Indoor Geolocation System Operational Test Results

Benjamin B. Peterson, Chris G. Kmiecik, Hung Nguyen, Beth Kaspar

Abstract:	Over the past two years, the United States Coast Guard Academy has been researching the development of an indoor, spread-spectrum geolocation system to track personnel inside buildings under a project funded by the Defense Advanced Research Projects Agency (DARPA) Small Unit Operations Geolocation program. Over that time, the system has evolved from a single time difference (TD) engineering test bed to a fully functional, six receiver geolocation system using a 256Mhz carrier, 51Mhz chipping rate and 204Mhz sampling rate. A battery powered, hand-held, spread spectrum transmitter is carried by the soldier as he enters the building and carries out a hostage recovery scenario. Six wideband receive antennas are placed outside of the structure with GPS one pulse-per-second and a spread spectrum reference transmitter supplying time synchronization to all of the receivers. Each antenna supplies a commercial, off-the-shelf (COTS) analog-to-digital (ADC) data acquisition card inside a Pentium based personal computer. Digital signal processing (DSP) is performed at each receiver to calculate time of arrival (TOA). Every second, TOA information is transmitted to a command center via a wireless network where a position solution is computed and the results displayed on an overlay of the floor plan of the building. On November 5, 1998, the system was deployed to Fort Benning, Georgia in their Military Operations on Urban Terrain (MOUT) site emulating a small village. In a live demonstration, the performance of the system was illustrated to leading government, contract, military, and international personnel. As the soldier entered the building, his progress was continuously monitored and verified by video cameras throughout the building. Floor plans for each floor were automatically updated as the soldier moved from floor-to-floor. The demonstration clearly showed which floor and which room the soldier was in (each room being approximately 250 square feet). Scientific data recorded showed a 100 percent fix solution every second over the 3,000 samples taken in 28 different points throughout the test area. 90% of the fixes fell within an error circle of radius 2.86 meters. A small, hand-held version of the receiver was also demonstrated using a pentium based PC104 system with a 250Msa/s PC104 ADC. Future research will include: further reducing the size and power consumption of both the transmitter and receiver; smaller wideband antennas; higher chipping rates; and, improved TOA calculations.
Published in:	Proceedings of the 55th Annual Meeting of The Institute of Navigation (1999) June 27 - 30, 1999 Royal Sonesta Hotel Cambridge, MA
Pages:	273 - 282
Cite this article:	Updated citation: Published in NAVIGATION: Journal of the Institute of Navigation
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