ION Technical Content
Availability Estimates for GNSS
| Abstract: | This paper discusses the use of the GNSS (Global Navigation Satellite System) Air Traffic Operations Model (GATOM) to assess GNSS availability. Many models estimate average availability [l] [23 [31. In addition to the average value, the GATOM output also includes the little-studied temporal and spatial characteristics of GNSS availability. These characteristics must be understood so that operationally meaningful availability requirements can be defmed, and augmentations to GNSS developed to allow the overall system to meet these requirements. GATOM is a comprehensive, Markov-process model that calculates a variety of statistical measures of the required services at locations specified by the user; the primary GNSS services modeled at present are navigation and the receiver autonomous integrity monitoring (RAIM) detection and isolation functions. Altimeter aiding is an option in the current version of GATOM; planned extensions to the model will address the effects of other augmentations and the integration of GNSS with other navigation systems. The paper briefly describes the current version of the model, and then presents the results of a recent analysis conducted with it. The analysis addressed GPS constellations of 24 to 32 satellites, and augmentation with baro-altimeter and geostationary satellites. The applications illustrated include Category I and non- precision approaches. |
| 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: | 429 - 438 |
| Cite this article: | Poor, Walter A., "Availability Estimates for GNSS," Proceedings of the 1993 National Technical Meeting of The Institute of Navigation, San Francisco, CA, January 1993, pp. 429-438. |
| Full Paper: |
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