RU2762376C1 - Method for transmitting and receiving signals in the mode of operating frequency hopping spread spectrum - Google Patents

Abstract

FIELD: radio engineering.SUBSTANCE: invention relates to the field of radio engineering and can be used in noise-proof radio communication systems with Frequency Hopping Spread Spectrum (FHSS). The expected result is achieved, in particular, by the fact that the transmission of an information signal, represented by a set of zeros and ones, is carried out at two different frequencies, each of which is not a frequency selected based on a pseudo-random sequence.EFFECT: increase in the noise immunity of receiving signals in the FHSS mode under the conditions of interference from radio electronic systems consistent with the signal spectrum.1 cl, 1 dwg

Description

The invention relates to the field of radio engineering and is intended for use in anti-jamming radio communication systems with pseudo-random frequency tuning (PFC).

A known method of generating a signal with pseudo-random tuning of the operating frequency, described in (RF Patent No. 2343638, "Radio communication line for signals with pseudo-random tuning of the operating frequency", IPC H04J 13/06, publ. 10.01.2009 Bull. No. 1) In this method, the input information is divided into K parallel streams, converted into modulated radio frequencies, transferred to output radio frequencies determined by a pseudo-random sequence, and the operating time at each frequency in each stream is regulated by changing the signal level in the i-th (1 <i≤K) stream.

However, the known method has a low noise immunity of receiving signals when exposed to interference from radio electronic means (RES), matched with the signal spectrum.

Known "Method for transmitting discrete information in a radio link with pseudo-random restructuring of the operating frequency". (RF patent No. 2228575, MPK Н04В 1/713, publ. 05/10/2004 Bull. No. 13). In this method, the signal frequencies are modulated with an error-correcting code, and the transmitter is re-tuned simultaneously for several frequencies.

However, this method, like the previous analogue, is characterized by low noise immunity of signal reception under the influence of interference from RES, matched with the signal spectrum.

The closest in technical essence (prototype) to the claimed invention is "Method of information transmission with intra-symbol pseudo-random tuning of the operating frequency" (RF Patent No. 2533077, IPC H04L 9/20, publ. 20.11.2014 Bull. No. 32).

According to the prototype method, the signal with frequency hopping is generated as follows.

On the transmitting side, the useful information is divided into symbols, each with a length of several bits, which, in turn, are separated into independent frequency elements, each of which is transmitted alternately at its own frequency in accordance with a given pseudo-random sequence. In this case, each frequency element is one of a 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, in accordance with a given pseudo-random sequence, for a given symbol, while the carrier frequency number and the code sequence number are determined for each frequency element. 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, matched with the signal spectrum. Since at each frequency used to transmit a signal in the frequency hopping mode, the parameters of the signal spectrum remain unchanged.

The objective of the invention is to create a method that allows due to the dragging of the signal base on the basis of frequency hopping technology and different methods of forming and processing a radio signal.

The technical result is to increase the noise immunity of receiving signals in the frequency hopping mode under the influence of interference from the RES, matched with the signal spectrum.

перед выбором очередной рабочей частоты в соответствии с заданной псевдослучайной последовательностью каждый раз задают новое число d, значение которого всегда целое и меньше чем n/2, определяют номер текущей рабочей частоты для передачи очередного бита информации следующим образом, если значение очередного информационного бита равно единице, то номер текущей рабочей частоты, далее определяемую как суммарная частота, вычисляют путем суммирования значения nil и числа d, а если значение очередного информационного бита равно нулю, то номер текущей рабочей частоты, далее определяемую как разностная частота, вычисляют путем вычитания из значения n/2 числа d, на текущей рабочей частоте формируют фазоманипулированный сигнал, который излучают в сторону корреспондента, на стороне корреспондента прием осуществляют одновременно и на суммарной, и на разностной частотах, значения которых вычисляют аналогичным передающей стороне образом, и над принятыми сигналами на длительности информационного бита осуществляют амплитудное детектирование, после чего сравнивают уровни детектированных сигналов, если уровень детектированного сигнала на суммарной частоте превышает уровень детектированного сигнала на разностной частоте, то принимают решение о принятом информационном бите равном значению единица, в противном случае - о принятом информационном бите равном значению нуля.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, which consists in the fact that before the communication session, n harmonic oscillations are formed, and n is always an even number used as operating frequencies for the mode of pseudo-random tuning of the operating frequencies , then each operating frequency is assigned a serial number

