INFLUENCE OF FREQUENCY NOISE IN A COMMUNICATION CHANNEL ON THE PROBABILITY OF A BIT ERROR DURING TRANSMISSION OF SIGNALS

Abstract

The purpose of the article is to analyze the combined effect of amplitude white Gaussian noise
(AWGN) present in the communication channel and frequency noise (FN) resulting from fluctuations in
the frequency of the signal in the communication channel on the probability of bit error when processing
QAM signals. Research tasks to be solved: 1. Development of a mathematical model for processing the
QAM signal, taking into account the combined effects of AWGN and FN in the communication channel.
2. Numerical study of the combined effect of AWGN and FN on the probability of bit error when processing
QAM signals. A mathematical model is proposed that establishes the relationship between the
signal-to-noise ratio in the channel and the mean square deviation of the signal frequency, on the one
hand, and the probability of bit error during A mathematical model is proposed that establishes the
relationship between the signal-to-noise ratio in the channel and the mean square deviation of the signal
frequency, on the one hand, and the probability of bit error during QAM signal demodulation, on the
other. The visualization of the effects associated with the presence of AWGN and FN in the channel on
the signal constellation of the received QAM signal is given. The main patterns associated with joint
action AWGN and FN in the communication channel are: - the appearance of FN in the communication
channel leads to a decrease in the signal level in the channel during the correlation processing of the
received signal and a corresponding decrease in SNR; - In addition to the blurring of the signal constellation
in the azimuthal direction, associated with the appearance of an integral phase fluctuation due to
frequency fluctuations during the pulse, an increase in the blurring of the signal constellation in the
radial direction causes a decrease in the SNR. Based on the results obtained, it is concluded that it is
necessary to take into account more fully the deviations of the signal parameters in the channel due to
both the presence of AWGN and FN.