Abstract:The data-aimed (DA) Signal-to-Noise Ratio (SNR) estimation algorithm, Decision-Directed (DD) SNR estimation algorithm and a new blind SNR estimation algorithm for MPSK signals are presented in this paper with maximum-likelihood principle. The detail performance analysis, computer simulation and performance comparing with other SNR estimation algorithms are completed. The analysis and simulation results show that the DA algorithm has a perfect performance and as good as the performance lower bounds. The performance of DD algorithm depends directly on the accuracy of decision, so it is good when the SNR is high. But when the SNR is low and, especially, less than OdB, the estimation has relatively great bias. The new blind SNR estimation algorithm has broad estimation range, good performance and low computational complexity for M=2 (BPSK), but the performance degrades while Mis increasing.