Joint Carrier Synchronization Algorithm by Open-Loop Acquisition and Closed-Loop Tracking in High-Dynamic Environments

高动态环境下联合开环捕获和闭环跟踪的载波同步算法

¹ No. 20 Research Institute of CETC, Xi'an 710068, China
² Xi'an University of Posts & Telecommunications, Xi'an 710100, China
³ Xidian University, Xi'an 710071, China

Received: 8 December 2017

Abstract

Considering the difficulty of carrier synchronization and the low tracking accuracy in high-dynamic environments, the joint open-loop acquisition and closed-loop tracking carrier synchronization algorithm is presented. Firstly, the algorithm derives the coarse estimation of Doppler frequency and Doppler rate via open-loop acquisition, then the residual Doppler frequency and Doppler rate are confined into a small range. Secondly, the residual Doppler rate is tracked by using a third-order phase-locked loop(PLL). The present algorithm has the advantages of fast acquisition and high tracking accuracy. Finally, the numerical simulation is conducted to verify the present synchronization algorithm. The simulation results indicate that at the signal to noise ratio(SNR) of and normalized Doppler frequency and Doppler rate ranging from to, the bit-error-rate(BER) performance degradation is as low as comparing with theoretical value.

摘要

针对高动态环境下载波同步困难和跟踪精度低的问题，提出联合开环捕获与闭环跟踪的高动态载波同步算法。首先，该算法通过开环捕获得到多普勒频率偏移及多普勒变化率偏移的粗估计，将剩余多普勒频率偏移和变化率偏移控制在一个较小的范围内。其次，在载波跟踪阶段采用三阶锁相环（PLL）对剩余多普勒频率偏移和变化率偏移进行跟踪。提出的算法同时具有快速捕获与精确跟踪的良好特性。最后，通过Matlab仿真对同步算法进行验证。仿真结果表明，当信噪比为8 dB，归一化多普勒频率偏移和多普勒变化率偏移分别在（-0.25，0.25）和（-10^-4，10^-4）范围内时，该算法的误码率相比理论值仅损失0.7 dB。