A fast and highly accurate carrier acquisition for deep space applications

On-board carrier acquisition in deep space telecommunications depends on the residual carrier, to overcome the detection difficulty of low-level received signal. Nowadays, it becomes reality for the receiver itself acquiring Doppler frequency offset. Frequency acquisition based on fast Fourier transform (FFT) has been applied extensively. In this paper, we introduce an algorithm of refined estimation after FFT frequency coarse estimation, which is theoretically analyzed to be maximum likelihood (ML) estimation. Its accuracy can achieve 10⁻⁴ when the signal-to-noise ratio (SNR) is 5dB. By the aid of data, the estimator performs well at low SNR ranges. In the design of carrier acquisition, the accurate estimation of frequency offset aids the phase-locked loop (PLL) into locked state. If the acquisition bandwidth of PLL is fixed, accurate estimation value helps to decrease the FFT size. Due to simple implementation and good performance, the algorithm can be applied in burst communications.