JPS60245387A - Centralized control system of looking and listening in catv system - Google Patents

Abstract

PURPOSE:To obtain a centralized looking and listening control method of CATV system whose overall constitution can be miniaturized in terms of a distribution system of the outdoor installation corresponding to plural terminals by inserting scramble signals in terms of time division corresponding to each channel. CONSTITUTION:A television signal and a data signal are separated from signals branched from a trunk line 21 in a data separation unit 28, and the data signal is demodulated by a demodulator 29, and inputted to a microprocessor 30, which stores the data in an ROM31 and acts according to the inputted data. A disturbing signal (scramble signal) is produced from a PLL circuit 32, and inputted to a subscriber unit 33 corresponding to each subscribing family. Then a disturbing signal which is controlled by said subscriber unit and produced in correspondence to each channel is coupled with the television signal separated by the data separation unit 28, and transmitted to each family.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention is mainly applicable to CAs that provide pay television programs, etc.
1 set of centralized viewing control method in TV system %] As a scrambling method in a conventional CATV system, the one shown in FIG. 1 is known. Here, reference numeral 1 is a CATV trunk line, which is connected to the center. 2 is a tap-off for branching this trunk line 1, and the branched signal is sent to each home. 3 is a data splitter that takes in the signal and separates it into a TV signal and a data signal; the separated TV signal is frequency-converted by a converter 4, and descrambled by a descrambler 5, or sent to a TV receiver while being scrambled. 9 is output. On the other hand, the data signal divided by the data signal generator is demodulated by the demodulator 6 and inputted to the controller 7. The controller 7 takes in this data signal and prepares an output signal for descrambling the television signal according to this information. A terminal device 8 including such a control system is installed in each home. In this way, several dozen channels of TV signals and data signals are frequency-divided and sent to the CATV main line 1. This data signal is taken into the terminal equipment 8,
The operation is controlled as described above. That is, the controller 7 generally includes a microprocessor, and the converter 4. It controls the descrambler 5. On the other hand, since the television signal has been tuned to a certain channel and frequency-converted by the converter 4, that channel is sent to the TV receiver 9 either as scrambled or descrambled by the second controller 7. 1 to roll data are stored in a memory built into the controller 7.

[Technical Problem 1] In such a system, it is necessary to install the above-mentioned terminal device in each home, and in order to make it viewable, it is necessary to descramble the scrambled signal. Therefore, installing the above-mentioned terminal device in each home brings about high costs, and there is a drawback that the above-mentioned terminal device can be destroyed or modified and viewed by unauthorized persons. Also, from the point of view of maintenance, it is inconvenient because a worker must enter each home. Furthermore, the TV signal has been scrambled in advance, and in order to scramble it at the terminal device, it is scrambled from the TV 4F": ';J (when the 2i signal is removed, the image quality deteriorates. Therefore, the center side An outdoor distribution unit is installed which transmits only the television signal and is compatible with a plurality of households. An IC centralized viewing control system has been proposed, which is equipped with a means to superimpose the TV signal on the TV signal of each home channel.In this system, each terminal device has only the minimum necessary components such as a converter built-in. , requires little maintenance, and for entertainment channels, a scrambled signal is added and is not descrambled, so you can get a good quality video, and the terminal. This method has the advantage of reducing costs because it does not require a descrambler or the like on the subscriber distribution system (including the distribution unit). Since it is necessary to arrange traps according to the video carrier frequency of the channel, there are problems such as there is a physical limit to the number of traps in one distribution system. The invention was made based on the above-mentioned circumstances, and when adopting an outdoor distribution system that supports multiple terminals, the cost is lower and scrambled signals are also inserted in a time-division manner for each channel. The present invention is intended to provide a centralized viewing control method for a CATV system that allows the overall configuration to be miniaturized.

[Structure of the invention]

To this end, the present invention provides means for receiving and demodulating control signals from a center, storing the decoded data, and oscillating in accordance with the data in a system for scrambling images by adding a disturbance signal to a television signal. The present invention is characterized in that it is equipped with a voltage controlled oscillator whose frequency is periodically changed in a time-division manner, and a means for removing unnecessary interference signals with pulses synchronized with the time-division signal.

【Example】

Hereinafter, one embodiment of the present invention will be described in detail with reference to FIGS. 2 to 5. In Fig. 2 glue), code 21
Is it CA T V I? There is a line line, 22 is a distribution system unit, and there are 2 drop lines for each household 24.
3 to distribute the television signal. −

