RU2602598C1 - Method of generating and processing signal built in masking interference - Google Patents

Abstract

FIELD: radio engineering and communications.

SUBSTANCE: invention relates to radio communication and can be used for transmitting confidential information over radio communication channels with limited frequency resource. Method of generating and processing a signal built in a masking interference involves formation of a useful signal and a masking interference at the transmitting side in the same transmitting device as an additive mixture, selecting the carrier frequency so, that the signal spectrum is within the bandwidth occupied by the masking interference, as well as selection of such structure of the masking interference, that its spectral components at frequency positions occupied by the useful signal are absent or the modulus of their amplitude does not exceed 5 % of the modulus of amplitude of spectral components of the useful signal, and on the other frequency positions, not occupied with the useful signal, the amplitude of spectral components of the masking interference in magnitude is equal to the amplitude of spectral components of the useful signal.

EFFECT: method of generating and processing a signal built in a masking interference implemented by one radio transmitter.

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Description

The invention relates to the field of radio communications and can be used to transmit confidential information via radio channels with a limited frequency resource.

A known method of protecting information exchange in a local radio communication system according to the patent of the Russian Federation No. 2114513 from 06/27/98, bull. Number 18. In the known method, the protection of information exchange in the local system is based on reducing the signal-to-noise ratio (SNR) for receivers receiving an attempt of unauthorized access to the transmitted information. For guaranteed protection in all kinds of situations, they provide less than one SNR due to the fact that during operation of the radio communication system they continuously emit noise signals having a power greater than the power of the working signals in the radio communication system and that cover the entire frequency band, used in the system.

The implementation of the known method involves the presence of two subsystems: the creation of noise interference and information exchange. Subscriber radio stations protect against noise exposure using a priori information about the structure of the interference.

The disadvantages of this method are as follows. According to the indicated method, it is supposed to use a communication system with code division of channels as an information subsystem, which is its functional limitation, since it is not applicable for communication systems with time division of channels. In addition, in the KB and VHF bands, the perimeter can be hundreds of kilometers. Therefore, the placement along the perimeter of tens and hundreds of interference transmitters having even insignificant radiation “backward” of the radiation patterns of their antennas will lead to a significant increase in the intensity of the interfering electromagnetic field inside the zone bounded by the perimeter and the possible appearance of local areas in it with unacceptable levels of the interference field.

A known method of information protection and a radio communication system with enhanced intelligence is RF Patent No. 2253184, published May 27, 2005.

In the known method, in a radio communication system containing an information subsystem and a noise interference subsystem, as well as elements of an information subsystem, elements of a noise interference generating subsystem, a unit for interconnecting elements of subsystems is introduced, which provides for staging obstacles in free time intervals and at allowed frequencies, included between information elements subsystems and subsystems for creating noise interference, elements of the information subsystem and elements of the subsystem for creating noise interference are integrated a single cell range, each element of information subsystem is designed as a multi-channel radio with time division multiplexing, and each element of the subsystem creating noise interference is in the form of protective interference transmitters (PPP) on the basis of avtostohasticheskih generators.

The disadvantage of this method is the technical complexity of its implementation, suggesting the presence of auxiliary equipment, which greatly complicates the subscriber radio station and thereby reduces its reliability. In addition, the use of PZP will lead to a significant deterioration in the conditions of electromagnetic compatibility for "friendly" electronic means operating nearby.

The closest in technical essence to the claimed one is the method implemented in the patent of the Russian Federation No. 2229608 "Coherent radio line" dated 02.26.2007, published July 20, 2008

The essence of the prototype method according to the patent of the Russian Federation No. 2229608 is to create a noise curtain from noise-like signals having a power greater than the power of the working (useful) signals in a coherent radio line to protect the transmitted discrete information from unauthorized access by unauthorized persons.

The solution of the problem in the prototype method is achieved by the fact that in a coherent radio line, containing on the transmitting side a series-connected source of discrete messages, an encoding device, a first modulator, a first transmitter and a first transmitting antenna, and on the receiving side, a series-connected receiving antenna, receiver, unit frequency search, a reference voltage extraction unit, the second input of which is connected to the output of the receiver, and the first synchronous detector, the second input of which is connected to the output of the receiver ka, the decoding device and the message recording and analysis unit connected in series are additionally provided on the transmitting side with two high-frequency generators, a pseudo-random sequence generator, a second modulator, a second transmitter and a second transmitting antenna, the first high-frequency generator connected to the second input of the first modulator, a second modulator is connected to the output of the pseudo-random sequence generator, the second input of which is connected to the output of the second high-frequency generator cells, a second transmitter and a second transmitting antenna, and on the receiving side a phase shifter at -30 °, a phase shifter at + 90 °, two subtractors, a second and third synchronous detectors, and a phase shifter at + 30 ° is connected in series to the output of the reference voltage isolation unit, the second a synchronous detector, the second input of which is connected to the output of the receiver, the first subtractor, phase shifter + 90 ° and the second subtractor, the second input of which is connected to the output of the first synchronous detector, and the output is connected to the input of the decoding device Twa, to the output of the reference voltage selection unit connected in series to -30 ° phase shifter and the third synchronous detector, a second input coupled to the receiver output, and an output connected to the second input of the first subtracter.

