RU2609525C1 - Method of generating signals and transmitting information in radar identification system - Google Patents

Abstract

FIELD: radar ranging.

SUBSTANCE: invention relates to radar ranging, radio communication, radio navigation and radio control and can be used in radar identification systems with noise-like signals. Said result is achieved due to that, known method of transmitting information in a radar identification system with noise-like signals includes encoding each information unit with an excessive code with error correction, as well as randomly select one of two carrier frequencies for each transmitted information unit.

EFFECT: technical result is higher resistance of radar identification system to impact of pulse interference.

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Description

The present invention relates to the field of radar, radio communications, radio navigation and radio control and may find application in radar recognition systems (RLS) with noise-like signals.

A known method of generating query signals in the form of pulse-time codes emitted at a fixed frequency. With this method, a code combination in the form of a set of units and zeros is represented in the form of pulses (in place of a unit) or their absence (in place of zero). The so-called smooth (narrow-band or simple) pulses are used. The method is used in the currently most common request-response systems of the Mark type (Mk-10 and Mk-12), as well as in the domestic system “Password” [Radio-electronic systems: Basics of construction and theory. Directory. Ed. 2nd, rev. and add. Ed. POISON. Shirman. - M .: Radio engineering, 2007. S. 412-413]. The main characteristics of such systems are imitation resistance and secrecy.

In the Password system, the interrogation signal includes a binary information code at 44 positions formed by a cryptographic device [Radio-electronic systems: Basics of construction and theory. Directory. Ed. 2nd, rev. and add. Ed. POISON. Shirman. - M .: Radio engineering, 2007, S. 413]. The disadvantage of this method of generating a query signal is its low noise immunity.

It is known that to increase the noise immunity, immitability, and stealth of radar recognition systems, instead of simple signals, noise-like (broadband) signals (BPS) can be used [Radar systems of multifunctional aircraft. T. 1. Radar - the information basis of the combat operations of multifunctional aircraft. Systems and algorithms for primary processing of radar signals. Ed. A.I. Kanaschenkova and V.I. Merkulova. - M .: Radio engineering, 2006].

Known methods for transmitting information in communication systems with noise-like signals [Patent No. 2085046 "System for transmitting discrete information"; Patent No. 22169660 “Radio communication line”; Noise-like signals in information transmission systems. Ed. V.B. Pestryakova. - M: Owls. Radio, 1973]. Known communication systems use noise-like signals (SHPS) obtained as a result of phase-shift keying of a carrier frequency signal by a pseudo-random sequence (PSP). In these communication systems, each bit of the transmitted information is encoded by the SRP, which allows for high noise immunity. However, such systems have a low information transfer rate, which is their disadvantage.

There is also known a method of transmitting information in a communication system with noise-like signals [L. Varakin Communication systems with noise-like signals. - M: Radio and communications, 1985, S. 16-18]. A known method of transmitting information includes the formation of carrier and clock signals. PSP is formed from the clock frequency signal and its phase manipulation is performed by a binary sequence of pulses coming from the information source. In the process of phase manipulation, depending on what needs to be transmitted (1 or 0), the pulses of the information source are replaced by a direct or inverse SRP. The carrier frequency signal is phase-manipulated (0.180) by a pseudo-random pulse train, phase-manipulated from the information source. The signal formed at the carrier frequency is amplified and emitted through a communication channel.

The disadvantages of the described method are: low information transfer rate, since only one bit of information can be transmitted during the memory bandwidth; low imitability and secrecy of the communication system, since only one memory bandwidth is used to encode information from the source.

The first of these disadvantages is eliminated by the methods described in patents No. 2279183 and No. 2286017 "Method for transmitting information in a communication system with noise-like signals." With this method, carrier and clock signals are generated. The SRP is formed from the clock signal, which is phase-manipulated from the information source, and the carrier signal is phase-controlled by a pseudorandom sequence of pulses, phase-manipulated phase from the information source. On the transmitting side, digital data coming from the information source over a time interval equal to the period of the SRP is one-to-one transformed into a shift of the elements of the generated SRP relative to the elements of the previously formed SRP. The signal formed at the carrier frequency is amplified and emitted through a communication channel. On the receiving side, the magnitude of this shift is determined and converted into digital data of the received information. This method allows for a time equal to the period of the SRP, to increase the speed of information transfer in log ₂ N + 1 times (where N is the number of elements of the SRP), however, as previously discussed methods when using them in the recognition system, does not provide the required imitation resistance and stealth .

