关键词: 深空测控通信, 多普勒频移, 高精度估计, 大频率动态, 极低信噪比, 快速傅里叶变换

Abstract: A high-accuracy estimation algorithm for fast changing Doppler frequency shift based on forecast information rough compensation and multi-stage accurate correction is proposed in deep space TT&C(Tracking Telemetry and Command) communication systems, Which overcomes the difficulty that the traditional algorithm has poor frequency estimation accuracy and low receiver sensitivity for deep space ultra-long distance TT&C signal with large-range frequency dynamic and extremely low Signal Noise Ratio(SNR). The carrier frequency of deep space TT&C signal is roughly compensated based on spacecraft orbit forecast information to compress the search scope of Doppler frequency shift. In order to cancel the frequency dynamic change, the process structure of multi-stage frequency correction is employed to accurately correct the Doppler frequency shift, first-order frequency rate and second-order frequency rate of deep space TT&C signal. The combined method with peak calculation and time-frequency correction is applied to accurately estimate fast changing Doppler frequency shift. The experiments and analysis verify that the proposed algorithm can achieve the frequency estimation precision up to 0.1Hz and the receiver sensitivity low to -160.4dBm for deep space ultra-long distance TT&C signal with large-range frequency dynamic and extremely low SNR, and significantly improve the frequency estimation precision and the receiver sensitivity in deep space TT&C communication systems. 

Key words: deep space TT&, C communication；Doppler frequency shift；high-accuracy estimation；large-range frequency dynamic；extremely low SNR；fast Fourier transform(FFT)