Abstract
A method of measuring the reflection coefficient for a double-layered scaled model using the inverse filter is presented. First, the response of the circuit and underwater acoustical channel is measured, and the retransmitted inverse signal isestimated with the least square method for solving the cost function, which is constructed by the inverse filtering theory. Then, by retransmitting the inverse signal, the incident signal at the position of the double-layered scaled model is focused with high-main-lobe resolution, low side-lobelevel and a narrow pulse signal in temporal domain. The focus improves the measurement accuracy of the reflection coefficient for the double-layered scaled model in low frequencies. The feasibility of replacing the whole cylindrical with the double-layered scaled model is verified by simulation. The validity of the proposed method is verified by experiments carried out in a cylindrical tank for a double-layered scaled model at the frequency 0.5 kHz~10 kHz. The experimental results show that the proposed method is effective to the measurement of the reflection coefficient for the double-layered scaled model.The experimental results for the double-layered scaled model with acoustical coating on different shells have strongly directive significance for the process design and improvement of the acoustical coating.
Highlights
A method of measuring the reflection coefficient for a doublelayered scaled model using the inverse filter is presented
This paper presents a method for measuring the reflection coefficient of the doublelayered scaled model using the inverse-filter transmission (IFT), which is distinguished with the method given by Ref. [12] by different objective functions
The acoustical coating covering on the internal or external shell has different performance for the double-layered scaled model.Because the shape of the double-layered scaled model is similar to the submarine and it was shown that its target strength curves are close to those of submarines(i.e. the whole cylindrical shell in this paper), so the results obtained from the double-layered scaled model, the simulations, and the real experimental results, have strongly directive significance for the process design and improvement of the acoustical coating
Summary
A method of measuring the reflection coefficient for a doublelayered scaled model using the inverse filter is presented. The validity of the proposed method is verified by experiments carried out in a cylindrical tank for a doublelayered scaled model at the frequency 0.5 kHz~10 kHz. The experimental results show that the proposed method is effective to the measurement of the reflection coefficient for the double-layered scaled model.The experimental results for the double-layered scaled model with acoustical coating on different shells have strongly directive significance for the process design and improvement of the acoustical coating. Method, but the effect of the channel response couldn’t be offset thoroughly due to the TR theory.[11] In addition, the measurement accuracy of the existing methods is decreasing with the frequency and the direct signal cannot be distinguished especially for a doublelayered scaled model, due to the influence of the multipath in a limited space environment and the double layers. The multichannel inverse filter method (MIF) degraded the side lobe, enhanced the resolution of the main lobe and realized the optimal focusingby utilizing the coherent information of the different transmitting-receiving channel,(12)but the more complicated procedures were necessary, and the focusing effect was influenced by the number of transmitted transducers and the receivers, i.e. a high requirement of the hardware was necessary
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
