\" A COMPARISON OF PRECISE POSITIONING USING DIFFERENT GPS DATA PROCESSING SOFTWARE PACKAGES \" Ref. No. LOC06_5

The GPS team at IIT Bombay has been working in the field of deformation measurements and analysis for estimating the subsidence in the Surat region, Gujarat, India. A GPS network consisting of 36 points has been established for this purpose; and four of these points are used as reference points. All these points are observed periodically in order to investigate the potential of GPS for subsidence measurements in the study area. GPS data is collected using dual frequency geodetic GPS receivers of Trimble make. This data is processed and analysed using two different software packages: the Trimble Geomatics Office (TGO) software, and Bernese GPS software, version 4.2. In this paper, a comparison of the results obtained using TGO and Bernese v4.2 software is presented. The GPS data used for the analysis is from the March 2006 field campaign. The methodology implemented for the data processing is that the reference stations are constrained using data from permanent GPS stations, and rest of the deformation points are processed to obtain their relative coordinates. Comparative graphs for few sample points, and the maximum and minimum difference between the results obtained from both the software are presented. It is conclude that for obtaining highest precision from the duel frequency GPS data, scientific software like Bernese should be used for data processing and analysis.