Patent ID: 8054160

Claim:
A method of conservation of battery power of an active, multi-modal Radio Frequency IDentification (RFID) tag in a system having a device including illuminator and/or reader functionality, and where said device has only illuminator functionality, a second device having reader functionality, said tag being associated with an asset or person to be tracked and including a microprocessor, a memory device, a battery, an illuminator signal sensor receiver and a transmitter, said method comprising the steps of: a) actuating said illuminator device to provide repeated cycles of output beacon trigger signal pulses of a first mode and of a selected duration within a field of view comprising a field of output coverage, said pulses having a fixed repeat period; b) actuating said tag to wake up periodically to identify said illuminator trigger signal pulse of said first mode type; c) determining the pulse cycle period of said identified illuminator trigger signal to create a periodic awaken/sense envelope for said tag comprising a tag awake period of sufficient duration to ensure it is awake to sense said identified illuminator trigger signal during at least a portion of said identified illuminator trigger signal pulse duration; d) synchronizing said tag awaken/sense envelope to periodically overlap said identified illuminator trigger pulse cycle; and e) actuating said tag to go into battery-conserving low power consumptive mode for N periods of said identified illuminator pulse cycles before re-awakening to sense and demodulate said entire illuminator signal to confirm identity of said illuminator trigger signal pulse whereby said battery life is extended from current life on the order of 6-months to on the order of several years.