一种GPS微弱信号的优化捕获算法仿真分析  

Optimized Acquisition Algorithm of GPS Software Receiver under Weak Signal Environment

作　　者：崔绍龙[1,2] 姚相振[1,2] 方金云[1] 

机构地区：[1]中国科学院计算技术研究所,北京100190 [2]中国科学院研究生院,北京100049

出　　处：《系统仿真学报》2014年第1期112-118,共7页Journal of System Simulation

基　　金：国家863项目(2009AA12Z315)

摘　　要：针对如何提高GPS软件接收机中卫星信号捕获灵敏度的问题,提出一种优化的捕获算法--压缩树算法。在微弱信号的环境下,GPS信号捕获是非常重要的阶段,但是由于导航数据比特位的跳变,使得通过延长相干累积时间来提高捕获灵敏度的方法受到了限制。提出的压缩树捕获算法针对这一问题,根据卫星信号的特点,将其捕获过程抽象为树形结构,通过对导航数据比特的估计,压缩搜索树的高度,提高相干累积时间,同时根据C/A码的相关性进行有效的剪枝操作,有效的提高了捕获的效率和灵敏度。仿真结果表明,该方法在SNR=-41dB的情况下,依然有80%捕获成功率,使捕获的性能有很好的提升。Acquisition of very weak GPS signals requires long coherent and incoherent integration. Increasing the coherent integration time improves sensitivity, but it is limited because of the unknown data and bit edges. Incoherent integration is less sensitive, because of squaring loss. A compressed tree algorithm about acquisition of software GPS receiver was proposed under the weak signal environment. The algorithm used circular correlation （FFT/IFFT）, abstracted the acquisition as a traversal of tree and estimated the most likely data bit combination, so the process of acquisition discarded error paths and increased the coherent integration time. Thus, this approach was developed to improve acquisition sensitivity and decrease the computation in acquisition. Simulations indicate that in the condition that SNR equal -41dB, the new algorithm still has as high as 80% acquisition rate and enhances the performance of acquisition effectively under the weak signal environment.

关 键 词：GPS 软件接收机 微弱信号 捕获 压缩树 相干累积 

分 类 号：TN967.1[电子电信—信号与信息处理]