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Now showing items 21-40 of 882
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EM phenomena in the ELF range: EM fields of submerged dipoles and finite antennas
(NATO. SACLANTCEN, 1965/06)The report is the first of a series of three that discusses various EM phenomena in the ELF range. The expressions for the various components of the EM field from submerged dipoles are presented. Although similar expressions ... -
EM phenomena in the ELF range: natural background noise and instrumentation for its measurement
(NATO. SACLANTCEN, 1965/06)The report is the second of a series of three that discusses various EM phenomena in the ELF range. A general outline of the natural background noise in the frequency range between 1 and 50 cps is given and the measurement ... -
Simple instrumentation for measuring temperature gradients at the sea-air interface, including the results of Winter 1964/65 measurements
(NATO. SACLANTCEN, 1965/07)Very little information is available on the temperature differences in the first several centimetres of air above the sea surface and the first few centimetres of water below the sea surface. Data of this kind are important ... -
A mechanical model for estimating the motion of low altitude satellites with respect to the Earth's surface
(NATO. SACLANTCEN, 1965/08)The principles and design of a mechanical model used for demonstrating or approximately estimating the motion of low altitude satellites with respect to the earth's surface are described. -
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 ... -
Sound attenuation between 200 and 10,000 cps measured along single paths
(NATO. SACLANTCEN, 1965/09)In the deep Mediterranean basins, the water is perfectly isothermal below 400 m, and the deep refracted ray gives clear signals up to 40 km, with a spreading loss free from any frequency-dependent effect. Exploiting this ... -
A compact thermometer for the study of microthermal structure from oceanographic buoys
(NATO. SACLANTCEN, 1965/10)A solid-state, thermistor thermometer, of small physical size (13 cm x 14 cm), low cost ($21.00 worth of parts), and long-term stability (of the order of 0.01 C in 60 days) is described. It has been used successfully - in ... -
Distortion of bottom reflected pulses
(NATO. SACLANTCEN, 1966/03)The theory of linear systems combined with numerical Fourier transformations and inversion is used to obtain the shape of a general pressure pulse after its reflection from a general multilayered sea floor. The method is ... -
The influence of a low velocity layer on the reflectivity from the sea floor
(NATO. SACLANTCEN, 1966/05)The influence on the reflectivity of a low velocity layer on top of a sand half-space has been investigated. By expressing sediment density and velocity in terms of porosity it has been possible to use this quantity as an ... -
Problems of pursuit and evasion
(NATO. SACLANTCEN, 1966/06)Problems of pursuit and evasion play significant part in naval warfare - particularly in ASW. They are of no less importance in aerial warfare and are now becoming important in space. Their practical importance has given ... -
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 ... -
Observed sound velocity and temperature profiles in the Strait of Gibraltar during the passage of an internal wave
(NATO. SACLANTCEN, 1966/10)Sound velocity and temperature measurements taken from the sea-surface to 350 m depth, close to one spot over a 24-hour period revealed the passage of an internal wave of approximately 60 m amplitude. The effect of this ... -
A compact buoy system for ship-use in the measurement of ocean micro-structures over a monthly period
(NATO. SACLANTCEN, 1966/10)The oceanographic buoy described is for ship use. It allows a single ship to make synoptic studies of a limited body of water using a number of buoys. The purpose was to create an economic, simple, dependable sea unit, ... -
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. ... -
A digital depth recorder
(NATO. SACLANTCEN, 1966/11)The depth recorder described has been designed for the direct computer processing of data, which it provides in digital form on perforated tape. It is intended as a supplement to the Precision Depth Recorder installed on ... -
Impulse response of a layered bottom
(NATO. SACLANTCEN, 1967/01)Numerical methods are used for the Fourier inversion of the frequency-dependent loss transfer function. Because of the non-zero finite values of the integrand for an infinite high frequency, the asymptotic value is subtracted ... -
A digital recording system for LORAN-C
(NATO. SACLANTCEN, 1967/04)A method for digitally recording the readings of a Collins LORAN-C Mk LR 101 Receiver on punched paper tape is described. The various advantages of automatically recording LORAN-C data are examined and it is shown how, ... -
Principles and methods of core analysis at the SACLANT ASW Research Centre
(NATO. SACLANTCEN, 1967/08)The methods and accuracy of measuring core parameters at the SACLANTCEN are described. Those for measuring sound velocity and electrical resistivity are explained in detail. -
The influence of quantizing and sampling on the signal-to-noise ratio of a complex correlator
(NATO. SACLANTCEN, 1967/09)The combined effects of sampling and phase-quantizing of phase- modulated signals in Gaussian noise are studied and expressed in terms of the output signal-to-noise ratio of a matched filter correlator. The obtained results ... -
The sub-bottom structure of the Gulf of La Spezia
(NATO. SACLANTCEN, 1968/12)The sub-bottom structure of the Gulf of La Spezia, Italy, has been investigated by continuous seismic profiling and sediment coring. The seismic profiles were used to develop contour plots of sub-bottom layers, which were ...