Patent ID: 7706811

Claim:
A Signal-Comparison Based Location-Determining Method, operable by at least one portable RF communications device in conjunction with at least two fixed-location service-area antenna stations capable of RF communication with the at least one device wherein the stations are substantially continuously operating, and the method is comprising the steps of: (A) registering a selected location by causing a first port able RF communications device at the selected location (i) to receive an RF communications signal from a first plurality of local fixed-location service-area antenna stations, and (ii) to measure reception signal strength associated with the received signal from at least two of said first plurality of antenna stations; (B) recording the selected location by electronically storing at least two of the reception signal strength measurements; (C) monitoring by causing said first portable RF communications device or a second portable RF communications device (i) to receive communications signals from said first plurality of local fixed-location service-area antenna stations or a second plurality of local fixed-location service-area antenna stations, and (ii) to measure reception signal strength associated with the signals; (D) determining if said first portable RF communications device or said second portable RF communications device of the monitoring step is at the selected location of the registering step by electronically comparing measurements in the monitoring step with the stored at least two measurements of the recording step, wherein the registering step includes identifying at least one ID within at least one of the received signals; and the recording step includes storing each of the at least one IDs with the reception signal strength measurement, and wherein the monitoring step includes identifying at least one ID within at least one of the received signals and the determining step includes electronically matching at least one ID of the monitoring step with the stored at least one ID of the recording step.