RU14713U1 - RADIO TRANSMISSION AND RECEIVING SYSTEM OF AUDIO AND VIDEO SIGNAL WITH COVER - Google Patents

Abstract

1. A radio system for transmitting and receiving audio and video signal with cover, including a transmitter with a main frequency-modulated generator with a radio frequency output and a receiver with a main frequency detector with a radio frequency input, characterized in that the transmitter is equipped with an additional frequency-modulated generator with a video signal input, an adder and a cover signal generator, while the adder inputs are connected to the outputs of an additional frequency-modulated generator and a cover signal generator, and its output - with the input of the main frequency-modulated generator, the receiver is equipped with an additional frequency detector with a video signal output and a filter, the filter input being connected to the output of the main frequency detector, and the output to the input of the additional frequency detector. 2. The radio system according to claim 1, characterized in that the transmitter is equipped with a frequency-modulated sound generator with an audio signal input and an output connected to an adder input, and the receiver is equipped with a frequency sound detector with an output connected to a filter output made according to a separation filter circuit. . The radio system according to claim 1, characterized in that the cover signal generator consists of an electric oscillation source, the output of which is connected to a filter input, the output of which forms the output of the cover signal generator.

Description

The utility model relates to special technical means intended for covert transmission of video and sound.

One of the tasks solved by such devices is to protect the transmitted signal from being intercepted by known means of receiving television images: television broadcasting receivers, satellite broadcasting devices, video signal analyzers and spectrum analyzers (including via side (spurious) radiation and reception channels) 1, 2 , 3, 4.

Known radio system for transmitting and receiving audio and video signal with cover, produced by the company LLC O.R.T. under the code U-5001 5 prototype.

The radio system consists of a transmitter with a main frequency-modulated generator with a radio frequency output and a receiver with a main frequency detector with a radio frequency input. The transmitter frequency is modulated directly by the signal coming from the video source in analog broadcast standard 1, and the sound is transmitted at a subcarrier frequency, the average value of which is higher than the upper frequency of the image signal.

In this system, protection from being intercepted by television broadcast receivers is carried out by going beyond the broadcast range (48.5 MHz - 958 MHz) 1, and using a different type of modulation (FM) compared to broadcasting. There are no spurious emissions of the transmitter on the subharmonics that fall into the broadcast television range, since the carrier is formed in the transmitter without frequency multiplication. Protection from interception by satellite broadcasting devices is provided by changing the polarity of the FM signal

images to the opposite. When a signal hits the main channel of the satellite tuner, it is perceived by the recognition system as a hindrance and is not transmitted further to the input of the television receiver.

However, experimental data show that all these measures are not quite sufficient when the television broadcast receiver or the input circuits of the satellite tuner is near the antenna of the transmitter.

With sufficient transmitter power, the following spurious channels for receiving video images will inevitably appear:

- direct detection of spurious amplitude modulation (PAM) by non-linear elements of the video path of a broadcast television receiver,

receiving the carrier of the transmitter at the harmonics of the local oscillator and detecting the FM on the slopes of the frequency response of the radio path of the television receiver,

FM polarity reversal in the mirror channel of a satellite tuner.

In addition, the system signal is not protected from being intercepted by a video analyzer having an FM image detector with direct and reverse polarities, and a reception range that covers both the broadcast AM band and the IF band of satellite FM tuners 4.

The spectrum analyzer also allows you to identify the image signal 3. This is due to the clearly distinguishable correlation of the spectrum parameters with changes in the illumination of the transmitted scene and the movements of its large parts.

The objective of the patented utility model is to eliminate spurious channels for receiving video images, as well as to increase the degree of protection against interception.

This is achieved by the fact that in a radio system for transmitting and receiving audio and video signals with a cover, including a transmitter with a main frequency-modulated generator with a radio frequency output and a receiver with a main

a frequency detector with a radio frequency input, unlike the prototype, the transmitter is equipped with an additional frequency-modulated generator with a video signal input, an adder and a cover signal generator, while the adder inputs are connected to the outputs of an additional frequency-modulated generator and a cover signal generator, and its output is connected to the input of the main frequency-modulated generator, the receiver is equipped with an additional frequency detector with a video output and a filter, moreover, the input of the filter is connected to the output o novnogo frequency detector, and an output - to an input of optional frequency detector.

And also the fact that the transmitter is equipped with a frequency-modulated sound generator with an audio signal input and an output connected to the adder input, and the receiver is equipped with a frequency sound detector with an output connected to a filter output, made according to the separation filter scheme.

And also the fact that the cover signal generator consists of a source of electrical oscillations, the output of which is connected to the input of the filter, the output of which forms the output of the specified cover signal generator.

In FIG. 1 shows a patented system for transmitting hidden audio and video signals;

in FIG. 2 - cover signal generator;

in FIG. 3 is a frequency diagram of a signal at the input to an additional frequency-modulated generator;

in FIG. 4 is a frequency diagram of a signal output from an additional frequency-modulated generator;

in FIG. 5 is a frequency diagram of a signal output from a cover signal generator; in FIG. 6 is a frequency diagram of the signal at the output of the adder;

in FIG. 7 is a frequency diagram of a signal output from a main frequency-modulated generator; in FIG. 8 is a frequency diagram of a sound signal;

in FIG. 9 is a frequency diagram at the output of a frequency-modulated sound generator;

in FIG. 10 is a frequency diagram at the output of the adder when transmitting both the video signal and the sound signal;

in FIG. 11 is a frequency diagram at the output of the main frequency-modulated generator when transmitting simultaneously a video signal and a sound signal.