. Сигнал несущей частоты манипулируют по фазе псевдослучайной последовательностью импульсов S^(t). Сформированный на несущей частоте фазоманипулированный сигнал (информационный импульс) усиливают и излучают в пространство. На приемной стороне для каждого принятого информационного импульса определяют номер функции Уолша, получают последовательность этих номеров и восстанавливают по ней переданный информационный код. Указанные меры позволяют обеспечить структурную скрытность запросных сигналов и низкую вероятность их имитации противником. Однако к недостатку прототипа следует отнести его низкую помехоустойчивость при воздействии импульсных помех.The closest in technical essence and the set of essential features to the claimed method of generating signals and transmitting information in a radar recognition system is a method of generating signals and transmitting information in a radar recognition system [utility model patent No. 125724 of 03/10/2013], which was chosen as a prototype. In this method, the transmitted information code (m-bit code combination) is divided into n code combinations of lower bit capacity k (k <m), called information blocks. On the transmitting side, carrier and clock signals are generated. From the clock signal form an array of covering SRP {G}. A digital code coming from an information source (cryptographic device) during the duration of one information block is uniquely converted into the number l of the Walsh function. For each information block, a phase-shift signal (SRP) S ^(t) is generated, which is the product of one of the SRP array {G} by the corresponding Walsh function

. The carrier signal is phase-manipulated by a pseudo-random pulse train S ^(t) . The phase-shift signal (information pulse) formed at the carrier frequency is amplified and radiated into space. On the receiving side, for each received information pulse, the Walsh function number is determined, a sequence of these numbers is obtained, and the transmitted information code is restored from it. The indicated measures allow ensuring structural secrecy of the interrogation signals and a low probability of their imitation by the adversary. However, the disadvantage of the prototype should include its low noise immunity when exposed to pulsed interference.

. Сигнал несущей частоты манипулируют по фазе псевдослучайной последовательностью импульсов S^(t). Сформированный на несущей частоте фазоманипулированный сигнал (информационный импульс) усиливают и излучают в пространство. При этом частота, на которой будет излучен информационный импульс, выбирается с помощью датчика (генератора) случайных чисел из двух возможных частот, разнесенных друг от друга в пределах выделенной для систем опознавания полосы частот. На приемной стороне для каждого принятого информационного блока определяют номер функции Уолша, получают последовательность этих номеров, по которой восстанавливают сначала закодированную кодовую комбинацию, а затем путем ее декодирования восстанавливают переданный информационный код.In the inventive method, the m-bit code combination coming from the information source (cryptographic device) is subjected to coding with redundant code with error correction. The resulting code combination containing m information and r check bits is divided into n + p information blocks of the same bit capacity k as in the prototype. Each information block is uniquely converted to the number l of the Walsh function. On the transmitting side, carrier and clock signals are generated. From the clock signals form an array of covering SRP {G}. For each information block, a phase-shift signal (SRP) S ^(t) is generated, which is the product of one of the SRP array {G} by the corresponding Walsh function

. The carrier signal is phase-manipulated by a pseudo-random pulse train S ^(t) . The phase-shift signal (information pulse) formed at the carrier frequency is amplified and radiated into space. In this case, the frequency at which the information pulse will be emitted is selected using a sensor (generator) of random numbers from two possible frequencies spaced from each other within the allocated frequency band for the identification systems. On the receiving side, for each received information block, the Walsh function number is determined, a sequence of these numbers is obtained, from which the encoded code combination is restored first, and then the transmitted information code is restored by decoding it.

Signs that have significant differences that are new to recognition systems are the introduction of coding of information received from a cryptographic device with an excess code with error correction, as well as the random selection of one of two carrier frequencies at which the next information pulse is emitted.

These signs have significant differences, because in known methods for generating signals in radar recognition systems are not detected.

