| The automatic identification of the modulation types has been applied to many fields such as source identification, interference identification, radio interception, electronic countermeasures, etc. In this paper, we introduce the modulation types and the orthogonal algorithm, then introduce the Hilbert transformation analyze with in time and phase domain, which is the base of the following works. This paper has carried on the discussion from three respects: First of all, proceed from method based on decision theory, studying automatic analogue modulation recognition, automatic digital modulation recognition and automatic union modulation recognition of analogue and digital of modulated signals . The method of modulation recognition can discern many kinds of analogue and digital modulated signals such as AM ,FM , USB , LSB , VSB , DSB , AM-FM , 2ASK , 4ASK , 2FSK , 4FSK , 2PSK , 4PSK ,etc.. With high research in the automatic identification with the symmetry of frequency domain, we offer four character parameter(P, B, S, U) to recognize the asymmetry signal such as AM,DSB-SC,LSB,USB. With the simulation of the computer, it can be recognized in good result. Secondly, from set out on the basis of method that parameter statistics, we study analogue and digital signals'automatic modulation recognition. And present some key features parameters(K,C,R,G a,G f) to recognize PM,FM,AM,DSB,ASK,FSK,PSK,QAM signal. According to the simulation of the computer, we can get good recognition result. With studying communicational signals'automatic modulation recognition base on decision theory and parameter statistics, we should be paid attention to some questions such as choosing the sampling rate, calculating the instantaneous frequency, estimating the carrier frequency and deciding the level of the characteristic parameter etc, the paper has done the detailed argumentation and proposed better solution too. Finally, proceed from form based on constellation picture of the signal, resume rebuilding the constellation picture to the signal that is received. We change the way of modulation recognition to the shape match of constellation of picture. We mainly introduce how to resume the constellation picture of the received signal, on this basis, carry on cluster's analysis to the constellation picture resuming, on cluster, have introduced the mountain peak cluster and subtraction cluster emphatically, then proposed the concrete algorithm of the constellation picture modulation recognition, finally, with simulation of the communication signals'modulation recognition .the simulation result indicates that the algorithm is feasible... |
