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Modulation identification of communication signals is an important research subject incommunication signal processing, it is an important element of electronic countermeasures,and it is also a rapidly developing field of signal analysis. It’s widely used in confirmationsignaling, interference identification, Radio interception and Signal monitoring and softwaredefined radio, satellite communication, etc. The purpose of Automatic modulation recognitionis under the premise of unknown modulation information content to judge the modulation modeof communications signals, and estimate the corresponding modulation parameters. This paperproposes an improved FCM algorithm and improve the PCA algorithm, and conducted thecomparative experiments with the traditional FCM algorithm and PCA algorithm, the mainresearch results are as follows:(1)Simulation of digital signal2ASK,4ASK2FSK,4FSK2PSK,4PSK and analog signalsAM, FM, DSB, SSB, PM modulation way based on software(2)Based on the traditional FCM algorithm, combining with four common distance similardegree functions, the paper puts forward a Distance weighted FCM algorithm, and experimentsshow that the improved FCM algorithm of modulation mode has higher signal recognition rate.(3) The paper puts forward a identification algorithms combined with a PCA algorithmand the improvement FCM algorithm The first using PCA algorithm to screen the large numberof features of the signal, reduce the complexity of the calculation, and then based on theimproved FCM algorithm to recognize signal datas. Through the experiment shows that themethod in real-time and recognition rate is superior to the traditional of FCM, and it has certainvalidity and feasibility.
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