JPS61145982A - Television signal transmission-reception system - Google Patents

Abstract

PURPOSE:To make it possible to receive polling signals always during a business hour of a broadcasting center superimposingly polling signals by transmitting superimposingly polling signals during a broadcasting center perpendicular blanking period and by switching a reception channel with other channel automatically, when a subscriber terminal is unable to receive the above signals correctly. CONSTITUTION:The polling signals POL are transmitted superimposingly during all channel TV signals perpendicular blanking period. When a broadcasting wave of a channel A stops during a receiving hour of the channel A, a selective controller 25 detects its wave stopping because of failing in receiving a synchrolizing signal extracting signal SYNC and AFT signal AFT. Once its stopping hour exceeds a prescribed hour, the selective controller 25 gradually switches a dividing ratio signal 1/N value to a dividing ratio of next channel; for instance channel B in accordance with a prescribed sequence. A PLL selective part 26 alters a voltage selective control signal DC on the basis of this dividing ratio signal 1/N and local oscillation signal LOS and consequently a tuner 21 allows a local oscillation frequency to change in order to tune to the channel B.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a television signal transmission and reception system, and in particular,
CATV (cable television)
), 5TV (5ubscription tv
This system is suitable for application to subscriber television systems such as .

[Conventional technology]

In a subscriber television system, a broadcasting center sends a television signal to a television receiver (hereinafter referred to as a subscriber terminal) K of a subscriber (hereinafter referred to as a subscriber) in addition to a communication between the subscriber and the broadcasting center. A polling signal is transmitted to transmit information including contract details, fee payment instructions, data transfer instructions, emergency contact, etc. to the sag scriber terminal as required by the broadcasting center.

Polling signals control subscriber terminals based on requests from the broadcasting center, so subscriber terminals must be kept in a state where they can receive polling signals at all times. The polling signal must be received even when the terminal is not playing back the television signal.

[Problem that the invention seeks to solve]

A conceivable method for transmitting and receiving polling signals to achieve this purpose is to provide a special transmitting and receiving system separate from the television signal transmitting and receiving system, and transmitting and receiving through this dedicated channel.

However, this method requires two transmitting and receiving systems, which inevitably increases the size and cost of the system as a whole, and is therefore not practical in a popular subscriber television system.

Conventionally, as a solution to this drawback, a specific channel (
A polling signal is superimposed on the vertical blanking period of the television signal of the home channel (hereinafter referred to as the home channel) and transmitted to the subscriber terminal, and if the viewer on the subscriber terminal side does not watch the television program, the subscriber terminal automatically A method is used in which a switching operation is performed to receive a home channel television signal to obtain a polling signal reception state.

However, this method has the disadvantage that polling signals cannot be received while viewing television broadcasts on channels other than the home channel. In addition, with this method, when the subscriber terminal is not in viewing operation and wants to watch a channel other than the home channel, the television signal reception status must be switched from the home channel each time. There is an inconvenience that when a viewer performs a switching operation to a channel that he or she wants to view, he or she cannot immediately view the program.

As a way to solve these shortcomings and improve services for subscribers, the broadcasting center transmits a polling signal superimposed on the vertical blanking period of the television signals of all channels, and On the terminal side, a method has conventionally been proposed in which a polling signal is received from a television signal of a channel being received regardless of whether a program is being viewed or not.

However, according to this method, when the television signal of the channel that the subscriber terminal is receiving is in a state where it would like to be transmitted from the broadcasting center due to a failure in the transmission system or because the broadcasting time has ended (this is stopped). The VC has the inconvenience of not being able to receive polling signals (referred to as state), and is still insufficient considering its original function of always receiving polling signals.

The present invention has been made in consideration of the above points, and provides a television signal transmission and reception system that can receive polling signals at all times while a broadcasting center is in business.

[Failure to solve the problem]

In order to achieve this object, in the present invention, the broadcasting center 10 transmits the television signal S12a of each channel.
During the vertical blanking period of -832e, a polling signal POL that controls the subscriber terminal is superimposed and transmitted to the subscriber terminal (9), and the subscriber terminal detects this when it is no longer able to accurately receive the polling signal POL. K to automatically switch the receiving channel to another channel.

[Effect]

The broadcasting center IO sends a polling signal POL to the subscriber terminal 20 to control the subscriber terminal. This polling signal POL is superimposed on the vertical blanking period of the television signals S12a to S12e of all channels, and therefore, if the subscriber terminal v@-'p can receive the television signal of any channel, it will receive the polling signal. You can receive POL.

