低载噪比GPS信号载波跟踪环路滤波算法

摘要

Suppressing jitter noises in a phase locked loop (PLL) is of great importance in order to keep the precise and continuous tracking of global positioning system (GPS) signals characterized by low carrier-to-noise ratio (C/N0). In this article, a PLL model based on Kalman filter theory is designed to process weak carrier signals in GPS software receivers. By correlating the model error noises and the measurement noises, this PLL model is in a position to make correct estimation of the carrier phase differences and Doppler shifts with less overshoots and noise disturbances, and to keep an effective track of PLL for GPS signal. Finally, the feasibility of this Kalman filter based PLL is verified by the simulation experiment.%抑制锁相环(PLL)中的抖动噪声对于连续精确跟踪低载噪比GPS信号具有重要意义。本文设计了一种基于Kalman滤波理论的PLL模型用于处理GPS软件接收机中的弱载波信号。该模型通过去相关模型误差噪声和测量噪声，使PLL具有更小的过冲和噪声干扰的载波相位差和多普勒频移的正确估计，保持了 PLL 对 GPS 信号的有效跟踪。最后，通过仿真实验说明了基于Kalman滤波器的PLL的可行性。