signals to the television receiver 8. At the place where the branch cable on each floor branches, a confidential talk control terminal 6 including a trap filter,
Install 6 ... By selecting an arbitrary channel on an arbitrary floor from the confidential talk centralized controller 4 of the headend device 1 and inserting a trap filter of the confidential talk control terminal, a specific channel on a specific floor can be made secret. It is also possible to make an arbitrary room secret by providing a secret control terminal for each room.

FIG. 2 is a block diagram of the confidential talk centralized controller 4 and the confidential talk control terminal 6 of an embodiment of the television co-listening system according to the present invention. In the secret control unit 4, the keyboard 41
In accordance with the guidance displayed by the MPU 42 on the monitor display unit 43 by the confidential communication centralized control processing unit 44, the location (the number of floors, etc.) to be the confidential control, the confidential channel or the confidential channel release, the confidential channel to be controlled, etc. are input. The MPU 42 uses the input data in accordance with the confidential talk centralized control processing unit 44 as a start code indicating the start of the control signal of the confidential talk control terminal, the ID code of the confidential talk control terminal corresponding to the confidential talk control target location (floor, etc.),
Convert to each code such as ON / OFF code indicating confidentialization or confidentiality cancellation, confidential control target channel number code, etc.
SIO (asynchronous serial input / output) interface 45
To serial data, and the PSK (pulse shift keying) modulator 46 puts it on the carrier frequency oscillated by the oscillator 47, mixes it with other TV carrier waves in the mixer 3, and secretly passes through the cable C1, the distributor 5, and the cable C2. It is transmitted to the control terminal 6. In the confidential talk control terminal 6, the separator 61
The carrier frequency of the confidential control signal is frequency separated, and the PSK decoder 62 converts it into a serial digital confidential control signal. The serial signal is converted into a parallel signal by the ASIO interface 63 according to the confidential control terminal processing unit 65, and the MPU 64
Take in. The MPU 64 monitors the start code and ID code of the same signal, and when they match the ID of the terminal set in advance on the DIP switch 66, decodes the subsequent on / off code and channel number code, According to the same code, the trap filters 68, 6 are set in the trap control unit 67 and correspond to each channel.
.. is controlled by the control signal C5 to achieve the intended purpose. In this case, confidential talk control can be performed simultaneously for the same number of channels as the number of trap filters.

FIG. 3 is a block diagram of the trap filter 68 of one embodiment of the television co-listening system according to the present invention. A resonance circuit 301 composed of a coil (L) and a capacitor (C) having a constant that becomes a trap frequency corresponding to the frequency of a predetermined channel is inserted in series in the branch cable C2, and an electromagnetic relay switch 302 is connected in parallel with this. To do. By turning on / off this electromagnetic switch with the trap filter control signal C5, it is possible to control the confidentiality and the confidentiality cancellation of the television signal of the channel number corresponding to the resonance frequency of the resonance circuit.

FIG. 4 is a block diagram of a trap filter 68 of another embodiment of the television co-listening system according to the present invention. A resonance circuit 401 composed of a coil (L) and a capacitor (C) having a constant that becomes a trap frequency corresponding to a frequency of a predetermined channel is inserted in series in the branch cable C2, and a DC stop capacitor 402 is connected in parallel with the branch circuit C2.
A switching diode 403 is connected via 402. By biasing the switching diode 403 forward / reverse bias with the trap filter control signal C5 to turn it on / off, it is possible to control whether the television signal of the channel number corresponding to the resonance frequency of the resonance circuit is kept secret or released. It will be possible. Switching diode 403
The forward / reverse bias of is performed as follows, for example. Connect one end of the switching diode to the DC power supply line C
The DC voltage supplied from 41 is divided by resistors 408 and 409 to be a constant voltage. The other end of the switching diode is connected to the trap filter control signal C5 and the voltage dividing resistor 404.
And switching transistor 406 driven by 405
Since the additional resistance 407 raises and lowers the voltage of approximately C41 and the ground voltage, the switching diode 403 is biased in the forward direction or the reverse direction.

