Research On The Automatic Recognition And Demodulation Algorithm Of MPSK/QAM

Since the concept of software radio and virtual radio systems have been put forward,as one of the important technology of software radio, full digital demodulation has gained more and more attraction in the field of communications technology. Depending upon the great capacity and formidable handling ability, virtual radio makes the system more flexible, so research on the automatic identification and demodulation algorithm becomes particularly important in virtual radio systems.A system of modulation recognition and demodulation is provided, based on analyzing the basic theory. Firstly, the ratio of the variance of the envelope to the square of the mean of the envelope, amplitude statistical and signal power spectrum of the second are combined to recognize MPSK and MQAM analyses. Then, the carrier recovery algorithm for different signal is designed, and timing recovery algorithm using interpolation to realize all-digital signal demodulation is introduced. Finally, the whole system is simulated by MATLAB. When SNR is more than 8dB, BPSK, QPSK, 16QAM and 64QAM are identified correctly more than 90%. When the SNR is 15dB, the identifications are 100%. The bit error rate performance for uncoded BPSK, QPSK, 16QAM and 64QAM are shown. The results of the simulation prove the advantages of the algorithm.