. В тех же условиях при использовании только кодирования поступающей от криптографического устройства информации кодом Рида-Соломона, исправляющим одну ошибку, требуемое отношение сигнал/шум снижается до величины 3,85 (см. фиг. 2 - кривая «с кодированием»). Если же вместе с кодированием используется случайный выбор одной из двух несущих частот, на которой излучается очередной информационный импульс, то требуемое отношение сигнал/шум снижается еще больше и составляет 2,21 (см. фиг. 2 - кривая «с кодированием и переключением частот»).The application of these signs will allow to increase the stability of the radar recognition system to the effects of both intentional and unintentional impulse noise. Thus, in accordance with FIG. 1 graphs of the dependence of the probability of the correct reception of the request signal R _{CR p} on the signal-to-noise ratio shows that to obtain the required probability P _{CR p} = 0.9 in the conditions of continuous interference in the prototype it is necessary to provide a signal-to-noise ratio of 1.78 action of impulse noise - 6.25. Therefore, in conditions of pulsed interference, the stability of the prototype system to their effects decreases in

. Under the same conditions, when using only the coding of the information received from the cryptographic device with a Reed-Solomon code correcting one error, the required signal-to-noise ratio is reduced to a value of 3.85 (see. Fig. 2 - “with encoding” curve). If, together with coding, a random choice of one of the two carrier frequencies is used, at which the next information pulse is emitted, then the required signal-to-noise ratio decreases even more and amounts to 2.21 (see Fig. 2 - curve “with coding and frequency switching” )

раза по сравнению с прототипом.Therefore, under the conditions of the considered specific example, the proposed method of generating signals in the radar recognition system can increase its resistance to impulse noise in

times compared to the prototype.

Implementation of the proposed method is possible with the help of FIG. 3 structural diagrams of the transmitter. To simplify the communication scheme of the control unit and the formation of control signals (synchronizer) with other blocks are shown conditionally (dashed lines, each of which can be a set of different clock pulses).

записывается в свою ячейку под номером l запоминающего устройства (ЗУ) 4, образуя массив {W} функций Уолша объемом N_W. Аналогично каждая из сформированных генератором 10 накрывающих ПСП G_γ

записывается в свою ячейку под номером γ запоминающего устройства 4, образуя массив {G} накрывающих ПСП объемом N_G. По сигналу управления, поступающему от блока управления и формирования управляющих сигналов 11, с первого выхода криптографического устройства 1 в кодирующее устройство 2 подается m-разрядная кодовая комбинация, которая преобразуется им в m+r разрядную кодовую комбинацию. По сигналу считывания с выхода кодирующего устройства в k-разрядный первый регистр адреса 3 записывается первый (t=1) блок информационного кода, а по сигналу управления со второго выхода криптографического устройства 1 во второй регистр адреса 3 записывается код адреса второго запоминающего устройства 4. Записанная в первом регистре адреса 3 кодовая комбинация представляет собой двоичный код адреса (номера ячейки памяти) первого запоминающего устройства 4, который по сигналу считывания поступает в l-тую ячейку первого запоминающего устройства 4. Аналогично записанная во втором регистре адреса 3 кодовая комбинация представляет собой двоичный код адреса (номера ячейки памяти) второго запоминающего устройства 4, который по сигналу считывания поступает в γ-ую ячейку второго запоминающего устройства 10. В результате с выхода первого ЗУ 4 на первый вход умножителя 5 поступает функция Уолша

с номером l, а с выхода второго ЗУ 4 на второй вход умножителя 5 поступает накрывающая ПСП

c номером γ. После посимвольного перемножения функции Уолша

на накрывающую ПСП

на выходе умножителя 5 получаем последовательность ШПС в виде фазоманипулированных (ФМ) сигналов, переносящую информационный код первого блока (ПСП S^(l)). Эта последовательность поступает в модулятор 6, в котором осуществляется балансная модуляция колебания, вырабатываемого одним из двух генераторов 9 несущей частоты, ФМ сигналом. При этом час юта, на которой будет излучен информационный импульс, выбирается блоком выбора несущей частоты случайным образом из двух возможных частот, разнесенных друг от друга в пределах выделенной для систем опознавания полосы частот.Clock pulses from the control unit and the formation of control signals 14, start the generators of the Walsh functions 8 and covering the SRP 10. Each of the 8 Walsh functions generated by the generator W _l

