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Satellite communication systems that use phase modulation of a signal designed to transmit useful information in a continuous mode face the problem of frequency uncertainty of the signal when used as intended. For demodulators of satellite modems of such systems operating with a continuous input signal, the most significant is the problem of synchronization in the frequency of carrier oscillations in the conditions of frequency uncertainty of the signal. This synchronization task is actually reduced to estimating the true parameters of the signal, namely the estimation of the carrier frequency. The complexity of the task of estimating the carrier frequency in a satellite channel with phase modulation is exacerbated by the presence of additional interfering actions of "neighboring channels" - signals with the same type of modulation and the same data rate. The paper specifies the algorithm for estimating the carrier frequency of the signal received by the satellite communication system in a continuous mode, taking into account the influence of "neighboring channels" of information transmission. This algorithm allows to estimate the carrier frequency according to the rule of maximum likelihood, taking into account the condition of uncertainty of all parameters of the signal received by the satellite communication system in continuous mode, taking into account the influence of "neighboring channels" of information with a minimum observation interval. It includes the steps of: calculating the readings of the amplitude spectrum of the received signal and counting the convolution of the obtained amplitude spectrum with frequency response UV; calculating the count of the derivative convolution and finding the initial estimate of the frequency; based on the obtained evaluation of the evaluation procedure based on the multiplication of the phase of the received signal and the calculation of the estimated carrier frequency of the received signal.In order to assess the effectiveness of this algorithm in the comparison of the effectiveness of the estimates provided by the proposed procedure and the estimates made on the basis of subtraction of the global maximum convolution of the amplitude spectrum of the received signal. The results of this assessment presented in the paper showed that the dependences of the normalized variance on practically do not differ. That confirms the efficiency and feasibility and practical value of the algorithm for estimating the carrier frequency given in the work, taking into account the influence of "neighboring channels" of useful signal transmission. A promising area for further study of the issues raised in the work is the adaptation of this algorithm to the carrier frequency estimation in combined phase synchronization systems that have the ability to increase the order of astatism, monitoring the carrier frequency (pilot signal), the phase of which is modulated by a deterministic Doppler signal.

sučasnì ìnformacìjnì sistemi

CLARIFICATION OF THE ALGORITHM FOR ESTIMATING THE FREQUENCY OF THE SIGNAL RECEIVED BY THE SATELLITE COMMUNICATION SYSTEM IN A CONTINUOUS MODE UNDER THE INFLUENCE OF «NEIGHBORING CHANNELS»