GPS载波跟踪环设计

GPS carrier tracking loop design

本文实现了一种基于科斯塔回路(Costa)的GPS载波跟踪环硬件设计。该设计首先采用数字混频器使中频信号与GPS本地数字频率合成器产成的同相和正交信号进行混频,然后经过低通滤波器滤除高频分量,再通过基于CORDIC算法的反正切电路计算出频率偏差。最后用频率偏差去修正本地数字频率合成器的输出频率,以达到消除多普勒频移,跟踪载波频率相位的目的。文中详细介绍了各个模块的设计思路以及实现,并进行了仿真。仿真结果表明,该设计具有良好的实时性和精确度。

This paper implemented a design of GPS carrier tracking loop based on Costa algorithm. This design first mixed intermediary frequency and local I＆Q by mixer, then filter high frequency using LPF, compute instant phase and frequency error using CORDIC module and fix the frequency output of NCO. Eliminate the Doppler frequency effect and tracking the frequency of GPS. In the paper, the outline of the design and realization are described in detail and process simulation. The results of simulation indicate that this design has advantages of real-time performance and precision.