Browsing Technical Reports by Issue Date
Now showing items 61-80 of 322
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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 ... -
Silent ship research applications and operation: proceedings of a conference held at SACLANTCEN on 2-4 October 1984 - volume 2: unclassified papers
(NATO. SACLANTCEN, 1985/01)Introduction: The project to construct an acoustically quiet research ship for the SACLANT ASW Research Centre provided a reason for SACLANTCEN to organize a conference on silent ships, their operation and applications. ... -
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 ... -
Deep-sea circulation in the Alboran sea
(NATO. SACLANTCEN, 1985/04)Alboran Sea circulation between 220 and 1100 m depth is studied. Interaction between three types of water masses in this area causes a complicated flow pattern. Atlantic water flowing as a jet through the Strait of Gibraltar ... -
Multiple beamforming
(NATO. SACLANTCEN, 1985/07)Beamforming techniques are generally based on the assumption that the received signal arrives from -
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 -
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 ... -
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 -
Efficient global matrix approach to the computation of synthetic seismograms
(NATO. SACLANTCEN, 1986/05)A numerically efficient global matrix approach to the solution of the wave equation in horizontally stratified environments is presented. The field in each layer is expressed as a superposition of the field produced by the ... -
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 -
Fast Fourier transformation algorithms: experiments with microcomputers
(NATO. SACLANTCEN, 1986/07)We describe experiments intended to exploit the potential of modern -
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 -
High-resolution beamforming techniques performance analysis
(NATO. SACLANTCEN, 1986/11)Seven different beamforming techniques (including both conventional and high-resolution types) have been analyzed and compared in order to develop a quantitative relationship between resolution performance on the one hand ... -
An analysis of selected satellite data of the Aegean area with the STARS software
(NATO. SACLANTCEN, 1986/11)Data from selected orbits of the NOAA-7 meteorological satellite are used for an exploratory analysis -
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 ... -
Logarithmic least mean square sound-field estimation
(NATO. SACLANTCEN, 1987/03)The report deals with narrowband beamforming techniques for passive sonar applications. In particular, the Least Mean Square fit parameter estimation technique is used to estimate the spatial sound-field power density. To ... -
Studies on information mechanics
(NATO. SACLANTCEN, 1987/04)Related issues connected with the transmission of information in a command and control environment -
The application of coupled-mode theory to propagation in shallow water with randomly varying sound speed
(NATO. SACLANTCEN, 1987/06)Sound propagation in the Baltic Sea cannot be described correctly by range independent propagation