SCAT-I Integrity Method: Detection or Estimation?

Karl Kovach, Larry Hutfman

Abstract:	This paper describes the results of a performance comparison between the two DGPS integrity methods suggested in the Special Category I (SCAT-I) Minimum Aviation System Performance Standards (MASPS), RTCADO-217. These two integrity methods are philosophically very different; the detection method based on fixed monitoring thresholds designed to alert when rare but catastrophic differential correction failures occur, and the estimation method based on determining the magnitude of the ever present -- but usually small -- differential correction errors. While both methods are able to satisfy the established integrity requirements and are compatible with the recently defined (redefined) SCAT-I uplink messages, they differ substantially in their accuracy, continuity, and availability performance. The differences between these two DGPS integrity methods in their non-integrity system performance characteristics have some important implications for the growth path taking aeronautical DGPS from privately owned and operated SCAT-I precision approach systems to public use Wide Area Augmentation System (WAAS) satellite constellations and Local Area Augmentation System (LAAS) ground installations.
Published in:	Proceedings of the 1997 National Technical Meeting of The Institute of Navigation January 14 - 16, 1997 Loews Santa Monica Hotel Santa Monica, CA
Pages:	103 - 119
Cite this article:	Kovach, Karl, Hutfman, Larry, "SCAT-I Integrity Method: Detection or Estimation?," Proceedings of the 1997 National Technical Meeting of The Institute of Navigation, Santa Monica, CA, January 1997, pp. 103-119.
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