基于PLL环路的卫星QPSK载波调制信号相位跟踪算法

卫星信号接收端天线接收的卫星信号经过射频前端处理后会变成数字中频信号，而相位跟踪是中频信号处理的重要环节，准确的相位跟踪可以为卫星信号解码、测距和定位等功能的准确性提供保障.基于此，该文提出了基于锁相环（Phase Locked Loop，PLL）的卫星QPSK载波调制信号相位跟踪算法.该算法利用多路正交载波和二象反正切鉴相器获取精确的相位差信息，形成闭合回路锁定载波相位以实现跟踪.实验结果表明，多路异相载波的方法可实现更快速的相位锁定，与传统Costas环路和松尾环相比，进入稳态时间分别减少了20%和24%以上，稳态方差分别减小21%和32%.

PLL Based Phase Tracking Algorithm for QPSK Modulated Satellite Carrier

The received satellite signal will be converted into digital Intermediate Frequency (IF) signal after the radio frequency front-end processing.As one of the crucial parts in IF signal processing,the accurate phase tracking can ensure the precise satellite signal decoding,distance ranging,and positioning.Based on this,this paper proposes a Phase Locked Loop (PLL) based phase tracking algorithm for QPSK modulated satellite signals.Specifically,the algorithm uses multiple orthogonal carriers and arc-tangent based phase detector to obtain accurate phase difference information,which finally forms a closed loop to lock the carrier phase for the tracking.Experimental results show that the multiple heterogeneous carrier is able to achieve fast phase locking.In addition,compared with the conventional Costas loop and Matsuo loop,the time cost for reaching steady state of our system is reduced by 20% and 24%,while the corresponding steady-state variance is reduced by 21% and 32% respectively.