FIG. 5 is a block diagram of a trap filter 68 of still another embodiment of the television co-listening system according to the present invention. Coil (L) 501 and stop capacitor 5
A variable capacitance capacitor (varactor diode) connected in parallel via 02 forms a resonance circuit, and this varactor diode is reverse-biased with a specific voltage to adjust the capacitance, and a trap frequency corresponding to the frequency of a predetermined channel is obtained. Have a constant. The reverse bias of the varactor diode is achieved, for example, by turning on the transistor 506 connected to one end to the ground potential and setting the other end to a constant voltage obtained by dividing the DC voltage supplied from the DC power supply line C41 by the resistors 508 and 509. You can do it. At this time, the channel is in a secret state. On the other hand, this varactor diode 503
Is forward-biased with the trap filter control signal C5, the resonance circuit is short-circuited, and the secret channel is released. The forward bias of the varactor diode 503 can be performed by turning off the switching transistor 506 to a voltage of approximately C51 by the trap filter control signal C5, the switching transistor 506 driven by the voltage dividing resistors 504 and 505, and the additional resistor 507. .

Another embodiment of the television co-listening system according to the present invention is as follows. In FIG. 2, in the confidential story centralized controller 4, according to the guidance displayed on the monitor display section 43 by the MPU 42 from the keyboard 41 according to the confidential story centralized control processing section 44, the location (floor number etc.) to be confidentially controlled, the confidentialization or the confidentiality cancellation. Separately, input the channel for confidential talk control. The MPU 42 shows the input data according to the confidential talk centralized control processing unit 44, a start code indicating the start of the control signal of the confidential talk control terminal, the ID code of the confidential talk control terminal corresponding to the confidential talk control target place (floor etc.), and the confidential talk or the confidential talk release. The ON / OFF code, the trap filter number code, and the voltage corresponding to the secret control target channel of the trap filter are converted into each code of the digitized signal, and converted into serial data by the ASIO (asynchronous serial input / output) interface 45, The carrier frequency oscillated by the oscillator 47 is added by the PSK (pulse shift keying) modulator 46, mixed with other TV carrier waves by the mixer 3, and transmitted to the confidential communication control terminal 6 via the cable C1, the distributor 5, and the cable C2. To do. In the confidential control terminal 6, the separator 61 frequency-separates the confidential control signal carrier, and the PSK decoder 62 converts the carrier into a serial digital confidential control signal.
The serial signal is converted into a parallel signal by the ASIO interface 63 in accordance with the confidential control terminal processing unit 65 and MP
Capture to U64. The MPU 64 monitors the start code and ID code of the same signal, and when they are preset in the DIP switch 66 and match the ID of the terminal, the subsequent ON / OFF code, trap filter number code,
Each code of the channel number code is decoded and set in the trap control unit 67 according to the trap filter number code to select each trap filter 68, 68, .... On the other hand, the signal code obtained by digitizing the voltage corresponding to the confidential control target channel is converted into an analog voltage by the digital / analog converters 69, 69, ... And applied to one end of the varactor diode in FIG. 6 and connected to the other end. The resonance frequency with the coil 601 is set to the frequency of a predetermined channel by turning on 606 and setting it to the ground potential. At this time, the channel is kept secret. On the other hand, by forward biasing the varactor diode 603 with the trap filter control signal C5, the resonance circuit is short-circuited and the confidentiality of the channel is released. The forward bias of the varactor diode 603 is the trap filter control signal C5, the switching transistor 606 driven by the voltage dividing resistors 604 and 605, and the additional resistor 6 thereof.
07, the switching transistor 606 is turned off and the voltage is set to approximately C51. In this case, confidential channel control can be performed simultaneously for the number of channels of the trap filter, and the confidential channel control of the number of channels corresponding to the type of voltage corresponding to the confidential channel control target channel of the trap filter can be switched.

Another embodiment of the television co-listening system according to the present invention is such that an amplifier 70 is inserted in series with a branch cable C2 in FIG. 2 and trap filters 68, 68 ,.
In addition to compensating the insertion loss of the cable C1, the loss of the cables C1 and C2 is also compensated. This eliminates the need to install a separate booster.

