underwater target imaging using acoustic waves is possible by employing the method used in synthetic aperture radars. in recent years, synthetic aperture sonar has been the subject of several researches. wherein imaging of underwater moving target is required, inverse synthetic aperture sonar (isas) idea can be used but specifications and limitations of underwater channel should be considered. ...

In this paper, we present mathematical analyses to consider the effect of material properties on the sensitivity of the Microelectromechanical systems (MEMS) piezoelectric hydrophone and improve the sensitivity by choosing the proper material. The selected structure in the present paper is a piezoelectric hydrophone able to work at low frequencies. The piezoelectric hydrophones are widely used ...

This paper is concerned with the problem of recognition of objects laying on the sea-bed and presented on sonar images. Considering that high resolution sonar system provides acoustic images of high-quality, several researches have been interested in Synthetic Aperture Sonar (SAS) and Sides can sonar images for underwater objects. This work presents recent detection algorithms targeting their m...

source localization is an essential part of array signal processing including radar, sonar, seismology and oceanography applications. the performance of the presented source localization methods are degraded substantially in practical situations. one of the conditions which decreases the performance o

This study proposes an alternative effective sonar image enhancement algorithm. The method basically composes of two steps, including noise reduction and image sharpening. The sonar image is first de-noised using Wiener and median filters, and then it is enhanced using unsharp masking and histogram equalization. The proposed algorithm has been verified on many sonar images of different underwat...

Although the causal link between sonar and stranding has not been described explicitly, beaked whales are one of the cetacean taxa more sensitive to use of Navy sonar (Moretti et al., 2014; Tyack et al., 2011). Despite their vulnerability, Blainville's beaked whale, Mesoplodon densirostris (Md), are routinely detected year-round on the AUTEC range, coincident with routine use of Navy sonar. Thi...

Abstmct Sonar as well as other related sequences were introduced by Golomb and Taylor in [2 ] . Following a similar approachiwe introduce the concept of an extended sonar sequence. It is similar to that of a sonar sequence but blank columns are permitted. Several constructions of extended sonars are given. Our constructions are very close to ordinary sonar sequences. However they provide good i...

Interferometry is used for bathymetric mapping with side scan and synthetic aperture sonars. The principle is based on estimating the time difference between arrivals for two vertically displaced receivers. An important additional feature with interferometric sonar is that an estimate of the signal-to-noise ratio can be derived from the coherence between overlaid data series from the two receiv...

A mechanicaly scanned imaging sonar, MSIS, produces a 2D image of the range and bearing of return intensities. The pattern produced in this image depends on the enviormental feature that caused it. These features are very useful for underwater navigation but the inverse mapping of sonar image pattern to environmental feature can be ambiguous. We investigate problems associated with using MSIS f...