Patent ID: 9727763
Date: 2017-08-08
CPC Classifications: G06K

Claim:
1. A method of addressing one or more RFID devices within a group of RFID devices, comprising: transmitting, to the group RFID devices at a first modulation depth, a first signal comprising a command to respond; receiving a response to the first signal from a first sub-group of RFID devices in the group, the first sub-group of RFID devices having circuitry that only responds to signals that have a minimum modulation depth of less than or equal to the first modulation depth; transmitting, to the group at a second modulation depth, a second signal comprising a command to respond, wherein the second modulation depth is higher than the first modulation depth; and receiving a response to the first and second signals from a second sub-group of RFID devices within the group, the second sub-group of RFID devices having circuitry that only responds to signals that have a minimum modulation depth less than or equal to the second modulation depth.