ซอฟต์แวร์สำหรับหาตำแหน่งจุดเดี่ยวความละเอียดสูงสำหรับข้อมูลจีพีเอสความถี่เดียว

Abstract

This research aims to develop GPS Precise Point Positioning software. The GPS data collected from both handheld GPS receiver and geodetic GPS receiver were used to assess the level of performance of the developed software. The precise orbit and precise satellite clock corrections were introduced into the software to reduce the orbit and satellite clock errors. For single-frequency users, ionosphere-free code and phase observations were constructed to mitigate the ionospheric delay. The remaining errors (i.e. receiver clock error, ambiguity term) are estimated using Extended Kalman Filtering technique. Tested GPS data were cut into 5-min, 10-min, 15-min and 30-min data segments. Each data segment was individually processed with the developed PPP software to produce final coordinates. Preliminary results indicate that a horizontal positioning accuracy obtained from 5-min data segments for both GPS receivers is better than 2.5 meters. Therefore, the result obtained in this study shows a potential of using the PPP technique to replace the conventional Differential GPS (DGPS) technique, and hence resulting in a reduction of operating another GPS receiver at the base station.