Therefore, the subscriber terminal I receives the polling signal P when the receiving channel stops broadcasting or breaks down.
When the polling signal POL cannot be accurately received, such as when the OL reception condition deteriorates, the reception channel is automatically switched to another channel so that the polling signal POL can always be received.

[lol example]

Hereinafter, an embodiment in which the present invention is applied to CATVK will be described in detail with reference to the drawings. In the figure, 10 is a broadcasting center, the title is an arbitrary subscriber terminal, and the broadcasting center 10 is
It is connected to all subscriber terminals 20 via cable connections.

In the broadcasting station 10, each channel A and B.

- television signal sources 11a, 11b for each E;

-11e, scrambler 12a, 12b, -1
2e, modulation circuits 13&, 13b@...13e are provided. The scramblers 12a to 12e scramble the video signals of the television signals S11a-5lie generated by the television signal generation sources 11a-wife based on scrambling commands SCRa-SCRe of the system controller 14 that controls the entire system. Television signal S 12 a-8 converted by
12e is sent.

The scramblers 12a-126 also multiply the polling signal POL given from the system controller 14 by nine times during the vertical blanking period of the television signals S12a-S12e and give it to the conversion circuits 13a-13e. The K word circuits 13a to 13e receive the television signal S12.
&-812e modulates the carrier signal to obtain RF signals RFa-RFe of each channel, which is converted into a mixed signal RFK in a mixer and transmitted to the subscriber terminal 20IC via a cable connection.

At the subscriber terminal Shu, the tuner 21 selects the received mixed signal 5 = channel I to be viewed from RF.
The RF signal RFi (i=ae) of (I=AE) is tuned, converted into an intermediate frequency signal IFi, and provided to the amplification/detection circuit 22. The amplification/detection circuit n is composed of a video intermediate frequency amplification circuit and a video detection circuit, detects the scrambled television signal 5121, and supplies it to the polling signal separation circuit and the display unit.

Polling signal separation circuit is received television signal 51
The polling signal POL is separated from 21 and given to the main controller A. The main controller controls the subscriber terminal fitting body, and when the reception condition of the polling signal POL is poor, the channel selection controller 25 is used.
A switching command signal SEL is given to the switch.

The tuning controller 5 receives a switching command signal SEL K, and synchronization signal extraction signals 5YNC and AFT (A
auto li'ine Tuning) signal AFT
is given. The channel selection controller δ stores receivable channels A to E (some channels depending on the contract between the subscriber and the center). In addition, the channel selection controller δ also outputs synchronization signal extraction signals 5YNC and AF.
When T signal AFT cannot be received or switching command signal S
When EL arrives, the next channel trap is switched in accordance with a predetermined order. In this case, the channel selection controller 5 switches the PLL channel selection section by supplying a frequency division ratio signal 1, which takes a value determined by each channel, to the PLL channel selection section. The channel selection controller 5 also receives the AFT signal AF.
When receiving T, a frequency division ratio signal 1/N having a value corresponding to the AFT signal AFT is given to the PLL tuning section.

Here, if the timer is set to display a specific channel after a predetermined time, or if the broadcast wave stops for a short time, the channel selection controller 5 transmits the division ratio signal to the next channel J. A trap is created so that the signal is not converted into a corresponding split ratio signal.

The PLL tuning section 26 includes a frequency dividing circuit that can vary the frequency dividing ratio.
) Has a circuit configuration. The local oscillation signal LO8 is received from the PLL channel selection line tuner 21, and the local oscillation signal LO8 is
is compared in phase with the output signal from the frequency dividing circuit, and a voltage tuning control signal DC corresponding to the phase difference is applied to one end of a variable capacitance diode included in the tuner 21 to vary the tuning frequency. At this time, the voltage tuning control signal DC
changes accordingly when the division ratio signal 1/N is changed, and the tuner 21 switches the receiving channel or controls the tuning frequency so as to obtain fine tuning.

In addition to the above configuration, a display section and an operation panel 4 are further provided. The display section includes a descrambler and a television monitor, and displays the television signal 512r on the monitor when a viewing status signal PW is applied from the operation panel 4 to switch to a program viewing status.

The operation panel 4 contains various switches that the viewer can operate, and displays the contents on the main controller when the program viewing switch is turned on, when the channel changeover switch is changed, or when the radio button is set. It sends out a command signal COM representing , and also gives a viewing status signal PW to the display section 28 when the program viewing switch is turned on.

The main controller is configured to stop automatic channel switching by the channel selection controller 5 while the program is being viewed.

In the circuit shown in this figure, while a program is being viewed, the polling signal separation circuit separates the polling signal POL from the television signal 512i (i=a) of the selected channel (for example, channel A). The information is sent to the main controller U, and the subscriber terminals are controlled by the broadcasting interface 10.

