Browsing by Subject "Ambient noise"

Now showing items 21-36 of 36

    • Noise measurements during MAPEX 2000 

      Harrison, Chris H. (NATO. SACLANTCEN, 2002/03)
      During MAPEX2000 some simultaneous ambient noise measurements with an HLA and satellite SAR images were collected. The aim was to predict shipping and wind noise from the satellite radar and to compare results with acoustic ...

    • Noise sources in the ocean - part 1 

      Wille, Peter C. (NATO. SACLANTCEN, 1975/10)
      Following a brief historical survey of the development of our knowledge of the origins and characteristics of ambient noise in the ocean, the principal known sources of noise are described. These are: environmental origin, ...

    • Noise sources in the ocean - part 2 

      Daintith, Maurice J. (NATO. SACLANTCEN, 1975/10)
      Following a brief historical survey of the development of our knowledge of the origins and characteristics of ambient noise in the ocean, the principal known sources of noise are described. These are: environmental origin, ...

    • Notes on the interpretation of ambient noise statistics 

      Cavanagh, Raymond C. (NATO. SACLANTCEN, 1982/06)
      Interpretation of statements about the character of ambient sea noise, as well as schemes to measure or model noise, are sensitive to the context or underlying view of what is essentially a stochastic process. A framework ...

    • The ocean noise coherence matrix and its rank 

      Harrison, Chris H. (CMRE, 2019/05)
      An expression for the cross-spectral density matrix of ocean noise naturally separates into a Toeplitz part and a Hankel part [Harrison (2017). J. Acoust. Soc. Am. 141, 2812?2820]. The Toeplitz part is shown to be substantially ...

    • Predicting underwater ambient noise with an evolutionary signal processing method 

      Alvarez, Alberto; Harrison, Chris H.; Siderius, Martin (NATO. SACLANTCEN, 2001/06)
      In this report we employ recent developments in non-linear physics and time series prediction to study the physical characteristics of measured underwater ambient sounds. Specifically, we examine the predictability of a ...

    • Role of propagation in ambient noise 

      Ross, Donald (NATO. SACLANTCEN, 1982/06)
      To be useful for modern ASW systems design and analyses, descriptions of ambient noise fields must go beyond average omnidirectional spectra and include horizontal and vertical patterns, fluctuations with time, dependencies ...

    • Seismic and hydroacoustic sensing of infrasonic noise in coastal waters 

      Schmalfeldt, Bernd; Rauch, Dieter (NATO. SACLANTCEN, 1982/06)
      Three-component ocean-bottom seismometers with radio links have been deployed in coastal waters to investigate natural and man-made noise at extremely low frequencies. Seismograms from one or up to three sensor stations ...

    • Separation of measured noise coherence matrix into Toeplitz and Hankel parts 

      Harrison, Chris H. (CMRE, 2017/08)
      The cross-spectral density of ocean ambient noise is usually estimated from the product of the complex hydrophone signals, each of which already corresponds to the summed responses of sources from all angles. The true ...

    • Site and frequency dependence of ambient noise in the North Eastern Pacific Ocean 

      Wilson, James H. (NATO. SACLANTCEN, 1982/06)
      One-hour averages of omnidirectional ambient noise measurements at 60 Hz and 165 Hz are analyzed for two nearby, deep ocean sites in the Northeastern Pacific during February and March 1981. Site A is a high noise site and ...

    • Target detection and location with ambient noise 

      Harrison, Chris H. (NURC, 2008/09)
      By placing a vertical array in an ambient noise field and forming an upward and a downward beam one obtains two time series which can be cross correlated to reveal a subbottom profile of the seabed [Siderius et al., J. ...

    • The seamount as a noise barrier 

      Medwin, Herman; Childs, Emily; Jordan, Edgar A. (NATO. SACLANTCEN, 1982/06)
      When the path from a localized noise source is intercepted by a seamount the shielded noise consists of a diffracted component and, if the seamount is close to a sufficiently smooth ocean surface , a multiply-reflected ...

    • Time dependence of infrasonic ambient seafloor noise on a continental shelf 

      Akal, Tuncay; Barbagelata, Alessandro; Guidi, Guido; Snoek, Michael (NATO. SACLANTCEN, 1986/06)
      SACLANTCEN is conducting a long term programme of ambient noise measurements that cover the frequency band from 1 to 100 Hz. A sea-bed sensor consisting of three seismometers and a hydrophone has been deployed close to the ...

    • Underwater ambient noise: proceedings of a conference held at SACLANTCEN on 11-14 May 1982 - vol. 2: unclassified papers, part 1 

      Underwater ambient noise conference (1982 May 11-14 : La Spezia, Italy) (NATO. SACLANTCEN, 1982/06)

    • Underwater ambient noise: proceedings of a conference held at SACLANTCEN on 11-14 May 1982, vol. 2 - Unclassified Papers, part 2 

      Underwater ambient noise conference (1982 May 11-14 : La Spezia, Italy) (NATO. SACLANTCEN, 1982/06)
      Contents: PROCESSING TECHNIQUES--A method of estimating the influence of ship's noise on ambient noise measurements; Optimal detection and tracking of acoustical noise sources in a time-varying environment; Influence of ...

    • Very low frequency ambient noise measurements in the Ionian Sea: data report 

      Desharnais, Francine; Urban, Heinz G.; D'Spain, Gerald L. (NATO. SACLANTCEN, 1997/09)
      This memorandum describes an experiment and provides a data