基于相位折叠的串行GPS L2C快速捕获算法

Fast Serial Acquisition Algorithm of GPS L2C Based on Phase-Fold Method

GPS L2C信号是GPS现代化后的一个新的民用信号,目前已经有9颗在轨的Block IIR-M向地面提供信号。L2C主要由CM码和CL码通过时分复用产生,与传统的C/A码有很大不同,20ms的CM码和1.5s的CL码周期时间,给捕获带来困难,传统的一些针对C/A码的快捕算法,已经无法直接用在L2C上。从分别频域和码域着手,采用一种相位折叠的快速CL码捕获算法,在保证灵敏度尽可能损失小的前提下,大大提高了捕获速度。

GPS L2C signal is a new kind of GPS modernized civil signal. There are nine in - orbit Block IIR - M Satellites providing such signals to the ground. L2C is produced mainly by Time Division Multiplexing method with two codes, CM code and CL code, which is extremely different from the conventional C/A code. The cycle time of CM code lasts as long as 20ms, while the time for L code is 1.5s, which is not applicable for C/A code fast acquisi- tion algorithm. In this article, beginning from the frequency domain and code domain respectively, we put forward a phase folded quick CL code acquisition algorithm. The simulation proves a great acceleration on the capture speed, at the same time, guarantees a small loss of asensitivity as much as possible.