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UDC 621.396

ANALYSIS OF COGNITIVE RADIO SYSTEMS CHARACTERISTICS ADAPTING TO NARROW-BAND INTERFERENCE EFFECT BASED ON SYNTHESIZED FOUR-POSITION RADIO SIGNALS

A. A. Lisnichuk, Ph.D. (Tech.), associate professor, RSREU, Ryazan; This email address is being protected from spambots. You need JavaScript enabled to view it.
S. N. Kirillov, Dr. Sc. (Tech.), full professor, Head of the Department, RSREU, Ryazan; This email address is being protected from spambots. You need JavaScript enabled to view it.

The aim is to analyze the characteristics of cognitive radio systems that perform multi-criteria synthesis of four-position radio signals for adapting to the action of narrow-band interference with different parameters. The analysis of cognitive radio systems characteristics adapting to narrow-band interference effect was carried out. In these systems, multi-criteria synthesis of radio signals is realized, taking into account the following quality indicators: noise immunity to the action of narrow-band interference and additive «white» Gaussian noise (AWGN); peak-factor (energy efficiency of signals) and the level of out-of-band radiation. The quality indices of cognitive radio systems adapting to narrow-band interference change are determined. Cognitive radio systems adapting to the most unfavorable (of the considered) narrow-band interference effect (central frequency was equal to carrier wave frequency of useful signal; spectrum width was 5 %) provide noise immunity at the same level as QPSK signal under the influence of only AWGN up to relation signal-interference -7 dB. The radio systems without adaptation using known modulation types are inferior at this quality indicator up to 27 dB.

Key words: multi-criteria synthesis of radio signal, cognitive radio system, multi-criteria optimization, noise immunity increase.

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UDC 621.396

MULTI-CRITERIA SYNTHESIS PROCEDURE OF DSSS SIGNALS FOR COGNITIVE RADIO SYSTEMS ADAPTATION TO COMPLEX INTERFERENCE ENVIRONMENT

A. A. Lisnichuk, Ph.D. (Tech.), associate professor, RSREU, Ryazan; This email address is being protected from spambots. You need JavaScript enabled to view it.

DSSS radio signals under AWGN action realize relatively high noise immunity, however, in the conditions
of complex, dynamically changing interference environment, signals with fixed parameters do not provide
the required characteristics. The aim is to develop multi-criteria synthesis procedure of DSSS signals
for cognitive radio systems adaptation to complex interference situation. The article shows that the minimization
of complex interference effect is recommended to be made by multi-criteria synthesis of elementary
pulses set as well as code sequences ensemble. This fact makes it possible to increase interference immunity
up to 10 dB (in comparison with QPSK signal with spreading of complemented M-sequences ensemble)
in complex signal-interference environment while maintaining BER at QPSK signal level for only AWGN
action.

Key words: radio signal synthesis, cognitive radio system, multi-criteria optimization, increase of noise
immunity.

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UDC 658.512.22:001.891.573

FALSE ALARM LEVEL STABILISATION WHILE DETECTING AN OBJECT IN THE BACKGROUND OF NON-GAUSSIAN NOISE

V. A. Belokurov, Ph.D. (Tech.), associate professor, radio technical systems department, Ryazan; This email address is being protected from spambots. You need JavaScript enabled to view it.

The task to calculate threshold detection level in the conditions of multi-frame accumulation of signals reflected from a small object in the background of non-Gaussian noise is considered. The aim of the work is to develop an analytical algorithm for calculating a detection threshold for multi-frame accumulation. The apparatus of characteristic functions to calculate the distribution density of sufficient statistics at the input of threshold device is proposed to be used. To assess the effectiveness, we compared detection thresholds calculated by the proposed algorithm and the thresholds calculated using simulation modeling for various values of non-Gaussian noise and false alarm probabilities.

Key words: characteristic function, numerical integration, rectangle method, probability distribution density and distribution function, gamma distribution.

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UDC 621.396.946

CONSTRUCTION ALGORITHM FOR RADIO VISIBILITY ZONE OF GROUND RECEIVING STATIONS FOR HIGHLY RELIABLE SPACE RADIO LINKS

A. A. Kascheev, Ph.D. (Tech.), associate professor, Department of Radio Control And Communication, RSREU, Ryazan; This email address is being protected from spambots. You need JavaScript enabled to view it.
S. I. Gusev, Dr. Sc. (Tech.), Vice-Rector for Science and Innovation, RSREU, Ryazan; This email address is being protected from spambots. You need JavaScript enabled to view it.

The article deals with the problem of constructing a zone of radio visibility for ground receiving stations (GRS), taking into account the reliability of radio link. The aim of the work is to estimate the geographical coordinates of radio visibility zone boundaries taking into account the reliability of radio link. The algorithm to calculate the geographical coordinates of boundaries has been developed. It is based on the comparison of current estimations of signal-to-noise ratio (SNR) at the input of GRS with SNR threshold at various information transmission bit error probabilities. Mathematical expressions are obtained for the conditions of spacecraft entry and exit, and also to estimate minimum angle of excess over the horizon for GRS, taking into account the fact of crossing zone boundary at different reliability of radio link. The influence of information
transmission error probability and the main parameters of radio signal (type and speed of noisecorrecting coding as well as phase manipulation index) on the size of radio visibility zone is studied. Recommendations for calculating the zone for radio links with varying degrees of reliability are given.

Key words: spacecrafts; ground receiving stations; on-board equipment; ground equipment; on-board storage device.

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UDC 621.396

THE CHOICE OF SIGNAL SEPARATION METHOD IN HYDROACOUSTIC CONTROL CHANNEL

B. I. Filippov, Ph.D. (Tech.), associate professor of NSTU, Novosibirsk; This email address is being protected from spambots. You need JavaScript enabled to view it.

One of the main issues in the development of hydroacoustic communication channels (HACC) is the choice of the ensemble of signals and the method for separating the signals of control commands between bottom stations (BS) and pop-up modules of satellite communication system (PM SCS). In principle, any of the known methods of channel separation can be used to separate the signals between hydroacoustic autonomous station (HBAS) and PM SCS: time, frequency and code (in the form of signals). The aim of this work is to justify that the signal exchange between the vessel and the bottom station is carried out by sessions and begins with the transfer of command from a ship. At HBAS there is no known time for the commencement of control command transfer from the vessel. If binary sequences are used as a start signal, address signals and commands, then a simple device consisting of a binary signal receiver can be used to receive them, the output of which includes decoders and other decoders corresponding to the received signals. The results of comparative tests of the considered digital DFM and DRPM receivers showed that they have similar characteristics of noise immunity. The use of DRPM signals provides a small, about 1,5 dB, power gain and cost savings for the implementation of equipment in comparison with the usage of DFM signals, which makes it possible to recommend the use of DRPM signals for the implementation of HACC equipment.

Key words: hydroacoustic channel, discrete modulation, methods of transmission and reception, digital receivers.

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