A modified carrier frequency estimation method based on self-correlation for QPSK signal

QPSK (Quaternary Phase Shift Key) signal is a carrier frequency restrained modulation signal. In this paper, a novel estimation method based on self-correlation for QPSK signal is proposed. At first, self-correlation biquadratic QPSK signal is analyzed, and then its carrier frequency is estimated with M-Rife (Modified Rife) algorithm instead of estimating frequency only by max frequency line position. The simulation results indicate that our carrier frequency estimation method is feasible and more accurate than the former method, and the RMSE (Root of Mean Square Error) of the modified method is close to CRLB (Cramer-Rao Lower Bound).