Abstract
An acoustic method that can be used in air has the potential to allow for a fast and accurate characterization of objects in air. Nevertheless, it is difficult to identify acoustic signals from small objects clearly because of environmental noise and the scattering of sound on the object surface. Therefore, a sensing system that enables the measurement of small objects in air must be developed. In this study, we performed the localization of small objects of size comparable to the sound wavelength using an M-sequence signal and the phase information of received signals in a noisy indoor environment. Using the M-sequence signal, we are able to improve the SN ratio and to measure in a stable manner the reflected waves that cannot be detected using a conventional impulse. The arrival direction information was used to extract signals reflected by targets from unwanted signals of the floor or ceiling. Using an M-sequence signal and the arrival direction information, the position detection of small objects in the indoor environment was enabled.
