Trial implementation of acoustic distance measurement method for very-close-range measurement based on standing waves using power and phase spectra of single-channel observations

Abstract

Since the distance to target is very important information, we have proposed an acoustic distance measurement (ADM) method using a standing wave, which is generated by interference between transmitted and reflected waves. This method is very simple in that the distance between the microphone and the target is estimated as the peak value of the range spectrum (i.e., the absolute value of the Fourier transform with respect to the power spectrum of the observed wave). However, in order to measure short distances, a transmitted wave with a wide bandwidth is required. Recently, we have theoretically developed the very-close-range ADM method based on the standing wave of audible sound using a single microphone (i.e., single-channel observations) by introducing an analytic signal instead of the power spectrum. The present paper newly describes a realization of compact system for very-close-range measurement and examines experimentally the effectiveness of the proposed system.