基于非相干积分时间调整的微弱GPS信号捕获

Weak GPS Signals AcquisitionBased on Incoherent Integration-time Adjustment

研究微弱GPS信号的捕获问题,由于实际接收信号存在多普勒现象,使信号减弱。针对传统方法快速傅立叶变换(FFT)不能有效捕获到GPS微弱信号,导致定位失败,为有效捕获微弱信号,提出了根据非相干积分时间调整的微弱GPS信号捕获算法。算法在FFT并行捕获的基础上,将相干积分的时间加长(批处理),同时对非相干积分做时间频率调整,从而既能提高整体信号强度,又能避免多普勒现象对捕获的影响。仿真结果表明,可以较好地避免多普勒现象引起的C/A码基码摄动,在处理的GPS数据为1s的情况下,能很好地捕获到信噪比低至16dB-Hz的GPS信号,为设计提供了可靠依据。

A signal acquisition problem for weak Global Positioning System（GPS） signal was studied.Aiming at the disadvantages that the weak GPS signal can not be acquisited efficiently by using the algorithm based on the Fast Fourier Transform（FFT） parallel acquisition algorithm and cause positioning failures,to.For acquire weak signal efficiently,a novel acquisition algorithm for weak GPS signals is proposed based on incoherent integration time adjustment.The algorithm consists of time growth of coherent integration（block processing） based on FFT parallel acquisition and adjusting incoherent integration time to improve overall signals strength.In the meantime,it avoids the effect of acquisition due to Doppler phenomenon.Simulations show the new method can effectively eliminate the effect of C/A code code-perturbation due to Doppler phenomenon,and a signal with carrier noise ratio（C/No） down to 16dB-Hz can be well acquired with the new method in the case of 1 second of data processing time,which provides a reliable foundation for the designs.