MODIFIED INVARIANT AMPLITUDE MODULATION WITH TWO REFERENCE SIGNALS

Abstract

The model of modified invariant amplitude modulation and demodulation with two reference signals considered in the article belongs to the field of systems, networks and devices of telecommunications and radio engineering and can be used in radio transmitting devices, telecommunication systems and devices where an amplitude-modulated transmitted signal is required for transmission through a communication channel. The achieved technical result of the modified invariant amplitude modulation and demodulation with two reference signals is aimed at the possibility of forming an amplitude-modulated transmitted signal with increased noise immunity characteristics to a specific type of interference. Algorithms of modified invariant amplitude modulation and demodulation with two reference signals are proposed, and based on these algorithms, block diagrams of a modified invariant amplitude modulator and a demodulator with two reference signals were developed. In order to obtain experimental data for the analysis of a modified invariant amplitude modulation and demodulation with two reference signals when it is affected by interference in the communication channel, the communication system was simulated and the necessary data calculated in Matlab. Additive white Gaussian noise was chosen as an interference in the communication channel. The article presents a simplified block diagram of the communication system of the experimental model. To compare the results, modified invariant amplitude modulation and demodulation with two reference signals will be used as a modulator and demodulator, in the first case, and in the second case, amplitude modulation and demodulation. As a result, estimates of the dependence of the standard deviation on the value of the signal-to noise ratio and the probability of a bit error on the value of the signal-to-noise ratio were obtained. The standard deviation for modified invariant amplitude modulation and demodulation with two reference signals has significantly lower values than the standard deviation for amplitude modulation and demodulation. The transmission of information with the same reliability through a communication channel with a modified invariant amplitude modulation with two reference signals requires a significantly higher signal-to-noise ratio than transmission through a communication channel with amplitude modulation.