Title: Multi-Channel Wideband GPS Anomalous Event Monitor
Author(s): Sanjeev Gunawardena and Frank van Graas
Published in: Proceedings of the 24th International Technical Meeting of The Satellite Division of the Institute of Navigation (ION GNSS 2011)
September 20 - 23, 2011
Oregon Convention Center, Portland, Oregon
Portland, OR
Pages: 1957 - 1968
Cite this article: Gunawardena, Sanjeev, van Graas, Frank, "Multi-Channel Wideband GPS Anomalous Event Monitor," Proceedings of the 24th International Technical Meeting of The Satellite Division of the Institute of Navigation (ION GNSS 2011), Portland, OR, September 2011, pp. 1957-1968.
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Abstract: In 2005, Ohio University and the FAA William J. Hughes Technical Center developed and deployed several remotely controlled, continuously operating GPS Anomalous Event Monitors (GAEMs) in a geographically diverse region to capture and study rare anomalous events. These systems, which have been in continuous operation, capture sampled intermediate frequency (IF) data of GPS L1 at a bandwidth of 2.2 MHz when triggered by GPS reference station monitors. This original system has enabled research to study various satellite-borne signal anomalies as well as local events attributable to ionospheric effects and interference. This paper reports on the follow-up to this work which involves a completely redesigned GAEM that was recently deployed to study signal anomalies and in-band interference with higher fidelity. The current system is based on Ohio University’s third generation Transform-Domain Instrumentation GNSS Receiver (TRIGR) technology, and is capable of self triggering and capturing IF samples from up to eight coherent RF channels of any center frequency from 800 MHz to above 1800 MHz at bandwidths up to 24 MHz per channel. The first section of this paper presents the architectural details and capabilities of the wideband GAEM (WB-GAEM). As a demonstration of the merits of multi-bit sampling for effective interference mitigation in modern GNSS receivers, this paper also presents a digital interference mitigation technique that is highly effective against most types of narrowband interference. The presented technique is relatively straightforward to implement and operates on individual multi-bit samples – such as those produced by TRIGR. The performance improvement gained by using the technique relative to standard receiver processing is illustrated using three types of narrowband interference generated in the lab.