before choosing the next operating frequency in accordance with a given pseudo-random sequence, each time set a new number d, the value of which is always an integer and less than n / 2, determine the number of the current operating frequency for transmitting the next bit of information as follows, if the value of the next information bit is equal to one, then the number of the current operating frequency, further defined as the total frequency, is calculated by summing the value of nil and the number d, and if the value of the next information bit is zero, then the number of the current operating frequency, further defined as the difference frequency, is calculated by subtracting from the value n / 2 numbers d, a phase-shift keyed signal is formed at the current operating frequency, which is emitted towards the correspondent, on the correspondent's side, reception is carried out simultaneously at the total and at the difference frequencies, the values of which are calculated in a similar way to the transmitting side, and over the received signals on the duration of the information bit amplitude detection is performed, after which the levels of the detected signals are compared, if the level of the detected signal at the sum frequency exceeds the level of the detected signal at the difference frequency, then a decision is made on the received information bit equal to the value one, otherwise - on the received information bit equal to the value of zero.

The technical result is achieved thanks to a new set of essential features. In the claimed method, the increase in noise immunity is carried out by increasing the signal base based on the frequency hopping technology and different methods of generating and processing the radio signal.

Let us explain the possibility of achieving the specified technical result.

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

Noise protection mode, methods of modulation and demodulation of signals during its generation and processing are known. Therefore, the effect of interference from RES, matched with the signal spectrum, leads to a decrease in noise immunity.

In the claimed method, before each transmission of an information bit, on the basis of a pseudo-random sequence, two operating frequencies are selected, symmetrically located relative to the central frequency of the numbered group of operating frequencies. The final selection of the current operating frequency is based on the value of the information bit to be transmitted. Based on the condition that the specific value of the information bit (zero or one) is random, then the choice of the current operating frequency for the countermeasure system will be random. 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. IN AND. Borisov; ed. 2nd, rev. and add. - M .: RadioSoft, 2008. - 512 p.] This mode is a pseudo-random restructuring of the operating frequency (PPRCH).

In addition, at the selected current operating frequency, phase modulation of the carrier is carried out, and the demodulation of the radio signal is performed by methods of amplitude detection on the duration of radiation simultaneously at two frequencies: at one frequency, a signal is transmitted, unintentional (noise) and interfering effect of the RES, the other is affected only by noise. Therefore, the noise immunity of receiving an information signal under given conditions increases.

For the countermeasure system, the radio signal at the current operating frequency is identified by the phase telegraphy radio signal, not the amplitude telegraphy signal. Thus, the scheme for processing a radio signal at the operating frequency during reception differs from the scheme for its formation, which complicates the decision to set up interference for the countermeasures system and improves the properties of the structural secrecy of the radio signal.

According to [Borisov VI, Zinchuk VM Interference protection of radio communication systems probabilistic-time approach. M .: Radio and communication, 1999. - P. 252. See pp. 10-20] the noise immunity of radio communication systems depends on the structural secrecy and noise immunity of the radio signal. And in the claimed method, an improvement in the properties of noise immunity and secrecy is realized, which determines the increase in noise immunity.

The claimed method is illustrated by the drawing, which shows: FIG. 1 - a) the timing diagram of the information bit "1";

b) timing diagrams of the sum and difference frequency signals;

c) the spectrum of the signal at the sum and difference frequencies;

d) timing diagrams of the detected signals at the sum and difference frequencies.

