JPH0531355B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a television apparatus in which a center and a terminal are connected by at least two transmission lines.

Conventional configuration and its problems In a CATV system, there are two cable systems that connect the center and terminal converters.
If the television signals transmitted through the system cables are broadcast with different contents in the same transmission frequency band, do not distinguish which of the two input terminals of the converter the television signals should be input to. If a subscriber subscribes to a certain frequency channel on one cable, by changing the cable connection, the subscriber will be able to watch the same frequency program on the other cable for free. The security at the top will be lowered. Therefore, in practical use, it is desirable to distinguish between cables and to prevent programs from cables to which you are not subscribed to from being received.

Purpose of the Invention The present invention focuses on the above points, and aims to improve management security by adding a cable discrimination function.

Structure of the Invention The present invention provides that when there are at least two systems of transmission lines such as the above-mentioned cable, and the television signals supplied to each transmission line A and B are in the same frequency band although the channels are different, the signals are transmitted from the center to the terminals. A code signal for transmission line identification is inserted into the vertical retrace period of the supplied video signal, and the signal is sent out.
At the terminal, when selecting a channel, a channel on the transmission line A side is selected, but a means is provided to determine whether the channel on the transmission line B side is selected, and this discrimination output is combined with the code signal sent from the center. If they match, the channel selection operation continues as is, and if they do not match, the channel selection is not performed, improving management security. It is something that can be done.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows an embodiment of the present invention.
This figure shows the overall configuration of a CATV device. First, the overall configuration will be explained using this diagram.

The device shown in Figure 1 is equipped with a scrambler on the center side that scrambles the video signal, and a descrambler on each terminal that descrambles the scrambled video signal. I am trying to get the image. More specifically, means for generating a scramble code, a random pattern generator for generating a random pattern based on the scramble code at the timing of a vertical synchronization signal, and a means for generating a video signal in units of one vertical period based on the random pattern signal. a video signal inverter that randomly inverts the polarity, a synchronization signal level shift circuit that shifts the level of the horizontal and vertical synchronization signals toward the video signal, and a synchronization signal level shift circuit that shifts the level shift of the synchronization signal at the timing of the vertical synchronization signal. and a means for generating timing information for decoding the random pattern and amplitude modulating the audio carrier wave using the timing information and modulating the scrambled video signal and audio signal, respectively, to generate an RF television. The center side is provided with means for transmitting the scrambled code as a digital signal, and means for modulating the scrambled code together with address data unique to each subscriber and transmitting the modulated code.

Then, a terminal connected to this center side by a transmission line such as a coaxial cable has a memory for storing the scramble code and a timing signal for demodulating the RF television signal and sending it by the audio carrier wave. means for accessing the memory and decoding the scrambling code based on the information; and generating a random pattern for descrambling based on the scrambling code;
A means for converting a video signal whose polarity is randomly inverted in units of one vertical period into a correct waveform and outputting it, and a means for level-shifting the level of the level-shifted horizontal/vertical synchronization signal to a normal level based on the above timing information. and scramble it,
It is designed to perform descrambling processing.

In the figure, 1 is an antenna, 2 is a retransmission device, where the RF television signal is amplified, etc., and then mixer 3
is supplied to 4 is another signal source, in which the output signal of the SHF receiver 4a is detected into a baseband video signal by the demodulator 5, and the output video signals from the video tape recorder 4b and the video camera 4c are directly sent to the scrambler 6. input, is scrambled here, and then sent to the next modulator 7.
It is converted into a BF television signal and sent to the mixer 3 above.
to go into. A line controller 8 controls the scrambling mode. The line controller 8 includes a scrambler controller 9a and a communication control unit 9b.
a microcomputer 9 including a memory 10
, a display device 11 and a keyboard 12
It is equipped with For example, 30 types of scramble codes are stored in the memory 10, and any one scramble code is selected and the scrambler controller 9a sends the scrambler 6 to the scrambler 6.
The scrambler 6 performs scrambling processing on the video signal according to the scramble code. The scramble code is simultaneously supplied to the modem 13 by the communication control unit 9b, where the signal is converted by modulating a carrier wave of, for example, 73 MHz, and sent through the mixer 3 to the terminal.
The scrambler 6 sends out timing information for decoding the scrambled video signal and audio signal together with the scrambled video signal and audio signal. 14
is a central control device for controlling the line controllers 8, and is installed at one facility for each line controller 8 of 10 facilities, for example. 15, 16 are modems connecting the microcomputer 9 and the central control unit 14. The above is the center side.

