Browsing by Title
Now showing items 115-134 of 882
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An acoustic, high resolution, sediment profiler
(NATO. SACLANTCEN, 1966/11)An acoustic sediment profiler is described that utilizes short 50 kHz pulses to achieve a high range resolution. In trials in shallow water, penetration depths of about 9 m and resolution of about 25 cm were obtained. ... -
An analogue recording system for recording pulse series
(NATO. SACLANTCEN, 1964/04)An analogue recording system for the visual display of pulse series intermittently received from oceanographic sensors is described. It is composed of a mechanically-modified pen recorder and a newly designed electronic ... -
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 -
An analytical study of source localization in shallow water by matched-field processing of horizontal arrays
(NATO. SACLANTCEN, 1992/08)Over the last few years a large number of studies have reported results of range-depth localization of sound sources by matched-field processing of vertical arrays in known environments. The performance of matched-field ... -
An approach to robust map generation from multibeam bathymetric data
(NATO. SACLANTCEN, 1997/10)During the last twenty years, many multibeam bathymetric sonars have been produced. The instrumentation is usually accompanied by a system able to produce a seafloor map from the sonar data. There are also several public ... -
An approximate form of the Rayleigh reflection loss and its phase: application to reverberation calculation
(NURC, 2012/04)A useful approximation to the Rayleigh reflection coefficient for two half-spaces composed of water over sediment is derived. This exhibits dependence on angle that may deviate considerably from linear in the interval ... -
An automated instrument for testing and monitoring oceanographic mooring cables and ropes
(NATO. SACLANTCEN, 1997/09)Underwater acoustic experiments at the NATO SACLANT Undersea Research Centre, La Spezia, Italy (SACLANTCEN) are largely dependent on moored and towed instrumentation. Every year up to 500 cable terminations am made and ... -
An automatic approach to ship detection in spaceborne synthetic aperture radar imagery: an assessment of ship detection capability using RADARSAT
(NATO. SACLANTCEN, 2000/12)This report describes a methodology for automated ship and wake detection in space-based synthetic aperture radar (SAR) imagery. The methodology incorporates a multistage approach involving several algorithms which can ... -
An autonomous undersea surveillance vehicle: concept and operational feasibility
(NATO. SACLANTCEN, 1988/12)The concept of autonomous undersea vehicles (AUVs) is becoming feasible through the increasing practicality of artificial intelligence, decreasing size and cost of computers, and improved technical capabilities. This paper ... -
An evaluation of digitized APT data from the TIROS-N/NOAA-A, -J series of meteorological satellites
(NATO. SACLANTCEN, 1984/03)The TIROS-N/NOAA-A,-J series of meteorological satellites transmit imagery data to the Earth in both digital and analogue formats. The analogue data are a processed subset of the digital dat and have lower resolution. A ... -
An experimental investigation of the contribution of sediment volume scattering to acoustic backscatter measured in the shallow waters of the Florida Strait
(NATO. SACLANTCEN, 1997)Experiments were conducted in the Florida Strait region of the United States in July 1995 for the purpose of investigating the contribution of sediment volume scattering to measured backscatter levels at frequencies between ... -
An experimental study in forming a long synthetic aperture in the sea
(NATO. SACLANTCEN, 1992/09)Successful experimental testing of synthetic aperture techniques for sonar systems have been very limited and only few results, including very stable CW signals, have been published. These experimental results and theoretical ... -
An experimental study of sediment discrimination using 1st and 2nd echoes
(NATO. SACLANTCEN, 1997)Analysis of Roxann seabed classification data, at 24 kHz and 200 kHz, using co-located echosounders is presented. Timeseries backscater data gathered at the same time as the Roxann data has also been anal~sed using variations ... -
An experimental verification of a geometric acoustic approximation
(NATO. SACLANTCEN, 1971/12)This paper sets out to show that a very simple ray treatment may be used to give a surprisingly good estimate of a sound field, even in conditions where the criteria for the use of geometric acoustics are apparently not fulfilled. -
An improvement in the design of the towed nuclear spin magnetometer
(NATO. SACLANTCEN, 1963/06) -
An instrument for measuring evaporation
(NATO. SACLANTCEN, 1965/09)An evaporation rate meter, or evaporimeter, has been devised that shows promise of directly measuring the rate of evaporation near the sea surface. The simplicity of the instrument indicates that it may be of interest to ... -
An introduction to adaptive array processing
(NATO. SACLANTCEN, 1979/12)Array processing systems which can respond to an unknown interference environment are currently of considerable interest. The fundamentals of such systems are by no means new - basically they depend on Weiner's filter ... -
An unrestricted linear random walk with negative exponentially distributed step lengths
(NATO. SACLANTCEN, 1966/06)An account is given of the theory of a doubly infinite linear random walk in which step lengths have a negative exponential distribution and the direction of each step is not necessarily equiprobable. The problem of first ... -
Analysis and problems of HF acoustic coherent and incoherent simulations in shallow water
(NATO. SACLANTCEN, 1997)Shallow water environments create complex scattering condit~ons due to the sea surface and bottom scattering mechanisms. An analysis of the effects of the scattering mechan~smso n sonar images of simple targets in shallow ... -
Analysis of a signal starting time estimator based on the Page test statistic
(NATO. SACLANTCEN, 1995/12)The time of the most recent reset to zero of the Page test statistic is proposed as an estimator of the starting time of a signal. The probability mass function of the estimator is determined analytically subject to a ...