Augmenting Kinematic GPS With a Pulsed Pseudolite to Improve Navigation Performance

David Lawrence, Stewart Cobb, Boris Pervan, Clark Cohen, Per Enge, J. David Powell, and Bradford Parkinson

Abstract:	The stringent availability and continuity requirements for precision approach and landing are difficult to achieve using unaugmented local area DGPS. Even more severe is the requirement on integrity. However, to check the integrity of a GPS position solution with Receiver Autonomous Integrity Monitoring @AIM), more than four ranging sources are needed. Therefore, to meet all of the Required Navigation Performance (RNP) parameters, it may be necessary to augment the GPS constellation with additional ranging sources. Such an augmentation may be achieved by placing a ground- based GPS transmitter (pseudolite) at or near the airport. To show the navigation performance improvements offered by pseudolite augmentation, flight tests were performed in a Piper Dakota. A pseudolite was placed at the airport and was pulsed to eliminate the near-far problem. The pseudolite signal was used as an additional ranging source to demonstrate the following tasks: l Centimeter-level positioning accuracy with only three satellites. 0 RAIM-based fault detection with only four satellites. l Single-channel fault isolation with only five satellites. These results show that a pulsed pseudolite can provide an additional kinematic ranging source to an aircraft on final approach. This low-elevation precision ranging source has the potential to greatly improve the navigation performance offered by a local area DGPS system. This paper presents the results of preliminary flight tests incorporating pulsed pseudolite augmentation.
Published in:	Proceedings of the 1996 National Technical Meeting of The Institute of Navigation January 22 - 24, 1996 Loews Santa Monica Hotel Santa Monica, CA
Pages:	537 - 545
Cite this article:	Lawrence, David, Cobb, Stewart, Pervan, Boris, Cohen, Clark, Enge, Per, Powell, J. David, Parkinson, Bradford, "Augmenting Kinematic GPS With a Pulsed Pseudolite to Improve Navigation Performance," Proceedings of the 1996 National Technical Meeting of The Institute of Navigation, Santa Monica, CA, January 1996, pp. 537-545.
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