Availability Modeling for Sea Based JPALS

Glyn Romrell, Jerry Wright and Joseph Hansen

Abstract:	System availability is a Key Performance Parameter (KPP) for the Sea Based Joint Precision Approach and Landing System (JPALS). This paper describes the Sea Based JPALS landing system availability model as developed by SNC and ARINC over the past two years. This model has been used to optimize the JPALS architecture, and will be used to validate that JPALS meets availability requirements. The Sea Based JPALS availability model was based upon availability concepts and standards developed for the civil community by RTCA for FAA LAAS and international GBAS applications. Because of the restricted landing area in sea based operations, the accuracy requirements for Sea Based JPALS are much more stringent than any current civil landing system, but must exhibit similar integrity, availability and continuity. This has required a different approach from LAAS in solving the positioning problem. The approach involves solving the integer ambiguities in the phase measurements and performing relative real-time kinematic processes. The phase ambiguities must be resolved with sufficient confidence, or integrity, to eliminate the possibility of an unknown bias. In order to solve the ambiguities, filtering time must be permitted, primarily in the shipboard system, to allow the uncertainty in the ambiguity to be reduced sufficiently to accurately determine the true ambiguity. This filtering acts as a mask on the satellites and directly impacts the availability. The availability model was updated to include the impact of jamming on the JPALS aircraft and the ship components under differing approach path conditions. The model has proven useful as a tool in defining Sea Based JPALS system requirements, optimizing system architecture, allocating performance to the airborne and shipboard components, and in performing availability sensitivity analyses to evaluate the impact of pseudorange and carrier phase accuracy on the ability to resolve ambiguities. Use of the model to evaluate the impact of both ship and airborne jamming on availability is shown. Availability results over the Sea Based coverage area are presented.
Published in:	Proceedings of the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2005) September 13 - 16, 2005 Long Beach Convention Center Long Beach, CA
Pages:	2861 - 2870
Cite this article:	Romrell, Glyn, Wright, Jerry, Hansen, Joseph, "Availability Modeling for Sea Based JPALS," Proceedings of the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2005), Long Beach, CA, September 2005, pp. 2861-2870.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In