基于LAMBDA方法的GPS整周模糊度解算研究

Study of GPS Integer Ambiguity Solution Based on LAMBDA

导航、大地测量的快速和高精度GPS定位需要解算双差分载波相位的整周模糊度值,基于经典最小二乘法求解的解整周模糊度一般为非整数解(浮动解),这种做法丢失了对提高未知参数估值的精度很有用的信息。而该文则详细讨论了基于整数最小二乘法及其降相关平差方法(LAMBDA)的原理极其算法,通过一个短基线的实例计算发现:较于未加限制的最小二乘搜索算法,LAMBDA方法在进行模糊度搜索解算时充分顾及了模糊度的整数特性,并在此基础上对模糊度协方差阵进行了降相关处理,从而改善了模糊度的方差域,消除了模糊度方差的不连续性,使得LAMBDA方法的搜索区域得到明显改善,相应的定位精度明显提高,具有较高的应用价值。

The fast and precise GPS positioning in navigation and geodesy needs solving the integer ambiguity from double differenced observations. The solution based on least square method often gives out non - integer（float） result. It ignores some info which is useful for improving the estimated parameters. This paper introduces the basic principles of both the integer least square method and the LAMBDA method for resolving the integer ambiguity solution. Through a short baseline example and compared with the unlimited least square method, the results show that, LAMBDA method considers the ambiguity＇s integer characteristic and also decorrelates ambiguity＇s covariance, so it meliorates the covariance field of ambiguity, avoids the covariance＇s discontinuity. So the LAMBDA method improves the search area and the related positioning precision apparently