Sources and Impact of GNSS Signal Degradation within a Vehicle Environment

B. Weinstein, M. Czerep, D. Akos

Abstract:	In the past decade, consumer Global Navigation Satellite System (GNSS) devices have become an integral component in many vehicles. However, the location of the device and its antenna, as well as the radio frequency (RF) characteristics of the vehicle itself, can cause significant signal degradation. This effect is especially detrimental when RF record and replay technologies are used in GNSS testing. This document investigates two causes of GNSS signal degradation: signal interference from noise or tones generated by the vehicle’s engine, electronics, or other accessories and electromagnetically?shielded windows. To investigate these phenomena, a portable RFI “sniffer” was created using a spectrum analyzer and either a patch or omni?directional cell phone antenna. The sniffer is used to map out these sources of GNSS signal degradation within a number of different vehicle makes and models. While the primary purpose of this survey is to select a vehicle that will minimize self?generated RF interference (RFI) during the capture of RF record and replay data for GNSS receiver testing, the ramifications extend into the consumer domain as well. For consumer as well as vehicle design and manufacturing applications, it is important to understand how GNSS receivers are affected by their location in the vehicle as well as the vehicle components themselves. For the purposes of RF record and replay, identifying a vehicle with the minimum tone and interference generation near the GPS L1 band, as well as a large, unshielded front or rear windshield is essential to eliminating any vehicle?originated bias in the recorded signal.
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:	1100 - 1111
Cite this article:	Weinstein, B., Czerep, M., Akos, D., "Sources and Impact of GNSS Signal Degradation within a Vehicle Environment," Proceedings of the 23rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2010), Portland, OR, September 2010, pp. 1100-1111.
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