Numerical Computational Technique for Scattering from Underwater Objects

T. Ratna Mani; Raj Kumar; Odamapally Vijay Kumar

doi:10.14429/dsj.63.779

T. Ratna Mani Naval Physical and Oceanographic Laboratory, Cochin
Raj Kumar Defence Institute of Advanced Technology, Pune
Odamapally Vijay Kumar Naval Physical and Oceanographic Laboratory, Cochin

DOI: https://doi.org/10.14429/dsj.63.779

Keywords: Mono-static, bi-static, acoustic wave, scattering, finite element time domain method and ramp response technique

Abstract

This paper presents a computational technique for mono-static and bi-static scattering from underwater objects of different shape such as submarines. The scatter has been computed using finite element time domain (FETD) method, based on the superposition of reflections, from the different elements reaching the receiver at a particular instant in time. The results calculated by this method has been verified with the published results based on ramp response technique. An in-depth parametric study has been carried out, by considering different pulse frequency, pulse length, pulse type (CW, LFM , SFM), sampling frequency, as well as different size , shape of the scatteringbody and grid size. It has been observed that increasing the pulse frequency, sampling frequency and number of elements leads to improved results. However, good amount of accuracy has been achieved with element size less than one third of wave length. The experimental result of the underwater object has been found very close to the`simulated result. This technique is useful for computing forward scatter for inverse scattering applications and as well as to generate forward scatter of very narrow and wide band signals of any pulse type and shape of body.

Defence Science Journal, 2013, 63(1), pp.119-126, DOI:http://dx.doi.org/10.14429/dsj.63.779

Author Biographies

T. Ratna Mani, Naval Physical and Oceanographic Laboratory, Cochin

Ms T. Ratna Mani received her MTech (Electronics), in 1988. She is currently working a as a Scientist at Naval Physical and Oceanographic Laboratory (NPOL), Kochi. She has authored seven technical papers in international conferences and few research reports. She is a Life Member of Institute of Electronics and Telecommunications. She has a special interest in image processing. She is working on sonar systems, in the area of signal processing and under water acoustics.

Raj Kumar, Defence Institute of Advanced Technology, Pune

Dr Raj Kumar has completed MTech and PhD in Microwave in 1992 and 1997 respectively from University of Delhi. Presently he is working as Scientist at Armament Research & Development Establishment, Pune. He has more than 190 technical papers in International Journal and conferences tohis credit. His area of interest is microwave components and antennas, with special interest in numerical technique, electromagnetic analysis and simulation.

Odamapally Vijay Kumar, Naval Physical and Oceanographic Laboratory, Cochin

Dr O. Vijaya kumar has received his PhD from Indian Institute of Science, Banglore, in 1990. He is presently working as anAssociate Director at NPOL, Kochi. He has special interest inshallow water acoustics. His areas of interest are : Under water transducers, ocean acoustics, target acoustics, and platform acoustics. He is Life Member of Acoustical Society of India.