THE INFLUENCE OF OVERHEAD OBSTACLES TO GPS DISPLACEMENT MEASUREMENTS AND A METHOD TO REDUCE THIS INFLUENCE

Abstract

The accuracy of displacement measurements using GPS depends on the environment surrounding the receiver set on the measurement point. Overhead obstacles of the receiver cause a disturbance to the signals transmitted from the satellites and a degradation of the measurement accuracy. In this paper, it is shown that the influence of overhead obstacles can be found by the double-difference phase, and a method for improving the measurement accuracy is proposed. In order to verify the method, it is applied to long-term measurement results. In addition, field experiments are conducted to detect small displacements. It is proven that the proposed method can be effective not only for improving the measurement accuracy, but also for shortening the time required to detect displacements.