Recognition Of Digital Modulation Signals Based On High Order Accumulation And Spectral Analysis

With the rapid development of communication technology,The modulation style of the digital communication signal becomes more diverse.The modulation recognition of the communication signals plays an increasingly important role in both civilian and military aspects.Modulation recognition has become a hot research topic in the field of signal processing.Its main task is to extract the appropriate characteristic parameters of the unknown signal,and then determines the modulation type according these parameters.It provides a basis for the processing and analysis of the signal.In this paper,the modulation recognition of digital communication signals in complex noise environment is studied mainly.The contents and major contribution of the paper are listed as follow.1.This paper introduces the basic principles,mathematical expression and key technologies of common modulation signal,which provides a theoretical basis for the subsequent identification of the digital modulation signals.2.The modulation recognition of signal in Gauss white noise environment is studied.Firstly,in order to solve the problems that the existing methods of modulation recognition based on higher order accumulation has a low number of recognition signals and poor performance of anti noise,a new modulation recognition method based on the eight-order accumulation and the square spectrum is proposed.Four characteristic parameters are constructed by using the four-order,eight-order accumulation of the signal and the spectrum characteristic of the square spectrum.4ASK?2PSK?QPSK?OQPSK?8PSK??/4-QPSK?2FSK?4FSK?8FSK?8QAM?16QAM?32QAM signals are identified by these characteristic parameters.Compared with the same kind methods in the literature in the same conditions.The results show that the proposed method can achieve the recognition rate of above 90% when the SNR is 4dB,and it is superior to the methods in the literature [43] and literature [45] in the aspects of the number of signals,anti-noise performance and recognition rate.3.This paper studies the modulation recognition of signal in non Gauss white noise environment.Modulation recognition technology based on signal cyclic spectrum is studied in Alpha noise environment mainly.Firstly,the meaning and characteristics of Alpha noise are introduced.In order to solve the problems that the existing methods has a poor performance in low mixed SNR and high complexity,a new method for modulation recognition based on cyclic spectral line characteristics in Alpha noise environment is proposed.Four characteristic parameters areconstructed by analyzing the characteristic of the cyclic spectrum of the pre processed signal.The recognition of 2PSK,QPSK,2FSK,4FSKand MSK signals is realized.Compared with the same kind of methods in the literature in the same conditions,the results show that the proposed method can achieve the recognition rate of 100% when the mixed SNR is 3dB,and it is superior to the methods in the literature [55] and literature [56] in the aspects of anti-noise performance and recognition rate.