Browsing by Title

Now showing items 335-354 of 882

    • Experimental data on the refraction of underwater explosion pulses 

      Barash, R. M.; Goertner, J. A. (NATO. SACLANTCEN, 1971/12)
      There are several reasons why a researcher in underwater acoustics might be interested in the use of explosion pulses as sources. The most generally recognized reason is that explosions are convenient and powerful sources ...

    • Experimental demonstration of the focused acoustic field in the ocean 

      Akal, Tuncay; Ferla, Melchiorre C.; Kuperman, William A.; Hodgkiss, W. S.; Song, H. C.; Jackson, Darrell R. (NATO. SACLANTCEN, 1998/10)
      An experiment conducted in the Mediterranean Sea in April1996 demonstrated that a time reversal mirror (or phase conjugate array) can be implemented to spatially and temporally refocus an incident acoustic field back to ...

    • Experimental evaluation of Net-LBL: an acoustic network-based navigation system 

      Sliwka, Jan; Petroccia, Roberto; Munafò, Andrea; Djapic, Vladimir (CMRE, 2019/06)
      This paper describes the use and in-field evaluation of a Networked-Long Base Line system (Net-LBL) where a network of underwater nodes cooperate to support the localisation and navigation of mobile vehicles. To avoid the ...

    • Experimental results of 300 kHz shallow water synthetic aperture sonar 

      Bellettini, Andrea; Pinto, Marc A.; Evans, Benjamin (NURC, 2007/11)
      The design of a shallow water synthetic aperture sonar (SAS) requires an understanding of key system and environmental issues. The main factors which limit SAS performance are micronavigation accuracy, where micronavigation ...

    • Experiments with multi-vehicle operations: the Rapid Environmental Picture Atlantic exercise 2014 

      Borges de Sousa, João; Pereira, João; Alves, João; Galocha, Madaleno; Pereira, Baptista; Lourenço, Claro (CMRE, 2019/06)
      The paper describes the Rapid Environmental Picture Atlantic exercise 2014 (REP14-Atlantic), with special focus on the experiments with autonomous underwater, surface and air vehicles, and discusses how large scale ...

    • Exploiting phase information in synthetic aperture sonar images for target classification 

      Williams, David P. (CMRE, 2019/05)
      It is demonstrated that the phase information present in complex high-frequency synthetic aperture sonar (SAS) imagery can be exploited for successful object classification. That is, without using the amplitude content of ...

    • Extended target tracking applied to X-band radar data 

      Vivone, Gemine; Braca, Paolo; Errasti, Borja (CMRE, 2019/06)
      X-band marine radar systems are flexible and low-cost tools for monitoring multiple targets in a surveillance area. They are able to provide high resolution measurements in both space and time. Such features offer the ...

    • Extended target tracking using joint probabilistic data association filter on X-band radar data 

      Vivone, Gemine; Braca, Paolo; Errasti, Borja (CMRE, 2019/06)
      X-band Marine radar systems are low-cost tools for monitoring multiple targets in a surveillance area. Although they may suffer from several sources of interference, high resolution measurements in both space and time can ...

    • Extended towed-array processor by overlapped correlator 

      Stergiopoulos, S.; Sullivan, Edward J. (NATO. SACLANTCEN, 1988/11)
      The development of an algorithm for extended towed-array measurements, which could be used by matched-field estimators to obtain information about depth and range of a source, is studied. This algorithm combines coherently ...

    • Extracting acoustic source information of shipping noise for dynamic ambient noise modelling 

      Pennucci, Giuliana; Jiang, Yong-Min (CMRE, 2019/05)
      Shipping traffic is one of the largest contributors to anthropogenic noise in the ocean. Noise generated by merchant ships elevates natural occurring ambient noise level by 20-30 dB in many areas of the world?s ocean. In ...

    • Fast Fourier transformation algorithms: experiments with microcomputers 

      Conolly, Brian W.; Hastrup, Ole F. (NATO. SACLANTCEN, 1986/07)
      We describe experiments intended to exploit the potential of modern

    • Fast unsupervised seafloor characterization in sonar imagery using lacunarity 

      Williams, David P. (CMRE, 2019/06)
      A new unsupervised approach for characterizing seafloor in side-looking sonar imagery is proposed. The approach is based on lacunarity, which measures the pixel-intensity variation, of through-the-sensor data. No training ...

    • Finite difference modelling of scattering by objects in the seabed 

      Fawcett, John A.; Grimbergen, Joris L. T. (NATO. SACLANTCEN, 1996/07)
      In this report we describe the theory and some implementation issues of a finite difference code used at SACLANT Centre. In particular, we consider the modelling of attenuation and the excitation of a remote incident field ...

    • Flow noise interference in measurements of infrasonic ambient noise 

      Strasberg, M. (NATO. SACLANTCEN, 1982/06)
      Estimates are presented of the local noise generated at infrasonic frequencies by turbulent water flowing in the vicinity of hydrophones used for measurements of ambient noise in the sea. Three situations are discussed: a ...

    • Formulae for bistatic signal and reverberation 

      Harrison, Chris H. (NATO. SACLANTCEN, 2002/12)
      This report demonstrates that it is possible to obtain closed-form solutions for signal and reverberation in a wide variety of bistatic scenarios including ducts and bottom bathymetry. These formulae adapt earlier monostatic ...

    • Forward looking sonar mosaicing for mine countermeasures 

      Ferreira, Fausto; Djapic, Vladimir; Micheli, Michele; Caccia, Massimo (CMRE, 2019/06)
      Forward looking sonars (FLS) are nowadays popular for many different applications. In particular, they can be used for Automatic Target Recognition (ATR) in the context of Mine Countermeasures. Currently, ATR techniques ...

    • Fostering marine robotics through competitions: from SAUC-E to ERL Emergency 2018 

      Ferri, Gabriele; Ferreira, Fausto; Djapic, Vladimir (CMRE, 2019/05)
      Marine robotics competitions and challenges are today very popular in the robotics community. Their value mainly lies in the opportunities they provide to teams (both student and professional) for developing and testing ...

    • Fostering the use of JANUS in operationally-relevant underwater applications 

      Petroccia, Roberto; Alves, João; Zappa, Giovanni (CMRE, 2017/11)
      This paper presents the use of JANUS in operationally-relevant underwater applications. JANUS is an open, simple and robust digital coding technology currently in process to become a NATO standard. Two underwater scenarios ...

    • Frequency deviation indicator 

      Rynja, Henk A. J. (NATO. SACLANTCEN, 1963/11)
      A new type of discriminator was developed to measure the frequency variation of electrical signals; it has the special feature to indicate without any delay the difference between the signal frequency and some fixed reference ...

    • From data to decision: an overview of CMRE's information supply chain 

      Berni, Alessandro; Cimino, Giampaolo; Camossi, Elena; Giannecchini, Simone (CMRE, 2019/06)
      Proper data curation is a prerequisite for the creation of long-lasting value from scientific datasets and for the generation of authoritative data-driven decision support tools. Availability of detailed information on ...