一种低复杂度GNSS信号快速捕获算法

A low complexity fast acquisition algorithm for GNSS signal

摘要:

为满足全球卫星导航系统(GNSS)接收机中高精度跟踪环路对捕获模块伪码相位搜索精度的需求,提出一种基于数据折叠的正交快速捕获算法．该算法对接收机输入离散采样信号进行压缩处理,将单个伪码周期内的长序列转变为两组较短的序列,并对每组序列与对应处理后的本地伪码序列进行基于FFT的快速相关运算,最终通过两组相关结果确定伪码偏移量．算法降低了快速捕获中所需的FFT点数,在保留伪码相位搜索精度的同时降低了捕获器的实现代价．分析及仿真结果表明,该算法能够在较小的检测概率下降的条件下,极大降低捕获模块的算法复杂度．

Abstract:

The acquisition block in the Global Navigation Satellite System (GNSS) receiver is used to provide initial pseudorandom code bias and carrier Doppler estimates of the received signal for the tracking loop. The demand of more accurate tracking loop requires higher resolution on the acquisition block. A variant of classical FFT-based fast acquisition algorithm is proposed, of which the idea is to compress the sequence of sampled signal to shorter sequences. The correlations of the compressed sequences with local replica are processed in parallel. Then the precise code bias is given according to the correlation results. Both analytical results and simulation results indicate that the proposed algorithm can dramatically reduce the computational payload of acquisition while suffering very limited loss in detection probability.