The implementation of the prototype method according to the patent of the Russian Federation No. 23239608 is as follows. Discrete messages from the output of the source through the encoder in the form of a modulating code are received at the first input of the modulator, the second input of which is supplied with high-frequency oscillation from the output of the high-frequency generator. At the output of the modulator, a phase-shift (FM) signal is generated, which, after amplification in the transmitter (power amplifier), is emitted by a transmitting antenna with a directional radiation pattern towards the receiving part of the coherent radio link. A pseudo-random sequence (PSP) from the output of the generator goes to the first input of the modulator, to the second input of which a high-frequency oscillation from the output of the high-frequency generator is supplied. At the output of the modulator, a noise-like signal (SHPS) is formed, the phase of which changes in accordance with the SRP. The specified signal after amplification in the transmitter (power amplifier) is emitted by a transmitting antenna with a directional radiation pattern towards the receiving part of the coherent radio link. The power of this signal is much greater than the power of the information signal for which it creates a noise curtain.

The mixture of the FM signal and the SHPS signal from the output of the receiving antenna through the receiver (high-frequency amplifier) simultaneously arrives at the first (information) inputs of synchronous detectors, the second inputs of which are supplied with reference voltages, respectively, from the output of the reference voltage isolation unit directly and through phase shifters to + 30 ° and -30 °. At the output of synchronous detectors, low-frequency voltages are respectively allocated. And at the output of the subtracter, a differential voltage is generated, which is an estimate of the ShPS signal and differs from the ShSS signal at the output of the synchronous detector by 90 ° phase rotation.

The differential voltage from the output of the subtractor goes to the input of the phase shifter by + 90 °, at the output of which a voltage is generated, which goes to the second input of the subtractor, the output of which is the difference voltage, which is an analog of the transmitted message. The voltage from the output of the subtractor goes to the input of the decoding device for further processing.

Thus, as a result of such a construction of a coherent radio line, a coherent radio line under the cover of a powerful noise curtain can successfully fulfill its functions.

The disadvantage of the prototype method is that it has a limited scope, since the effective operation of the radio line requires the presence of additional equipment for the formation and radio transmission of the SHPS signal.

The aim of this invention is to expand the scope of the prototype method, namely the development of a method for generating and processing a signal built into the masking noise, implemented by a single radio transmitting device.

This goal is achieved by the fact that in the method of generating and processing a signal built into the masking noise, a useful signal and a masking noise are generated on the transmitting side of the radio line, they are transmitted on the radio line, receiving and isolating the useful signal by compensating for the masking noise as a result of coherent processing on the receiving side radio lines. In this case, a useful signal and masking noise are formed on the transmitting side in one radio transmitting device, and the carrier frequency of the useful signal is selected so that the frequency spectrum occupied by it is within the frequency band occupied by the masking interference. In this case, the structure of the masking interference is chosen so that at the frequency positions occupied by the useful signal, the spectral components of the masking interference are absent or the modulus of their amplitudes does not exceed 5% of the values of the amplitude module of the spectral components of the useful signal, and at the other frequency positions not occupied by useful signal, the amplitude of the spectral components of the masking interference modulo would be equal to the amplitude of the spectral components of the useful signal.

Due to the new set of essential features, which consists in the formation of a useful signal and masking interference on the transmitting side in one radio transmitting device, in the selection of the carrier frequency so that the spectrum of the signal is within the frequency band occupied by the masking noise, as well as the choice of such a masking interference structure, so that its spectral components at the frequency positions occupied by the useful signal are absent or the magnitude of their amplitudes does not exceed 5% of the magnitudes of the amplitudes spectral components of the useful signal, and at other frequency positions not occupied by the useful signal, the amplitude of the spectral components of the masking interference modulo would be equal to the amplitude of the spectral components of the useful signal.

The claimed method is illustrated by drawings, in which:

in FIG. 1 - modules of the spectrum of the useful signal and masking interference, and in the spectrum of the masking interference at the frequency positions corresponding to the spectral components of the useful signal, the amplitude of the spectral components of the masking interference has values close to zero;

in FIG. 2 - the spectrum module of the total signal representing the additive sum of the useful signal and masking interference;

in FIG. 3 - module spectrum of masking interference, which is additively subtracted in the radio receiving path;

in FIG. 4 - spectrum of the restored useful signal obtained by subtracting the masking noise from the total signal;

in FIG. 5 is a temporary representation of: the total signal masking the interference, the restored useful signal as a result of additive subtraction from the total signal of the masking noise and the original signal.

