Patent ID: 11914018
Assignee: CORNELL UNIVERSITY
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 8:
9. A radio-frequency system for range finding, comprising:
a transceiver configured to:
modulate a reference signal having an intermediate frequency, fIF, to a downlink signal having a carrier frequency, fc, using a clock signal;
transmit the downlink signal;
receive a backscattered uplink signal from a tag, wherein the uplink signal is at a harmonic frequency of the carrier frequency; and
demodulate the uplink signal using the clock signal such that transceiver is a coherent transceiver;

a tag configured to receive the downlink signal at fc and to backscatter the uplink signal at the harmonic frequency of the carrier frequency; and
a processor configured to receive the demodulated uplink signal and calculate a distance between the tag and the transceiver based on comparing the reference signal to the demodulated uplink signal comprising: determining a difference between a phase of the reference signal and a phase of the demodulated uplink signal, and determining the distance as a linear function of the difference between the phase of the reference signal and the phase of the demodulated uplink signal.