Patent ID: 6265963
Filing Date: 2001-07-24
Classification: G01S,G06K,G07B

Abstract:
A wireless communications method comprising:sending a RF transmission from an interrogator configured for transmitting and receiving RF communication data;receiving the transmission at a plurality of RF identification devices respectively having integrated circuitry including a receiver configured for receiving RF transmissions by the interrogator and a transmitter configured to transmit a reply back to the interrogator; andprior to the transmitting of the reply, respective RF identification devices delaying transmission of their respective replies to the interrogator for an amount of time which is less than the amount of time required to transmit the reply, said delaying being initiated by the RF identification device responsive to RF communication data received from the interrogator, the amount of delay being different for different of the RF identification devices, wherein if there is a collision between replies from two RF identification devices, the collision can be more readily detected by the interrogator, using a checksum analysis, than if there was no delay.