CHARGING A TRANSPONDER IN A SECURITY SYSTEM

摘要

A transponder is adaptively energized using a charging electromagnetic field created by a transceiver in a security system. A partial charging electromagnetic field is transmitted providing a plurality of spaced frequency components so that one to the spaced frequency components energizes the transponder by an amount causing it to produce a partial transmission which provides an calibrated signal for identifying a frequency upon which the transponder will be transmitting. A full charging electromagnetic field limited to a single frequency component is transmitted to the transponder determined in response to a frequency calibration signal received from the transponder.