Further, 17 is a bidirectional main line amplifier connected to one output end of the mixer 3 via a transmission line 18 made of a coaxial cable, and 19 is connected to another output end of the mixer 3 via a coaxial cable. This is a main line amplifier connected via a transmission line 20. For example, from one output end of mixer 3,
Television signals for 60 channels are output from the other output terminal of the mixer 3, and television signals for 60 channels from the 101st to the 160th channels are output, respectively. Here, the frequencies of both television signals are channel 1 and channel 101, channel 2 and channel 1
02 channel, etc. are in the same frequency band. Further, 21 and 22 are branchers (the illustrated example is a 4-brancher) connected to the bidirectional trunk amplifier 17 and the trunk amplifier 19, respectively.

Next, the terminal side will be explained. The terminal side includes a converter 23 that includes a channel selection device for selecting a desired channel, a means for decoding a scrambling code based on timing information, and descrambling the video signal that has been scrambled at the center. A television receiver 24 connected to this converter 23 is provided.

The converter 23 enters from the branch 21
Switch circuit 2 for switching between the RF television signal and the RF television signal input from the branch 22
5 and selected by this switch circuit 25.
Tuner 26 into which the RF television signal is input
, a demodulator 27 for demodulating the video intermediate frequency signal from the tuner 26, a descrambler 28, and a demodulator 27 for converting the output video signal and audio signal from the descrambler 28 into a high frequency television signal of a specific channel. modulator 29 of
, a PLL synthesizer type station selection device 30 including a microcomputer, a keyboard 31 equipped with channel selection buttons, power on/off buttons, and volume adjustment buttons, and a place for storing scramble codes sent from the center. An addressable control unit 32 including a non-volatile memory and a microcomputer, and a modem 33 are provided.

Furthermore, here, in order to enable remote control, a transmitter 34 and a receiver 35 for remote control are provided. The scramble code sent from the center by the data carrier is transmitted to the bidirectional trunk amplifier 1.
7. The signal is demodulated by the modem 33 through the branching device 21 and written into the non-volatile memory. on the other hand,
The timing information sent by the RF television signal is demodulated by the demodulator 27 and separated from the video signal and the audio signal to the descrambler 2.
The microcomputer enters the microcomputer at step 8 and starts reading and decoding the scramble code. The video signal is descrambled based on this scramble code so that a normal image is displayed on the television receiver 24.

In addition, in this example, when determining the channel to which the subscriber wishes to subscribe, the subscriber informs the center of the channel that the subscriber wishes to subscribe to, and writes the channel to the above-mentioned non-volatile memory of the terminal through the center.
Therefore, when actually selecting a channel, only the registered channel can be received. When each subscriber informs the center of the channel they wish to subscribe to, the channel data is stored in memory 1.
0 and read out and sent to the terminal by a data carrier together with the address data for each subscriber, and the channel data is written to a non-volatile memory. Therefore, in actual channel selection, reception of that channel is only possible when the selected channel matches the channel registered in the non-volatile memory, and selection of other channels is not possible. Furthermore, in this example, a program request for a channel to which the terminal is not subscribed can be made via a transmission line from the terminal to the center, and in this case, a request code signal is generated from the keyboard 31 or the remote control transmitter 34. channel selection device 30, addressable control unit 32, modem 33
The signal is supplied to the center via one transmission line 18.

