基于小波处理的P码直捕及实现研究

相对于C/A码,GPS的P码信号不仅定位精度高,且具有很强的抗干扰和保密能力。由于P码信号具有多普勒频移大、码周期长以及码速率高等特点,给P码的直接捕获带来了很大的技术难度。提出了采用小波滤波进行辅助捕获的捕获策略。在辅助捕获阶段,通过小波处理,减低需处理数据的数据率,从而提高了搜索速度,经二维搜索估计出接收P码信号的相对时延和多普勒频率等先验信息。利用该先验信息指导同步跟踪电路对接收信号进行捕获、跟踪与同步,从而达到提高捕获速度、降低硬件资源消耗的目的。仿真结果证明了该辅助捕获策略的正确性。

Research for direct P-code acquisition based on wavelet filtering

Compared with the C/A-Code,GPS P-Code offers not only much higher accuracy but also the higher tolerance to jamming and spoofing.It has large Doppler frequency shift,long code period and high code rate.According to these characters,a new scheme for direct P-Code acquisition using auxiliary acquisition is proposed,which estimates the phase and Doppler of the received P-Code signal in the two dimensional search.In order to finish the auxiliary acquisition rapidly,the wavelet is used to decrease the quantity of data.True phase alignment is detected using a conventional parallel search scheme,where the initial phase and Doppler are set to the values obtained by the auxiliary acquisition and whose amount of parallel channels is required less.The computer simulation shows the proposed scheme can achieve the priori information of phase and Doppler faster and correctly.