RU2767181C1 - Method of transmitting and receiving signals in mode of pseudorandom tuning of operating frequency under response to interference - Google Patents

Abstract

FIELD: radio engineering and communication.

SUBSTANCE: invention relates to radio engineering and is intended for use in noise-immune radio communication systems with pseudorandom operating frequency tuning. Method of transmitting and receiving signals in mode of pseudorandom tuning of operating frequency under response to interference consists in the fact that before the communication session on the receiving side, the noise level is successively measured at each operating frequency, a test sequence of units is formed on the transmitting side, each bit of the test sequence of units is successively manipulated with the amplitude of the harmonic oscillation at the operating frequency, a radio signal is emitted towards the correspondent, at the receiving side at each of the operating frequencies, the value of the phase difference of the harmonic oscillation is calculated, from the obtained values, a phase difference vector is formed, phase difference vector is transmitted to the correspondent, during the communication session on the transmitting side, the useful information is divided into bits, each bit is alternately transmitted at its frequency, each bit of information is manipulated with amplitude of harmonic oscillation at operating frequency, radio signal is emitted towards correspondent, at the receiving side, reception is carried out at frequencies, the amplitude of the radio signal is detected based on the threshold value of demodulation at the operating frequency, the obtained information bits are transmitted to the recipient of the message. Phase of the harmonic oscillation on the receiving side is measured at ten periods at the end of radiation and ten periods at the beginning of radiation. Phase of the harmonic oscillation on the transmitting side is shifted by a value corresponding to the value of the received phase difference vector. Reception frequencies are determined in accordance with the given pseudorandom sequence.

EFFECT: high noise immunity of receiving signals.

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Description

The invention relates to the field of radio engineering and is intended for use in noise-immune radio communication systems with pseudo-random hopping of the operating frequency (PRFC).

Known "Method of generating a signal with pseudo-random tuning of the operating frequency" (RF Patent No. 2648291, publ. 23.03.18, bull. No. 2).

In this method, the generation of the primary signal is carried out in the basis of spline-character functions (BFSH). Next, it is modulated by a digital sequence. The modulated signal is multiplied with the reference waveform. Moreover, the frequencies of the reference oscillation are determined in accordance with the first given random code digital sequence, and the values of the changing parameters of the FSH are selected in accordance with the second given pseudo-random code digital sequence synchronously with the change in the frequency of the reference oscillation.

However, the known method has a low noise immunity of signal reception when exposed to response interference from radio electronic equipment (RES), the emission time of which is consistent with the emission time of the radio signal at operating frequencies that are non-uniform in terms of interference.

Known "Method of generating a signal in the mode of software tuning of the operating frequency with a changing frequency band " (RF Patent No. 2749863, publ. 06/17/2021, bull. No. 17).

In this method, the primary signal is modulated with a digital sequence extended by Barker codes of various bit depths, the selection of which is carried out in accordance with a given first pseudo-random code digital sequence (PCSD). Then the received signal is multiplied with the reference oscillations, the frequencies of which are changed in accordance with the second PCCP. After that, the generated signal is transmitted to the receiving side. At the same time, synchronous selection of the frequency number and the Barker code number is carried out, in accordance with the first and second PCCPs.

However, this method, like the previous analogue, is characterized by low noise immunity of signal reception when exposed to response interference from RES, the emission time of which is consistent with the emission time of the radio signal at operating frequencies that are not uniform in terms of interference.

The closest in technical essence (prototype) to the claimed invention is the "Method for transmitting information with intra-symbol pseudo-random tuning of the operating frequency" (RF Patent No. 2533077 publ. 20.11.2014, bull. No. 32).

According to the prototype method, the frequency hopping signal is generated as follows. On the transmitting side, useful information is divided into symbols, each several bits long, which, in turn, are divided into independent frequency elements, each of which is transmitted in turn at its own frequency in accordance with a given pseudo-random sequence. In this case, each frequency element is one of the given ensemble of orthogonal phase-modulated code sequences, the same within one symbol, the number of which is also associated with the transmitted symbol. And on the receiving side, reception is carried out symbol by symbol at all possible frequencies for a given symbol, in accordance with a given pseudo-random sequence, while for each frequency element the carrier frequency number and the code sequence number are determined. After that, a time-frequency matrix is compiled, on the basis of which, and also taking into account the number of the code sequence, the transmitted symbol is determined and the information bits corresponding to the symbol are transmitted to the recipient of the message.

The disadvantage of the prototype method is the low noise immunity of receiving signals in the frequency hopping mode when exposed to interference from the RES, the emission time of which is consistent with the emission time of the radio signal at non-uniform interference levels of operating frequencies.

The aim of the invention is to create a method that makes it possible to increase the noise immunity of signal reception under the influence of response interference, the emission time of which is consistent with the emission time of a radio signal at operating frequencies that are not uniform in terms of interference.

