恒虚警GPS信号自适应捕获研究

Study on GPS Signal Adaptive Acquisition Based on Constant False Alarm Rate

在GPS信号衰减的环境下,针对信号强度和噪声水平都发生改变的情况,本文提出了将自适应结构应用于GPS接收机.相对于传统的自适应结构而言,本文针对GPS信号的特点,提出了新的GPS信号中噪声水平的估计方法.同时,与GPS接收机不同,传统的自适应结构中对多普勒频移有欠考虑.本文将自适应结构应用于GPS接收机的同时,考虑了可能发生较大多普勒频移的情况,并且提出了相应的解决方法.最后,通过仿真验证了本文提出方法的有效性.

When acquiring GPS signal,signal strength and noise level is time varying in the environments,indoor,in urban street or in the woods.In the challenging environments,adaptive scheme is considered to be employed in GPS receiver design in this paper.Derived from conventional adaptive structure,a novel method of noise level estimation is proposed which fully considers the characteristic of GPS signal.Furthermore,possible large Doppler shift is seldom considered in existing adaptive structure.Aiming at the possible Doppler shift,a solution based on partial correlation is proposed.In the final part of this paper,simulation is carried out to test this novel structure.The experimental results of the proposed method demonstrate more stable acquisition performance than conventional ones.