Characterization of Narrow-Band Interference Mitigation Performance versus Quantization Error in Software Radios

C. Cutright, J.R. Burns, M.S. Braasch

Abstract:	The mitigation of interference, either intentional or unintentional, in Global Positioning System (GPS) receivers is an area of great interest to the GPS community at this time. Over the years several methods of interference mitigation (e.g. adaptive array antennas or notch filtering) have been developed and tested. These methods have been well-tested and their effectiveness has been quantified. However, most conventional methods of interference mitigation are implemented in hardware and tested using conventional receivers. The recent development of software-defined receivers (a.k.a., software radio) for GPS allows one to develop and test new methods of interference mitigation. One such method is the frequency-domain analysis and excision of continuous wave (CW) interference. Although this technique has been around for a number of years, the issue of quantization error has not been fully addressed. Specifically, the number of bits utilized by the analog-to-digital converter (ADC) plays a key role in the performance of frequency-domain interference mitigation techniques. This paper will discuss work performed at Ohio University's Avionics Engineering Center to evaluate interference mitigation performance as a function of the number of bits used in the ADC of the software radio front-end. Following the simulation tests that were presented at the ION Annual Meeting in June 2002 [6], hardware verification tests (i.e., tests with actual RF signals) were performed in Fall 2002 and Winter 2003. Both the software simulation and bench test results show a highly non-linear function of performance versus the number of bits in the ADC. These results are discussed along with their impact on future commercial GPS receiver development.
Published in:	Proceedings of the 59th Annual Meeting of The Institute of Navigation and CIGTF 22nd Guidance Test Symposium (2003) June 23 - 25, 2003 Hyatt Regency Hotel Albuquerque, NM
Pages:	323 - 332
Cite this article:	Cutright, C., Burns, J.R., Braasch, M.S., "Characterization of Narrow-Band Interference Mitigation Performance versus Quantization Error in Software Radios," Proceedings of the 59th Annual Meeting of The Institute of Navigation and CIGTF 22nd Guidance Test Symposium (2003), Albuquerque, NM, June 2003, pp. 323-332.
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