Rapid lbmaround GPS Ephemerides from the National Geodetic Survey

Mark S. Schenewerk, J. Ross MacKay, William Kass, Miranda Chin, and Gerald Mader

Abstract:	The National Geodetic Survey (NGS) has produced high precision daily GPS ephemerides with only a three to five day delay during normal operating conditions since January 1, 1993. Baseline measurement repeatability indicates these ephemerides are accurate at approximately 0.01 parts per million (ppm). These production standards are an order of magnitude improvement in quality and timeliness over the previous NGS efforts. These ephemerides are derived using 24 hour data segments from the global network coordinated by the International GPS Service (IGS) and site coordinates consistent with the International Terrestrial Reference Frame at reference epoch 1991.0 (ITRFX). The ephemerides are available from the Coast Guard bulletin board by modem and from NGS by computer network. An overview of the current ephemeris production at NGS will be presented. The tracking network, site coordinates, processing software, products, and product availability will be described. The production reliability will be discussed. Ephemeris quality will be displayed using baseline measurements and contrasted with the current broadcast ephemerides. The quality of an ephemeris predicted to real-time by this production method will be presented.
Published in:	Proceedings of the 6th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1993) September 22 - 24, 1993 Salt Palace Convention Center Salt Lake City, UT
Pages:	247 - 255
Cite this article:	Schenewerk, Mark S., MacKay, J. Ross, Kass, William, Chin, Miranda, Mader, Gerald, "Rapid lbmaround GPS Ephemerides from the National Geodetic Survey," Proceedings of the 6th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1993), Salt Lake City, UT, September 1993, pp. 247-255.
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