Patent ID: 7272394

Claim:
A method of locating a portable device wherein a signal is transmitted from the portable device and received at various strengths at plural receivers in plural zones or wherein plural signals are transmitted from plural transmitters in plural zones and received at various strengths by the portable device, the method comprising: ranking the signals received at various strengths in the order of strength; considering the m strongest signals to be a first subset, where m is a positive integer; when a majority of the m strongest signals of the first subset are associated with a same zone, considering that same zone to be a candidate zone; adding a value k to the strongest signal not in the first subset, which may or may not change the ranking of the signals received at various strengths in the order of strength; considering the m strongest signals to be a second subset; when a majority of the m strongest signals of the second subset are associated with a same zone, determining whether that same zone matches the candidate zone, and if so, determining the portable device to be located in the candidate zone.