Acoustical imaging of underwater objects using the bistatic ramp response signals

Abstract

Underwater acoustical imaging techniques and the inverse analysis of acoustic scatteringproblems have now found many important engineering applications. Most of the inversetechniques use the backscattering signals in the acoustical far field to retrieve the shapeand size information of an underwater object, such as the ramp response technique.This paper addresses a modified ramp response technique, which could be usedto reconstruct the 3D image of an object for the bistatic case. This techniqueshows that the bistatic ramp response is proportional to the profile function of anunderwater object based on the small bistatic angle assumption. The numericalexamples demonstrate that the bistatic ramp response technique is still validto obtain an excellent profile function even for the bistatic case with a fairlylarge bistatic angle. The numerical results also suggest that, if the object is of amore slender shape, then its bistatic ramp response will be closer to the exactprofile function for a larger bistatic angle. Finally, a 3D image of a spheroid witha/b = 5 has been reconstructed using the bistatic ramp response signals in three incident directions.This bistatic ramp response technique allows us to reconstruct the 3D image of anunderwater object with only one receiver.