INTEGRATED ADJUSTMENT OF CHINESE 2000' GPS CONTROL NETWORK

Abstract

Since the beginning of the nineteen nineties, China has established six nationwide GPS networks by corresponding campaigns for different objectives. With the support of the international GPS service (IGS) network and advanced data processing strategies, an accurate and unified national GPS control network with more than 2500 stations integrating the 6 existing GPS networks has been established, which is called “National 2000' GPS Control Network”. In the integrating adjustment of the nationwide GPS networks, some systematic model parameters were introduced into the adjustment functional model, in order to control the influences of systematic errors of the sub networks; the variance component estimation technique is used for adjusting the a priori precision of the different GPS networks and different observation sessions; the error detection and deleting technique is used in the data pre-processing of sub networks and observation sessions for resisting the effects of outlying observations; and a bifactor robust estimation theory is applied for controlling the influences of the outliers of the correlated baselines on the last coordinate parameters. It is shown that the average standard deviation for the horizontal component is smaller than 1.0cm, for the vertical component is smaller than 2.0cm, and for the three dimensional (3-D) position of geocentre coordinates is smaller than 3.0cm. The exterior checking accuracy for the 3-D position is averagely better than 0.9cm.