The technical result is to increase the noise immunity of signal reception.

The technical result is achieved by the fact that in the method of transmitting and receiving signals in the mode of pseudo-random tuning of the operating frequency under the influence of response interference, which consists in the fact that on the transmitting side the useful information is divided into bits, each of which is transmitted in turn at its own frequency, the choice of which is carried out in accordance with a given pseudo-random sequence, on the receiving side, reception is carried out at frequencies, in accordance with a given pseudo-random sequence, the received information bits are transmitted the recipient of the message, and before a communication session, on the receiving side, the interference level is measured sequentially at each operating frequency, which is set as the threshold value of demodulation at the operating frequency, on the transmitting side, a test sequence of units is formed, each bit of which is sequentially manipulated by the amplitude of the harmonic oscillation at the operating frequency, determined in in accordance with a given pseudo-random sequence, a radio signal is emitted towards the correspondent, on the receiving side at each of the operating frequencies, the value of the phase difference of the harmonic oscillation, measured at ten periods at the end of radiation and ten periods at the beginning of radiation, is calculated, from the obtained values a phase difference vector is formed, which transmitted to the correspondent, during the communication session on the transmitting side, each bit of information is manipulated by the amplitude of the harmonic oscillation at the operating frequency, the phase of which is preliminarily shifted by an amount corresponding to the value of the received difference vector and phases, emit a radio signal towards the correspondent, receive a radio signal on the receiving side, detect the amplitude of the radio signal based on the demodulation threshold at the operating frequency.

The technical result is achieved thanks to a new set of essential features. Let us explain the possibility of achieving a technical result.

In the prototype method, an algorithm for generating a radio signal in the frequency hopping mode is implemented, in which the choice of the operating frequencies of the reference oscillation and the spacing of information symbols into frequency elements is uncertain.

The noise protection mode, methods of modulation and demodulation of signals during its formation and processing are known. Therefore, the impact of response interference from RES at time intervals coinciding with the intervals of radio signal emission at each of the operating frequencies, according to [Borisov V.I., Zinchuk V.M., Limarev A.E. frequencies // ed. V. I. Borisov; ed. 2nd, revised. and additional - M.: RadioSoft, 2008. - 512 p.] leads to a decrease in noise immunity. Additionally, the prototype does not take into account the heterogeneity of operating frequencies in terms of the level of unintentional interference, which determines the decrease in the noise immunity of signal reception [D.D. Klovsky. Theory of signal transmission. Textbook - M. 1973].

In the claimed method, to expand the signal base, the hopping mode is also implemented. However, together with the frequency hopping mode, amplitude keying of operating frequencies is used, in which the radiation of the radio signal is carried out only during the transmission of information units. Since the effect of response interference implies the presence of radio emission [Borisov V. I., Zinchuk V. M., Limarev A. E. Noise immunity of radio communication systems by expanding the spectrum of signals by the method of pseudo-random tuning of the operating frequency // ed. V. I. Borisov; ed. 2nd, revised. and additional - M.: RadioSoft, 2008. - 512 p.], then when transmitting information zeros, there will be no impact from the RES.

In addition, in the claimed method, based on the transmission of the test sequence at each of the operating frequencies, a phase shift is carried out, at which the condition for adding the levels of the radio signal and the response interference from the RES is achieved, which determines the increase in the reliability indicators for amplitude detection [D.D. Klovsky. Theory of signal transmission. Textbook - M. 1973].

Also, in the claimed method, the selection of the demodulation threshold is carried out separately at each of the operating frequencies, depending on the level of the interference environment, which implements the methods of adaptive control of the demodulation threshold. Thus, in the claimed method, according to [Borisov V. I., Zinchuk V. M., Limarev A. E. Noise immunity of radio communication systems by expanding the spectrum of signals by the method of pseudo-random tuning of the operating frequency // ed. V. I. Borisov; ed. 2nd, revised. and additional - M.: RadioSoft, 2008. - 512 p.] the noise immunity of signal reception under the influence of response interference and non-uniform operating frequencies is increased.

The claimed method is illustrated by the drawing, where in Fig. 1 shows:

a) timing diagram of information bits;

b) timing diagram of the test sequence;

c) timing diagram of amplitude manipulation of the test sequence;

d) time diagram of response interference from electronic means.

The implementation of the proposed method in accordance with figure 1 is as follows.

1. On the transmitting side, useful information is divided into bits U _and ( t ) (Fig. 1 a), each of which is transmitted in turn at its own frequency, the choice of which is carried out in accordance with a given pseudo-random sequence.

2. On the receiving side, reception is carried out at frequencies in accordance with a given pseudo-random sequence.

3. The received information bits are transmitted to the recipient of the message.

Procedures according to paragraphs. 1-3 are identical to the prototype method.