Next, the scrambling and descrambling methods of the CATV device shown in FIG. 1 will be explained using FIGS. 2 to 4. 2 shows the overall structure of the scrambler and descrambler parts, FIG. 3 shows a specific example of the structure of the scrambler 6, and FIG. 4 shows a specific example of the structure of the date scrambler 23.

The scrambler 6 includes a sync separation circuit 41 for separating a sync signal from a composite video signal, a reference sync signal generator 42 for generating a stable reference sync signal from the output of the sync separation circuit 41, and a sync signal generator 42 for generating a stable reference sync signal from the output of the sync separation circuit 41. A vertical blanking pulse generator 43 and a horizontal blanking pulse generator 44 respectively generate vertical blanking pulses and horizontal blanking pulses based on the outputs of 42, and each A sync signal level shift circuit 45 shifts the level of the sync signal to the video signal side for a certain period of time, and a random pattern is generated based on a scramble code sent from the microcomputer 9 using a vertical blanking pulse as a timing signal. a video signal inverter 47 that inverts the polarity of the video signal whose synchronization signal has been level-shifted in units of one vertical period using a random pattern signal; a first timing signal generator 48 for inserting timing information for decoding the random pattern within the line period;
and a second timing signal generator 49 for placing timing information indicating the start position of the level shift of the synchronization signal before and after the timing information for decoding the random pattern.

On the other hand, as shown in FIG. 4, the descrambler 28 determines whether the RF television signal is a normal (unscrambled) television signal based on the presence or absence of timing information obtained by demodulating the RF television signal. A normal/scramble determination circuit 51 determines whether the signal is a scrambled television signal, and based on this determination signal, if it is a normal television signal, the output terminal 52 is connected to the normal terminal N, and the scrambled signal is output. If so, a switch 53 controlled by the microcomputer 32a in the addressable control unit 32 connects the output terminal 52 with the scramble terminal S.
and a random pattern generator 54 that reads the scramble code written in the nonvolatile memory 32b based on timing information for decoding the random pattern, and generates a random pattern from the output obtained by decoding it with the microcomputer 32a. a video signal inverter 55 for converting a scrambled video signal into a normal video signal based on a random pattern signal; Synchronous signal level swift circuit 5 for returning the signal level to its original correct state
Consists of 6. This synchronization signal level shift circuit 56
The output terminal of is connected to the scramble terminal S.

Next, its operation will be explained. A scramble mode is determined by the central line controller 8, and the scramble code is supplied to the scrambler 6 and modem 13, respectively. The scramble code input to modem 13 is 73MHz
The frequency is modulated into FS and sent to the terminal side through the mixer 3. On the other hand, in the scrambler 6, the synchronization signal is separated from the baseband video signal to create vertical blanking pulses and horizontal blanking pulses, and the synchronization signal level shift circuit 45
During the period of both blanking pulses (in the horizontal period, period a in the waveform of the video signal in FIG. 5), the level of the synchronizing signal is shifted to the video signal side. FIG. 6A shows the waveform of the video signal in which the synchronization signal is level-shifted as described above. The random pattern generator 46 uses the vertical blanking pulse as a timing signal to generate a random pattern according to the scramble code generated by the line controller 8. The video signal inverter 47 uses this random pattern signal.
Inverts the polarity of the video signal whose synchronization signal has been level-shifted in units of one vertical period. FIGS. 6A and 6B show an example of such a state. If A is an even field, B is an odd field, and the polarity of the video signal is inverted with respect to the even field. The inverted state of this video signal can be set randomly and can be determined by a scrambling code. The first timing signal generator 48 inserts, for example, a 4-bit timing signal (information) _S3 for decoding the random pattern within the vertical retrace period using the falling edge of the vertical blanking pulse as timing. The second timing signal generator 49 adds a timing signal _S2 indicating the start position of the level shift of the synchronization signal to the timing information for decoding the random pattern. This timing signal is shown in FIG.

