The Research Of The Channal’s Blind Equalization And Modulation Classification Of Digital Signal

Military electronic countermeasure technology is the foundation to win theinformation warfare in the future. Modulation classification of communication signal is akey link to intercept the enemy’s useful message. The multi-path effect can seriouslyinterfere with the signal and induced to exert inter-symbol interference. The inter-symbolinterference can make heighten the degree of difficulty of modulation classification. Inthis paper the main research contents are blind equalization algorithms, modulationclassification of commonly used digital signals and high the recognizable rate ofmodulation classification under fading channel in the communication system.Firstly this paper introduces the equilibrium principle of CMA which is used widelyin the field of communication. Based on the algorithm, the paper makes some furtherimprovement and puts forward new modified blind equalization algorithm ofVS-UMMMA + DD-LMS algorithm, FSE-MCF algorithm, and FSE-VSDFE algorithm.The result of simulation shows that the equalization performance of the new blindequalization algorithms have been greatly improved.Secondly, this paper introduces the methods of modulation classification of signals ofMPSK, MFSK, MQAM, which include the methods of intra-class classification andinter-class classification. In this paper, the intra-class classification is fulfilled by gettingthe wavelet transformed signal’s amplitude’s variance; the inter-class classification ofMPSK is fulfilled by getting phase difference between adjoining symbols after wavelettransform; the inter-class classification of MFSK is fulfilled by getting frequencyinformation of symbols after wavelet transform; the inter-class classification of MQAM isfulfilled by sub-cluster. The result demonstrates that the methods can gain the highaccurate discrimination.Finally, this paper deals with the capability of modulation classification method underthe influences of fading channel. In view of the characteristic of fading channel, we takesuitable blind equalization firstly, and then take intra-class classification and inter-classclassification of modulation signal. Treated so as to achieve comparatively high correction identification ratio.