4. Sequentially, at each operating frequency, the interference level is measured, which is set as the demodulation threshold at the operating frequency.

The procedure for measuring the level of interference is known and is given, in particular, in [Patent of the Russian Federation No. 2520567 dated 17.06.11 "Measuring module for selective assessment of the signal-to-interference power ratio in the radio channel", authors Boldyreva A.A., Bubenshchikov A.A. and others], and also implemented in the frequency adaptation equipment R-016V.

The procedure for sequential tuning to operating frequencies for measurements is carried out similarly [RF Patent No. 2710027 dated December 24, 2019 "Method of active control of operating frequencies", authors Dvornikova S.V., Pshenichnikova A.V. etc.] or similarly to the restructuring of the frequency synthesizer, see, for example, [RF Patent No. 2702572 dated 11/28/19 "Frequency Synthesizer", authors D.S. and etc.].

5. On the transmitting side, a test sequence U _t ( t ) is formed from units (Fig. 1 b).

The procedure for generating a test sequence is known and is given, in particular, in [Patent of the Russian Federation No. 2702572 dated 11/28/19 "Method for adaptive data transmission in a radio link with pseudo-random tuning of the operating frequency", authors Dvornikov S.V., Pshenichnikov A.V. and etc.].

A distinctive feature of this procedure is the formation of only "units", which can be implemented, for example, on the basis of trigger circuits. In this case, the duration of the bit of the test sequence is chosen equal to the duration of the information bit. The number of bits of the test sequence is determined based on the condition of its transmission at all operating frequencies in the frequency hopping mode. In particular, as a given value, a doubled repetition period (in cycles) of a pseudo-random sequence can be selected [Borisov V. I., Zinchuk V. M., Limarev A. E. Noise immunity of radio communication systems by expanding the spectrum of signals by the method of pseudo-random reorganization of the operating frequency // ed. V. I. Borisov; ed. 2nd, revised. and additional - M.: RadioSoft, 2008. - 512 p.].

6. Each bit of the test sequence U _t ( t ) is sequentially manipulated by the amplitude of the harmonic oscillation at the operating frequency U _{f p} ( t ), determined in accordance with a given pseudo-random sequence (Fig. 1 c).

The amplitude shifting procedure is known and is given, in particular, in [D.D. Klovsky. Theory of signal transmission. Textbook - M. 1973].

Determining the operating frequency in the frequency hopping mode is carried out similarly to the prototype method.

7. Radiate a radio signal towards the correspondent.

This procedure is similar to the prototype method.

8. On the receiving side, at each of the operating frequencies, the value of the phase difference of the harmonic oscillation, measured at ten periods at the end of radiation and ten periods at the beginning of radiation, is calculated.

When implementing this procedure, the operations of selection and amplification of a high-frequency radio signal are initially carried out. These operations are known and are carried out in a radio receiver, see, for example, [C.V. Dvornikov and others. Radio receivers. Textbook - St. Petersburg. WAC, 2016].

Further, at time intervals equal to five periods of high-frequency harmonic oscillations at the operating frequency at the beginning and at the end of the test message, the phase of the oscillation is measured. The phase measurement procedure can be implemented on the basis of digital signal processing, similarly, for example, [RF Patent No. 2654945 dated May 23, 2018 "Digital method for measuring the phase of a harmonic signal", author Tutygin V.S.].

The choice of time intervals with a duration of ten periods of harmonic oscillations at an operating frequency can be based on the implementation of synchronization methods in the frequency hopping mode (see, for example, [Zavadsky S.V. et al. Joint clock and code frame synchronization in an adaptive HF hopping radio communication system. I METHODS, No. 4-SPB, 2014, pp. 12-14]) based on the element base of microprocessor technology. Carrying out measurements at selected time intervals at the beginning and end of the radiation is determined by the peculiarity of the impact of response interference U _{f resp p} ( t ), which consists in delaying the interference of the RES by the time of its response t _p necessary to determine the operating frequency of the radio emission in the frequency hopping mode (Fig. 1 G).

After measurements, the value of the phase difference at the operating frequency is determined and the frequency number and the difference value are memorized.

It is advisable to implement these procedures on the basis of microprocessor technology, similarly, for example, [RF Patent No. 2273099 dated March 27, 2006 "Radio link with software tuning of the operating frequency", authors A.V. Pshenichnikov, M.A. Semisoshenko].

9. From the obtained values, a phase difference vector is formed, which is transmitted to the correspondent.

These procedures are carried out on the basis of the formation of a digital sequence, the first element of which corresponds to the phase difference at the first frequency, the second - at the second frequency, etc., with subsequent transmission to the correspondent. In this case, the transmission is carried out in the frequency hopping mode with amplitude keying.

The technical implementation of these operations is similar, for example, to the formation and transmission of a vector of frequency weights [Patent RF No. 2273099 dated March 27, 2006 "Radio link with software tuning of the operating frequency", authors Pshenichnikov A.V., Semisoshenko M.A.].