In this way, a baseband video signal in which the synchronization signal is level-shifted and the video signal is scrambled by randomly inverting the polarity in units of one vertical period based on the scrambling code, and timing information for decoding the random pattern. Timing information indicating the start position of the synchronization signal level shift is sent to the next modulator 7 together with the audio signal. In the modulator 7, the scrambled video signal and the audio signal are subjected to amplitude modulation and frequency modulation processing similar to ordinary television signals, and timing information is amplitude-modulated on the audio carrier wave and sent out on the audio carrier wave. That's what I do. In this way, the video signal, audio signal and timing information are output from the modulator 7 as an RF television signal and sent through the mixer 3 to the terminal.

In the modem 13, the scrambling code is
The address data for each subscriber and the subscribed channel data are output to the terminal by a data carrier. The scramble code and the channel data are demodulated via the modem 33 and written into the nonvolatile memory 32b in the addressable control unit 32.
On the other hand, the RF television signal is selected by the channel selection device 30 to any one channel, and the demodulator 2
7, the state before input to the modulator 7, that is, scrambled video signal, audio signal,
It is demodulated into timing information, separated, and output. The normal scramble determination circuit determines that the scramble processing has been completed based on the presence of timing information, and sends the determination output to the microcomputer 32a. The microcomputer 32a connects the switch 53 to the scramble terminal S based on the above-mentioned discrimination output. On the other hand, the microcomputer 32a reads the non-volatile memory 3 using timing information _S1 for decoding the random pattern.
2b is read and decoded, and the random pattern generator 54 is controlled accordingly. Using the output signal of the random pattern generator 54, the video signal inverter 55 returns the randomly inverted state of the scrambled video signal to a correct waveform. Then, in the next synchronization signal level shift circuit 56, the level of the synchronization signal is shifted to the original correct level based on the timing of the timing information _S2 , and the scramble terminal S. switch 53 is shifted to the original correct level.
The descrambled video signal is outputted to the output terminal 52 via. This normal video signal is input to the modulator 29 together with the audio signal at the terminal 57.
It is modulated into an RF television signal of a specific channel and supplied to the television receiver 24. Therefore, an image is correctly projected on the Braun tube screen of the television receiver 24.

Note that when the scrambling process is not completed, the switch 53 is connected to the normal terminal N, and the input video signal is outputted from the output terminal 52 as it is. According to this configuration, the polarity of the video signal is randomly inverted in units of one vertical period, and the synchronization signal level is shifted to perform video signal scrambling processing, while timing information for decoding the random pattern, synchronization signal level In order to restore the shift, timing information indicating the level shift start position is sent to the terminal along with the video signal using an audio carrier wave, and a scramble code for determining the random pattern is sent to the terminal along with address data, etc. Write to the memory 32b on the terminal side, decode the scramble code in the memory 32b based on the timing information,
A random pattern is generated based on this to restore the inverted state of the video signal to its normal state, and the synchronization signal is also descrambled by level shifting to the original correct waveform based on the timing information. The security of scrambling can be increased, which is more advantageous in practice, and the scrambling mode can also be changed arbitrarily at the center.

In a CATV device having two transmission lines 18 and 20, television signals of 60 channels from channels 1 to 60 are currently being transmitted to the transmission line 18.
Television signals of the same 60 channels from 101st to 160th are output to the transmission line 20, and the channels of each transmission line 18 and 20 are in the same frequency band (1st channel = 101st channel, 2nd channel = 160th channel). 102 channel, 3rd channel = 103rd channel...), and if a subscriber subscribes to the 1st channel, transmission line 1
The transmission line from branch 21 leading to input terminal A
There is no problem if the other transmission line is connected to input terminal B, but if the transmission line is connected incorrectly and the transmission line from branch 21 leading to transmission line 18 is connected to input terminal B, then the other transmission line is connected to input terminal B. When the transmission lines are respectively connected to the input terminals A and the tuning operation of the first channel is performed using the keyboard 31, for example, the tuning voltage applied to the tuner 26 from the tuning device 30 is the same for the first channel and the 101st channel. Because there is
The converter 23 will receive the 101st channel, allowing the subscriber to view programs on channels to which he has not subscribed.

