Patent ID: 8446277

Claim:
A method for providing a proximity warning comprising: generating a plurality of magnetic fields defining a plurality of zones, wherein each of the plurality of magnetic fields at least partially overlaps at least one other of the plurality of magnetic fields, and wherein each of the plurality of zones is defined by a particular combination of the presence or absence of single or multiple magnetic fields of the plurality of magnetic fields, each zone being either a warning zone in which a warning is to be issued or a silent zone in which a warning is not to be issued; determining a location of a detector device with respect to the plurality of magnetic fields, wherein the location is determined by detecting at least one of the plurality of magnetic fields using the detector device; determining whether a warning is to be issued based on a particular one of the zones in which the detector device is located, wherein it is determined to issue a warning if the detector device is located in a warning zone and it is determined to not issue a warning if the detector device is located in a silent zone; and if it is determined to issue a warning, issuing the warning.