High Dynamic, Dual Frequency Tracking With a Low Bandwidth Digital Translator

Alison Brown, Amir Matini, and Dennis Caffery

Abstract:	In order to provide precision navigation solutions using differential GPS or kinematic GPS, dual-frequency observations are required. Currently, the only method of providing these measurements for high-dynamic applications is to use a keyed P/Y code L l/L2 receiver. Codeless Ll/L2 receivers do not operate well in a high dynamic environment due to the low signal-to-noise ratio following squaring on the L2 channel. NAVSYS has developed a dual-frequency L l/L2 digital translator under contract to SSDC. This device allows highly accurate carrier phase observations to be made from a high dynamic platform, without requiring a PPS-SM on-board the vehicle being tracked. L 1 translators have been in use for a number of years to provide real-time and post-test TSPI data in support of range applications. These operate using the CIA code signals only, since conventional range telemetry channels are limited to a 2 MHz bandwidth. NAVSYS has developed a reduced bandwidth, high dynamic signal processing algorithm that supports P-code (20 MHz) tracking on the Ll and L2 frequencies using only a 2 MHz telemetry channel. By including the PPS-SM in the ground-based translator processing system, PN code operation can be supported without requiring the use of security keys on the missile. Carrier phase observations can be provided on both the Ll and L2 frequencies under acceleration of up to 1OOg and jerk of 100 g/s using an innovative carrier-aided, high dynamic tracking loop developed by NAVSYS. In this paper, the architecture of the reduced bandwidth, dual frequency digital translator and translator processing system is described. The carrier phase tracking performance is demonstrated using high dynamic data generated from the NAVSYS GPS software signal simulator.
Published in:	Proceedings of the 9th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1996) September 17 - 20, 1996 Kansas City, MO
Pages:	1709 - 1717
Cite this article:	Brown, Alison, Matini, Amir, Caffery, Dennis, "High Dynamic, Dual Frequency Tracking With a Low Bandwidth Digital Translator," Proceedings of the 9th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1996), Kansas City, MO, September 1996, pp. 1709-1717.
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