Implementation of the claimed method of forming and processing a signal built into the masking noise is as follows. A useful signal is generated on the transmitting side and a masking interference is generated. Moreover, the masking interference is formed so that the spectrum of the useful signal is located within the frequency band occupied by the masking interference. In this case, the structure of the masking interference is chosen so that at the frequency positions occupied by the useful signal, its spectral components are absent or the magnitude of their amplitudes does not exceed 5% of the values of the amplitude module of the spectral components of the useful signal, and at other frequency positions not occupied by the useful signal , the amplitude of the spectral components of the masking interference modulo would be equal to the amplitude of the spectral components of the useful signal. As an example in FIG. 1 shows the modules of the spectra of the useful signal and masking interference, satisfying the above conditions.

Since the useful signal and the masking noise are formed in the same radio transmitting path, the output of the radio transmitting path will be a total signal representing an additive mixture of the useful signal and masking interference, and the spectrum of the total signal will be close in structure to the masking interference spectrum, in which all spectral coefficients have approximately equal values. As an example in FIG. Figure 2 shows the spectrum modulus of the total signal, the spectral coefficients of which have approximately equal values.

As a result of performing the procedures specified in the claimed method, the formation and processing of a signal built into the masking interference is provided.

The signal embedded in the interference becomes inaccessible to the radio, which does not know the shape of the spectrum of the masking interference.

A useful signal is received and isolated by compensating for masking interference as a result of coherent processing at the receiving side of the radio link. The implementation of these procedures is carried out as a result of subtracting the masking interference from the received total signal.

As an example in FIG. 3 shows the spectrum modulus of the masking interference, which is additively subtracted in the radio receiving path. In FIG. 4 shows the spectrum of the reconstructed useful signal obtained by subtracting the masking noise from the total signal.

In FIG. Figure 5 shows a temporary representation of: the total signal masking the interference, the restored useful signal as a result of additive subtraction from the total signal of the masking noise and the original signal.

Visual analysis confirms the proximity of the structure of the restored useful signal and the original useful signal, which indicates the physical feasibility of the procedures of the proposed method.

The procedures for generating and receiving a useful signal and masking interference over the radio channel are known, see patent RU (11) No. 2253184 of 05/19/2003 "Method of information protection and a radio communication system with enhanced intelligence".

The procedures for the formation of signal spectra, as well as the technical features of their reception and processing, are known, see RF Patent No. 2229608, dated February 26, 2007, “Coherent Radio Link”.

The procedures for the formation of an additive mixture of a useful signal and masking noise, which may be played by Gaussian noise, are known, see p. 124, Sklar B. Digital Communication. Theoretical foundations and practical application: Per. from English M .: Williams, 2003.1104 p.

The procedures for coherent signal processing (the implementation of the additive subtraction operation of masking interference) are known, see p. 207, Sklar B. Digital Communication. Theoretical foundations and practical application: Per. from English M .: Williams, 2003.1104 p.

Thus, in the inventive method, when it is implemented by performing the procedures for generating a useful signal and masking interference on the transmitting side in one radio transmitting device, in selecting a carrier frequency so that the signal spectrum is within the frequency band occupied by the masking interference, as well as the choice such a masking interference structure that its spectral components at the frequency positions occupied by the useful signal are absent or the magnitude of their amplitudes does not exceed 5% of the mod I amplitudes of the spectral components of the desired signal, while the remaining frequency positions not occupied by the desired signal, the amplitude of the spectral components of noise masking modulo would be equal to the amplitude of the spectral components of the desired signal, is provided by expanding the scope of a method for forming and signal processing integrated in the masking interference.

Claims (1)

A method of generating and processing a signal embedded in a masking noise, which consists in generating a useful signal and masking noise on the transmitting side of the radio line, transmitting them on the radio line, receiving and extracting the useful signal by compensating for masking interference as a result of coherent processing on the receiving side of the radio line, characterized in that they form a useful signal and masking noise on the transmitting side in the form of an additive mixture, and the carrier frequency of the useful signal is chosen so that the frequency spectrum that he emitted was within the frequency band occupied by the masking noise, while the structure of the masking noise was chosen such that the frequency components occupied by the useful signal were absent or the modulus of the masking interference was not greater than 5% of the values of the amplitude modulus spectral components of the useful signal, and at the other frequency positions not occupied by the useful signal, the amplitude of the spectral components of the masking noise modulo was equal to the amplitude of ktralnyh component of the desired signal.

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