JPS5947888A - Scramble television system - Google Patents

Abstract

PURPOSE:To make interception difficult, by inserting optionally inversely a signal during the horizontal period from a horizontal synchronizing signal to the next one. CONSTITUTION:In inputting a horizontal synchronizing signal to an input 32 of a waveform shaping circuit 30, the signal is converted into a horizontal period pulse signal at the circuit 30, and applied to a gate input terminal 27 of a gate switch circuit 26. When a normal television signal is inputted to an input 25 of the circuit 26, the signal at the horizontal period is outputted to an output terminal 28 at the circuit 26, other television signals are outputted to an output terminal 29, and a scramble television signal is formed at an inversion synthesis circuit 31 consisting of a differential amplifier or the like, and extracted from an output terminal 33.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a signal system for a television scramble system that can be received only by a specific television receiver, and its generation and reproduction circuit.

Recently, pay television broadcasting has become popular in the United States.

In order to prevent eavesdropping, this broadcast modifies the television signal so that it cannot be received by ordinary television receivers.
A no-clample system is used, which has a built-in special receiving circuit and can only receive images from four TV receivers.

FIG. 1 shows a normal television signal consisting of a vertical synchronizing signal 1, a horizontal synchronizing signal 2, a burst signal 6, and a video signal 4. Here, the period of the horizontal synchronization signal 2 and the burst signal 6 is called a horizontal blanking intercostal interval. The carrier wave that transmits this television signal
When AM modulation is performed, the amplitude of the transmitted carrier wave 6 changes with the television signal 7, as shown in FIG.

FIG. 3 shows the waveform of the scrambling method for this normal AM modulated wave. As is clear from the figure, for the normal AM modulated wave, the carrier wave 9 in the horizontal blanking period 8
And the amplitude of the modulated television signal 10 is reduced. When this modulated signal is received by a regular TV receiver, the horizontal synchronization signal cannot be extracted, so the screen becomes 4'//
The image is distorted to 4 and cannot be received. The scrambled modulated wave shown in FIG. 3 can be realized by simply reducing the horizontal period of the normal AM modulated wave shown in FIG. 2.

Therefore, in order to return this scrambled modulation wave to a normal modulation wave, horizontal blanking 3114 of the scrambled modulation wave must be performed.
All you have to do is amplify the gap. FIG. 5 shows this conventional circuit configuration.

Antella 1, tuner 2, IF amplification 16, video detection 1''4, video amplification 15, color detection 16, audio BPF 1
7. The configuration of a normal television receiver includes an audio detection 18, an audio amplification 19, a cathode ray tube 20, and a speaker 21, and a horizontal blanking period pulse generation circuit 22 is arranged here. Now, the subcarrier of 31.5 KHz is taken out from the audio detection 18 and input to the horizontal blanking period pulse generation circuit 22 via the line 23, and the horizontal blanking period pulse generation circuit 22 divides the frequency of the subcarrier into 15. 7
The same 15.75 KHz horizontal synchronization signal is generated using the 5KE (z signal, and a horizontal blanking period pulse signal is generated from this horizontal synchronization signal. Using this horizontal blanking period pulse signal, IF amplification is performed. By increasing the gain during the 16 horizontal blanking periods, the scrambled signal is regenerated into a normal television signal.

This conventional scrambling method and blind generation circuit have a simple configuration of gain control; It is easy to be eavesdropped on, and it requires a strong will to control the gain or attenuator in a stable manner, and if this is not stable, it has the disadvantage of causing double-sided disturbances such as flicker. Unfortunately, this scrambled signal only exists in AM, and in li'M using satellite broadcasting, which is planned in the future, burst signals are suppressed, so FM satellite broadcasting with weak electric field reception will cause color noise. It also has the disadvantage of increasing image quality and significantly deteriorating image quality.

SUMMARY OF THE INVENTION An object of the present invention is to provide a scrambling system that is difficult to eavesdrop on and compatible with future satellite broadcasting FM by eliminating the problems of easy eavesdropping and instability of gain control, which were conventional drawbacks.

Since the drawback of the conventional method was the suppression of the horizontal synchronization signal and burst signal during the horizontal blanking period, the Kinei ψ arbitrarily inverts and inserts the horizontal period signal from the horizontal synchronization signal to the next water synchronization information +5. By using the scrambled TV signal of ``, it is possible to make eavesdropping more difficult, and without using gain jli control, it is possible to correspond to the future FM of Ijusei Broadcasting.

Hereinafter, the present invention will be explained in detail according to embodiments shown in the drawings. 5 and 6 show the basic waveforms of scrambled television signals of the present invention, in which a television signal of 24 horizontal periods from horizontal synchronization to horizontal synchronization is inverted and inserted into the normal television signal shown in FIG. Therefore, as shown in Fig. 5, the signal is completely inverted and inserted, or as shown in Fig. 6, it is inconvenient to use the inverted signal.

By using this signal, a normal television receiver cannot extract the horizontally open 1tJj signal and therefore cannot receive the image. Furthermore, since the burst signal is not suppressed, it can also be used for weak electric field FM such as satellite broadcasting. FIG. 7 shows this television signal generation circuit.

