JPS60220687A - Looking and listening control system of catv - Google Patents

Abstract

PURPOSE:To realize a high-degree scramble, by transmitting out-band data separately from the picture band from the transmitting side and changing the out- band data to decode key signals by putting the out-band data in in-band data at the terminal side. CONSTITUTION:At a transmission side, key codes added to a modulator 14 are given from a random number generator 8 through an exclusive OR gate 21 and signals from a system code 23 are also inputted in the OR gate 21. The signals from the system code 23 are inputted in a center command generator 24 and supplied to a terminal as out-band data after they are modulated at an FSK modulator 25. At the terminal side, signals from a controller are inputted in an exclusive OR gate 22 and the exclusive OR of the signals and output signals of a demodulator 15 is inputted in a shift register 16. By switching a switch 18 which is switched by a synchronizing signal from a synchronism detector 17, whether or not a switch 19 to an amplifier 20 is to be switched is selected.

Description

[Detailed description of the invention] [Industrial application field]

The present invention mainly relates to a CATV viewing control method for scrambling to advantageous channels.

[Prior art] In the terminal device, in the circuit shown in FIG. The data signal can be divided into FSK
The signal detected by 3 and given to controller 1-roller 4 is
By comparing the selected channel number from the channel select key 5 and the address signal from the address 6, it is determined whether or not TV viewing is possible. From the controller 4, a control signal is given to the converter 1 by PLL type chiconing, and a descramble signal is given to the descrambler 2 in accordance with the key code extracted from the data signal. Note that in the figure, reference numeral 7 is a channel indicator. A general scrambling method in a CATV system incorporating such a terminal device uses a center side circuit as shown in FIG. Here, a key code is output from the random number generator 8 to the shift register 9. The synchronization detector 10 detects the horizontal synchronization timing of the image signal,
When the key code is 11111, a switch signal is applied to the switch 12 via the switch 11, so that the image signal is applied to the modulator 14 via the attenuator 13, and compression is applied to the horizontal synchronization part. The key code 7 divides the horizontal synchronization of one field into an appropriate number of blocks and compresses the horizontal synchronization level for each block number. This code is used to encode and transmit a pattern of ``P1°'' or ``O11'' for each error. On the other hand, this code is used to determine the correct answer (g
Therefore, by modulation such as frequency multiplexing, the horizontal synchronization is actually sent one field before the compressed field. As a result, on the receiving side, as shown in FIG. 2, the code is demodulated by the demodulator 15 in the descrambler 2 and set in the shift register 1G. When the switch 18 is turned on by the signal from the synchronization detector 17 in the next field, the switch 19 is operated to extend or not extend the horizontal synchronization level. When the angle is 1°', the video signal is passed through the amplifier 20. In this way, all horizontal synchronization returns to normal levels. In this case, the correct signal is not limited to one type, and may be different for all channels in each field. [Technical Issues] The digital scrambling method realized in this way was thought to be a powerful countermeasure to prevent unauthorized viewing because it could use a random key code for each field. Once the key load modulation method is known, the correct signal can be extracted as is by demodulating it accordingly, and the meaning of scrambling is lost. In other words, at the terminal, the control signal going from the controller 1 to the descrambler is disconnected,
Image amount 4? , If you set the OK mode (enable) to 1, a key code will appear there depending on the IN key, so if you follow the input and make it expand, you will be able to spy on it. It's put away. OBJECTS OF THE INVENTION The present invention has been made based on the above-mentioned circumstances, and is capable of applying PA'! The key code restoration code for synchronization expansion is included as data), and the TV screen 4 is transmitted from both bands.
By enabling Iw4, viewing on CATV allows for scrambling that is resistant to fraud such as theft.
The aim is to provide a method for controlling

[Technical configuration of the invention]

For this purpose, the present invention transmits a key code as in-band data using a frequency multiplexing method within an image band, and uses the above-mentioned in-band data as a decode key signal on the terminal side. This is characterized in that outband data is transmitted as a center command in a frequency band different from the above, and on the terminal side, the outband data is incorporated into the inband data and used as a decode key signal.

