Precise position measurement of objects using a coded acoustic signal in an indoor environment

• Published in: The Journal of the Acoustical Society of America 2006-11, Vol.120 (5_Supplement), p.3139-3139
• Main Authors: Nishihara, Kuramitsu, Yamaguchi, Tadashi, Hachiya, Hiroyuki
• Format: Article
• Language: English
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/1.4787750

Acoustic sensing in the air might serve as an effective technique for acquiring information about an object, such as its distance, shape, and surface configuration. Nevertheless, it is difficult to identify acoustic waves clearly because many mirror reflections or environmental noises exist in the air. In addition, acoustic measurement requires a longer time than measurements using lasers or electromagnetic waves because sound propagates much more slowly than light. For this study, we attempted highly precise position measurement using an M-sequence signal in an indoor environment. The degrees of M-sequence were 7–14; the transmitting frequency was 25 kHz. A signal reflected from various angles was received by moving the receiving unit, which contained three microphones. Measurement results with the M-sequence signal showed that the signal-to-noise ratio (S/N) improved 20–40 dB compared with a burst wave. Furthermore, the distance resolution improved when the M-sequence degree was changed. The distance and the angle of multiple objects installed indoors or in walls were detectable as a result of construction of a two-dimensional plane based on received signals.