Terminal 25 is a signal input of a gate switch circuit 26 for signal separation, terminal 27 is a gate signal input, and terminals 28 and 2
9 is a separation signal output. This gate switch circuit 26
A waveform shaping circuit 60 that generates a horizontal period pulse signal from a horizontal synchronization signal is connected to the gate input terminal 27 of the
The output terminals 28 and 29 of the gate switch circuit 26 are connected to the inputs of the inverting and combining circuit 31, respectively. Now, when a horizontal period signal is input manually to the input 62 of the waveform shaping circuit 60, the waveform shaping circuit 1ift path 30 converts it into a horizontal period signal (g, p+)tl (gate input terminal 2 of the gate switch circuit 26).
7. When a normal television signal is input to the signal input 25 of the gate switch [01 path 26, the gate switch circuit 26 outputs the signal of the horizontal period to the output terminal 28, and the other television signals are output to the output terminal 29. The scrambled television signal shown in FIG. 5 is formed in an inverting/synthesizing circuit 31 composed of a dynamic amplifier or the like, and is taken out from an output terminal 53. This scrambled television in Figure 5 (No. I)
I) Chemical 11. The lt path is the same as the 11th path in FIG. 7. As shown in the conventional example, when a horizontal periodic signal is generated from the f-voice subcarrier %Zl and applied to the terminal 52, the Sfuranzuru television signal () input from the input terminal 25 is as follows. Terminal 35 is picked up by a normal TV @ number.
is output from. In the generating circuit shown in FIG. 7, when irregularly missing horizontal synchronization 4B M is inputted to the terminal 62, the scrambled television signal shown in FIG. 6-1 is obtained.

FIG. 8 shows a reproduction circuit for a scrambled television signal in which the television signal in the horizontal period is irregularly inverted. The figure shows the seventh
A gate switch circuit 34 and a waveform shaping circuit 65 are added to the scrambled television signal generation and reproduction circuit shown in the figure, and the input and output signal waveforms (a-h) of each part are shown in FIG. There is.

The scrambled television signal a shown in FIG. 6 inputted from the terminal 25 is distributed to the gate switch circuits 26 and 34, and in the gate switch circuit 64, when a horizontal synchronization signal formed from an audio subcarrier or the like is applied to the gate terminal 66, the scrambled television signal a shown in FIG. , the voltage waveform C at the time of the horizontal synchronizing signal is sampled and output, and when only the upper pulse of this waveform C is taken out by the waveform shaping circuit 65, a waveform d of only the horizontal synchronizing signal which is an inverted scrambled television signal is obtained. - This waveform d is expanded into a horizontal period pulse signal by the waveform shaping circuit 60 to form a waveform e, which is applied to the gate terminal 27 of the gate switch circuit 26. subordination
Then, the signal f of the horizontal period which has been inverted and inserted is outputted to the output 28 of the gate switch circuit 26, and the other signal g is outputted to the output 29.h-1 These signals f and g are outputted to the inverted synthesis circuit 61. A normal TV signal is output.

Although the above embodiment has been explained based on the generation/regeneration circuit shown in FIG. 7, this gate switch circuit may be arranged in a subsequent stage as shown in FIG. 10. That is, a scrambled television signal can be generated and reproduced by arranging an inverting distribution circuit 37 having two outputs, a positive polarity and a negative polarity, which is constituted by a differential amplifier or the like, and by combining the two outputs with a gate switch circuit 68. Furthermore, it is clear that the same effect can be obtained even if this circuit is applied to the configuration shown in FIG.

According to the scrambling system of the present invention, since the television signal in which the signal of the horizontal period from one horizontal synchronizing signal to the next horizontal synchronizing signal is inverted and inserted is used, the generation and reproduction circuits may be switch circuits, and conventional gain control is not required. By eliminating instability and performing irregular inversions, eavesdropping is made difficult and burst signals are not suppressed, making it possible to use weak electric field FMK for satellite broadcasting.

[Brief explanation of the drawing]

Figure 1 is a normal TV signal waveform diagram, v2 diagram is a normal AM signal waveform diagram.
Figure 6 is a conventional scrambled AM waveform diagram, and Figure 4 is a block diagram of a conventional scramble playback television receiver configuration. , 1, 5th and 1, 6th
The figure shows a TV signal waveform diagram of the scrambling system of the present invention.
7 and 10 are block diagrams of a signal generation and reproducing circuit of a scrambling system according to an embodiment of the present invention, FIG. 8 is a block diagram of a reproducing circuit of an embodiment of the present invention, and FIG. FIG. 3 is a waveform diagram showing a reproduction process. 1... Vertical synchronization signal, 2... Horizontal synchronization signal, 6.
... Burst signal, 4... Image 1 signal, 5.3...
・Horizontal blanking period, 6.9...Carrier wave, 7...TV signal, 10
...Horizontal blanking period signal, 11...Antenna, 12...Tuner, 16...IF amplification,
14...Video detection, 15...Video amplification,
16...Color reproduction, 17...Audio BPF, 1
q...hT↓・amplification, 26...feeder, 22...
Water ~ blanking period pulse generation circuit, 20...Flaun tube, 21...Speaker, 24...Horizontal period, 26.34.38...Gate switch ILI
Circuit, 30,! 15... Waveform shaping circuit, 61...
・Inversion synthesis 1φ1 path, 67...Inversion distribution is path. Figure 3 δ size diagram

Claims (1)

[Claims] 1. In a scrambled television system that uses television signals that cannot be received by ordinary television receivers and can only be received by television receivers equipped with a specific receiving circuit, the signals in the horizontal period from one horizontal synchronizing signal to the next horizontal synchronizing signal are A scrambled TV system characterized by using a TV@book that is completely reversed or irregularly reversed and inserted.