Results 151 to 160 of about 1,058 (187)

Sonar array characterization, experimental results

IEEE Journal of Oceanic Engineering, 1998
Measurements in the Levantine Sea with a seismic-type array [i.e., the high-frequency array (27 wavelengths at 348 Hz), the mid-frequency array (27 wavelengths at 175 Hz), and the low-frequency array (21 wavelengths at 58 Hz)] were found to have on average results within 1 dB of the theoretical signal gain.
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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 ...
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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.
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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 ...
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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 ...
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Array detection of active sonar signals

Ocean '74 - IEEE International Conference on Engineering in the Ocean Environment, 1974
A linear array of sensors is considered for detecting a signal echo from a stationary target in the presence of reverberation. The structure of the optimum (likelihood ratio) detector is compared with that of a beamformer - matched filter detector.
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Processing techniques for circular sonar arrays

6th International Conference on Electronic Engineering in Oceanography, 1994
Briefly reviews the properties of modally-excited circular and cylindrical arrays and their application to sonar systems. The authors present the basis of two new techniques, namely: (i) sectoral phase modes, which are directional patterns with the same spatial variation of phase as phase modes, allowing direction finding with improved immunity to ...
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Adaptive motion compensation in sonar array processing.

2006
In recent years, sonar performance has mainly improved via a significant increase in array ap-erture, signal bandwidth and computational power. This thesis aims at improving sonar array processing techniques based on these three steps forward. In applications such as anti-submarine warfare and mine hunting motion of the sonar needs to be accounted for.
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Amplitude tolerance analysis of curved sonar arrays

2021
Andreas Austeng
exaly  

Sonar sequences from Costas arrays and the best known sonar sequences with up to 100 symbols

IEEE Transactions on Information Theory, 1993
R A Games, O Moreno
exaly