JPS60191533A - Picture signal transmission system - Google Patents

Abstract

PURPOSE:To obtain a ciphering communication system where a signal is hardly decoded externally by superimposing a prescribed digital pattern on a picture signal and transmitting the signal while a clock signal and a synchronizing signal are inserted. CONSTITUTION:A digital pattern signal generator 1 inputs a clock signal CLK and a synchronizing signal SYC, generates a pattern taking the CLK as a bit period and the SYC as a pattern period, a synthesizer 3 synthesizes it with the CLK through a BPF 2 and the result is outputted to a band rejection filter BRF4. The BRF4 decreases the spectrum of the synchronizing information frequency and outputs the result to a synthesizer 5. The synthesizer 5 synthesizes an output of the BRF4 and a picture signal VD and inputs the output to a synthesizer 5. A modulator 6 modulates a subcarrier SCR by using the SYC, synthesizes its output at the synthesizer 7 with an output of the synthesizer 5 and outputs the result as a base band signal BB. A reception side extracts the clock and the synchronizing signal from the signal BB, generates (1) a digital pattern, inverts (11) it to eliminate the digital pattern from the signal BB and regenerates picture information.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to an image signal transmission system in which an interference signal is superimposed on an image signal to provide sufficient confidentiality.

(2) Background of the Technology In recent years, not only audio signals but also image signals have been transmitted using wireless communication in video conferences and the like.

However, when transmitting information that is desired to be kept secret, such as confidential information from a certain company, it is necessary to prevent others from reproducing the image signal from the received signal.

(3) Prior Art and Problems Various methods have been studied and are being put into practical use for creating a disturbance in the image signal on the wireless transmitting side for secret communication. One method is to create several interference waves on the baseband image signal, and a simple sine wave without modulation is used as the interference waves. In this case, on the predetermined receiving side, processing can be easily performed by simply using a band-rejection filter that removes the frequency of the interference wave. However, if a third party uses a frequency analyzer, they can easily detect the frequency of the interference wave.
Confidentiality could not be maintained unless the frequency was changed from time to time. Another method is to utilize the properties of the image signal and perform waveform processing on the image signal itself, but since the audio is in a different band from the image signal, it is possible to interfere with the audio at the same time. The drawback was that it was too complicated to send.

(4) Object of the Invention The object of the present invention is to improve the above-mentioned drawbacks, and to provide an image processing method in which signal processing is easily performed in the baseband band of an image signal, and superimposed interference signals are difficult to decipher from the outside. Our goal is to provide the following.

(5) Structure of the Invention According to the present invention, the transmitting side superimposes an interfering signal on an image signal and transmitting the image signal, and the receiving side reproduces the interfering signal and removes the interfering signal from the received signal. In the image signal transmission method for obtaining the original image signal, the transmitting side superimposes a digital signal that repeats a predetermined pattern as an interference signal on the image signal, and also uses the clock information of the digital signal and synchronization corresponding to the repetition period of the digital signal. The receiving side extracts the clock information and the synchronization information from the received signal and generates a digital signal with the same pattern as the sending side. This is achieved by providing an image signal transmission system characterized by reverse polarity and one-zeta alignment.

(6) Examples of the invention Examples of the present invention will be described below.

In the embodiment of the present invention, a predetermined digital pattern is superimposed on the image signal, and a synchronization signal is also inserted into the image signal, and the receiving side extracts the corresponding I:1 test signal and synchronization signal. The digital pattern is generated and removed from the received signal.

FIG. 1 is a block configuration diagram of the transmitting side according to the first embodiment of the present invention. In the figure, ▪ indicates a digital signal pattern generator, and 2 indicates a band-pass filter.

3 is a first synthesizer, 4 is a band elimination filter, 5 is a second synthesizer, 6 is a modulator, 7 is a third synthesizer, VD is an image information material L
K is a clock signal, and syc is a synchronization signal.

SCR indicates a synchronization signal subcarrier, and BB indicates a baseband signal.

In FIG. 1, the digital signal pattern generator 1 is
Input the clock signal CLK and synchronization signal syc,
A digital signal pattern with LK as the bit period and syc as the pattern period is generated and output to the first synthesizer 3. The bandpass filter 2 limits the band of CLK and outputs it to the first synthesizer 3. A first synthesizer 3 synthesizes the output and the output of the digital signal pattern generator 1 and sends the result to a band-removal FF waveform generator 4 . A band-elimination filter 4 inputs the output and reduces the spectrum of the frequency at which synchronization information will be inserted later.
Output to synthesizer 5. The second synthesizer combines the output and the image signal V
D and output to the third synthesizer 7. The modulator 6 modulates the subcarrier SCR using the synchronization signal syc, and the third synthesizer 7 modulates the subcarrier SCR.
I'm going to go to. A third combiner 7 combines the output with the second combiner 5.
The output is combined and output as a baseband signal BB. The baseband signal is then modulated onto the main carrier and transmitted.

