Design and Testing of the ARINC Veracious Differential Reference Station

Karl L. Kovach dz Patricia A. Alexander

Abstract:	An important aspect that must be considered in the design of any differential GPS (DGPS) system is the degree of integrity inherent in the differential correction data provided by that system. Differential integrity is required for safety of flight, marine, and land navigation operations. Currently available DGPS systems provide only partial integrity due to one or more of the following reasons: (1) they are restricted to single operating mode integrity, (2) they are capable of failure detection only with no fault isolation, or (3) they are based upon reference station (RS) designs that are limited as to the type of user receivers with which they are compatible. This paper describes a novel integrated system concept for a DGPS RS design that is veracious, robust, and flexible. This design is “veracious” because of the advanced quality control features which allow it to guarantee its accuracy, its not-to-exceed error (NTE) levels, and its integrity. It is robust in that it concentrates on assuring the quality of the individual pseudorange (PR) and range rate (RR) corrections rather than just monitoring one or more position solutions achieved with those corrections. And it is flexible since it may be used with all types of DGPS user receivers via its rigorous use of a standardized interface (RTCM SC-104, Version 2.0). We have assembled and tested a prototype version of this ARINC veracious differential RS (AVERS) as part of an ongoing research and development project to investigate differential integrity. The prototype was aimed at determining whether the differential data veracity specitications for civil aviation can be met using off-the-shelf GPS and/or DGPS hardware components integrated together and operating as a total system. The target veracity specifications for the AVDRS prototype included: a PR correction accuracy of 1 meter, l-sigma; an NTE PR correction error of 3 meters; and a PR correction integrity of 0.999999. The AVDRS prototype test program results described herein indicate that many off-the-shelf GPS receivers and stand-alone DGPS RSs, when integrated together per the AVDRS design concept, should be able to support civil aviation requirements for differential data veracity.
Published in:	Proceedings of the 1993 National Technical Meeting of The Institute of Navigation January 20 - 22, 1993 Parc 55 Hotel San Francisco, CA
Pages:	375 - 388
Cite this article:	Alexander, Karl L. Kovach dz Patricia A., "Design and Testing of the ARINC Veracious Differential Reference Station," Proceedings of the 1993 National Technical Meeting of The Institute of Navigation, San Francisco, CA, January 1993, pp. 375-388.
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