基于UofC模型的多系统组合PPP解算性能分析

针对GNSS多系统组合进行PPP定位的问题，推导了基于UofC模型的多系统组合PPP的函数模型和随机模型。最后采用IGS观测站30 d的部分观测数据对不同组合模式的PPP进行了解算。试验分析结果表明：GNSS多系统组合PPP收敛时间与GPS单系统相比可以缩短30%~50%。对于定位精度，在观测时长较短时（如0.5 h），GNSS多系统组合PPP整体上具有较优的定位精度，N、E方向偏差和标准差分别为0.3、0.5 cm和1.9、4.3 cm，短时间内由于对流层参数与垂直方向的强相关性，使得U方向精度稍差。此外，在卫星高度截止角大于40°的条件下，单系统可见卫星数不足从而导致无法进行连续定位，但多系统组合具有更多的可视卫星，仍能获得较好的定位精度，使其在建筑物密集区、山区和卫星遮挡较为严重的恶劣条件下具有实际应用价值。

The Multi-system Combination PPP Computational Performance Analysis Based on the UofC Model

In view of the GNSS system combination for the PPP positioning problem,we deduced the function model and stochastic model of the multi-system combination PPP based on the UofC model,and calculated different combination mode of PPP by using part of the data observed from IGS stations 30 d.The experimental analysis results showed that the GNSS multi-system combination PPP could shorten the convergence time by 30%~50% compared with the GPS system. For positioning accuracy,when the observation time was relatively short (e.g.,0.5 h),the GNSS multi-system combination PPP had better performance,(N,E) direction deviation and standard deviation could reach(0.3,0.3)cm(1.9,4.3)cm respectively,but in a short period of time,U direction accuracy was a bit poor because of the strong correlation of the troposphere parameters and the vertical direction. In addition,under the condition of the satellite altitude cut-off Angle was greater than 40°,single number visible satellite system deficiency leading to continuous cannot locate,but the combined system could still get a good positioning accuracy because it had more visible satellites,which had practical application value in the building concentration areas,mountains and the area where the satellite was seriously blocked.