A Novel Approach to GPS System-Level Testing

E. Weston, G.A. Schroeder, B. Chadil, P.A. Herre, E. Weston

Abstract:	GPS system-level testers are often constrained by operational limitations on using actual Space Segment (SS) and/or Control Segment (CS) assets for development testing. Due to developmental changes, the GPSW/SE&I needed to perform a system test of both the CS Architecture Evolutionary Plan (AEP) and a wide spectrum of GPS receivers to ensure that the signal-inspace broadcast by the satellites, and determined by the CS, is compatible with fielded GPS receivers and meets security requirements. No suitable test bed currently exists capable of securely testing a representative cross section of GPS receivers in a ‘realistic environment’ while using actual MCS data. SE&I resolved this test bed limitation by designing a method to collect MCSgenerated navigation message data and converting this data into System Test Vectors (STV) for use with GPS Space Segment (SS) Simulators. The SS simulator models the GPS constellation by radiating high-fidelity GPS L1 and L2 signals modulated with a navigation message. Using the STVs, the SS simulator will broadcast an MCS-generated navigation message. The STV process described in this paper allows the GPSW to comprehensively test a broad variety of GPS receivers. The GPSW Test and Verification branch leads this STV development process co-jointly with GPSW/SE&I and GPSW Participating Test Organizations (PTOs). Navigation data is currently being collected in the GPS Support Facility (GSF), in lieu of the Master Control Station (MCS) of the CS. The GSF houses CS hardware and software, which is functionally nearly identical to the MCS (referred to as the “replica MCS”). The GPSW/SE&I will maintain the STV development process, and it is anticipated that the GPSW can make the developed STVs available to GPS receiver manufacturers for test and performance evaluation of their receivers.
Published in:	Proceedings of the 23rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2010) September 21 - 24, 2010 Oregon Convention Center, Portland, Oregon Portland, OR
Pages:	1350 - 1354
Cite this article:	Weston, E., Schroeder, G.A., Chadil, B., Herre, P.A., Weston, E., "A Novel Approach to GPS System-Level Testing," Proceedings of the 23rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2010), Portland, OR, September 2010, pp. 1350-1354.
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