Patent ID: 6219613
Filing Date: 2001-04-17
Classification: G01S,G07B,G08G

Abstract:
A vehicle position determination system for determining the position of a moving vehicle having a transponder, comprising:a first antenna positioned to receive periodic radio frequency data signals from the transponder when the transponder is moving through a first predetermined coverage zone having a width that is orthogonal to the travel path of the moving vehicle and a length that is parallel to the travel path of the moving vehicle, the length of the first coverage zone varying in a predetermined manner across the width thereof;a second antenna positioned to receive periodic radio frequency data signals from the transponder when the transponder is moving through a second predetermined coverage zone that partially overlaps the first coverage zone and has a width that is orthogonal to the travel path of the moving vehicle and a length that is parallel to the travel path of the moving vehicle, the length of the second coverage zone varying in a predetermined manner across the width thereof; andprocessing means responsive to the antennas to count the number of periodic data signals received by each of the antennas from the transponder during a time period and determine based on the count a probable location of the vehicle.