城区环境下鲁棒定位算法

在城区环境下,不依赖于辅助的手段,获得定位结果面临两大困难.由于信号非常微弱,接收机不能获得伪距等观测量导致无法得到定位解.接收机即使通过弱信号处理等增强措施,获得伪距等观测量,但是由于观测量误差较大,依然不能获得满足要求的定位结果.本文主要针对以上两个问题,提出了各自的解决方案：常规接收机需要完整跟踪4颗或者以上的卫星才能获得定位结果.在城区环境下很难有4颗以上的卫星同时满足要求,因而无法实现定位.本文提出了一种新的方法来解决该问题.只要接收机进入到跟踪模式,即获得1ms以内的观测量即可实现定位.通过延长相干积分的方式,即使信号功率电平在解调门限以下,只要接收机能够跟踪信号,就可以获得定位结果.针对城区环境下多径现象引入的测距误差,导致定位结果偏差较大,本文利用故障诊断的原理,对获得的伪距观测量进行非线性加权处理来改善定位精度.为了验证该算法,采用实际采集的数据来进行验证.

Robust positioning algorithms in dense urban

There are two difficulties to obtain positioning results in dense urban without auxiliary means.Due to the signal is very weak,receiver can＇t obtain positioning results because pseudo-ranges are unavailable.Though the receiver can obtain pseudo-range observations through some senior weak signal processing algorithms,the receiver still can＇t achieve the required positioning results.This paper is mainly aiming at the above two problems,and proposed a two-solutions to resolve them.Solutions are as follow：the conventional receiver needs to get 4 or more satellites measurements to give a positioning result,but four satellites measurements is difficult to obtain in dense urban.This paper proposes a solution that as long as the receiver enters into the tracking mode,namely 1 millisecond measurement can be obtained,this receiver can give the positioning results.If the quality of measurements in dense urban is poor,the positioning results become the worse than in the open sky.This paper proposes another solution that using the fault diagnosis principle to improve the position result.The bad measurements can be processed through the non-linear weighting method.In order to verify the efficiency of the above algorithms,the paper processes the actual data.