A QPSK Carrier Estimation Method Based on Modified FFT

In this paper, an improved carrier estimation method used in coherent demodulation of MPSK signal is proposed, which is based on zoom FFT and frequency domain interpolation. The carrier is estimated approximately in time-frequency field through nonlinear transformation and zoom FFT, then it is distilled accurately by intervene in frequency domain. Simulation results show that the algorithm has a higher accuracy, and it is estimated that the maximal relative estimation variance is denoted by 10^-6. This method does not require a specific pattern of pre-character and has a more simple structure. It is proved that the carrier can be estimated adaptively within a larger frequency range and real-time hardware can be easily realized at high SNR circumstances.