在GPS网络差分定位技术中,用户站与参考站间的高程差异会引起对流层误差改正数中存在系统性偏差,造成对流层改正精度降低,影响用户定位的效果.在常规两维线性组合模型的基础上,考虑高程因素影响,利用三维位置信息对内插模型参数进行约束,将对流程延迟改正数分为距离相关和高程相关两部分,通过卡尔曼滤波器分别估计,提出了一种能修正高程偏差的对流层三维线性组合模型.以重庆连续运行参考站系统中5个站作为研究对象,实验验证结果表明,在地形起伏较大的地区,三维线性组合模型可将对流层改正精度从20～40 cm提高到5～6 cm,相对于常规方法提高了4～6倍,消除了网络差分定位中高程差引起的对流层改正系统偏差.%In network differential GPS, the deviations between user station and reference station would cause systematic errors in troposphere error corrections, resulting in lower troposphere correction accuracy, and affecting the effect of user location. Based on conventional two-dimensional linear combination model, and considering the elevation factors, three-dimensional location information is used in parameter constraint for interpolation model. The troposphere delay correction is divided into two parts, the elevation-related and the distance- related, and is estimated by Kalman filter. Then three-dimensional linear combination model is proposed to modify troposphere error in elevation. By taking five stations in Chongqing continuous operational reference station system as research subjects, the experiment is taken which shows that, in large areas of terrain, the troposphere correction accuracy by three-dimensional linear combination model is increased is from 20-40 cm to 5-6 cm, which is 3-5 times higher than that of conventional methods, and the systematic errors in troposphere correction caused by the elevation differences in network differential GPS is eliminated.
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