ESTIMATION OF RANGE AND DEPTH OF A SUBMERGED MOVING OBJECT BY USING NOISE CEPSTRUM

This paper attempts to come up with a method to measure the range and depth from the sound source to the receiver by analyzing radiated noise cepstrum of a moving vessel or torpedo. Two sets of formulas have been deduced in the process. The paper uses a moving object as an illustrative example. The normalized short-time spectrograph of the radiated noise from a submerged moving object is analyzed to establish an interference pattern. Through the analysis of cepstrum, a cepstrum graph with two bright lines is obtained. The bright lines represent the two time delay differences—that between the direct path and the sea surface reflection path and that between the direct path and the sea bottom reflection path. If both time delay differences are available at the same time, the first set of formulas can be used to calculate the range and depth of the sound source. If only one time delay difference is available, the second set of formulas can be used to measure the range of the sound source by supposing that the depth is already known. An experiment demonstrates that the range and depth calculated by the formulas conform to the on-site results.