WAAS Sensor Interference Testing

Trent Skidmore and Mark Johnson

Abstract:	The concern over potential radio frequency interference to the planned FAA Wide Area Augmentation System (WAAS) can be greatly reduced with the careful development of testing procedures designed to ensure proper operation of a WAAS sensor in the presence of various types of interference. This paper provides the justification and theoretical background for the interference tests that a WAAS sensor/receiver must be subjected to before certification. These tests follow the information contained in the RTCA Minimum Operational Performance Standard (MOPS) for Global Positioning System/Wide Area Augmentation System Airborne Equipment. The interference types to be tested fall into three primary categories: narrow-band (continuous wave) interference, broad-band interference, and pulsed interference, each of which has a unique requirement and test procedure. The requirements and tests are further categorized depending upon the particular phase of flight (en route, non precision approach, and precision approach) for which the sensor is designed. Described are the specific parameters to be quantified, including navigation-mode position accuracy, channel specific pseudorange accuracy, or data demodulation (bit error rate). Also included is a discussion of the test procedure for validating that the receiver produces no harmful misleading information (HMI), under any level of interference, that could constitute an integrity threat. This paper is of particular interest tb two groups: 1) GPS/WAAS manufacturers whose sensors must show compliance, and 2) Civil aviation authorities who must certify the sensors and also determine appropriate regulatory measures given the limitations of the WAAS receivers.
Published in:	Proceedings of the 8th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1995) September 12 - 15, 1995 Palm Springs, CA
Pages:	695 - 703
Cite this article:	Skidmore, Trent, Johnson, Mark, "WAAS Sensor Interference Testing," Proceedings of the 8th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1995), Palm Springs, CA, September 1995, pp. 695-703.
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