In order to solve this problem, the present invention inserts a code signal for transmission line identification into the vertical retrace period of the video signal and sends it to the terminal. For example, 60 channels of the 1st to 60th channels supplied via transmission line A
A code signal of '1' is assigned to the channel, and a code signal of '0' is assigned to the 101st to 160th channels supplied via the transmission line B.
At the terminal, when operating a channel line station,
Are you tuning up to channel 60, or channels 101 to 101?
The microcomputer in the addressable control unit monitors whether up to the 160th channel is selected, and sets '1' if it is the 1st to 60th channel, and '0' if it is the 101st to 106th channel. ', and the microcomputer judges whether these code signals and the code signal sent from the center match or not. If they match, the channel selection operation continues as is. If not, the system is configured to forcibly select a specific channel. As a result, it has an extremely large effect on preventing eavesdropping.
Management security can be improved.

This will be explained in detail using the drawings below. Here, it is assumed that television signals of channels 1 to 60 are supplied to the transmission line A18, and television signals of channels 101 to 160 are supplied to the transmission line B20. Each frequency of the 1st to 60th channels and the
Each frequency of the 101st to 160th channels is the same frequency. The converter 23 has two input terminals A and B, and the television signal transmitted via the transmission line A18 is input to the input terminal A, and the television signal transmitted via the transmission line A18 is input to the input terminal A.
It is assumed that the television signals transmitted through the terminals 20 and 20 are inputted to the input terminals B in the correct state.

At the center, the first timing signal generator 48 of the scrambler 6 shown in FIG. 3 inserts a code signal _S1 for transmission line identification into the vertical retrace period of the video signal as shown in FIG. '1 for television signals sent to transmission line A18, that is, signals from channels 1 to 60.
For the television signals sent to the transmission line B20, that is, the signals of the 101st to 160th channels, a code signal of '0' is inserted. Of course, this relationship may be reversed. Now, the branch 21 leading to the transmission line A18
The transmission line from the branch 22 leading to the transmission line B20 is connected to the input terminal A, and the transmission line from the branch 22 leading to the transmission line B20 is connected to the input terminal B, and the subscriber has subscribed to all channels 1 to 60 or some of them. Assume that Therefore, at this time, switch circuit 2
5 is closed so that input terminal A and tuner 26 are connected.

Here, when one of channels 1 to 60 is selected using the keyboard 31 or the remote control transmitter 34, the television signal of that channel passes through the tuner 26 and is demodulated by the demodulator 27. The code signal '1' for transmission line discrimination is sent to the microcomputer 32.
input to a.

On the other hand, the microcomputer 32a is currently selecting channels 1 to 60, or channels 101 to 160 based on a coded channel selection signal applied to the channel selection device 30 from the keyboard 31 or remote control transmitter 34. It monitors whether the channel is selected, and if any channel from 1st to 60th is selected, a code signal of '1', 101st
If any channel from 160 to 160 is selected, a code signal of '0' is generated for each channel. Therefore, in the above case, the microcomputer 32
A determines that both code signals match, and continues the channel selection operation.

