PHYSICAL MODELING OF TEXT INFORMATION OF DIGITAL MICROWAVE COMMUNICATION CHANNELS WITH A FREQUENCY-KEYED SIGNAL IN THE MATLAB ENVIRONMENT

Abstract

The article is dedicated to the study of signals with binary frequency shift keying (BFSK). As a physical model, a block diagram of a communication system with a BFSK (Binary Frequency Shift Keying) signal is proposed, which consists of a transmitter, a communication channel and a receiver. The information source of the proposed scheme can be either an analog signal in the form of text or speech, or a digital signal in the form of a binary code consisting of ones (1) and zeros (0). The developed programs in the Matlab environment visually represent the graphs of the information signal and the modulated microwave signal with binary frequency shift keying without interference, and under the influence of noise interference. The proposed communication system is evaluated by spectral efficiency. The spectral characteristics of the BFSK signals are obtained using the fast Fourier transform. The noise immunity of receiving microwave radio signals with BFSK is considered as the probability of a symbol error depending on the signal-to-noise ratio. A comparative analysis of the noise immunity for signals with frequency shift keying in relation to signals with amplitude and phase manipulations has been carried out. The dependence of the probability of distortion of letters in the text depending on the signal-to-noise ratio is presented.