JPS60142687A - Wiretapping prevention system - Google Patents

Abstract

PURPOSE:To stop immeidately the normal movement of a converter to prevent wiretapping in case of wiretapping is executed by inserting a channel code peculiar to each TV channel into its image signal part. CONSTITUTION:An image signal 104 inputted by an image input 102 is added with a channel code peculiar to the image signal part by a channel code encoder 301. The encoder 301 is provided with a channel code peculiar to a send out channel by a SW303 for setting a channel code. A channel code additional image signal 302 to which a channel code is added is added to a scrambler 106 to be scrambled, where a method to insert a channel code by either inserting pulse data during a vertical blanking period or inserting tone burst data during an equivalent pulse is adopted.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an eavesdropping prevention system in a CATV system or a direct satellite broadcast system. The video and audio signals are scrambled to prevent eavesdropping, so that people other than subscribers cannot watch paid programs without paying twice the fee. Various scrambling methods have been proposed, and the techniques have become more complex and sophisticated year by year, including synchronous compression and video inversion for video, and spectrum inversion for audio. In addition, in combination with the above scrambling method, an addressable method is generally used in which descrambling is controlled by adding numbers to individual terminals and specifying those terminals from a center device. FIG. 1 shows a general configuration of a CATV system that combines these scrambling and addressable systems.

In FIG. 1, a video signal 104 from a VTR or the like is input to a video input 102 and an audio input 103 in a center device 101.
When the audio signal 106 is added, the scrambler 106 performs scrambling processing on both or either of the video signal 104 and the audio signal 105,
The modulator 107 applies the high frequency TV signal 108 to the mixer 1093°. On the other hand, address data 111 for the addresser pull generated from a data signal generator 110 composed of a microprocessor or minicomputer, etc.
The signal is modulated into a predetermined signal format by the addressable encoder 112, mixed with the TV signal 108 by the mixer 109 as a data signal 113, and sent to the CATV trunk cable 115. Generally, as the frequency of the data signal (l"l: a frequency that does not overlap with the TV signal is selected.1) The data signal generator 110 generates a scrambler control signal 114 for controlling the scrambler as necessary. The TV signal and data signal sent to the trunk cable 115 pass through a branch 116 and are guided to a CATV converter 118 located in the home via a lead-in line 117 to the home.CATV converter 11
The TV signal and data signal inputted from the RF input terminal 119 of No. 8 are demultiplexed by a duplexer 120 and decomposed into a TV signal 121 and a data signal 122 again. TV
An arbitrary wave of the signal 121 is selected by the synthesizer tuner 123, and descrambled by the descrambler 124 if the selected screen is scrambled, resulting in a normal video signal 125 and audio signal 126.
is obtained. Note that in recent years, synthesizer tuners have been used in CATV converters. These video signals 1
25 and the audio signal 126 are modulated again by the RF modulator 127 and output from the CAT V converter 118 through the RF output terminal 129 at a predetermined frequency, for example, the frequency of channel 1 or channel 2, to the general TV connected thereto. The program is input to the receiver 128 and can be received with a normal screen and sound.

On the other hand, the data signal 122 extracted by the demultiplexer 120
The addressable decoder 130 performs demodulation and discrimination processing on the data signal, and if the address specified by the data signal matches its own as a result of the discrimination processing, a control signal is sent to control the descrambler 124. 131 is output to the descrambler 124. If the subscriber does not pay the viewing fee according to the control signal 6.°] parameter 131, the descrambling operation is forcibly stopped, thereby preventing the subscriber from receiving a normal screen and sound. .

However, in the conventional configuration as shown in FIG. 1, wiretapping may not be prevented no matter how complicated the scrambling method or addressable method is used. In other words, by simply inserting a wiretapping device consisting of a simple conventional converter and a duplexer between the RF input terminal 119 of the CATV converter 118 and the lead-in line 117, the subscriber can pay the listening fee for one channel and pay for all other channels. You can watch the channel for free. This will be explained using FIG. In FIG. 2, the same parts as in FIG. 1 are designated by the same numbers used in FIG. 1. Trunk cable 1167 branch 116 in FIG. The TV signal and data signal that have passed through the lead-in line 117 are converted into a TV signal 203 by a splitter 202 in the eavesdropping device 201.
and a data signal 204. In this case, the duplexer 2
It is also possible to achieve the desired purpose with a simple band pass filter that extracts only the data signal 204 without using the data signal 204. TV signal 203 is basic converter 2
05. The basic converter 205 selects any TV channel from a large number of TV channels and outputs it as a fixed channel.
It has the most basic functions as a V converter that is generally available in the world. Basic converter 205
The frequency-converted TV signal is converted to a fixed channel, usually Channel 1 or Channel 2.

Converter output signal 20 converted to the fixed channel
6 is mixed with the data signal 204 by a mixer 207 to become an eavesdropping device output signal 208.

