Evaluation of Radionavigation Systems in an Urban Environment

Lance Miller, Steven Bartlett, Benjamin Peterson and Michael McKaughan

Abstract:	During the summer of 1994, the Advanced Research Projects Agency and the United States Coast Guard Academy collected extensive radionavigation data in the New York City area. The purpose was to determine the feasibility of using an existing radionavigation system for tracking applications in an urban environment. The data includes the accuracy and availability of the Global Positioning System (GPS) and LORAN, a comparison of electric field (whip) and magnetic field (loop) antennas at both LORAN and DifferentiaI GPS frequencies, and the increased availability of both GPS and LORAN by adding a precise clock input to the receivers. The data was collected among the narrow streets and tall buildings in the Wall Street area, among the tall buildings but wider streets of Third Avenue, in the relatively more open streets and smaller buildings of the Bronx, in the vicinity of the large metallic structure of the George Washington Bridge, and under the cover of foliage along the New Jersey side of the Hudson River. Preliminary analysis of the data shows: (1) in the deep urban canyons of Wall Street and under heavy foliage the availability of LORAN (either E or H field) is much higher than that of GPS; (2) in almost all scenarios, the LORAN magnetic field signal is easily detectable and has repeatable phase characteristics. In contrast, the LORAN electric field signal strength is frequently highly attenuated and undetectable especially in the Wall Street area and under the elevated train tracks in the Bronx; and (3) the availabihty of radionavigation fixes can be substantially enhanced in these urban areas by the integration of LORAN and GPS navigation information and by the use of a precise clock which allows a geographic fm to be made by measuring the Times of Arrival from as few as two transmitters, i.e. one GPS satellite and one LOW station. Therefore, it is concluded that the use of an integrated GPS/LORAN receiver with a precise time standard and an inertial navigation system can be used to track an object (a vehicle, a person, etc.) through the streets of an urban environment with much greater availability than with a GPS or LORAN receiver alone.
Published in:	Proceedings of the 1995 National Technical Meeting of The Institute of Navigation January 18 - 20, 1995 Disneyland Hotel Anaheim, CA
Pages:	293 - 302
Cite this article:	Miller, Lance, Bartlett, Steven, Peterson, Benjamin, McKaughan, Michael, "Evaluation of Radionavigation Systems in an Urban Environment," Proceedings of the 1995 National Technical Meeting of The Institute of Navigation, Anaheim, CA, January 1995, pp. 293-302.
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