Testing of the International Space Station and X-38 Crew Return Vehicle GPS Receiver

James Simpson, Charles Campbell, Russell Carpenter, Ed Davis, Semion Kizhner, E. Glenn Lightsey, George Davis, Larry Jackson

Abstract:	This paper discusses the process and results of the per-formance testing of the GPS receiver planned for use on the International Space Station (ISS) and the X-38 Crew Return Vehicle (CRV). The receiver is a Force-19 unit man-ufactured by Trimble Navigation and modified in software by the NASA Goddard Space Flight Center (GSFC) to per-form navigation and attitude determination in space. The receiver is the primary source of navigation and attitude information for ISS and CRV. Engineers at GSFC have de-veloped and tested the new receiver with a Global Simula-tion Systems Ltd (GSS) GPS Signal Generator (GPSSG). This paper documents the unique aspects of ground test-ing a GPS receiver that is designed for use in space. A discussion of the design of tests using the GPSSG, docu-mentation, data capture, data analysis, and lessons learned will precede an overview of the performance of the new re-ceiver. A description of the challenges that were overcome during this testing exercise will be presented. Results from testing show that the receiver will be within or near the specifications for ISS attitude and navigation performance. The process for verifying other requirements such as Time to First Fix, Time to First Attitude, selection/deselection of a specific GPS satellite vehicles (SV), minimum signal strength while still obtaining attitude and navigation, nav-igation and attitude output coverage, GPS week rollover, and Y2K requirements are also given in this paper.
Published in:	Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999) September 14 - 17, 1999 Nashville, TN
Pages:	865 - 874
Cite this article:	Simpson, James, Campbell, Charles, Carpenter, Russell, Davis, Ed, Kizhner, Semion, Lightsey, E. Glenn, Davis, George, Jackson, Larry, "Testing of the International Space Station and X-38 Crew Return Vehicle GPS Receiver," Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999), Nashville, TN, September 1999, pp. 865-874.
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