【Example】

This will be explained in detail with reference to . In addition, in the figure, the same parts as those in the previous description are given the same reference numerals, and the description thereof will be omitted. The difference in circuit configuration in this embodiment is that on the transmitting side, as shown in FIG. With,
The signal from the system code 23 is also input to the OR gate 21, and the signal from the system code 23 is input to the center command generator 24, as shown in FIG.
FSK Hi 11 device 2 according to the center format shown in 1.
5 modulation and is supplied to the terminal as an outband signal. In addition, in the terminal device, as shown in Figure 5, the signal (system code) from the controller
is input to the exclusive OR gate 22, exclusive ORed with the output signal from the demodulator 15, and sent to the shift register 16.
It is determined whether or not the switch 19 is switched to the amplifier 20 by switching the switch 18, which is input to the synchronization signal from the synchronization detector 11. In such a configuration, on the transmitting side, as shown in FIG. 4, the system code 23 and the random number generator 8 are exclusive ORed, and this is called the key code. On the other hand, system code 23 is part of the center command and 'U F
The signal is sent out from the SK modulator 25 as outband data. On the other hand, on the terminal side, after demodulating with the FSK demodulator 15, the system code from the second controller 4 is subjected to exclusive OR and set in the shift register 16, thereby controlling the expansion operation of the horizontal synchronization part. Process. FIG. 7 is an example of a center command in a conventional system, and is shown in comparison with the present invention shown in FIG. In the center command of the present invention, since the system code is at one end with the command, the controller 4 performs synchronization detection, address comparison, validation check, etc., and if it is determined that the command is addressed to itself, the controller 4 Incorporating
It performs the descrambling process 1-j and sends the system code to the descrambler. Note that the code output from the random number generator 8 may be a different code for each field, but this is not possible with the system code. Because in-band (video frequency band)
This is because it is difficult to completely synchronize the timing of the out-band and out-of-band signals. If this cycle deviates even slightly, the TV screen will be distorted. Therefore, in actual operation, random numbers may be used as the system code, but it is preferable to change the system code at breaks between programs. For fraudsters, if this system code changes in a short period of time,
Even if you try to steal pAvIi, it will actually be quite troublesome. In other words, out-of-band data is also involved in the TV screen descrambling process, and even if you simply force the OK/NG signal into OK mode, if the system code coming from out-of-band is unknown, the screen will remain distorted. It will become.

【Effect of the invention】

As described in detail above, the present invention provides not only an in-band data signal but also an out-band data signal, and allows the terminal to participate in descrambling processing of this out-band data, thereby making it possible to A high degree of scrambling can be achieved, improving the effectiveness of preventing eavesdropping.

[Brief explanation of drawings]

(Fig. 1 is a block diagram of a conventional transmission side scrambling method, Fig. 2 is a block diagram of a terminal side descrambler, Fig. 3 is a block diagram of the same terminal, and Fig. 4 is a block diagram of an embodiment of the present invention). 5 is a block diagram of the descrambler on the terminal side, FIG. 6 is a 71 cock diagram of the terminal, FIG. 7 shows an example of a conventional center command, and FIG. The figure shows an example of a center command related to the present invention. 1...Converter, 2...Discrambler, 3.
...FSK, 4...Controller, 5...Channel select 1-key, 6...Address, 7...Ditunnel display, 8...Random number generator, 9... Shift register, 1o... Synchronization detector, 11.12... Switch, 13... Attenuator, 14... Modulator, 15 River 11j adjuster..., 16... Shift register, 17・
...Same 1111 Detector, 18-19...Sui Ngu 2o...Hai 1 Hing 21, 22...Or Gate, 23
...System code, 24...Center command generator, 25...FSK modulator. Patent applicant: Pioneer Co., Ltd. Agent: Patent attorney: Makoto Kobashi Ukiyo Patent attorney: Susumu Ri J.

Claims (1)

[Claims] In a system in which a key code is transmitted as in-band data using a frequency multiplexing method within an image band, and the above in-band data is used as a decode key signal on the terminal side, the transmitting side transmits a center command in a frequency band different from the above image band. /j CAT
Viewing control method in V.