Study And Implementation Of Modulation Recognition For Non-Cooperative Communication Signals

Modulation recognition is a key technology between signal detection and signal demodulation,whose main task is to identify the modulation mode,so as to realize the intelligent modulation signal receiving and processing,it has important significance for signal demodulation in communication system,information extraction and signal detection,especially in the field of non-cooperative communication has very important research value.On the basis of analyzing and summarizing the research results and the latest research progress at home and abroad,the paper has carried on the quite thorough research,in view of the low recognition rate of the current modulation recognition algorithm at low SNR,and has completed the modulation recognition algorithm FPGA realization.The main research of this paper include the following aspects:Firstly,this paper introduces the research background and research status at home and abroad of the communication signal automatic modulation recognition technology,the simulation and analysis of the modulated signal spectrum and constellation is used to verify the correctness of the modulation principle,this paper focuses on the algorithm for high order cumulant and wavelet transform theory,and introduces the application of the theory in modulation recognition technology.Secondly,the study of digital signal modulation recognition algorithm based on instantaneous information,according to the four characteristic parameters of instantaneous information extraction,the discrimination process of seven kinds of digital modulation signals to be identified is designed based on decision tree classifier.The performance of the algorithm is analyzed by simulation.The simulation results show that when the SNR is greater than 13 dB,the correct recognition rate can reach more than 98%.Because all kinds of instantaneous information are greatly affected by noise,this method requires higher SNR,it is more suitable for the higher SNR and low complexity of the algorithm,In the condition of low SNR,the recognition performance is not satisfactoryThirdly,in order to solve the problem of low recognition rate in low SNR,a hybrid modulation recognition algorithm based on high order cumulant and wavelet transform is proposed.The algorithm uses two parameters based on wavelet transform,and constructs a new feature parameter based on the four order and six order cumulant,and the back propagation neural network classifier is used to identify the modulation signal.The simulation results show that the proposed algorithm can achieve a recognition rate of more than 98% when the signal to noise ratio is lower than 2dB,which proves the effectiveness and robustness of the proposed method.Finally,the paper studies the FPGA implementation of modulation recognition algorithm based on instantaneous information.After the introduction of the hardware and software platform,this paper studies the realization principle,implementation steps.Finally,the identification results of the project are analyzed to prove the correctness of the whole project.