Patent ID: 8779968

Claim:
A system for measuring distance between an RFID tag and an RFID tag reader and mitigating detrimental effects of noise, clutter and multi-path signals, comprising: an RFID reader; an RFID tag; and a pulsed radar system coordinated with said RFID reader wherein said RFID reader is configured to cause said tag to respond to received signals in a first backscatter state at a first time and a second backscatter state at a second time; said pulsed radar system is configured to receive a signal from said RFID reader indicating said backscatter states and to transmit pulses during said backscatter states of said RFID tag, and to receive reflected pulses from said RFID tag, said pulsed radar system is configured to calculate a difference signal between radar signals obtained during said first and second backscatter states of the tag to obtain an uncorrupted measure of a round trip time of flight of said radar pulses between said pulse radar system and said RFID tag and to calculate the distance between the RFID tag and the RFID reader based on said round trip time of flight.