Abstract:

A frequency estimation algorithm for the deep space telemetry, tracking and control (TT&C) system under low Carrier\|Noise Ratio (CNR) and high dynamic conditions is presented in this paper. Considering the drawbacks of the exist algorithms, an advanced closed loop carrier tracking algorithm based on the unscented Kalman filter (UKF) is proposed. This new algorithm combines the advantages of the discriminator of the frequency lock loop and UKF to obtain a wide estimation range, high estimation accuracy and low CNR threshold. In addition, it is found on the basis of the analysis of the two kinds of models that this new algorithm cost much less computational effort than the conventional UKF. The high dynamic trace of receiver is simulated in this paper. The results show that the proposed loop structure can apparently improve dynamic capability, convergence performance and tracking accuracy, thus effectively completing the task of frequency estimation under low CNR and high dynamic conditions. Compared with the frequency estimation algorithm based on extended Kalman filter (EKF), this new algorithm has a much smaller frequency estimation error so that it will have prospective application potential.

Key words: Deep space TT&, C；Frequency estimation；Low CNR；High dynamic；Unscented Kalman filter