2009 Volume 30 Issue 1 Pages 18-24
Distance to target is fundamental and very important information in many engineering fields. In some applications sound is often used to measure distances to targets. For this purpose, the time delay of reflected wave is typically used. This method, however, can not measure short distance because the transmitted wave, which has not attenuated enough as of reception of reflected waves, suppresses the reflected waves for short distance. Meanwhile, in the research field of microwave radar, to measure distances to multiple targets even if they are short, a novel method by using standing wave has been recently proposed. In this paper, we apply the fundamental principle of this method to measurement of short distance for multiple targets using sound wave. Specifically, we focus our attention on audible band-limited signal with random phases. To verify the validity and effectiveness of our method, we perform computer simulations and experiments. As a result, it has been confirmed that short distances to multiple targets, such as the distances of two targets located at 0.5 m and 1 m, can be measured by our method.
