Results 181 to 190 of about 336,461 (224)

Acoustic decoupler for a sonar array

The Journal of the Acoustical Society of America, 1992
An inner decoupler for a sonar array including a linear array of hydrophones and consisting of an alternating multi-layer configuration of acoustic compliance elements in the form of acoustic baffles and acoustic non-compliance elements in the form of water or other acoustic mass-like element located between the hydrophones and the outer surface of a ...
openaire   +1 more source

Disappearing baffle for sonar arrays

The Journal of the Acoustical Society of America, 1989
A selectively transparent baffle means for controlling beam pattern dispel or direction, further comprising a plurality of parallel, vertically oriented, compliant tubes each of which attach to one of two header tubes at one end while the opposite ends are open to sea pressure. The headers provide air fill or vent.
openaire   +1 more source

Phased array Doppler sonar transducer

The Journal of the Acoustical Society of America, 1987
A plurality of piezoelectric or magnetostrictive rectangular planar staves are held in side-by-side relation in a laminate assembly including insulative spacers. The widthwise polarity of adjacent pairs of the staves are inverted relative to each other.
Robert L. Simmons, Clifton M. Wyant
openaire   +1 more source

Layout-optimized cylindrical sonar arrays

Oceans '04 MTS/IEEE Techno-Ocean '04 (IEEE Cat. No.04CH37600), 2005
The cost of sonars scales to the number of active elements. Therefore, it is favorable to reduce the number of elements without loss in imaging quality. This is a combinatorial problem, but of such a large dimension, even for small arrays, that an exhaustive search is futile. In this work, we have found layout-optimized sparsed cylindrical arrays, i.e.
J.E. Kirkebo, A. Austeng, S. Holm
openaire   +1 more source

Receiver array technology for sonar

1985
In sonar, we are concerned with the detection of targets against a background of unwanted signals. These unwanted signals may be noise in several forms, or reverberation. The task of the receiving system designer is to ensure an optimal system response to the wanted signal and minimal response to the unwanted signal.
openaire   +1 more source

Matched array processing for wideband passive sonar

ICASSP '81. IEEE International Conference on Acoustics, Speech, and Signal Processing, 2005
The Matched Array Processor (MAP) is quadratic adaptive matrix filter designed to optimize detection and bearing estimation of a desired wideband target signature in the presence of interferences. It is made adaptive in the spatial domain to remove interferences entering through the beam sidelobes and it is spectrally matched to the signal of interest.
openaire   +2 more sources

Parametric array Doppler sonar apparatus

The Journal of the Acoustical Society of America, 1982
Parametric array Doppler sonar apparatus includes an acoustic lens containing a flat disk-like central portion and an annular outer portion serving as a convergent lens. Multiple transducers are positioned between the lens and the focal plane so as to launch collimated acoustic beams in specified directions through the central portion of the lens and ...
openaire   +1 more source

Azimuth adaptive phased array sonar

The Journal of the Acoustical Society of America, 1987
In ultrasonic transmission from and reception by an array probe in a phased array sonar, when an ultrasonic beam is directed substantially in front of the array probe, an ultrasonic wave having a high center frequency fo, or a bandwidth extending into higher frequencies, is transmitted and/or received in order to insure a high image resolution.
openaire   +2 more sources

Amplitude shading of sonar transducer arrays

The Journal of the Acoustical Society of America, 1974
Amplitude shading is an important technique for controlling the beamwidth and sidelobe level of transmitting and receiving arrays in sonar and radar. The traditional method of Dolph–Tchebyscheff synthesis for the determination of array amplitude shading or weighting coefficients is, however, highly restrictive despite the extension and generalizations ...
openaire   +1 more source

Array Modeling of Active Sonar Clutter

OCEANS 2007, 2007
Active sonar systems operating in shallow-water environments often deal with excessive false alarms, generically referred to as clutter, that are more numerous than expected for Rayleigh-distributed reverberation. The clutter probability density function, and therefore the probability of false alarm (P fa), depends on the scattering sources ...
openaire   +1 more source