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In non-cooperative communication, symbol rate estimation is an important basis for blind estimation and blind demodulation of digital signals. The traditional symbol rate estimation methods, such as the cyclic correlation method and the envelope spectrum method, show a dramatic decline of performance in low SNR. To solve this problem, a method based on wavelet transform is studied, and the optimal range of its best wavelet function and flex factor is deduced. Theoretical analysis and simulation experiments show that the proposed algorithm has many advantages, such as low data demand, high estimation accuracy, and so on. It has good robustness and universality in low SNR environment.

A new accurate estimation algorithm of frequency and phase suited for low signal-noise ratio (SNR) environment is proposed here. Coarse estimation of frequency and phase is acquired from the peak frequency of the received signal. New interpolation technique and modified formula are made to get fine and unbiased estimation. Simulations indicate that, accurate results close to the Cramer-Rao bound (CRB) within a wide frequency offset range are achieved by using this algorithm.