Nordic Semiconductor ASA
RADIO FREQUENCY DISTANCE DETERMINATION

Abstract:

A method of determining a distance between a radio frequency device and a target is disclosed in which the radio frequency device receives a radio frequency signal from the target. The method comprises determining a time domain channel response from the received radio frequency signal, determining an amplitude of a largest peak in the time domain channel response, determining an amplitude of a second, earlier, peak in the time domain channel response, comparing the second peak amplitude to a threshold based on the largest peak amplitude, identifying the largest peak as a shortest path peak if the second peak amplitude is less than the threshold, identifying the second peak as a shortest path peak if the second peak amplitude is greater than the threshold, and calculating the distance between the radio frequency device and the target based on a time corresponding to the shortest path peak.