A New Network-Based Rapid-Static Module for the NGS Online Positioning User Service Ð OPUS-RS

Israel Kashani, Pawel Wielgosz, Dorota A. Grejner-Brzezinska, Gerald L. Mader

Abstract:	"The National Geodetic Survey (NGS) operates the Online Positioning User Service (OPUS) as a means to provide the GPS users with easier access to the National Spatial Reference System (NSRS). OPUS allows the users to submit their GPS data files to NGS, where the data are processed to determine position coordinates using NGS computers and software. OPUS is fully automatic, and the results are emailed back to the user, usually within a few minutes. OPUS is intended for the use in the conterminous U.S. and most territories. Currently, OPUS accepts a minimum of two hours of GPS data, with a recommendation of submitting at least four hours to improve the solution. In order to reduce the required user session duration, a rapid-static module (OPUS-RS) is currently under implementation, in collaboration with the Satellite Positioning and Inertial Navigation (SPIN) Lab at The Ohio State University. The OPUS-RS is based on the Wide Area Rapid-Static (WARS) module of the Multi Purpose GPS Processing Software (MPGPSª), and it is an implementation of the Network RTK algorithm applied in the software. The new module reduces the required session duration to 10Ð15 minutes while centimeter-level accuracy is still achievable. Presented in this paper is the first demonstration and feasibility test of the OPUS-RS. The analyses consist of a subnetwork of the State of Michigan CORS with station separations of 247Ð292 km and base-rover distances of 135Ð162 km. A 24-hour data set was post-processed in 144 sessions of 10 minutes each with 30-s data sampling rate. The ambiguity resolution success ratio, speed and reliability, along with the positioning results are analyzed. The results show that 97% success ratio was achieved. Applying a second iteration to the unresolved cases improved the success ratio to 100%. The analyses were performed on 18 February 2005 under unfavorable ionospheric conditions when a minor geomagnetic storm took place with maximum Kp = 6+. The resulting coordinate accuracy is better than 1 cm for the horizontal components and than 3 cm for the vertical one. "
Published in:	Proceedings of the 61st Annual Meeting of The Institute of Navigation (2005) June 27 - 29, 2005 Royal Sonesta Hotel Cambridge, MA
Pages:	928 - 936
Cite this article:	Kashani, Israel, Wielgosz, Pawel, Grejner-Brzezinska, Dorota A., Mader, Gerald L., "A New Network-Based Rapid-Static Module for the NGS Online Positioning User Service Ð OPUS-RS," Proceedings of the 61st Annual Meeting of The Institute of Navigation (2005), Cambridge, MA, June 2005, pp. 928-936.
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