传统的GNSS接收机只跟踪一路信号,它是直达和多径成分的合成信号,利用该信号进行定位运算必然会产生多径误差.本文提出了一种用于GNSS接收机的抗多径新技术,它基于改进的Rake模型,将合成信号中的直达和多径成分分离,并对它们分别保持跟踪,在跟踪直达信号的指峰(Finger)中,将其他指峰所跟踪的多径成分从合成信号中减去,从而减小多径误差.文章介绍了改进的Rake模型的原理,通过仿真验证了该模型的功能,将其在基于FPGA的GPS接收机中实现.测试结果表明,存在多径信号的情况下,使用该技术能够提高接收机的定位精度.

Traditional GNSS (Global Navigation Satellite System) receiver tracks only one signal,which is the composite of direct path and multipath components.Multipath error can be generated if the signal is used for navigation processing.This paper presents a new anti-multipath technique for GNSS receiver.It is based on MRake (Modified Rake) model that separate the direct path and multipath components,and keep tracking with them.In the Finger that track direct path component,multipath components tracked by other Fingers are subtracted from the composite signal,so multipath error can be reduced.MRake model's principle is introduced,and then its function is verified by simulation.It is implemented in an FPGA based GPS receiver,and test results show that receiver using the new technique can improve its positioning accuracy in presence of multipath propagation.