RU2506702C2 - Device for synchronisation in radio communication system with pseudorandom operational frequency readjustment - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: invention relates to radio engineering and can be used in communication systems with pseudorandom operational frequency readjustment. One device combines functions of filtering pseudorandom operational frequency readjustment (PROFR) signals, delay search and demodulation of PROFR signals and uses, during delay search, information PROFR signals having an identical form. The device includes an analogue-to-digital converter, a "window" signal processing unit, a fast Fourier transform unit, a PROFR demodulator, a signal weighted summation unit, a hypothesis selection unit, a control unit, a hypothesis selector, a PPS reference generator and a PSP generator.

EFFECT: shorter signal delay search, high radio security and noise-immunity of the radio line.

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Description

The present invention relates to radio engineering and may find application in radio communication systems using software tuning of the operating frequency.

Known radio communication systems with pseudo-random tuning of the operating frequency (MHF), presented in monographs:

1. Melnikov L.A. and others. "Radio lines with software tuning of the operating frequencies." - Leningrad, VOLKAS, 1989

2. R.K. Dixon. "Broadband systems." - M .: Communication, 1979, p. 191-192, Fig. 6.9c. Signal delay search devices with pseudo-random tuning of the operating frequency.

Closest to the technical nature of the claimed device is a radio communication system with frequency hopping, described in the monograph by V.I. Borisov and others. "Noise-resistant radio communication system with the expansion of the signal spectrum by the method of pseudo-random tuning of the operating frequency." - M .: Radio and communications, 2000, p.24, Fig. 1.7a and 1.7b, adopted as a prototype.

The device comprises a mixer, the input of which comes from the output of the code sequence generator, a code sequence identical to the code sequence of the transmitter signals with some random shift at a phase determined by the amount of signal delay in reception relative to the transmission signal, as well as the frequency difference of highly stable crystal oscillators in reception and transmission and errors in the initial installation of pseudo-random frequency sequences at reception and transmission. At the other input of the mixer, the frequency sequence of the transmitter code generator is supplied. From the output of the mixer, the signals are fed to the input of a narrow-band filter, the output of which is connected to the input of the decision block, which makes a decision on the presence or absence of synchronization by comparing the voltage at the output of the detector with a certain threshold voltage Z ₀ installed at the second input of the decision block.

By changing the delay value of the signals of the code sequence generator, a cyclical scan of the interval of possible delays of the received frequency hopping signal relative to the transmitted one is carried out until the resolving device generates a signal about the presence of synchronization.

The disadvantages of all analogues are the relatively long search time for the delay and low noise immunity.

The aim of the invention is to reduce the synchronization time (search by delay) by simultaneously checking all hypotheses (assumptions) about the possible value of the signal delay in reception with respect to the value of the signal delay in transmission.

This goal is achieved due to the fact that an analog-to-digital converter (ADC), the input of which is the input of the device, and the output is connected to the input of the unit, are introduced into the synchronization device in a radio communication system with a pseudorandom tuning of the operating frequency, containing a clock generator, a tunable frequency generator “Window” signal processing, the output of the “window” signal processing unit is connected to the input of the fast Fourier transform unit (FFT), the output of the FFT unit is connected to the first input of the signal demodulator with pse by pre-random tuning of the operating frequency (PFRCH), the output of the PFRCH demodulator is connected to the input of the weighted signal addition unit, one of the outputs of the weighted signal addition unit is the output of the received information signals, and the other is connected to the input of the hypothesis selection unit, the other input and output of the hypothesis selection unit are connected respectively with the output and input of the control unit, the other outputs of which are connected to the input of the hypothesis selector, the input of the FFT unit, and the second input of the FFT unit is connected to the output of the reference generator, other outputs PORN generator are respectively connected to the input of the ADC input of "windowing" the signal processing unit and the input of FFT generator of pseudorandom sequences (PRS); the output of the PSP generator is connected to the input of the hypothesis selector, which is controlled from the output of the control unit, and the output of the hypothesis selector is connected to the second input of the frequency hopper demodulator.

The drawing shows a block diagram of a synchronization device in a radio communication system with pseudo-random frequency tuning. It contains:

1 - analog-to-digital Converter (ADC);

2 - block "window" signal processing;

3 - block fast Fourier transform (FFT);

4 - frequency hopper demodulator;

5 - block weight addition signals;

6 - hypothesis selection block;

7 - control unit;

8 - hypothesis selector;

9 - reference generator;

10 - PSP generator

The operation of the device is as follows.

