摘要：Under high dynamic and weak signal environment in the satellite Tracking, Telemetry and Command (TT&C) systems, the carrier acquisition and tracking can't be easily achieved. In this paper, an improved two-stage high dynamic and weak signal carrier acquisition and tracking are presented for perfect carrier synchronization. The typical U.S. Jet Propulsion Laboratory (JPL) high dynamic carrier model is adopted here to develop the proposed carrier acquisition and tracking performance. In the first stage, the fast Fourier transformation (FFT) based cyclic shifting accumulation periodogram carrier acquisition method is proposed to obtain the coarse carrier frequency offsets as well as the Doppler rate efficiently and quickly. In this procedure, the replacement of the time domain multiplication with the frequency domain cyclic shifting is proposed for low complexity. Also a variable rate sampling is adopted for better accuracy of FFT carrier spectrum calculation. In the second stage, a second-order Frequency Locked Loop (FLL) assisted by a third-order phase locked loop (PLL) is proposed to correct the residual carrier frequency and phase offsets and achieve a much fine carrier recovery. In these two stages, the structure of the proposed algorithm is also analyzed for optimal synchronization parameter selection. The simulation results show that the proposed carrier acquisition and tracking method performs efficiently under a high dynamic and low Signal-to-Noise Rate (SNR) environment for the satellite transmission applications. Therefore, the proposed carrier synchronization method is quite pragmatic and it can be effectively applied in the high dynamic and low SNR satellite communications with high efficiency and low complexity.
