A High Integrity Local Area Differential GNSS Data Link for Category IIIb Landings

Andrew Nelson

Abstract:	The aviation community has been searching for a viable data link for high integrity Differential GPS (DGPS) precision approach operations. Existing proposals such as the Draft Special Category I Minimum Aviation Systems Performance Standards (SCAT-I MASES) have short comings which do not qualify it for full Category III operations, and leaves serious questions as to the MASPS’s ability to meet Category I requirements. This paper presents a data link concept which is designed to meet the stringent data link requirements presented in precision approach and landing operations. Statistical analyses and test data from evaluations of the data link concept are addressed in the paper which show that Category III data link integrity requirements can be met. It is noted that with the data word structure proposed, ample capacity remains for growth. The data link consists of: 1) data recognized as required for DGPS precision approach operations (RTCM- SC-104, SCAT-I MASPS and others) including kinematic carrier phase techniques; 2) existing high integrity data word structures and modulation techniques used in other precision landing operations; and 3) existing and unused frequency spectrum in the 5090 - 5150 MHz band reserved for aeronautical navigation purposes. The paper outlines the institutional issues regarding this data link; the technical parameters of the data link including overall capacity analyses; the scientific analyses previously performed which verified the integrity of the data link including laboratory and flight tests; and the actual recommended formats for the data link based on previously recommended data structures. Additional recommendations for continued development and fast track international standardization of the concept are provided.
Published in:	Proceedings of the 6th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1993) September 22 - 24, 1993 Salt Palace Convention Center Salt Lake City, UT
Pages:	1479 - 1499
Cite this article:	Nelson, Andrew, "A High Integrity Local Area Differential GNSS Data Link for Category IIIb Landings," Proceedings of the 6th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1993), Salt Lake City, UT, September 1993, pp. 1479-1499.
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