Patent ID: 6989741

Claim:
A method of locating objects, comprising the steps of: attaching an E-tag to each object, each E-tag having a unique ID associated with the object to which the E-tag is attached, each E-tag adapted to receive a LF carrier signal, each E-tag adapted to receive a HF carrier signal, each E-tag adapted to determine whether a received LF carrier signal contains the E-tag's unique ID, each E-tag adapted to determine whether a received HF carrier signal contains the E-tag's unique ID, each E-tag adapted to transmit a response signal indicating a LF carrier signal was received, and each E-tag adapted to transmit a response signal indicating a HF carrier signal was received; transmitting a LF carrier signal containing the unique ID associated with an object to be located; transmitting a first response signal from any E-tag that receives a LF carrier signal containing the E-tag's unique ID, the first response signal indicating that a LF carrier signal was received; checking whether a first response signal is received; transmitting a HF carrier signal containing the unique ID contained in the transmitted LF carrier signal if no first response signal is received; transmitting a second response signal from any E-tag that receives a HF carrier signal containing the E-tag's unique ID, the second response signal indicating that a HF carrier signal was received; and checking whether a second response signal is received.