10. During a communication session on the transmitting side, each bit of information U _and ( t ) (Fig. 1 a) manipulates the amplitude of the harmonic oscillation at the operating frequency, the phase of which is previously shifted by an amount corresponding to the value of the received phase difference vector.

The amplitude manipulation procedure is carried out similarly to step 6.

The phase shift of the harmonic oscillation at the operating frequency in the frequency hopping mode is carried out on the basis of phase shifters. The phase shifter circuit is known and is given, for example, in [RF Patent No. 2738316 dated 12/11/20 "Controlled phase shifter", author Kholopov S.I.].

11. A radio signal is emitted towards the correspondent, a radio signal is received at the receiving side, the amplitude of the radio signal is detected based on the threshold value of demodulation at the operating frequency.

The procedure for emitting a radio signal is similar to the prototype method.

The reception of a radio signal involves the operation of selection and amplification of a high-frequency radio signal at an operating frequency, see, for example, [C.V. Dvornikov and others. Radio receivers. Textbook - St. Petersburg. WAC, 2016].

The choice of operating frequency in the frequency hopping mode is carried out similarly to the prototype method.

Amplitude detection is performed based on amplitude detector circuits that are known. In particular, the scheme of the amplitude detector is given in [Patent RF No. 2328068 dated June 27, 2008 "Amplitude detector", author Zezyunov V.P.]. A distinctive feature of this operation is the choice of the threshold value during detection (see paragraph 4), which is used in the reference voltage source of the presented circuit.

The functional model of signal transmission and reception based on the developed method can be represented as follows.

Before a communication session on the receiving side, the level of interference is measured sequentially at each operating frequency, which is set as the threshold value of demodulation at the operating frequency. After that, a test sequence of units is formed on the transmitting side, each bit of which is sequentially manipulated by the amplitude of the harmonic oscillation at the operating frequency, determined in accordance with a given pseudo-random sequence. They emit a radio signal towards the correspondent.

On the receiving side, at each of the operating frequencies, the value of the phase difference of the harmonic oscillation, measured at ten periods at the end of radiation and ten periods at the beginning of radiation, is calculated. From the obtained values, a phase difference vector is formed, which is transmitted to the correspondent.

During a communication session on the transmitting side, useful information is divided into bits. Each bit of information is manipulated by the amplitude of the harmonic oscillation at its operating frequency, the choice of which is carried out in accordance with a given pseudo-random sequence. Moreover, the phase of the harmonic oscillation at the operating frequency is shifted by an amount corresponding to the value of the received phase difference vector. They emit a radio signal towards the correspondent.

On the receiving side, reception is carried out at frequencies in accordance with a given pseudo-random sequence. The radio signal amplitude is detected based on the demodulation threshold at the operating frequency. The received information bits are transmitted to the recipient of the message.

The results of the simulation of the transmission of binary bits in the MatLAB environment based on the developed method showed a significant reduction in the probability of receiving a signal element in comparison with the prototype method under the influence of response interference from the RES, the emission time of which is consistent with the emission time of the radio signal on heterogeneous interference levels workers frequencies.

Thus, in the claimed invention, when it is implemented, noise-immune transmission and reception of signals in the frequency hopping mode when exposed to response interference is ensured, which indicates the achievement of the technical result and the purpose of the invention.

Claims (1)

A method for transmitting and receiving signals in the mode of pseudo-random tuning of the operating frequency under the influence of response interference, which consists in the fact that on the transmitting side the useful information is divided into bits, each of which is transmitted in turn at its own frequency, the choice of which is carried out in accordance with a given pseudo-random sequence, on the receiving side is receiving at frequencies in accordance with a given pseudo-random sequence, the received information bits are transmitted to the recipient of the message, characterized in that before the communication session on the receiving side, the interference level is measured sequentially at each operating frequency, which is set as the demodulation threshold at the operating frequency , on the transmitting side, a test sequence of units is formed, each bit of which is sequentially manipulated by the amplitude of the harmonic oscillation at the operating frequency, determined in accordance with a given pseudo-random sequence, radio is emitted the signal towards the correspondent, on the receiving side at each of the operating frequencies, the value of the phase difference of the harmonic oscillation is calculated, measured at ten periods at the end of the radiation and ten periods at the beginning of the radiation, from the obtained values a phase difference vector is formed, which is transmitted to the correspondent during the communication session on the transmitting side, each bit of information is manipulated by the amplitude of the harmonic oscillation at the operating frequency, the phase of which is preliminarily shifted by an amount corresponding to the value of the received phase difference vector, the radio signal is emitted towards the correspondent, the radio signal is received at the receiving side, the amplitude of the radio signal is detected based on the threshold value of demodulation on the working frequency.

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