Signal Deformation Monitoring Scheme Implemented in a Prototype Local Area Augmentation System Ground Installation

F. Liu, M. Brenner, C.Y. Tang

Abstract:	Honeywell is implementing a prototype system of the FAA’s Local Area Augmentation System (LAAS) ground facility. One of the critical steps in guaranteeing the system’s overall integrity is to ensure the integrity of the GPS satellite signals. This paper presents a novel scheme, which Honeywell implements in its Provably Safe Prototype (PSP) system, for assuring the satellite integrity by monitoring the correlation function. Under this scheme, the ground facility detects satellite signal deformation (SD) and informs the airborne user in time to assure that no hazardous misleading information (HMI) is used in the airborne positioning system. The proposed scheme consists of two major processes, deformation monitoring and parameter evaluation. The first process transforms measurements from multiple correlator monitoring points into a discriminator to determine if a signal deformation is in presence, while the second one provides and monitors the parameters used in the monitoring process. A major obstacle that needs to be overcome in applying the scheme is to characterize the mean and variance of the measurements from the monitoring points along the correlation function. The mean of the measurements depends on biases introduced by the receivers and satellites, whereas the variance of the measurements depends on thermal noise and diffuse multipath. Methods to estimate and compensate for the biases are presented in this paper. The variance estimation algorithm is developed based on computer modeling and real data. Finally, using both real data and simulation, the overall performance of the scheme is verified to meet the continuity and integrity requirements. Specifically, we show through data analysis that continuity performance meets requirements and we show through simulation that all specified signal deformations can be effectively detected to meet integrity requirements.
Published in:	Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006) September 26 - 29, 2006 Fort Worth Convention Center Fort Worth, TX
Pages:	367 - 380
Cite this article:	Liu, F., Brenner, M., Tang, C.Y., "Signal Deformation Monitoring Scheme Implemented in a Prototype Local Area Augmentation System Ground Installation," Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006), Fort Worth, TX, September 2006, pp. 367-380.
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