recorded in its cell under the number l of the storage device (memory) 4, forming an array {W} of Walsh functions of volume N _W. Similarly, each of the 10 coverings formed by the generator 10 covering the bandwidth G _γ

recorded in its cell under the number γ of the storage device 4, forming an array {G} of covering SRP volume N _G. According to the control signal coming from the control unit and generating control signals 11, from the first output of the cryptographic device 1, an m-bit code combination is supplied to the encoding device 2, which is converted by it into an m + r bit code combination. The first (t = 1) block of the information code is written to the k-bit first address register 3 by the read signal from the encoder output, and the address code of the second memory device 4 is written into the second address register 3 by the control signal from the second output of the cryptographic device 1 in the first register of address 3, the code combination is a binary code of the address (memory cell number) of the first storage device 4, which, according to the read signal, enters the l-th cell of the first storage device wa 4. Similarly, the code combination recorded in the second address register 3 is a binary address code (memory cell number) of the second storage device 4, which, by a read signal, enters the γth cell of the second storage device 10. As a result, the output of the first memory 4 to the first input of multiplier 5 is the Walsh function

with the number l, and from the output of the second memory 4 to the second input of the multiplier 5 receives the covering bandwidth

with number γ. After symbol-wise multiplication of the Walsh function

on covering PSP

at the output of the multiplier 5, we obtain a sequence of SHPS in the form of phase-shifted (FM) signals that transfers the information code of the first block (SRP S ^(l) ). This sequence enters the modulator 6, in which the balanced modulation of the oscillation generated by one of the two generators 9 of the carrier frequency, the FM signal. In this case, the hour at which the information impulse will be emitted is randomly selected by the carrier frequency selection unit from two possible frequencies spaced from each other within the allocated frequency band for the identification systems.

After amplification of the generated signal in the power amplifier 7, the signal enters the antenna and is radiated into space. Simultaneously with the read signal from the first register of address 3 of the first block of the information code, the second (t = 2) block of the information code is written into it and the process described above is repeated until all n + p blocks of the excess code are transmitted.

On the receiving side, for each received information block, the Walsh function number is determined, a sequence of these numbers is obtained, from which the encoded code combination is restored first, and then the transmitted information code is restored by decoding it.

The structure of the carrier frequency selection block, consisting of such known elements as first and second frequency generators 9, OR circuit 11, first and second keys 12, inverter 13, random number sensor 15 and threshold device 16, is shown in FIG. 3. The principle of operation of this unit is obvious and does not require special explanations. The structure of coding and decoding devices that implement various redundant error-correcting codes is known and is given in the corresponding literature [for example, Shlyapobersky V.I. Fundamentals of discrete messaging technology. - M: Communication, 1973, S. 300-374; Bleikhut R. Theory and Practice of Error Control Codes: Per. from English - M .: Mir, 1986, S. 162-163; Sklyar B. Digital Communication. Theoretical foundations and practical application: Per. from English - M.: Williams, 2003, S. 474; Copyright certificate No. 1716609 "Reed-Solomon code coding device"].

Claims (1)

A method of generating signals and transmitting information in a radar recognition system, namely, that the transmitted information code is divided into n information blocks of the same length on the transmitting side, carrier and clock frequencies are generated, an array of pseudorandom sequences (PSP) is formed from the clock frequencies, each the information block is encoded by its PSP, which is the product of the covering PSP by the corresponding Walsh function, the number of which is uniquely determined by binary m the code of the information block, this PSP is manipulated in phase by the carrier frequency signal, and the phase-manipulated signal generated at the carrier frequency is amplified and radiated into space, on the receiving side, for each received information block, the Walsh function number is determined and a sequence of these numbers is obtained, characterized in that the incoming from an information source (cryptographic device) the information code is transformed by encoding with a redundant code with error correction into n information and p verification blocks of equal length, is not discernable in further processing, as well as randomly selecting one of two carrier frequencies for each transmission block, the reception side of the obtained sequence is first Feature Number Walsh recovered encoded codeword, and then through its decoding restore transmitted information code.

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