[In the registered home 24, a converter 25 and a TV receiver Ia 26 or a cable ready TV receiver G427 are being installed. Φ> in FIG. 2 indicates the internal configuration of the distribution system unit 22. Here, a signal branched from the main line 21 is separated into a television signal and a data signal by a data separation unit 28. The data signal is demodulated by a demodulator 29 and input to the microprocessor 3o. The microprocessor 30'C: stores this input data in a non-volatile memory (ROM>31) and operates according to this data. Also, reference numeral 32 indicates a phase comparator, a low-pass filter, a voltage controlled oscillator ( PLL including VCO)
It is a circuit and is controlled by the microbe 1] celli-30 mentioned above. Interference (No. 8 (scrambled signal) is generated. This PL
The output of the L circuit 32 is input to a subscriber unit 33 corresponding to each contracted household. The interference signal controlled by the subscriber unit 33 is
The signal is separated by the data separation unit 1-28, coupled with the lζ television signal, and sent to each home. Note that reference numeral 34 in the figure indicates a signal for synchronizing the PLL and the subscriber unit. Here, the distribution system unit 22 is responsible for the tap-off function from the 0ATV main line 21 and the scrambling function. That is, the unit 22 determines the scrambled channel according to the data signal from the center computer, and receives the scrambled De1 Novi F3 through the drop line 23 except for the channels subscribed to by the individual subscribers. In detail, in the distribution system unit 1-22, the interference frequency for adding interference waves to the television signal is generated in response to a Booyan channel to be scrambled. A plurality of scramble channels can be freely set. The frequency of the interference wave periodically shifts in response to the frequency of the channel that was set incorrectly. If a subscriber subscribes to the scramble channel, the interference will not be added to the GJ TV issue for the duration of the channel's existence. The subscriber unit 33 does this, and takes the form of an RF switch controlled by the microprocessor 30, for example. This is synchronized with the frequency shift of the jammer. The upper part of FIG. 3 (2) shows the output of PLL, whose frequency is periodically changed in a time-division manner as an interference wave. Here, CI-4, A to CI-1. E is a scramble channel. The lower part of the third diagram shows the function of the RF switch in the supply subscriber unit 33, which opens the RF switch during the period when the interference waves are moving and does not add interference waves to the drop line 23. For example, if Cl-1 and D are subscribed to, the RF switch remains open in that frequency range, indicating that no interference waves enter the drop line 23 on CH and D. Such control is performed by the microphone [1 processor 9-30. The interference wave output and the RF switch are synchronized using a timing pulse with a period t. This signal is generated using an interrupt by the microprocessor 30 using an internal timer. This timing generation pulse and RF switch data are input to the subscriber unit 33 in the form of an OR. -h1 The above timing pulse also serves as a latch pulse for PLL data. As shown in ) in FIG. 3, PLL data is output before the timing pulse and is latched by the timing pulse. As a result, P
The output frequency of LL changes and becomes a stable frequency after tFf1. 5 and 6, the microprocessor 3
0 flowchart is shown. Further, in the above embodiment, as shown in FIG. 2, a unidirectional 0ATV system is described, but a bidirectional CΔ
The centralized viewing control method of the present invention can also be adopted for TV systems. Furthermore, in FIG. 2(1)), by increasing the number of subscriber units 1-33, one distribution unit 1 can control many subscribers. In addition, at the output of the PLL circuit 32, the interference wave time (third
By changing t/T) in the figure, the scrambling effect can be changed. Note that in a single PLL circuit, as the number of scrambling channels increases, the scrambling effect decreases, so when scrambling many channels, or in order to increase the scrambling effect, it is necessary to use multiple PLL circuits. It is good to use it. [Effects of the Invention] As described in detail above, the present invention can obtain the following effects. By installing the distribution unit at the position of (→Tap A in the conventional 0ATV system), the destructive power of the terminal device is not generated as in the case of indoor installation, preventing eavesdropping. This is achieved by reducing the cost of the terminal device. (o) Since it is a format in which interference waves are inserted for each channel using a PLL circuit, etc., it does not affect the quality of the video being viewed. Image reception is realized. 9. The output of the voltage controlled oscillator is periodically time-divided, and in order to output interference waves corresponding to each channel, traps are set for each of the 12 image carrier frequencies of the right rice channel. Since there is no need to align them, the overall configuration can be made smaller.
It is not affected by an increase or decrease in the number of channels. 0 By changing the control signal from the center, the data can be changed and the time division control of the oscillation frequency can be changed, so the scrambling effect can be improved.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional example, Fig. 2 a>(b>) is a block diagram showing an embodiment of the present invention, and Fig. 3 (2). pt-, ?4S4 and Figure 5 are microphone [■
Brohissa's 70-yard. 21...CA-r VI? Line pline 22...
Distribution system unit, 23...drop line, 2
4...Home, 25...'' Mbaata, 26...TV
Receiver, 27... Google Ready TV, 28... Data separation unit, two... Data demodulator, 30...
・Microprocessor, 31...Nonvolatile memory, 3
2...PL1 circuit, 33...Subscriber unit. Patent Applicant Pioneer Co., Ltd. Representative Patent Attorney Nobu Kobashi Kazuyoshi Patent Attorney Susumu Masui

Claims (1)

[Claims] In a system that scrambles an image by adding an interference signal to a television signal, there is a means for receiving and demodulating a control signal from a center and storing the decoded data, and a means for periodically time-sharing the oscillation frequency according to the data. 1. A centralized viewing control method for a CATV system, comprising a voltage controlled oscillator that changes the voltage, and means for removing unnecessary interference signals with pulses synchronized with the time-division signal.