The implementation of the proposed method in accordance with Fig. 1 is carried out as follows:

1. Before the communication session, n harmonic oscillations are formed, and n is always an even number, used as operating frequencies for the mode of pseudo-random tuning of operating frequencies, then each operating frequency is assigned a serial number

The procedure for forming an even group of harmonic oscillations is similar to the procedure for synthesizing frequencies, which can be obtained on the basis of known methods of direct or indirect synthesis of frequencies [see, for example, RF patent No. 2702572 dated 11.28.19 "Frequency synthesizer", authors Ochkov DS, Formalnova I.S. and etc.].

является известной и приведена, в частности, в [Патенте РФ №2602990 от 20.11.16 «Способ адаптивной передачи данных в радиолинии с псевдослучайной перестройкой рабочей частоты», авторов Дворникова С.В., Пшеничникова А.В. и др.].Procedure for generating a numbered frequency group

is known and is given, in particular, in [RF Patent No. 2602990 dated 20.11.16 "Method for adaptive transmission of data in a radio link with pseudo-random tuning of the operating frequency", authors SV Dvornikov, AV Pshenichnikov. and etc.].

2. Useful information is divided into bits, each of which is alternately transmitted at its own frequency, the choice of which is carried out in accordance with a given pseudo-random sequence.

This procedure reflects the procedure for selecting operating frequencies in the frequency hopping mode and is completely identical to the prototype method.

3. Before choosing the next operating frequency in accordance with the given pseudo-random sequence, each time set a new number d, the value of which is always integer and less than n / 2.

The operation of obtaining an integer d less than n / 2 from a random code sequence is based on the choice of the interval number of a segment of length nil, depending on the code sequence. This operation is known and is given, for example, in [RF Patent No. 2273099 dated 03/27/06 "Radio link with programmed tuning of the operating frequency", authors AV Pshenichnikov, MA Semisoshenko]. A distinctive feature of this operation is the setting of integer values of the interval boundaries. Another implementation option can be based on the generation of random numbers with a maximum value limitation, see, for example, [RF Patent No. 2424551 dated 04/10/11 "Method for generating random numbers", author Minakov VA].

равно единице (см. фиг. 1а), то номер частоты, далее определяемую как суммарная частота

вычисляют путем суммирования значения n/2 и числа

а если значение очередного информационного бита равно нулю, то номер частоты, далее определяемую как разностная частота

вычисляют путем вычитания из значения n/2 числа d (Δ=n/2-d).4. Determine the number of the current operating frequency for transmitting the next bit of information as follows, if the value of the next information bit

is equal to one (see Fig. 1a), then the frequency number, further defined as the total frequency

calculated by summing the value n / 2 and the number

and if the value of the next information bit is equal to zero, then the frequency number, further defined as the difference frequency

calculated by subtracting the number d (Δ = n / 2-d) from the value n / 2.

These operations are logical-arithmetic operations and can be implemented in software based on digital processors. Such a method of implementation is given, for example, in [RF Patent No. 2273099 dated 03/27/2006 "Radio link with programmed frequency tuning", the authors are AV Pshenichnikov, MA Semisoshenko].

5. At the current operating frequency, a phase-shift keyed signal is generated, which is emitted towards the correspondent (see Fig. 1b).

The phase modulation procedure is known and is implemented, for example, in [RF Patent No. 2481700 from 08.20.12 "Method for phase modulation and demodulation of high-frequency signals and a device for its implementation", authors AA Golovkov, IA Milyutin].

и на разностной

частотах, значения которых вычисляют аналогичным передающей стороне образом (см. фиг. 1в).6. Receive a signal at frequencies determined in accordance with a given pseudo-random sequence, simultaneously and at the total

and on the difference

frequencies, the values of which are calculated in a similar way to the transmitting side (see Fig. 1c).

The procedure for receiving a signal in accordance with a given pseudo-random sequence characterizes the pseudo-random rearrangement mode and is identical to the prototype method. In contrast to the prototype method, reception is carried out simultaneously at the total and difference frequencies, the numbers of which are calculated in accordance with clause 4.

