微弱扩频信号捕获的积分时间延拓技术

摘要

For general spread-spectrum receiver,weak spread-spectrum signal acquisition needs more inte-gration time in order to obtain processing gain. However,PN code Doppler-shift,which leads energy not continuously accumulated onto a single code phase,may limit further increasing of integration time. A time prolonging technology for spread-spectrum signal acquisition is proposed. The technology adds an integra-tion time prolonging unit to search for the paths of integration time prolonging results,which effectively rela-xes the integration time restriction caused by code Doppler-shift. The results of simulation and real data show the proposed algorithm has a higher upper-limit of integration time than traditional acquisition algo-rithm. For in-band signal-to-noise ratio( SNR) is below -50 dB GPS L1 P code acquisition,when certain hardware resource restriction is given,acquisition probability of the proposed algorithm is superior to that of the traditional algorithm by 3 dB.%相对于普通扩频接收机，微弱扩频信号捕获需要更长的积分时间以获得处理增益。然而，伪码多普勒频偏导致能量不能在一个码相位上持续积累，限制了积分时间的进一步增加。为此，提出了一种扩频信号捕获时间延拓技术，增加了扩展积分单元，通过对扩展积分结果进行路径搜索，从而有效地减少了码多普勒引起的相位滑动对相关运算积分时间的限制。仿真和实测结果表明所提技术突破了传统全球导航卫星系统( GNSS)捕获算法的积分时间上限，提高了系统灵敏度。针对带内信噪比低于-50 dB的GPS L1 P码捕获，给定硬件资源约束和5 kHz多普勒范围，算法的捕获概率优于传统算法约3 dB。