Digital Translators for GPS TSPI Applications

Alison Brown and Mark Sturza

Abstract:	Currently analog Translator designs are used to instrument missile tests in applications such as the Trident and ERIS test programs. The Translator installed on-board the missile converts the received L-band GPS signals to S-band and rebroadcasts them to a ground-based Translator Processing System (TPS) where the location of the vehicle is determined. The advantage of this approach over using the GPS Range Pod Subsystem is that the size, weight and cost of the flight hardware is substantially reduced. Also, by employing special purpose tracking loops in the TPS, the GPS signals may be tracked under very high dynamics up to 50 g accelerations and 50 g/set jerk. In addition, the custom signal processing in the TPS allows the translator signals to be acquired very rapidly, within a few seconds. The RAJPO BMT Translator is packaged in 40 cu. in. and weighs 5 Ibs. It is possible with existing technology to develop a significantly smaller instrumentation package using a digital Translator design. As shown in the paper, the digital approach permits significant improvements in tracking performance for some applications and also provides additional capabilities such as the potential for signal encryption for secure programs. A digital Translator can be manufactured using current technology that can be packaged in a 5 cu. in. chip set volume. The paper includes an overview of the design of such a device and a discussion of the applications where the reduced size and superior performance over the analog design would be of benefit.
Published in:	Proceedings of the 3rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1990) September 19 - 21, 1990 The Broadmoor Hotel Colorado Spring, CO
Pages:	361 - 365
Cite this article:	Brown, Alison, Sturza, Mark, "Digital Translators for GPS TSPI Applications," Proceedings of the 3rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1990), Colorado Spring, CO, September 1990, pp. 361-365.
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