一种GPS软件接收机自适应门限快速捕获算法

当前GPS接收机的搜索策略是基于C/A码相位和载波频率的串行搜索．基于二维串行搜索，本文推导了不同累加次数下捕获到信号的概率密度函数和未捕获到信号的概率密度函数，提出一种新颖的自适应门限捕获算法．该算法能根据接收卫星信号功率的不同自动地调整门限，同时保证误捕率恒定．相对于传统的固定门限的捕获算法，该算法捕获速度更快，从而减小了首次定位时间．

An Adaptive Threshold Algorithm of Fast Acquisition for Software GPS Receivers

Current GPS receiver search strategies are based on the sequential search of the C/A code phase and carrier frequency. Based on the two-dimensional sequential search, the probability density functions of detecting signal and undetecting signal are deduced with different numbers of accumulation. A novel acquisition algorithm using adaptive threshold is presented, which can automatically change the threshold according to different satellite signal power and keep the probability of false acquisition invariable. This algorithm is faster than the traditional algorithm using fixed threshold, thus the time to the first fix is reduced.