Patent ID: 6233459
Filing Date: 2001-05-15
Classification: G01S,H01Q

Abstract:
In a communications system including at least one mobile transceiver capable of spread spectrum coded radio frequency emission and communication with at least one base station, said base station capable of spread spectrum coded radio frequency emission and communication, each said base station having at least one transmitter and at least one receiver having an antenna coupled thereto, a system for providing geolocation of a selected mobile transceiver, said system comprising:means for synchronizing each mobile transceiver and each said base station in time;a means for identifying a code of interest in a spread spectrum coded radio frequency emission received from a mobile transceiver;a direction finding means for determining an angle of arrival of said spread spectrum coded radio frequency emission from said selected mobile transceiver wherein said direction finding means includes a digital signal processor for calculating the angle of arrival of a radio frequency emission from a mobile transceiver from antenna array response vectors associated with said radio frequency emission received from said mobile transceiver;determination means coupled to said direction finding means for determining a range between said selected mobile transceiver and said receiver, said determination means utilizing a propagation time of the identified code of interest wherein the determination means determines the range between a mobile transceiver and a base station in accordance with:r={(t2-t1)*c}/2where t1 is the measured transmit time, t2 is the measured receive time, and c is the speed of light; andmeans for calculating the geolocation of said mobile transceiver using the determined angle of arrival of said spread spectrum coded radio frequency emission and the determined propagation time of the identified code of interest.