GPS测站位移速率的解算方法

对目前4种常用的利用GPS复测资料解算测站位移速率的方法进行了分析，通过实例对比了4种方法的结果。坐标法可以直接利用多期复测结果得到测站大地坐标，但要求坐标在同一参考框架内，并采用相同的参考椭球；基线方法可以消除或削弱观测系统的系统误差，与参考框架无直接关系，但在平差计算时至少要引入1个起算点，起算点高程方向的误差会削弱其他点平面坐标的精度，并进而影响位移速率的精度；在选定不同基准解算位移速率时相似变换方法是十分有效的，但如果复测结果不在同一参考框架中，其结果存在框架不一致所带来的误差；QOCA方法能够综合利用多种观测数据，可以把区域观测数据和全球观测数据稳健地结合起来，在削弱观测期间突变因素的影响方面比其他方法具有便利之处。

METHODS FOR CALCULATING DISPLACEMENT VELOCITY OF GPS STATION

Four methods frequently used for calculating the velocities and displacements of GPS stations are briefly introduced and their characteristics are discussed in detail through comparing their computational results. The geodetic coordinates of GPS stations obtained from repeated GPS surveys can be directly used by the coordinate method which requires that the geodetic coordinates of all stations should be in the same reference frame and consistent ellipsoid should be employed.By baseline method,systematical errors can be removed and reduced because baselines are independent from reference frame, but this method needs at least one station as reference point and the height error of the reference stations may lower horizontal precision of other stations.The similarity transform method is very simple but effectively in selection of reference points, whereas there may exist frame errors in its results.Several kinds of surveying data can be comprehensively employed together and regional GPS data and IGS data can be effectively combined by means of QOCA method which is more convenient than the others in weakening the effect of disturbing factors during the observation.