소형수조에서 음향재료의 반향음감소와 투과손실 측정시스템 구성

Abstract

Since the detection probability is critically dependent on the target strength (TS) in active sonar and on the radiated noise level (RNL) in passive sonar, the acoustic materials for echo reduction (ER) and transmission loss (TL) are widely used for the stealth of underwater targets. In this thesis, a measurement system based on the small water tank, for the frequency range of greater than 30㎑, is developed and verified using reference targets. In order to design the water tank and the geometry of test samples, a program is developed to calculated the arrival times of interfering signals due to the reflection from water tank walls and also due to the diffraction from the edge of the test samples. Considering all the interfering signals, an optimal experimental configuration for water tank and test samples is designed and used throughout the experiment. Next, the signal processing algorithms to estimate ER and TL are developed based on the measured propagation loss reflecting the geometric spreading characteristics of the transducer. Finally, a set of reference targets such as aluminium plate and perfectly reflecting plate are used in a small scale acoustic water tank to verify the developed measurement system.