基于小波变换的单频GPS快速精密定位整周模糊度的解算

对于GPS短基线,载波相位双差观测量已基本消除了卫星轨道误差、钟差、大气折射误差等系统偏差的影响,主要包含距离观测量信息及随机测量误差,其中测量误差是高频的测量噪声,小波变换可将GPS载波相位双差观测量中的观测噪声(高频部分)分解出来。本文利用Coiflets小波基函数对GPS快速定位的原始载波相位双差观测量进行5层分解,通过重构第5层低频系数获得去除噪声的"干净"的载波相位双差观测量,然后利用"干净"的双差观测量进行最小二乘参数估计,以减小测量噪声对GPS快速定位病态方程解的扰动。计算结果表明该方法能够显著提高GPS快速定位中模糊度浮点解的精度,仅利用几个观测历元的数据就可以准确地固定模糊度。

Ambiguity solution of GPS rapid precise positioning based on Wavelet transform

For GPS short baseline,double-differenced carrier measurements mainly include distance information and observation error,the latter is high frequency observation noise,because most of systematic biases are eliminated,such as orbit biases,atmospheric biases,receiver and satellite clock biases,and so on.The wavelet transform can be used to achieve enough frequency resolution to discriminate observation noise in the original double-differenced carrier measurements.In this paper,GPS double-differenced carrier measurements are decomposed and recomposed using Coiflets wavelet base by 5 scaling function,and the high-frequency noise is removed.Then the de-noised double-differenced measurements are used to estimate unknown parameters to reduce the effect of measurement noise on the solution of ill-conditioned equations.Examples shows that the method can greatly improve the precision of float solution of ambiguity in GPS rapid positioning,which can fixed ambiguities successfully only by a few epochs' observations.