GPS Receivers - TIDGET-PLUS: Urban Navigation with Stand-Alone GPS

Alison Brown and Dave Reed

Abstract:	In order to operate reliably in urban areas, the majority of GPS manufacturers are adopting integrated receiver architectures which require dead-reckoning sensors to “coast” through areas with poor satellite visibility. However, this approach significantly adds to the per-unit cost of the in-vehicle sensor. The primary problem is that GPS signals are obscured by buildings and other structures. Satellite visibility is often insufficient for navigation for all but brief periods of time, in fact too brief for a traditional receiver to acquire and track signals.NAVSYS has developed a new receiver architecture TIDGET”-PLUS, which allows stand-alone GPS operation even in an obstructed urban environment. This includes a new “zero-acquisition time” tracking process that provides GPS measurements whenever satellites are visible, for example when passing through intersections or when a satellite appears briefly between buildings. NAVSYS has also developed sophisticated map-aiding software that operates in the client’s PC workstation. This combination of enhanced tracking and map aiding allows the vehicle’s location to be derived even in a dense urban environment without dead-reckoning sensors being required. In this paper, the innovative TIDGET-PLUS sensor is described with test results demonstrating the sensor performance in downtown Denver. The low cost and improved performance offered by this new GPS sensor design will open up a wide variety of new applications for GPS vehicle tracking.
Published in:	Proceedings of the 6th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1993) September 22 - 24, 1993 Salt Palace Convention Center Salt Lake City, UT
Pages:	959 - 966
Cite this article:	Brown, Alison, Reed, Dave, "GPS Receivers - TIDGET-PLUS: Urban Navigation with Stand-Alone GPS," Proceedings of the 6th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1993), Salt Lake City, UT, September 1993, pp. 959-966.
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