Method for Determining a Distance Between an FMCW Ranging Device and a Target

摘要

A method for determining a distance between a ranging device and target, wherein a valid interference profile, if already available, is subtracted from a frequency-domain echo profile that is analyzed to determine the distance of the target, where to obtain or update the valid interference profile, a low-frequency portion of the frequency-domain echo profile is stored as a temporary interference profile after each measurement, and if the target is not proximal to the ranging device and the valid interference profile is not available, the temporary interference profile is saved as the valid interference profile, otherwise if the valid interference profile is available, the valid interference profile is updated via the temporary interference profile, otherwise if the target is distal and the valid interference profile is not yet available, the temporary interference profile is first subjected to a quality check before being saved as the valid interference profile.

主权项

1. A method for determining a distance between a frequency modulated continuous wave ranging device and a target, comprising:
transmitting a transmit signal toward the target; receiving a receive signal caused by reflections of the transmit signal from the target; determining a frequency difference signal of the transmit signal (6) and the receive signal; calculating a frequency-domain echo profile from the frequency difference signal; storing a low-frequency portion of the echo profile as a temporary interference profile; subtracting, if already available, a valid interference profile from the frequency-domain echo profile; analyzing one of (i) the frequency-domain echo profile and (ii) an interference-free echo profile to determine the distance of the target; and returning to said transmitting the transmit signal if (i) the target is in close range to the ranging device and (ii) the valid interference profile is available; otherwise subtracting the temporary interference profile from the frequency-domain echo profile; analyzing the echo profile minus the temporary interference profile for another determination of the distance of the target; saving the temporary interference profile as the valid interference profile if a difference of a result of two determinations of the distance is within a specified tolerance; and returning to said transmitting the transmit signal if the valid interference profile is not yet available; otherwise updating the valid interference profile by using the temporary interference profile; and returning to said transmitting the transmit signal if (i) the target is not in close range to the ranging device and (ii) the valid interference profile is available; otherwise saving the temporary interference profile as the valid interference profile; and returning to said transmitting the transmit signal if the valid interference profile is not yet available.