As is clear from the above explanation, the eavesdropping device output signal 208 is the frequency of the TV signal and data signal in which one channel selected from among the many TV channels sent through the lead-in line 117 is converted into a fixed channel. It becomes something with components.

These signals are connected to CATV converter 1 similar to that shown in Figure 1.
8 is input through all of the RF input terminals 119 and is input to 7-pu. Therefore, the CATV converter 118 only needs to always select one fixed channel using the synthesizer tuner, and can receive any TV channel by simply selecting the basic converter 205 in the eavesdropping device 201. Instead, subscribers can subscribe to only the fixed channels, pay a viewing fee, and then listen to all other channels for free. Furthermore, since data signals from the center are always input to the CATV converter 118, there is no change from the normal state from the CATV converter 118's perspective, and the addressable decoder 130 in the CATV-1 inverter 118 also detects eavesdropping. There was a problem that it could not be detected and could be eavesdropped despite using advanced scrambling technology.

OBJECTS OF THE INVENTION The present invention obviates these conventional drawbacks,
The purpose is to obtain an excellent eavesdropping prevention effect.

Structure of the Invention JP-A-142687 (3) The wiretapping prevention method of the present invention inserts a false code indicating a channel-specific number into the video signal of each TV channel, and extracts the code within the converter. However, eavesdropping is prevented by determining the channel number within the converter, and the eavesdropping caused by connecting a basic converter in front of the CATV converter as in the past is totally eliminated.

Description of examples Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 shows the configuration of a part for adding a channel code to be inserted before the scrambler 106 in the center device 101 of FIG. 1 used to explain the configuration of the conventional example. The same numbers are used for parts common to those in FIG. Third
A channel code encoder 301 adds a channel-specific channel code to the video signal portion of the video signal 104 inputted from the video input unit 102 shown in the figure. In the channel code encoder 301, a channel code with 91 ψ transmission channels is set by a channel code setting SW 303. A channel code-added video signal 302 with a channel code added to the video signal by the channel encoder 301 is added to the scrambler 106 and scrambled. There are various methods for inserting the channel code into the video signal portion in the channel code encoder 301. There is a method of inserting pulse-like data into the vertical blanking period using a time division multiplexing method, as shown in Figure 5a.
As an example of another method, FIG. 6 shows a method of inserting tone bursts in the equalization pulse period in the vertical blanking period according to the channel code.

In the center device 101, the TV signal into which the channel code has been inserted passes through the same route as in FIG.
It is input to the RF input terminal 119 of the ATv converter 401. Similar to FIG. 1, the video signal 125 restored to the original normal signal by the descrambler 124 is input to the newly provided channel code decoder 404, and the video signal 125 is input to the newly provided channel code decoder 404, as shown in FIG. 5a.

By extracting the inserted channel code using the method shown in 1o pub b and comparing it with the selected channel data 403 for frequency setting taken out from a part of the synthesizer tuner 132 shown in FIG. If the selected channel data and channel code match, a channel code match signal 402 is output. Therefore, the synthesizer tuner 13 of the CATV converter 401
2, the channel code match signal 402 is always output when the channel is tuned properly, and when the channel is viewed by illegal means as shown in FIG. 2, the channel code match signal 402 is output. Not done. Therefore, if the channel code match signal 402 is not output by gated using the control signal 131 from the addressable decoder 130 and the gate 401, the descrambler 1
24 is not controlled, and the desk lamp 124 outputs a scrambled signal that cannot be restored normally.
It is possible to prevent wiretapping by illegal means.

11! Effects of the Invention As described above, in the present invention, by inserting a unique channel code for each TV channel into the video signal portion, even if wiretapping is done by illegal means using a basic converter etc., each By detecting the channel and the pair of channel codes inside the converter, the normal operation of the converter can be immediately stopped in the event of unauthorized wiretapping, which prevents wiretapping and improves the scrambling method. The more you use it, the more effective it will be.

[Brief explanation of the drawing]

Figure 1 is a general configuration diagram of an 0ATV system, Figure 2 is a configuration diagram showing a wiretapping method for illegal wiretapping, and Figure 3 is a diagram showing how to add a channel code in a wiretapping system according to an embodiment of the present invention. FIG. 4 is a block diagram of a CATV converter according to an embodiment of the present invention, and FIG. 6 is a waveform diagram showing a state in which a channel code is inserted. 119...RF input terminal, 120...
Duplexer, 124...Descrambler, 125.
...Video signal, 127...RF modulator, 129...RF output terminal, 130...
...Addressable converter. 131...Control signal, 132...Sizer tuner, 400...CATV converter, 401...Gate, 402...
Channel signal matching signal, 403...Selected channel data, 404...Channel code decoder.

Claims (1)

[Claims] A unique code signal indicating a channel number is inserted into each video signal to be transmitted, and the signal is sent from a center device, and the channel code is extracted in a receiving terminal device, and the extracted code signal is inserted into the video signal. A wiretapping prevention system that detects and prevents wiretapping by comparing a channel code and channel selection data for frequency setting of a synthesizer tuner section in the receiving terminal device.