A signal-delay search device with a pseudo-random tuning of the operating frequency, containing a reference oscillator, an SRP generator, contains a series-connected analog-to-digital converter (ADC), to one input of which signals are fed in the frequency hopping frequency band, and to another input from a highly stable reference oscillator the clock frequency f _s necessary to provide a discrete Fourier transform in the frequency hopping frequency band (see Richard Lyonis. "Digital signal processing". - M .: Binom, 2006, p. 49-58). From the ADC output, the readings of the voltage values in the strip go to the input of the “window” signal processing unit, which ensures the construction of the frequency spectrum in the frequency hopper band using the discrete Fourier transform (DFT) (see Richard Lionis. “Digital Signal Processing”. - M .: Beanom, 2006, p. 90-98). From the output of the “window” signal processing unit, the digital sequence is fed to the input of the unit performing the “fast” Fourier transform (FFT). The corresponding clock sequence from a highly stable reference generator is supplied to one of the inputs of the FFT block, and each FFT bin is considered as a result of filtering the voltage received at the input of the receiving part, while the passband of each such “filter” in the frequency hopper band is determined by the “window” processing option , frequency sampling and the number of used ADC samples.

The results of the processing of synchronization signals in the frequency hopper frequency band, carried out in the FFT unit, are input to the frequency hopper demodulator. At the same time, signals from the output of the hypothesis selector corresponding to possible delay values of information signals within the allowable delay interval are received at the other input of the frequency hopper demodulator.

The hypothesis selector provides the formation of a set of time-frequency matrices for all possible delay values of information signals. The formation of this set of matrices is carried out in the hypothesis selector using the time-frequency matrix corresponding to a fixed signal delay, which is taken as the initial one, which comes from the SRP generator to the input of the hypothesis selector.

Since the information is known at the reception during the time interval allotted for determining the delay, the value of the delay at which this information comes from the output of the weight addition block of the fast hopping signal elements to the input of the hypothesis selection block about the delay will mean the completion of the procedure synchronization and the beginning of the issuance of information from the output of the block weight addition of signal elements to the recipient of information. The hypothesis multiplication procedures after determining the signal delay value are implemented by the control unit. Until the end of the transmission of the message, only the hypothesis about the amount of signal delay determined during the synchronization is used to demodulate the frequency hopping signals.

Thus, in the inventive device provides a reduction in the search time for the delay due to the simultaneous verification of all hypotheses about the possible magnitude of the delay. Moreover, the reduction in the delay time is determined by

T _o / N,

where T _about - the time of testing one hypothesis about the magnitude of the delay,

N is the number of tested hypotheses,

where ΔT is the possible time interval of the delay of signals at the reception,

δ is the permissible error in estimating the delay time. The device provides a combination of the synchronization functions and the reception of frequency hopping signals, as well as the use of frequency hopping signals, identical to information, to provide a search for signals by delay (synchronization).

Claims (1)

A synchronization device in a radio communication system with a pseudo-random tuning of the operating frequency, containing a reference generator (OG) and a pseudorandom sequence generator (PSP), characterized in that an analog-to-digital converter (ADC), a window signal processing unit, a fast Fourier transform unit ( FFT block), a signal demodulator with pseudo-random tuning of the operating frequency (frequency hopper demodulator), a weighted signal addition block, a hypothesis selection block (selection block), a control block and a hypothesis selector, the ADC input is the input of the device, and the ADC output is connected to the first input of the window signal processing unit, the output of which is connected to the first input of the FFT unit, the output of which is connected to the first input of the frequency hopper demodulator, the output of which is connected to the first input of the weighted signal addition unit, whose first output is the output of the received information signals, and the second output of the weighted signal addition unit is connected to the first input of the selection unit, the second input of the selection unit and the second input of the weighted signal addition unit are connected respectively with the first and second outputs of the control unit, the third and fourth outputs of which are connected respectively to the second input of the FFT block and the first input of the hypothesis selector, the second input of which is connected to the output of the PSP generator, the output of the hypothesis selector is connected to the input of the frequency hopper demodulator, the second input of the control unit is connected with the output of the selection unit, and the first, second, third, fourth and fifth outputs of the exhaust gas are connected respectively to the second input of the ADC, the second input of the window processing unit, the third input of the FFT unit, the input of the PS generator P and the first input of the control unit.