Figure 2 shows Figure 1 (al~(spectrum of ClO point O
jtsuku signal, SCR is the frequency of the subcarrier for synchronization signals.

SYC each indicates a sub-single transmission wave modulated with a synchronization signal.

The image signal VD inputted in Fig. 1(a) has a luminance signal Y, a color signal C, and an audio signal VCE as shown in Fig. 2(al).
are synthesized.

As shown in Figure 2, No. 44 in Figure 1 (bl) has a reduced broad spectrum power due to the digital signal pattern. .

As shown in FIG. 2(e), the baseband signal qBI3 outputted in FIG. 1(C) has the spectrum of the digital signal pattern superimposed on the spectrum of the image signal, and synchronization information is further inserted. Since the digital signal pattern is superimposed, it is extremely difficult for someone who does not know the digital signal pattern to extract the original image information even if the baseband signal is received and demodulated.

FIG. 3 is a block configuration diagram of the receiving side related to FIG. 1, in which 1 is a digital signal pattern generator;
8 is a clock signal extraction circuit, 9 is a subcarrier extraction circuit, 1
0 indicates a synchronization signal extraction circuit, 1 signal, syc a synchronization signal, and SCR a subcarrier.

In FIG. 3, a clock signal extraction circuit 8 extracts a clock signal from the received ffi-tuned baseband signal BB and outputs it to the digital signal pattern generator 1. The subcarrier extraction circuit 9 extracts the subcarrier SCR from the baseband signal, and the synchronization signal extraction circuit 1 extracts it and outputs it from the digital signal pattern generator 1. The digital signal pattern generator 1 generates the same digital signal pattern as that on the transmitting side from C1°K and SYC and outputs it to the polarity inversion circuit 11.

The polarity inversion circuit 11 inverts the polarity of the digital signal pattern and outputs it to the fourth synthesizer 12. A fourth combiner 12 combines the signal and the baseband signal, removes the spectrum due to the digital signal pattern from the baseband signal,
Take out the original image signal VD. Although the clock signal and synchronization information still remain in the original image signal, by removing the frequency of these signals from the video signal and audio signal bands as shown in FIG. 2, there is no effect.

Next, a second embodiment of the present invention will be described.

The fourth part is a block configuration diagram of the transmitting side according to the second embodiment of the present invention, in which 1 is a Dinkle signal pattern generator, 2 is a bandpass filter, 3 is a first synthesizer, and 4 is a band elimination device. filter, 5 is the second combiner, 6 is the modulator, 7 is the third
Combiner, 13B M/N multiplier, VD is image signal, CLK
is a clock signal, SYC is a synchronization signal, and BB is a baseband signal.

In FIG. 4, the M/N multiplier 13 uses the clock signal CL
The frequency is multiplied by M/N from K to sub-1 general transmission wave S for synchronization signal.
Creating a CR. This eliminates the need for an oscillator for SCR. At this time, a reset is applied by the synchronization signal SYC, and the phase of the synchronization signal subcarrier is synchronized with the SYC. This is to align the phases of subcarriers between transmitting and receiving.

The rest is the same as the first embodiment.

FIG. 5 is a block configuration diagram of the receiving side related to FIG. 4, in which 1 is a digital signal pattern generator;
8 is a clock signal extraction circuit, 10 is a synchronous signal extraction circuit,
11 is a polarity inversion circuit, 12 is a fourth synthesizer, and 13 is M/N.
BB is a multiplier, BB is a subband signal, CI is a clock signal, SCR is a subcarrier, SYC is a synchronization signal, and VD is an image signal.

In FIG. 5, when the M/N multiplier 13 is extracted from the baseband Shinji BB by the clock signal extraction circuit 8, it is reset by the synchronization signal SYC, synchronizes the phase of the subcarrier with the synchronization signal, Align the phase with the transmitted wave. The subcarrier in the baseband signal is modulated by the synchronization signal, but the CLK is not, so the subcarrier created from CLK is better than the subcarrier extracted from the base/X node signal. is more stable.

The rest is the same as in the first embodiment.

Next, a third embodiment of the present invention will be described.

FIG. 6 is a block diagram of the transmitting side according to the third embodiment of the present invention, in which ] is a digital signal pattern generator, 4 is a band-elimination filter, 5 is a second synthesizer, and 6 is a modulator. , 7 is the third synthesizer, 14 cyokaii*a4@”16
．． v D t, statue No. 16, 5ycc good, period signal.
SCR indicates a synchronization signal subcarrier, and B13 indicates a baseband signal.

