RU2608769C1 - Method for generating and detecting sync pulse of noise-like signal - Google Patents

Abstract

FIELD: communication.

SUBSTANCE: invention relates to communication and can be used in communication systems using noise-like phase-shift keyed signals. Method of generating and detecting sync pulse of noise-like signal involves the following: formation of a pseudorandom sequence at the transmitting side, using which phase of carrier frequency of sync pulse of noise-like signal is modulated, which is followed by addition of Walsh function and its generating sequence using module 2, and at the receiving side the decision to detect of the sync pulse of noise-like signal is made only in case, if the exceeded value of the correlation function is simultaneously detected, calculated using the correlator, value, developed using the adaptive detection of noise level, and confirmation of formation of sync pulse of noise-like signal with the help of Walsh function.

EFFECT: technical result is increased throughput capacity of communication system and its reliability.

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Description

The invention relates to the field of communication and may find application in communication systems that use noise-like phase-shifted signals [Communication systems with noise-like signals, L. Varakin, M., Radio and communication, 1985].

In communication systems, information is transmitted using service and information elements. The service element (clock) of a noise-like signal is detected. Using information elements, information is transmitted (L. Varakin, “Communication systems with noise-like signals.” - M: Radio and Communication, 1985, p. 324, Fig. 19.1). The phase modulation of the carrier frequency of the service and information elements is performed by pseudo-random sequences.

The detection of the clock pulse of the phase-shifted signal is carried out by the optimal receiver, which consists of a matched filter (SF), an adaptive determinant of the noise level and a threshold device.

The operation of such a detector is based on the Correlator calculating the correlation function (CF) of the currently observed signal with a sequence that modulated the phase of the clock pulse ( _{SR SR} ). The adaptive noise level calculator calculates a threshold. When the value of the correlation function is exceeded, the value of the calculated threshold. The threshold device detects signal detection.

In a number of patents, this method of detecting a clock pulse is used to increase the noise immunity of the detector (RU 2310978 C2, H03H 17/00, 11/20/2007; RU 2394365 C2, H03H 17/06, 07/10/2010), to increase the range of reliable reception of information (RU 2385542 C2, H04L 27/14, 03/27/2010), to increase the protection of the radar from impulse noise (RU 2428712 C1, G01S 13/04, 09/10/2011).

The disadvantage of such a detector, and therefore the proposed methods, is that when calculating the CF, "false detection" may occur associated with:

- poor correlation properties of the SRP _SR sequence;

- the presence of internal noise at the input of the receiving device;

- an increase in the side peaks of the CF sequence of the SRP _SR due to external interference.

Selection of SRP _SR sequences having good correlation properties (small side peaks) significantly reduces their number.

The decrease in the intensity of the internal noise of the receiving device leads to a deterioration in the sensitivity of the communication system.

There are practically no ways to combat external interference (with the exception of increasing the signal power).

By “false detection”, processing of “false information elements” of the signal is started. In some cases, “false detection” can be determined at the stage of processing one of the information elements of the signal. In other cases, “detection falsity” is determined after processing all the information elements of the signal.

Closest to the technical nature of the claimed method is a method of combating "false detection" of phase-shifted signals described in patent RU 2505934 C1 (H04L 27/233, 01/27/2014), which dynamically changes the value of a given threshold of a resolver in accordance with certain parameters the signal at the output of the matched filter, for which the average Cp is calculated and the peak Up value is measured, the signal value at the output of the matched filter, then the value of the given threshold is calculated by the formula P = k * (Cn-Cp) + Cp de k - a constant proportional to the relative size of the side peaks ACF specified NLS.

The disadvantage of this method is that its implementation requires the calculation of Cp and Yn, and then the value of P, which requires certain hardware and time. In addition, for each SRP, its own value of k is necessary, which should be selected based on the magnitude of the side peaks of the ACF of the selected SRP. The technical solution indicated above due to the occurrence of “false detections” reduces the throughput of the communication system, its reliability and requires additional computing resources for processing “false information elements”.

The technical result of the claimed technical solution is to increase the throughput of the communication system and its reliability.

To achieve the indicated technical result, a method for generating and detecting a clock pulse of a noise-like signal is proposed, in which on the transmitting side the formation of a pseudorandom sequence ( _{SR SR} ), which modulates the phase of the carrier frequency of the clock pulse of a noise-like signal, is carried out by modulo 2 adding the Walsh function (FS _SI ) and its producing sequence (SRP _N ), and on the receiving side, the decision to detect a clock pulse of a noise-like signal is made only in that case e, if at the same time the excess of the value of the correlation function calculated by the correlator is fixed, the value generated by the adaptive determinant of the noise level, and confirmation of the formation of a clock pulse of a noise-like signal using the Walsh function (FU _SI ).

The operation of the method is illustrated in FIG. one.

On the transmitting side, the phase modulation of the carrier frequency of the clock pulse of a noise-like signal is carried out by a modulating sequence:

where FU _SI is the Walsh function that acts as a sign of signal detection by the "main peak of the CF", and PSP _N produces a sequence that makes FU _SI noise-like.

On the receiving side, the decision to detect is made only if the sign “main peak KF” has been detected.

The correlator 1 calculates the KF of the currently observed signal with the reference sequence of _{SR SR} . If the KF value is exceeded by the value obtained by the Adaptive noise level determinant, the Threshold device transmits a “detection” signal to the Solver.

, а затем Коррелятором 2, у которого в качестве опорной последовательности используется ФУ_СИ, определяется идентичность ПСП_Х и ФУ_СИ.At the same time, the presence of the sign “main peak of CF” is determined. For this is calculated

and then by Correlator 2, in which FU _{SI is} used as a reference sequence, the identity of the SRP _X and FU _{SI is} determined.

, то Определитель признака «основной пик КФ» посылает в Решающее устройство сигнал «ложь». Если же ПСП_Х=ФУ_СИ то в Решающее устройство посылается сигнал «истина».If

, then the identifier of the sign “main peak KF” sends a signal “false” to the Solver. If the SRP _X = FU _SI, then the signal "true" is sent to the Decider.

In the Solver, the decision to detect a signal is made only if the KF value is exceeded by the adaptive threshold value and the “true” signal is present.

With this method of combating "false" detections, the probability that randomly the SRP _X = FU _SI is 1/2 ^m , where m is the signal base.

As can be seen from FIG. 1, the detection of _{SR SRP} and the determination of the presence of the sign “main peak CF” is carried out in parallel by working the same type of correlators. The temporary difference in the parallel branches is determined only by calculating the SRP _X.

On the currently available publicly available element base, the detection of a sync pulse with a base of 256 and the determination of the _SI FU _is carried out in a time of 80-120 ns. The increase in this time associated with the calculation of the SRP _X is 16-32 ns. Such an increase is not comparable with the time of “false detection” detected during processing of “false information elements”, which amounts to hundreds of microseconds.

The claimed method of generating and detecting a sync pulse of a noise-like signal allows you to:

- minimize signal detection time;

- improve the throughput of the communication system;

- significantly improve the operation of the communication system when exposed to various kinds of interference;

- increase the sensitivity of the communication system;

Claims (1)

A method for generating and detecting a sync pulse of a noise-like signal, in which a pseudo-random sequence is generated on the transmitting side, which modulates the phase of the carrier frequency of the sync pulse of a noise-like signal, by modulo 2 adding the Walsh function and its generating sequence, and on the receiving side, the decision to detect a clock pulse of a noise-like signal accepted only if at the same time an excess of the value of the correlation function is recorded, calculating constant correlator values generated determinant adaptive noise and to confirm the formation of noise-like clock signal with a Walsh function.

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