Software Processing of Signals with Amplitude Modulation of Many Components

Abstract

Software processing of radio signals, in particular SDR (Software Defined Radio) technology has great potential for research of various approaches to radio signal processing. This potential can be substantiated by the great adaptability and flexibility of SDR platform, the possibility of software reconfiguration of various radio parameters (frequency range, modulation scheme, etc.) without direct intervention into the component base of the radio system. Such features make it possible to experimentally test various concepts and ideas in practice. The article reviews the works of other authors devoted to different ways of using SDR as one of the main elements of the radio communication process or for solving the applied problems. Taking into account the advantages of SDR over purely analog methods of transmitting and receiving information via radio channels when using non-standard types of modulation, a variant of amplitude-phase modulation has been chosen, which is characterized by greater interference resistance in comparison with the widely used quadrature amplitude modulation — amplitude modulation of many components (AMMC). The coordinates of the 8-AMMC signal constellation were calculated and a model of the modulator and transmission channel has been created on their base. To implement the model of the receiving part of the telecommunication system, the one-dimensional convolutional neural network model proposed earlier by the authors was chosen. The proposed model was adapted to the GNU Radio environment and included in the receiving part as a separate information processing block. The procedure for inputting and outputting information in the model was improved for better interaction with other GNU Radio blocks. A hardware base supporting both GNU Radio and the TensorFlow library, which was used to form the neural network model, is proposed. The probability of correct acceptance of the symbol in the formed system is determined. A software-hardware implementation of the model of the receiving part of the telecommunications system is proposed, which is characterized by greater adaptability and flexibility compared to traditional AMMC signal receivers, which ensured an increase in the accuracy of receiving such signals.