CMRE Publications: Recent submissions
Now showing items 721-740 of 882
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Deep water mass circulation in the Alboran Basin: Measurements - August to November'83: ALBORAN III
(NATO. SACLANTCEN, 1988/02)The circulation of the deep water mass in the western Alboran Sea is studied. Interaction between the -
Oceanographic data from the southern Tyrrhenian Sea: August to October 1984: Part 1 - Floats and moored instruments: Part 2 - Hydrography
(NATO. SACLANTCEN, 1988/02)A SACLANTCEN observational programme in the Southern Tyrrhenian Sea comprised a sequence of three cruises during the period August to November 1984. The primary purpose was to investigate the late summer water-mass variability ... -
The effect of gravity-forced oscillations at the base of the duct on its effective depth as a channel for acoustic rays
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Target motion effects on passive sonar: an appraisal of basic factors
(NATO. SACLANTCEN, 1986/12)Detection and tracking by passive sonar involve the observation of the target-radiated noise in bearing-cells and time-cells that have their dimensions predetermined by a combination of physical limitations, e.g. the size ... -
Measurements of correlation loss and time-spreading in linear FM sweeps and pseudo-random noise signals transmitted over long ranges in shallow water
(NATO. SACLANTCEN, 1986/12)The results of some transmission measurements made in shallow water are described. The ranges were about 15 km, 20 km, and 34 km, and the sound source was either suspended about 10 m above the bottom or was on the bottom ... -
Wave theory modelling of convergence zone propagation in the ocean
(NATO. SACLANTCEN, 1987/06)Improved numerical techniques together with continual advances in computer technology have now -
The determination of permeability in in-situ marine-floor sediments
(NATO. SACLANTCEN, 1985/11)A method of evaluating in situ permeability of unconsolidated marine floor sediments has been -
The influence of fluctuations in acoustic travel time on locating the position of an underwater sound source
(NATO. SACLANTCEN, 1985/10)This paper investigates the accuracy of an underwater acoustic positioning system in locating a sound source that transmits at unknown times in conditions in which the acoustic travel times between -
Application of beam-forming techniques to measurements of acoustic scattering from the ocean
(NATO. SACLANTCEN, 1986/10)Signals from an explosive source backscattered from the seafloor and received at long range by -
Automatic picture transmission receivers for weather satellite images: a brief introduction and survey of some commercially-available equipment
(NATO. SACLANTCEN, 1986/06)The Automatic Picture Transmission (APT) signal is broadcast from several polar-orbiting weather -
Virtual beams from an FFT beamformer and their use to assess the quality of a towed-array system
(NATO. SACLANTCEN, 1983/01)Linear towed arrays with sophisticated signal processing systems have become popular for passive sonar and seismic prospecting. This is due to the ease of mobility and the large spatial gains achievable. However, because ... -
A microcomputer-controlled digital acquisition and analysis system for the expendable bathythermograph
(NATO. SACLANTCEN, 1985/10)For a number of years the expendable bathythermograph (XBT) has been an important tool for basic and applied oceanographic survey work. This has led to a significant body of work being done on the accuracy of the XBT system ... -
Fast Fourier transformation algorithms: experiments with microcomputers
(NATO. SACLANTCEN, 1986/07)We describe experiments intended to exploit the potential of modern -
Multiple beamforming
(NATO. SACLANTCEN, 1985/07)Beamforming techniques are generally based on the assumption that the received signal arrives from -
Temporal and spatial variabilities in shallow water acoustics: measurements and predictions
(NATO. SACLANTCEN, 1985/03)An acoustic signal propagating in the sea is generally degraded not only by interactions with the bottom and surface boundaries, but also by volume inhomogeneities caused by non-uniformities in temperature, density, and ... -
Special formulation of modified ray analysis for machine computation
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Horizontal array gain in shallow water
(NATO. SACLANTCEN, 1980/12)Some results of a comprehensive model study on the use of horizontal hydrophone arrays in shallow water are presented. Well-known signal processing techniques are applied to a shallow-water sound propagation model in order ... -
High-resolution analysis of non-stationary data ensembles
(NATO. SACLANTCEN, 1980/10)Estimation of an unknown parameter of a random data ensemble is usually done by maximizing a certain power estimator by varying the unknown parameter. This method is convenient where the data are a nonlinear function of ... -
Effect of different bandwidths for the detection of extended targets in reverberation
(NATO. SACLANTCEN, 1993/08)In this paper, firstly the theoretical background of bandwidth effects on detection in noise and reverberation is presented in some detail, and secondly the relevant results of sea. trials with a low frequency active sonar ... -
Real time-frequency active sonar processing: a massively parallel approach
(NATO. SACLANTCEN, 1993/08)A paradigm for massively parallel processing of matched filters, replica correlators, ambiguity functions and time-frequency distributions using an SIMD (Single Instruction Multiple Data) programming methodology is presented. ...