In FIG. 6, the N/M multiplier 14 multiplies the frequency of the synchronizing signal subcarrier SCR by N7M to generate the clock signal CLK.
is being created. In other words, the clock information is included in the subcarrier, and there is no need to insert the clock information. At this time, the synchronization signal SYC causes N/M
The multiplier 14 is reset and the phase of CLK is synchronized with SYC. This is to make it easier to align the CLK phase between the transmitter and the receiver.

The rest is the same as the first embodiment.

FIG. 7 is a block configuration diagram of the receiving side related to FIG. 6, in which 1 is a digital signal pattern generator;
9 is a subcarrier extraction circuit; 10 is a synchronization signal extraction circuit; 11 is a synchronization signal extraction circuit;
is a polarity inversion circuit, 12 is a fourth combiner, 14 is an N/M multiplier, BB is a baseband signal, SCR is a subcarrier, CL
K is a clock signal, , S Y C is a synchronization signal, VD
indicate image signals, respectively.

In FIG. 7, the N/M multiplier 14 generates the clock signal CLK by multiplying the frequency by N7M from the synchronization signal subcarrier SCR extracted from the baseband signal BB by the subcarrier extraction circuit 9.

At this time, the synchronization signal SYC extracted from the baseband signal by the synchronization signal extraction circuit 10 causes the N/M multiplier 14 to
is reset, and the phase of CLK is synchronized with SYC to align the phase with CLK on the transmitting side.

The rest is the same as the first embodiment.

(7) Effects of the Invention According to the present invention, as described above, a digital signal is superimposed on an image signal as an interfering signal, and the image double amount is secretly transmitted, so that it is effective as a secret communication. Furthermore, it has the effect of simultaneously concealing the voice. It also has the effect that the device on the receiving side does not become too complicated.

[Brief explanation of the drawing]

3 is a block configuration diagram of the receiving side related to FIG. 1, FIG. 4 is a block configuration diagram of the transmitting side according to the second embodiment of the present invention, and FIG. 5 is related to FIG. 4. FIG. 6 is a block diagram of the transmitting side according to the third embodiment of the present invention, and FIG. 7 is a block diagram of the receiving side related to FIG. 6. 5 is a band-elimination filter, 5 is a second combiner, and 6 is a modulator. 7 is a third synthesizer, 8 is a clock extraction circuit, 9 is a subcarrier extraction circuit, 10 is a synchronization signal extraction circuit, 11 is a polarity inversion circuit, 12 is a fourth synthesizer, 13 is an M/N multiplier, 14 is N/
M multiplier, VD is image signal. CLK represents a clock signal, SCR represents a subcarrier, SYC represents a synchronization signal, and BB represents a baseband signal. 11ko:・;2"l;:31

Claims (1)

[Scope of Claims] (1) A transmitting side superimposes an interference signal on an image signal and transmits it, and a receiving side reproduces the interference signal and removes the interference signal from the received signal to obtain an original image signal. In the signal concealment method, the transmitting side superimposes a digital signal that repeats a predetermined pattern as an interference signal on the image signal, and further inserts clock information of the digital signal and synchronization information corresponding to the repetition period of the digital signal. The receiving side extracts the clock information and the synchronization information from the received signal, generates a digital signal with the same pattern as the sending side, adds the digital signal to the received signal with the opposite polarity, and superimposes it. An image signal transmission method characterized by eliminating digital signals that have been previously transmitted. (2) The image signal transmission method according to claim 1, wherein a part of the spectrum of the digital signal is reduced on the transmitting side, and the synchronization information is inserted into the reduced frequency. (3) The image signal transmission method according to claim 1, wherein the synchronization information is a signal obtained by modulating a synchronization signal subcarrier with a synchronization signal synchronized with the repetition period. The number is multiplied by M/N to create the subcarrier, and on the receiving side, the frequency is multiplied by M/N from the clock signal extracted from the received signal to create a subcarrier, and the subcarrier is used to generate a synchronization signal from the received signal. 4. The image information transmission method according to claim 3, wherein the synchronization signal is used to synchronize the clock phases of the transmitting side and the receiving side. (5) The clock information G is included in the synchronization signal subcarrier, and on the transmitting side, the frequency is multiplied by N7M from the subcarrier to create a clock signal for a digital signal, and on the receiving side, the subcarrier t! is extracted from the received signal. ll Transmit frequency to N7
4. The image signal transmission system according to claim 3, wherein a clock signal for a digital signal is created by multiplying the clock signal by M, and the clock phases of the transmitting side and the receiving side are synchronized by the synchronizing signal.