The patented radio system consists of a transmitter 1 and a receiver 2. The transmitter 1 includes an additional frequency-modulated generator 3, an adder 4, a main frequency-modulated generator 5 and a cover signal generator 6, and may also include a frequency-modulated sound generator 7 with an audio signal input. The additional frequency-modulated generator 3 has a video signal input, and the main frequency-modulated generator 5 has a radio-frequency output. The inputs of the adder 4 are connected to the outputs of the additional frequency-modulated generator 3, the frequency-modulated sound generator 7 and the cover signal generator 6, and its output is connected to the input of the main frequency-modulated generator 5. The receiver 2 includes a main frequency detector 8, a filter 9, and an additional frequency detector 10, and may also include a frequency sound detector 11 with an audio signal output. The main frequency detector 8 has a radio frequency input, and an additional frequency detector 10 has a video signal output. The input of the filter 9 is connected to the output of the main frequency detector 8, and its outputs are connected to the input of the additional frequency detector 10, as well as to the input of the frequency detector of sound 11. When receiving together with the video signal and the sound signal, the filter is performed according to the separation filter scheme. Cover signal generator

6 consists of a noise source, the output of which is connected to the input of the filter 13, the output of which forms the output of the specified cover signal generator 6.

Patented radio system works as follows.

The video signal from a video camera or other source with a band from 0 to FB is fed to the modulating input (Fig. 3) of an additional frequency-modulated generator 3 and transferred to the frequency range from F1 to F2 (Fig. 4), where Fn is the center frequency of the specified generator 3.

The cover signal generator 6 generates a cover signal in the band from O to Pvp located below the frequency F1 (Fig. 5).

In the adder 4 is the addition of information and covering signals, after which the group signal is fed to the modulating input of the main frequency-modulated generator 5 with an RF output (Fig. 6).

In the indicated generator, both components of the group signal (information and covering) jointly act on the modulated parameter, which leads to mixing of their spectral components on the carrier radio frequency, as shown schematically in the frequency diagram (Fig. 7).

The shape, amplitude and spectrum of the covering signal are selected so as to make it impossible to receive video in the presence of this signal through known interception channels due to the additive effect on the video reception path system (synchronization and auto-adjustments), as well as on the brightness channel itself.

In order to complicate the identification of the signal using a spectrum analyzer, the modulation parameters are set such that the components of the spectrum at frequencies close to (Rnes), where N 0,1,2 ... visually overlap (see the section of the diagram between F3 and F5) .

Reception and injection of a useful signal on the receiving side of the system (receiver 2) is carried out in the reverse order of the output signal generation sequence.

At the beginning, group frequency demodulation occurs and the cover modulation is removed from the image subcarrier (diagram of Fig. 6), and then the video signal itself is demodulated at the subcarrier frequency Fn by any of the methods 6 known and traditional for frequency modulation.

To transmit sound to the device circuit, an additional frequency-modulated sound generator 7 of the sound frequency subcarrier is introduced. Frequency diagrams of the formation of such a signal for the case when the frequency of the sound subcarrier Rpz is located between Rvp and Fn are shown in Figs.

The source of the covering signal may be noise fluctuations.

of physical origin, for example, amplified noise of a zener diode 7, or a pseudo-random M-sequence of long length 8, as well as any other electrical oscillation that provides an impact on the system (systems) and (or) the path of video capture equipment, making it impossible to restore the original video image.

The formation of the spectrum of the necessary width and shape, so as not to interfere with your own receiver, is provided by an electric filter 9.

Sources of information taken into account:

1. Documents of the CCIR. Report 624-3. Geneva 1986

2.GOST 7845-79. Broadcast Television System. Main parameters. Measurement Methods.

3.Hewlett - Packard. Test & Measurement Catalog 1998.Signal Analysers.

5. Radio transmission system for video / audio information with remote control U5001. Technical description and instruction manual. LLC O.R.T. 1999 prototype.

6.L.Ya. Cantor. Methods to increase the noise immunity of receiving FM signals.

7. Reference book on the elements of electronic devices. Edited by V.N.Dulin, M.S. Zhuk. Moscow "Energy 1977

8.R.K. Dixon. Broadband systems. Per. from English / Ed. V.I. Zhuravleva // M .: Communication, 1979.-304 p.

9.G. Hanzel. Filter calculation reference. Moscow “Soviet Radio 1974

Claims (3)

1. A radio system for transmitting and receiving audio and video signal with cover, including a transmitter with a main frequency-modulated generator with a radio frequency output and a receiver with a main frequency detector with a radio frequency input, characterized in that the transmitter is equipped with an additional frequency-modulated generator with a video signal input, an adder and a cover signal generator, while the adder inputs are connected to the outputs of an additional frequency-modulated generator and a cover signal generator, and its output - with the input of the main frequency-modulated generator, the receiver is equipped with an additional frequency detector with a video signal output and a filter, the filter input being connected to the output of the main frequency detector, and the output to the input of the additional frequency detector.  2. The radio system according to claim 1, characterized in that the transmitter is equipped with a frequency-modulated sound generator with a sound signal input and an output connected to the adder input, and the receiver is equipped with a frequency sound detector with an output connected to the filter output, made according to the separation filter scheme . 3. The radio system according to claim 1, characterized in that the cover signal generator consists of an electric oscillation source, the output of which is connected to the filter input, the output of which forms the output of the cover signal generator.