位长截取及抽取对捕获性能影响分析

Analysis of Intercept Word-length and Resample Effect on C/A Code Acquisition Performance

为设计军民兼容的GPS接收机,针对卫星信号负的信噪比,采用截取中频卫星信号,只保留3位有效字长的方法(也即3 b的量化)。由于民码带宽较窄,需对数据进行滤波抽取及位长截取以节约硬件资源,着重分析了有效字长截取和滤波抽取对捕获性能的影响,给出了影响较小的实现方法。仿真表明分析基本可靠,并在牺牲一定信噪比的情况下减少了运算量,获得较快的捕获速度。

For military and civil compatible GPS receiver, the method of intercepting IF signal and holding 3bit valid word- length is applied, which based on minus SNR, the filters, resample and word - length - interception are designed for saving limited hardware resource. The influence on acquisition is analyzed and discussed. The valid method of realization is presented. The simulation results indicate that the method is correct and useful for rapid acquisition at the expensive of little SNR.