微弱北斗信号捕获算法优化

An Modified Weak BDS Signal Acquisition Algorithm

恶劣环境中北斗卫星信号强度往往低于-133 d BW,针对北斗卫星信号中相干积分的时间受二次编码符号组合的限制问题,提出一种新的串并结合的算法,首先在一个周期的主码上进行串行搜索得到主码相位,而后在整周期二次编码上并行搜索确定二次编码的相位和多普勒频偏,达到延长相干积分时间实现微弱北斗信号捕获的目的,仿真证明在设定捕获阈值4 d B时算法仍能够捕获-150 d Bm的信号。

The Beidou satellite signal strength is often less than-133 dBW under the weak environment,the coher-ent integration time are limited only in a period of primary code. A new algorithm which is based on combining seri-al and parallel search was presented to extended the coherent integration time so as to achieve acquisition of the weak Compass signal. Firstly,obtain the code phrase of the primary code by serial search within a period of PRN code,and then get the secondary code phase and Doppler shift by parallel search on the entire secondary code , thereby extending the coherent integration time to achieve weak Compass signal acquisition,simulation shows that the algorithm could be able to achieve accurate acquisition even the strength of the signal as low as-150 dBm.