By the way, I accidentally connected the transmission line A18.
Connect the transmission line from the branch 21 leading to the input terminal B
When the transmission lines from the branching device 22 leading to the transmission line B20 are connected to the input terminal A, the 101st to 101st to 160 channels of television signals are input. Here, when the first channel is selected using the keyboard 31, the television signal of the 101st channel is selected and demodulated, thereby inputting a code signal '0' to the microcomputer 32a. On the other hand, the code signal from the channel selection device at this time is '
1', the microcomputer 32a determines that the two code signals do not match, and does not select the 101st channel, but selects another specific channel, such as the 160th channel, if it is set to the Barker channel. Then, the channel selection device 30 is controlled to select the 160th channel.
Therefore, subscribers to channels 1 to 160 will not be able to watch the same frequency program from the other transmission line even if they connect the transmission line incorrectly, improving administrative security. can be measured. On the contrary, the same effect can be obtained even when a contract is made with some of the channels (101st to 160th channels) output to the transmission line B20. And this time the 60th
If the channel is set to the Barker channel, for example, even if the 101st channel is selected, the 1st channel will not be selected and the 60th channel will be selected.

By the way, the Barker Channel, for example,
If only channel 60 is set, if you subscribe to some of channels 1 to 60 and make a mistake in connecting the transmission line, channel 60 will be selected instead of channel 160. It must be controlled so that the signal is transmitted. So in this case,
Further, the channel selection device 30 and the switch circuit 25 are connected by a control line, and the addressable control unit 32 controls the channel selection device 30 to select the 60th channel, and the switch circuit 25 is connected to the transmission line A18. The switching input terminal B and the tuner 26 are controlled to be connected to the input terminal B side to which the transmission line leading to the input terminal B is connected.

Effects of the Invention As explained above, according to the present invention, there are at least two transmission lines connecting the center and the terminal converter.
If the television signals flowing through these two transmission lines are in the same frequency band, a code signal for identifying the transmission line is inserted into the vertical line period of the video signal and sent to the terminal, and the terminal It is determined whether or not the code signal indicating whether the channel on the transmission line side is selected, the code signal folded from the center side, and the code signal sent from the center side match. If the subscriber is subscribed to a channel on one side of the transmission line, the program will be received on that channel if it matches, and the program on that channel will not be received if it is not matched. Even if a connection is made incorrectly, viewing of the same frequency program on the other transmission line side can be prohibited, which is highly effective in preventing eavesdropping and improving management security.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the overall configuration of a television apparatus according to an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of the scrambler and descrambler parts, and FIG. 3 is a specific example of the scrambler. 5 is a waveform diagram of a normal video signal, FIGS. 6A and B are waveform diagrams of a scrambled video signal, and FIG. 7 explains a method of transmitting timing information and transmission line discrimination signals. This is a diagram for 6...Scrambler, 7,29...Modulator,
8... Line controller, 3... Mixer, 1
3, 33...modem, 17...bidirectional main line amplifier, 18, 20...transmission line, 19...main line amplifier, 21, 22...brancher, 23...converter, 24...television receiver, 26... tuner, 28... descrambler, 30... channel selection device, 32... addressable control unit, 32a... microcomputer, 32
b...Nonvolatile memory.

Claims (1)

[Scope of Claims] 1. At least two transmission lines connecting the center and the terminals are provided, and each of the television signals of a plurality of channels is supplied from the center to the terminals through the respective transmission lines, and The television signals of the channels supplied to the transmission line are configured to be supplied in the same frequency band, and a means for performing scrambling processing is provided at the center, and the video signal in the television signal is vertically A code signal for discriminating the transmission line is inserted during the retrace period, and means is provided for detecting the code signal for discriminating the transmission line inserted into the television signal at the terminal. A terminal is provided with a means for determining whether a channel on the transmission line side is selected but a channel on the other transmission line side is selected, and a means for performing a tuning operation including descrambling processing based on the determination result. The discrimination output signal of the discrimination means indicating which channel has been selected on the side is compared with the code signal detection output signal sent from the center, and if both signals match, the selection including the descrambling process is performed. A television apparatus characterized in that the channel is selected and descrambled by the means for operating the channel, and if the channel does not match, the channel is not selected. 2. Claim 1 in which the means for performing a channel selection operation is controlled to forcibly select a specific channel if the discrimination output signal and the code signal sent from the center do not match. Television equipment as described in Section 1.