If a signal outage occurs in this program viewing state, the program will not be displayed on the monitor.The viewer will be aware of the occurrence of a signal outage and will perform operations such as changing channels or turning off the viewing switch. it is conceivable that. When the channel is switched, the polling signal POL can be separated from the switched channel, and when the viewing switch is turned off, the channel is automatically switched as described below. The polling signal POL can be separated from the channel that has been switched to without causing any problems.

In this program viewing state, when the viewing switch is turned off, the display section is switched to a state in which no program is viewed, and the main controller M shifts the subscriber terminal I to a state in which channels can be automatically switched. However, when this program is not viewed, the tuner 21, amplification/detection circuit section, channel selection controller 5, PL
The L selection station operates by continuing to tune to the person on the receiving channel immediately before turning off the viewing switch.

During reception to this channel, when the broadcast wave of channel A stops, the channel selection controller 5 detects the stop when the synchronization signal extraction signal 5YNC and the AFT signal AFT do not arrive.

When the stop time exceeds a predetermined time, the channel selection controller δ sends a division ratio signal to the division ratio of the next channel (for example, channel B) according to a predetermined order, and gradually changes the value of N. This division ratio signal 17N and local oscillation signal LO8
Based on this, the PLL tuning section 5:3 changes the voltage tuning control signal DC, and in response to this, the tuner 21 changes the local excavation frequency by tuning to channel BK.

Despite this switching, if the synchronization signal extraction signal 5YNC and AF'T signal AFT do not arrive at the channel selection controller 5, the channel selection controller 5 further changes the division ratio of the next channel (for example, channel C). divide ratio signal 1
The value of /H is gradually changed.

Thereafter, the channel selection controller 5 similarly switches the value of the channel division ratio signal 17H, that is, the reception channel, in a predetermined order until the synchronization signal extraction signal 5YNC and the AFT signal AFT are obtained.

During this operation, the synchronization signal extraction signals 5YNC and AF
When the T signal AFT is obtained, the channel selection controller 5 fixes the value of the channel division ratio signal 1c and sets the channel at that time as the receiving channel. In addition, at this time, the channel selection controller 5
finely adjusts the value of the division ratio signal 17N based on the incoming synchronization signal extraction signal 5YNC and AFT signal AFTK so as to obtain fine tuning.

In this way, when the broadcast wave of the receiving channel is interrupted, the channel automatically switches to the other channel that is currently transmitting. Therefore, even when a program is not being viewed, the polling signal POL is always applied to the main controller, allowing the broadcasting terminal 10 to control subscriber terminal additions.

Here, if it is determined that the reception condition of the polling signal POL arriving from the main controller is poor, a switching command signal SEL is given to the channel selection controller B to execute the above-mentioned automatic switching operation.

Additionally, if a subscriber sets a timer to watch a program on a specific channel after a predetermined period of time,
The main controller controls each circuit according to the command COM indicating the contents, so that when the broadcast wave stops or the reception condition of the polling signal POL deteriorates, the automatic channel switching operation is not performed during that period. do. this is,
This is to prevent the channel being viewed from becoming different from the channel set by the subscriber due to the elapse of the set time of the timer.

According to the circuit shown in the figure, all channels include the polling signal POL, and if the broadcast wave of the receiving channel stops due to a failure or the end of the broadcast time, or the polling signal POL
If the OL reception status is poor, the channel is automatically switched to another channel, so the subscriber terminal (9) always receives the polling signal P while the broadcasting center 10 is in business.
The OL can be separated, and the broadcast center 10 can control the subscriber terminals more reliably and more precisely.

Note that in the above embodiment, automatic switching is performed when a program is not being viewed, but the present invention is not limited to this.
Pressure may be applied to perform automatic switching even in the program viewing state.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to easily obtain a television signal transmission and reception system that allows subscriber terminals to constantly receive polling signals transmitted from a broadcasting center to subscriber terminals while the broadcasting center is in business. .

[Brief explanation of drawings]

The figure is a block diagram showing one embodiment of the present invention. 10...Broadcast center, nod...subscriber terminal,
21...Tuner, n...Amplification and detection circuit, Tsu...
Polling signal separation circuit command 24...Main controller, section...Tuition selection controller, A...PLL channel selection section, POL...Polling signal, 811a to 5lle
t 512a-512e. 512i...television signal.

Claims (1)

[Claims] The broadcasting center superimposes a polling signal to control the subscriber terminal during the vertical blanking period of the television signal of each channel and transmits it to the subscriber terminal, and when the subscriber terminal can no longer accurately receive the polling signal, A television signal transmission/reception method that detects the signal and automatically switches the reception channel to another channel.