TIDGET Applications for Missle Tracking and Guidance

Alison Brown and Thomas Kelecy

Abstract:	Historically, missile tracking in support of range safety and TSPI applications has been performed using GPS translators. These are analog devices that upconvert the GPS L-band signals and retransmit them at S-band for processing on a ground station. This approach provides high accuracy data and is far superior in performance to radar systems. However there are some important disadvantages associated with the use of analog translators. Notably, they are relatively large compared with a GPS receiver and significantly more expensive. The associated ground equipment is also very large and expensive. The wide bandwidth of the translated GPS data (2 MHz) also uses a large portion of the spectrum. As the size and cost of GPS receivers has decreased, a number of agencies have begun to consider using receiver-based missile tracking systems. However, GPS receivers also have several disadvantages. Since the missile cannot generally track satellites before launch, a receiver must go through an extensive pre-initialization to minimize the time-to-first-fix (TTFF). The shock of the missile launch will tend to shift the GPS receiver clock frequency which also lengthens the TTFF. Since translators are passive devices, they require no initialization, are not sensitive to high acceleration, and the ground equipment can rapidly acquire and track the GPS signals. NAVSYS has developed a low cost sensor, the TIDGET, which combines the best features of a GPS translator and a receiver for missile tracking applications. The TIDGET is a miniaturized sensor that generates sampled GPS data for transmission across a standard range telemetry link. Since this data is processed remotely, the TTFF is minimized, allowing rapid acquisition and tracking of the missile in support of range safety, TSPI, and even tactical applications. This paper describes a TIDGET-based tracking and processing system for missile tracking applications. Translator-based solutions for an aircraft flight test are compared with standard GPS receiver measurements taken simultaneously during approach and landing exercises.
Published in:	Proceedings of the 7th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1994) September 20 - 23, 1994 Salt Palace Convention Center Salt Lake City, UT
Pages:	899 - 906
Cite this article:	Brown, Alison, Kelecy, Thomas, "TIDGET Applications for Missle Tracking and Guidance," Proceedings of the 7th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1994), Salt Lake City, UT, September 1994, pp. 899-906.
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