초록 ▼

The unwanted influence a noise-source environment upon a modulated (e.g., FSK-encoded) magnetic field-based communication system is diminished by a non-modulated AC magnetic field communication scheme that uses a demodulatorless magnetic field detector. When installed in a tag to be tracked by a geo

The unwanted influence a noise-source environment upon a modulated (e.g., FSK-encoded) magnetic field-based communication system is diminished by a non-modulated AC magnetic field communication scheme that uses a demodulatorless magnetic field detector. When installed in a tag to be tracked by a geolocation system, the demodulatorless detector responds when the tag comes within a prescribed proximity of the field generator producing the non-modulated AC magnetic field. The received signal is downconverted to baseband and processed to detect a valid AC magnetic field tone and indicate whether the tag is within a prescribed proximity of the AC magnetic field source.

대표청구항 ▼

1. A method of controlling the operation of a system for geolocating objects within a monitored environment, wherein RF transmissions from tags associated with said objects are detected at a plurality of spaced apart monitoring locations containing tag transmission readers, and outputs of said tag t

1. A method of controlling the operation of a system for geolocating objects within a monitored environment, wherein RF transmissions from tags associated with said objects are detected at a plurality of spaced apart monitoring locations containing tag transmission readers, and outputs of said tag transmission readers are processed to geolocate said tags and thereby their associated objects within said monitored environment, said method comprising the steps of:(a) generating, from at least a location of the monitored environment that is proximate to a region which a tagged object may enter, an unmodulated magnetic field having a constant frequency representative of information intended for a tag entering said region; and (b) at a tag that has entered said region, detecting said unmodulated magnetic field and causing said tag to perform a prescribed function.