[0029]

As described above, by inserting the trap filter which can be controlled from a remote place into the branch cable of the television co-listening system, the location and the channel to be made secret can be set from the head end of the television co-listening system. Since it can be controlled, it is possible to control the confidential talk of a specific channel in a specific range. Therefore, for example, in a complex building or the like in which a plurality of companies live, a CATV system can be constructed only within each company in the co-listening system.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a television co-listening system according to the present invention.

FIG. 2 is a block diagram of a confidential talk centralized controller and a confidential talk control terminal of an embodiment of a television co-listening system according to the present invention.

FIG. 3 is a block diagram of a trap filter of an embodiment of a television co-listening system according to the present invention.

FIG. 4 is a block diagram of a trap filter of another embodiment of the television co-listening system according to the present invention.

FIG. 5 is a block diagram of a trap filter of still another embodiment of the television co-listening system according to the present invention.

FIG. 6 is a block diagram of a trap filter of still another embodiment of the television co-listening system according to the present invention.

[Explanation of symbols]

 1 Head-end device 2 Television receiver 3 Mixer 4 Secret communication central control device 5 Distributor 6 Secret communication control terminal 7 Distributor 8 TV receiver C1 Main cable C2 Branch cable 41 Keyboard 42 MPU 43 Monitor display unit 44 Secret communication central processing unit 45 ASIO interface 46 PSK encoder 47 Oscillator 61 Separator 62 PSK decoder 63 ASIO interface 64 MPU 65 Secret terminal control processing unit 66 DIP switch 67 Trap controller 68 Trap filter 69 Digital / analog converter 70 Amplifier 301 Resonance circuit 302 Electromagnetic Switch 401 Resonant circuit 402 Capacitor 403 Switching diode 404 Resistor 405 Resistor 406 Transistor 407 Resistor 408 Resistor 409 Resistor 501 Coil 502 Capacitor 503 varactor diode 504 resistance 505 resistance 506 transistor 507 resistance 508 resistance 509 resistance 601 coil 602 capacitor 603 varactor diode 604 resistance 605 resistance 606 transistor 607 resistance

Claims (9)

[Claims] 1. In a television common listening system, a trap filter and a control means for inserting / not inserting the trap filter at a branch destination of each distribution cable, and a centralized control means capable of controlling the control means from another specific place. A television co-listening system that is equipped with a trap location and controls the insertion / non-insertion of each trap filter to control the confidential talk of an arbitrary channel at an arbitrary branch destination and the secret talk control of canceling the secret talk. 2. The television co-listening system according to claim 1, wherein a control signal from a specific location of the centralized control means to each trap filter is transmitted by being frequency-separated and superimposed on a television signal on a distribution cable. . 3. The PSK (Pulse Shift Keying) signal modulated by a digital signal is used for transmitting the control signal from a specific location of the centralized control means to each trap filter. Television co-listening system. 4. The television co-listening system according to claim 1, wherein the control of insertion / non-insertion of the trap filter is performed by switching an electromagnetic relay. 5. The television co-listening system according to claim 1, wherein the control of insertion / non-insertion of the trap filter is performed by changing a bias voltage of a switching diode. 6. The trap filter comprises a variable capacitance diode and a coil, and insertion / non-insertion control of each trap filter is performed by changing the polarity of the bias voltage of the variable capacitance diode. The television co-listening system according to claim 1, claim 2 or claim 3. 7. A television co-listening system according to claim 6, further comprising remote control means for controlling the attenuation frequency of the trap filter, wherein the same trap filter controls and switches the confidential channels. 8. The trap filter is composed of a variable capacitance diode and a coil whose capacitance changes according to an applied voltage, and digitizes a voltage corresponding to the applied voltage of the variable capacitance diode which gives an attenuation frequency from a specific location and transmits the digitized data to make it confidential. 8. The television co-listening system according to claim 7, wherein the channels are switched. 9. The secret control terminal comprising a trap filter or the like also functions as a booster for a television signal, claim 1, claim 2, claim 3, claim 4, claim 5, claim 6, claim 6. The television co-listening system according to claim 7 or claim 8.