ION Technical Content
Global Corrections for GPS
| Abstract: | Objectives for a global descendent of Differential GPS (DGPS) and Wide Area Differential GPS (WADGPS) include the following: competitive operating costs, accurate performance available everywhere, system integrity with quality control, and compatibility with other DGPS operations. A practicable system to meet these objectives is evolving as a descendant of single-station DGPS and WADGPS in a bootstrap process which uses current commercial systems as R&D infrastructure for each succeeding advancement step. The system currently provides DGPS and WADGPS commercial service, and performance indicates that the global objectives are achievable. GPS Navigation with fault protection and performance equivalent to DGPS available everywhere is evolving from existing commercial systems. Compatibility among disparate classes of users is achieved by using standard RTCM SC104 message streams augmented by special messages. Network operators feed message streams from reference stations to a central processor. The central processor uses iterative comparison processes involving WADGPS output and all station measurements to reject faulty measurements before releasing the output. Network operators use satellite communications to distribute the output stream from the central processor to navigators, DGPS navigators use the standard portion of the RTCM stream. WADGPS navigators use the standard stream plus special messages to obtain improved accuracy and extended operating area. Developmental global navigators use the standard stream plus special messages to calculate corrections from global components. For example, developmental global navigators recover satellite clock errors from Type 1 messages: the clock errors are applicable globally, the stream is compatible with local users, and the need for a costly clock correction message is postponed. All navigators receive rapid warnings of faulty satellites via the Type 1 messages. |
| Published in: |
Proceedings of the 7th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1994) September 20 - 23, 1994 Salt Palace Convention Center Salt Lake City, UT |
| Pages: | 1025 - 1033 |
| Cite this article: | Robbins, James, "Global Corrections for GPS," Proceedings of the 7th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1994), Salt Lake City, UT, September 1994, pp. 1025-1033. |
| Full Paper: |
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