Browsing Reprints by Title
Now showing items 70-89 of 548
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Advances in cots side scan sonar for MCM applications
(NATO. SACLANTCEN, 1997)The Persian Gulf War has elevated the awareness to the problems of shallow water mine detection. Today's high technology shallow water anti-invasion mines, such as the Italian made "MANTA" and the Swedish manufactured ... -
Ambient noise levels in the Northeast Pacific ocean as measured by aircraft-dropped sonobuoys
(NATO. SACLANTCEN, 1982/06)Ambient noise measurements obtained from sonobuoys air-dropped by U.S.Navy P-3 aircraft during operations over the northeastern Pacific Ocean from January 1978 to December 1980 have been analysed for spatial and temporal ... -
Ambiguity reduction of underwater targets in framework of topic modeling
(CMRE, 2019/06)An unsupervised track classification approach based on appropriate discriminative and aggregative features derived from beamformed and normalized matched-filtered data is applied to sonar multistatic tracking and extended ... -
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 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 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 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 ... -
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 broad-band echosounder data over a gassy seabed
(NATO. SACLANTCEN, 1997)Calibrated echosoundings from a well-characterized gassy seabed were examined. Acoustic reflection was significantly higher than expected. It is hypothesized that gas bubbles are responsible. Anomalously high levels of ... -
Analysis of JANUS and underwater telephone capabilities and co-existence
(CMRE, 2019/06)This document aims at offering a concise look into the co-existence of Underwater Telephone and JANUS digital communication methods. This topic is of particular interest as both methods (one a well-established STANAG and ... -
Anomaly detection and tracking based on mean-reverting processes with unknown parameters
(CMRE, 2019/05)Piecewise mean-reverting stochastic processes have been recently proposed and validated as an effective model for long-term object prediction. In this paper, we exploit the Ornstein-Uhlenbeck (OU) dynamic model to represent ... -
Antisubmarine warfare applications for autonomous underwater vehicles: the GLINT09 field trial results
(NURC, 2012/05)Surveillance in antisubmarine warfare (ASW) has traditionally been carried out by means of submarines or frigates with towed arrays. These techniques are manpower intensive. Alternative approaches have recently been suggested ... -
Application of ray tracing with horizontal gradient to monostatic boundary reverberation
(NATO. SACLANTCEN, 1971/12)Presented is the current work being done at the Naval Research Laboratory (NRL) on the development of a series of computer programs to predict long range, low frequency, monostatic boundary reverberation. The emphasis is ... -
Application of the Riesz potential to the Cauchy problem for wave propagation in an inhomogeneous medium
(NATO. SACLANTCEN, 1971/12)The method of Riesz [Ref. l] for the solution of hyperbolic partial differential equations is applied to the Cauchy problem for the wave equation. It is shown that the first term in the Riesz potential function, which is ... -
Approximate methods for ray tracing
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Arctic ambient noise statistical measurement results and their implications to sonar performance improvements
(NATO. SACLANTCEN, 1982/06)Recent analyses of FRAM II arctic data have shown that under ice ambient noise can be at times highly impulsive and non-Gaussian. The analyses included time domain statistical measurements which were consistent with ... -
Areal seabed classification using backscatter angular response at 95kHz
(NATO. SACLANTCEN, 1997)A sediment classification scheme is developed based on the angular response (AR) of the seabed backscatter strength. The AR is characterised based on its mean level and slope over predefined angular sectors, and the presence ... -
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 ...