Browsing CMRE Publications by Subject "Acoustic reflection"
Now showing items 1-20 of 20
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A detailed study of sound reflections from a layered ocean bottom
(NATO. SACLANTCEN, 1965/05)The effect of layered sediments on sound reflection from the ocean bottom has been investigated theoretically and experimentally. Very detailed, systematic and computer-aided calculations of the reflection coefficient of ... -
Acoustic bottom reflectivity
(NATO. SACLANTCEN, 1989/06)Acoustic reflectivity from the seafloor is often an important factor influencing the performance of ASW systems in different environments, such as in deep water when the bottom bounce paths are used, and in general in ... -
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 ... -
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 ... -
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 ... -
Evaluation of experimental techniques for determining the plane wave reflection coefficient at the sea floor
(NATO. SACLANTCEN, 1986/06)One of the most commonly used techniques for determinati on of the geoacoustical properties of the sea bed is the measurement of plane wave reflection coefficients at the ocean bottom. An incident field is pr oduced by ... -
Glider-based seabed characterization using natural-made ambient noise
(CMRE, 2019/06)Seabed characteristics (geoacoustic properties and scattering strength) are critical parameters for sonar performance predictions. However, this bottom information is considered very difficult and expensive to achieve in ... -
High resolution geoacoustic inversion in shallow water: a joint time and frequency domain technique
(NATO. SACLANTCEN, 1998/12)High resolution geoacoustic data are quired for accurate predictions of -
Highlights of bottom topography inferred from received depression and bearing angles
(NATO. SACLANTCEN, 1975/10)Statistical properties of the acoustic reflection from the ocean floor have been studied for a var i.ety of bottom types including deep, smooth, flat topography thorough, jagged bottom in shallower (~l km) depths. Explosive ... -
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 ... -
Ocean-bottom reflectivity (a point of view)
(NATO. SACLANTCEN, 1975/10)The analysis procedures for extracting bottom loss values from pulsed acoustic signals that have interacted with the ocean bottom do not inherently consider sub-bottom refraction and reflection of sound, which are important ... -
Reflection of sound from a layered ocean bottom
(NATO. SACLANTCEN, 1975/10) -
Refraction of sound in the sea floor
(NATO. SACLANTCEN, 1975/10)A major mode of propagation of acoustic energy at low frequencies is a shallow refracted path through unconsolidated sediments of the sea floor. Successful modelling of the bottom-refracted mode of propagation requires ... -
Separability of scattering and reflection parameters in reverberation inversion
(NURC, 2007/11)A premise of reverberation inversion is that one can separate geoacoustic reflection properties from scattering properties since their effects on reverberation are distinguishable. Some doubt has been cast on this premise ... -
Separability of seabed reflection and scattering properties in reverberation inversion
(NURC, 2007/02)Separation of scattering properties (Lambert's mu) from reflection properties (the reflection loss angle derivative alpha) presents difficulties in the geoacoustic inversion of long range reverberation in isovelocity ... -
Sub-sea floor buried reflectors imaged by low frequency active sonar
(NATO. SACLANTCEN, 1996/06)Low Frequency Active Sonar (LFAS) utilizes low-frequency acoustic -
The effect of a layer of varying density on high-frequency acoustic reflection, forward propagation loss and backscattering strength
(NATO. SACLANTCEN, 1997/06)This report examines the impact that a thin layer of varying density would have on high-frequency reflection, forward loss and backscattering of acoustic plane waves from the seafloor. A functional form for density ... -
The sea surface as a random filter for underwater sound waves
(NATO. SACLANTCEN, 1974/06)In this dissertation the phenomenon of scattering and reflection of underwater sound waves from the sea surface is studied by considering the surface sound channel as a random, time-dependent filter. This filter can be ... -
Theory of scattering and reflection of sound from the sea surface
(NATO. SACLANTCEN, 1975/10)Theoretical work on scattering and reflection of sound from the random timevarying rough sea surface is critically reviewed. It is shown that sound scattering from the sea surface may be treated as a purely acoustic boundary ...
