基于均值法的P码直接捕获改进算法

An Improved P Code Direct Acquisition Algorithm Based on Average Method

为确保GPS在C/A码信号受到干扰时仍然可用,必须进行P码的直接捕获。研究了循环相关的性质,针对均值法提出了一种改进的P码捕获算法。改进算法对输入信号不补零,通过比较捕获统计量大小选择合适的本地P码与接收信号进行循环相关。分析了改进算法与均值法的捕获概率与捕获统计量。仿真实验表明,在低载噪比时,改进算法相比于均值法捕获概率增加较多;在高载噪比时,改进算法捕获概率仍高于均值法。

In order to insure usability of GPS when C/A code is jammed,it is essential to acquire P code directly. The property of circular correlation was researched and an improved P code acquisition algorithm in view of the average method was proposed. The improved method does not need zero padding. It selects the appropriate P code by comparing the size of acquisition statistic,which is associated with the received signal. Acquisition probability,and acquisition statistic of the improved method and the average method were analyzed. The simulations demonstrate that acquisition probability of the improved method is much higher than the average method when carrier-to-noise ratio is low. Besides,acquisition probability of the improved method is still higher than average method when carrier-to-noise ratio is high.