Browsing CMRE Publications by Issue Date
Now showing items 361-380 of 882
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Interpretation and representation of the synoptic features in the Iceland-Faeroe-Shetland region
(NATO. SACLANTCEN, 1993/07)The kinematic structure of the sub-inertial fluctuations of measured current and temperature fields from 6 moorings deployed during the June -
Scattering from a rough sedimental seafloor containing shear and layering, as determined by perturbation theory
(NATO. SACLANTCEN, 1993/07)First-order perturbation theory is applied to reverberation from a rough sedimental seafloor. In addition to existing approaches, the seafloor is allowed to be shear-supporting or to be layered. Scattering strengths are ... -
Shallow-water ASW sonar design
(NATO. SACLANTCEN, 1993/08) -
Bottom time spread and bistatic scattering by rough basalt
(NATO. SACLANTCEN, 1993/08)Scattering from oceanic basalt affects low-frequency active sonar systems in at least two important ways: (1) Significant time, angle and frequency spreading reduces target echo levels when systems over-resolve the spread; ... -
Spatial and temporal coherence in a long range, upslope environment
(NATO. SACLANTCEN, 1993/08)In an active acoustic test conducted off the USA Pacific Coast in November-December 1991, a low-frequency source, kept stationary over the deep basin, insonified from long range the coastal slope and shelf. An autonomous, ... -
Shallow-water sound transmission measurements taken on the New Jersey continental shelf
(NATO. SACLANTCEN, 1993/08)Calibrated acoustic measurements were made under calm sea state conditions on the New Jersey shelf near the AMCOR 6010 borehole, a surveyed area with known geophysical properties. The experiment was conducted in 73 m water ... -
Performance assessment of broadband impulsive noise jammers
(NATO. SACLANTCEN, 1993/08)A noise jammer raises the noise level observed by a threat sonar to degrade the sonar's detection performance. In this paper we assess the potential for a specific noise jammer waveform used to countermeasure low frequency ... -
Acoustic characterization of a shallow water site
(NATO. SACLANTCEN, 1993/08)Results are presented from an exercise aimed at providing a low frequency active sonar environmental characterization of a specific shallow water site in the Gulf of Mexico. Downward refracting acoustic transmission and ... -
Array performance and variability at short range near Vestfjorden
(NATO. SACLANTCEN, 1993/08)An experiment was conducted in October 1989 in shallow water near Vestfjorden in support of low frequency active sonar system research at SACLANTCEN. This report addresses some acoustic measurement results from that test ... -
Model-aided data adaptive suppression of reverberation
(NATO. SACLANTCEN, 1993/08)We propose a processing methodology which is based on the piece-wise modeling, adaptive estimation, and removal of reverberation components. An important feature of this approach is that backscatter models and information ... -
Source localization for a low frequency active multistatic sonar system
(NATO. SACLANTCEN, 1993/08)In a low frequency active bistatic or multistatic sonar system, it is essential tohave accurate knowledge of the location of the transmitting source ship. Inaccuracies inthis information translate directly to errors in the ... -
Array and cable tracking data through ship maneuvers
(NATO. SACLANTCEN, 1993/08)This paper presents tracking results from two sea tests in which a towed cable and array were tracked at the Atlantic Undersea Test and Evaluation Center (AUTEC). The tracking tests involved instrumenting the cable with ... -
A shallow water system for maximizing echo to reverberation ratio
(NATO. SACLANTCEN, 1993/08)A method for increasing incident energy on mid-depth targets while at the same range reducing boundary reverberation for shallow water ducts has been devised. The basis of the approach is couched in range dependant normal ... -
Measurements for satellite validation made from the RV Alliance during October and November 1991
(NATO. SACLANTCEN, 1993/08)Measurements of sea-surface temperature, surface meteorology and atmospheric profiles were taken from the RV Alliance between 1 October -
Channel-adapted source for shallow water
(NATO. SACLANTCEN, 1993/08)In shallow water areas the utilization of active sonar is complicated by the fact that in these environments the performance of active systems is degraded by source signal interaction with channel boundaries. These boundary ... -
Low frequency active sonar (LFA) bottom loss requirements
(NATO. SACLANTCEN, 1993/08)A bottom interaction simulator was developed to investigate LFA bottom bounce losses, i.e., the mismatch losses, which occur in matched filter processing of bottom and target reflected signals due to the time spreading ... -
Comparison of measured reverberation on the transmission loss data with modelled results on the West Florida continental shelf
(NATO. SACLANTCEN, 1993/08)Acoustic data from the September, 1992 Area Characterization Test (ACT I) are compared to ADAM (Advanced Development Acoustic Model) output. Conduct of harsh shallow water acoustic exercises, and data interpretation mandates ... -
Array shape determination with a real-time model
(NATO. SACLANTCEN, 1993/08)A shape estimation scheme based on precomputed frequency-domain solutions of array motion is presented. The boundary conditions supporting each solution are discrete Fourier transform (OFT) components of sensor measurements, ... -
Achievable signal gains for line arrays in shallow water
(NATO. SACLANTCEN, 1993/08)The well-documented conformance of signal gain to a 20 log n relationship for deep water, refracted paths, does not apply to shallow water where angular spreading effects from boundary roughness limit the signal gains that ... -
Surface duct propagation loss measurements and model predictions at low and mid frequencies
(NATO. SACLANTCEN, 1993/08)Side-by-side measurements of low- and mid-frequency propagation loss were obtained during a sea test conducted in the North Atlantic during February of 1992. These measurements are compared to each other and with model ...