北斗系统三频载波相位整周模糊度快速解算

摘要

北斗导航定位系统播发三个频率观测值，有助于载波相位整周模糊度的快速、准确固定。传统的几何无关模型三频载波相位模糊度固定算法通常采用遍历整数搜索的方法确定载波相位－伪距组合系数，组合后的噪声因子较大，模糊度固定成功率不高。在分析了北斗系统伪距测量误差特性的基础上，给出了加权组合噪声因子的定义及其约束下的最优组合系数的求解方法。采用Hatch滤波提高电离层延时误差实时估计精度，成功固定三组线性无关组合系数对应整周模糊度，进而确定基础整周模糊度。利用北斗系统短基线、长基线实测数据对算法性能进行了验证，实验表明：提出的算法可优化超宽巷、宽巷组合噪声因子20％以上，模糊度固定成功率提高10％～18％左右，30s历元平滑后的基础模糊度固定成功率可达90％以上。%BeiDou navigation satellite system transmits triple-frequency signals which are benefit for the fast and accurate fixation of carrier phase integer ambiguity.Traditional TCAR (Three Carrier Ambiguity Resolution ) method based on geometry-free model finds the suitable combination coefficients of carrier phase and pseudo-range observations by using traversal integer search method,which makes the higher noise level and the lower success reliability.In the analysis of the error characteristics of the pseudo-range observations,the weighted combined noise level was defined and a new procedure within its constrains to select the optimal combination coefficients was introduced.With using Hatch filter to improve the real-time estimation accuracy of ionospheric delay,the integer ambiguity of three linearly independent combination coefficients was fixed successfully,thus the basic integer ambiguities were determined.Finally,the performances of the improved TCAR are showed both in short-baseline and long-baseline condition:compared with traditional TCAR method,the total noise level has decreased by 20%for extra-wide lane and wide lane;the fixation success rate of ambiguity has improved about 10%~18%;the success reliability of basic ambiguities has achieved 90%with 30 seconds epochs smoothing.