GPS软件接收机微弱信号捕获算法研究

Algorithm for weak signal acquisition in GPS software receiver

捕获是GPS接收机信号处理中的关键部分,在微弱信号情况下,传统方法不能很好地捕获到卫星信号。本文将介绍一种新型捕获方法——批式捕获法来取代传统的FFT相关搜索法,为高灵敏度GPS软件接收机提供理论依据。根据GPS信号的特征,利用软件模拟出各种信噪比数值的数据,分别采用以上2种方法对其进行捕获仿真。仿真结果表明,传统方法仅能捕获到信噪比低至42dB-Hz的信号;而批式捕获法能够在较短时间内捕获到信噪比低至29dB-Hz的微弱信号,并能有效避免由导航数据位翻转造成的误捕获。

Signal acquisition is the key phase of GPS signal processing. Sometimes,GPS signals are too weak to be received or processed by traditional methods. This paper presents the block acquisition method instead of the traditional methods,to address the problems of weak signal acquisition for high-sensitivity GPS receivers, Signals with different carrier noise ratios are sent into simulation. The results shows that the traditional method can only acquire the signals which carrier noise ratio is as low as 42 dB-Hz,while the block acquisition can acquire the signals which carrier noise ratio is as low as 29 dB-Hz in a short time. And it can solve the problem brought by navigation data signal transition during the correlation process.