7. Amplitude detection is performed over the received radiations for the duration of the information bit (see Fig. 1d).

The amplitude detection procedure is known and is presented, for example, in [RF Patent No. 2328068 dated 06/27/2008 "Amplitude detector" by VP Zezyunkov].

8. The amplitude detection time is set by the emission time of the binary sequence block, and the detection band is selected based on the duration of its element.

The procedures for determining the parameters of amplitude detection are known and are given, in particular, in [CB. Dvornikov and other radio receivers. Textbook - SPB. YOU, 2016], [D.D. Klovsky. Signal transmission theory. Textbook - M. 1973].

превышает уровень детектированного сигнала на разностной частоте

то принимают решение о принятом информационном бите равном значению единица (см. фиг. 1 г), в противном случае - о принятом информационном бите равном значению нуля.9. Compare the levels of the detected signals, if the level of the detected signal at the sum frequency

exceeds the level of the detected signal at the difference frequency

then a decision is made on the received information bit equal to the value one (see Fig. 1 d), otherwise - on the received information bit equal to the value of zero.

The operation of determining the maximum value of the detected signal levels can be implemented based on comparison with a known threshold value, is known and described, for example, in [RF Patent No. 2705357 dated 07.11.19 "Method for transmitting information over a short-wave communication channel using frequency-shift keyed signals" , authors Dvornikov S.V., Pshenichnikov A.V., Prisyuzhnik S.P. and etc.].

The frequency numbers correspond to the levels of the amplitude-detected signals, which makes it possible to implement the operation of selecting the frequency number with a large signal level and determining the excess of this number of the value n / 2, in particular on the basis of microprocessor processing, see, for example, [RF Patent No. 2273099 dated 03/27/2006 "Radio link with software tuning of the operating frequency", authors Pshenichnikov A. V., Semisoshenko M. A.].

The formation of a bit of the information sequence based on the level of amplitude detection, the transmission of the bit to the recipient of the message is an operation of post-detection processing and is described, for example, in [S.V. Dvornikov and other radio receivers. Textbook -SPB. YOU, 2016], [D.D. Klovsky. Signal transmission theory. Textbook - M. 1973].

The results of the carried out simulation of the transmission of binary messages in the MatLAB environment based on the developed method showed a significant decrease in the probability of an error in receiving a signal element under the influence of interference from RES, matched with the signal spectrum, in comparison with the prototype method, thereby increasing the noise immunity of signal reception.

Thus, in the claimed invention during its implementation, noise-immune transmission and reception of signals in the frequency hopping mode is provided, which indicates the achievement of a technical result.

Claims (1)

A method for transmitting and receiving signals in the mode of pseudo-random tuning of the operating frequency, which consists in the fact that on the transmitting side, the useful information is divided into bits, each of which is alternately transmitted 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 to the recipient of the message, characterized in that n harmonic oscillations are generated before the communication session, and n is always an even number used as operating frequencies for the mode of pseudo-random tuning of operating frequencies, then each the operating frequency is assigned a serial number

before choosing the next operating frequency in accordance with a given pseudo-random sequence, each time set a new number d, the value of which is always an integer and less than n / 2, determine the number of the current operating frequency for transmitting the next bit of information as follows, if the value of the next information bit is equal to one, then the number of the current operating frequency, further defined as the total frequency, is calculated by summing the value n / 2 and the number d, and if the value of the next information bit is zero, then the number of the current operating frequency, further defined as the difference frequency, is calculated by subtracting from the value n / 2 numbers d, at the current operating frequency form a phase-shift keyed signal, which is emitted towards the correspondent, on the correspondent's side, reception is carried out simultaneously at the total and at the difference frequencies, the values of which are calculated in a similar way to the transmitting side, and over the received signals on the duration of the information bit amplitude detection is carried out, after which the levels of the detected signals are compared, if the level of the detected signal at the sum frequency exceeds the level of the detected signal at the difference frequency, then a decision is made on the received information bit equal to the value of one, otherwise - on the received information bit equal to the value of zero ...

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