Results 151 to 160 of about 1,151,241 (199)

Synthetic aperture active sonar imaging

[Proceedings] ICASSP-92: 1992 IEEE International Conference on Acoustics, Speech, and Signal Processing, 1992
The main problems involved in synthetic aperture sonar imaging are medium instability, slow mapping rate, and platform motion. Proposed solutions to these problems are reviewed, and a new technique for synthetic aperture sonar imaging is presented which allows a fast mapping rate and improved motion compensation.
Brett L. Douglas, Hua Lee
openaire   +1 more source

Sequential Synthetic Aperture Sonar System-A Prototype of a Synthetic Aperture Sonar System

IEEE Transactions on Sonics and Ultrasonics, 1977
A prototype of a synthetic aperture sonar system is presented which displays computationally reconstructed images on a CRT. The image information is obtained sequentially by the scanning in twodimensions of a transmitter-receiver unit which produces and detects pulsed ultrasonic waves.
T. Sato, O. Ikeda
openaire   +1 more source

Azimuthal Ambiguities in Synthetic Aperture Sonar and Synthetic Aperture Radar Imagery

IEEE Journal of Oceanic Engineering, 1992
It is shown that azimuthal ambiguities are not eliminated by the nulls of a sonar (or radar) beam pattern and have a definite influence on image quality. In synthetic aperture systems that are strongly limited in spatial sampling, particularly in ocean borne synthetic aperture sonar (SAS) and spaceborne synthetic aperture radar (SAR), azimuthal ...
Henrik Schmidt
exaly   +2 more sources

Synthetic aperture sonar on AUV

Oceans 2003. Celebrating the Past ... Teaming Toward the Future (IEEE Cat. No.03CH37492), 2003
Synthetic aperture sonars (SAS) and autonomous underwater vehicle (AUV) are two of the most exciting technologies under development by the underwater research and development community. Integration of these technologies promises to produce underwater acoustic imaging systems of tremendous capability and versatility.
J.E. Fernandez, J.T. Christoff, D.A. Cook   +2 more
openaire   +1 more source

Bionic synthetic aperture sonar

The Journal of the Acoustical Society of America, 1997
Dolphinlike sonar signals are used to obtain synthetic aperture images of complicated, three-dimensional (3-D) objects from transmitter–receiver positions that are above the plane of effective target rotation. This geometry allows 3-D information to be incorporated into a SAS image.
Richard A. Altes, Patrick W. B. Moore
openaire   +1 more source

Simulation of synthetic aperture sonars

The Journal of the Acoustical Society of America, 1994
Coastal Systems Station is developing a high-fidelity simulation of low- and high-frequency imaging synthetic aperture sonars in coastal regions. This simulation includes a coherent bottom and surface reverberation model that treats reverberation as a Gaussian random process; 3-D coherent beam patterns for the projector and receiver arrays; a 3-D ...
G. S. Sammelmann, J. T. Christoff, J. D. Lathrop   +2 more
openaire   +1 more source

An introduction to synthetic aperture sonar

Proceedings of the Tenth IEEE Workshop on Statistical Signal and Array Processing (Cat. No.00TH8496), 2002
DTI has demonstrated that synthetic aperture sonar (SAS) can provide orders of magnitude improvement in cross-range resolution when compared to conventional sonar beamforming. Like synthetic aperture radar (SAR), SAS processing requires coherence over multiple measurements, but has long been impractical due to the nature of the ocean environment.
D. Marx, M. Nelson, E. Chang, W. Gillespie, A. Putney, K. Warman   +5 more
openaire   +1 more source

Multipath in synthetic aperture sonar

The Journal of the Acoustical Society of America, 2002
Synthetic aperture sonar is capable of producing high resolution images. As the detection range increases multipath effects can become important. In this paper we present the results of at-sea tests in the Gulf of Mexico and St. Andrew Bay with a dual-frequency (20 kHz and 180 kHz) synthetic aperture sonar.
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Synthetic Aperture Sonar Primer

1997
Abstract : The goal of the Synthetic Aperture Sonar (SAS) primer is to understand the effect of the ocean water properties on the propagation of acoustic signals for frequencies and horizontal ranges that are applicable to SAS Navy systems currently being developed.
Kevin Williams, Frank Henyey
openaire   +1 more source

Evaluation of a synthetic aperture sonar with a multi-aperture transducer

Proceedings of 1998 International Symposium on Underwater Technology, 2002
This paper presents a synthetic aperture sonar with a multi-aperture transducer. The pulse repetition frequency (PRF) is automatically modified so that conditions for both maximum search range and azimuth resolution are simultaneously satisfied. The PRF modification makes the ratio of two aperture lengths an integer, each of which is obtained for the ...
I. Yamaguchi, J. Kato
openaire   +1 more source