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Wyświetlanie 1-5 z 5
Tytuł:
High resolution multi-beam side looking sonar
Autorzy:
Elminowicz, A,
Zajączkowski, L.
Powiązania:
https://bibliotekanauki.pl/articles/332745.pdf
Data publikacji:
2005
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
The conventional side–scan sonars does not ensure sufficient angular and range resolution to detect very small objects with small target strength. Decrease of beam width leads to the increase of angular resolution but requires the decrease of towing speed what means reduction of searched area. Other method of the angular resolution increased is designing multi–beam sonar or sonar with synthetic aperture. The paper presents a design of effective multi–beam side looking sonars with a large angular and range resolution operates with 100 kHz, 200 kHz, 400 kHz and 600 kHz. The sonar, described in the paper, operates with 200 kHz frequency; LFM modulation – 20 kHz and 40 kHz band; array provides 32 elements with d/ë spacing what ensure a shaping of 5 or 9 beams with 0,40° width. The range of sonar is from 250 m to 300 m, the level of side lobes are smaller than -20 dB and level of grating lobes for 5 beams are smaller than -30 dB. The principle of sonar performance and wideband effective processing are presented. Effectiveness of processing depends on beams number and decrease of beams number, together with the range increased, leads to increase of processing effectiveness.
Źródło:
Hydroacoustics; 2005, 8; 37-46
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of high resolution methods to underwater data processing
Autorzy:
Minassian, G. R.
Powiązania:
https://bibliotekanauki.pl/articles/332479.pdf
Data publikacji:
1997
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
The statistical approach to the high resolution acoustic signal parameter estimation is considered. The models of the Green's function for a deterministic and a random oceanic waveguide are presented. A brief discussion of popular superresolution methods with application to direction-of-arrival (DOA) and travel time estimation is done. Application of high resolution methods (HRM) to underwater data processing requires that certain modeling assumptions be made. Using maximum likelihood theory, the optimum processing algorithm for amplitudes, angles of arrival and travel times estimation is developed. The proposed techniques take into account the deterministic and the stochastic structure of the acoustic field.
Źródło:
Hydroacoustics; 1997, 1; 209-212
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High resolution methods of the analysis of acoustic signals in medicine
Autorzy:
Lis, W.
Schmidt, J.
Powiązania:
https://bibliotekanauki.pl/articles/332161.pdf
Data publikacji:
1999
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
The paper describes an analysis of the possible parametric methods used to estimate the spectrum of short acoustic signals of law oscillations. These kinds of signals often appear in acoustic waves emitted by the temporomandibular joint as it moves [1-2,5]. There is reason to suppose that the frequency which is characteristic of these oscillations could be an essential parameter confirming the pathology of the joint under examination. The measurement of low oscillations is difficult and not accurate, especially when nonparametric methods are used. The paper presents the results of analysis of a simulated short oscillating pulse using the DFT non-parametric method and the parametric method of linear prediction, using Burg algorithm. Finally, results of patient analysis are given, using the FFT and parametric methods.
Źródło:
Hydroacoustics; 1999, 2; 335-340
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Extraction of seabed geomorphologic features of Svalbard fjords using high-resolution side scan sonar
Autorzy:
Tęgowski, J.
Giżejewski, J.
Zieliński, A.
Powiązania:
https://bibliotekanauki.pl/articles/331637.pdf
Data publikacji:
2008
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
Svalbard fjords
side scan sonar
sea bed
Opis:
This paper presents results of a study on the relationship between features of side scan sonar acoustic imagery of zones with active bedforms and geomorphologic seafloor characteristics. Acoustic measurements were conducted in Hornsund, a Svalbard fjord representing a periglacial environment with great intensity of morphodynamic processes and rapidly progressing changes of tidewater glaciers. Due to the intensity of these processes, Arctic fjords are the most promising areas to study the effects of climate change on the ecosystem. Acoustic identification of sedimentary structures and morphological forms created by currents and iceberg transport of glacier sediment away from the ice margin was performed. The spectral and fractal features of the recorded signals were analysed. The proposed analysis scheme allows identification of the morphodynamic active zones in the changing Arctic fjord environments. Measurements of acoustical features of seafloor surface were made during the 2006 Arctic cruise of r/v Oceania.
Źródło:
Hydroacoustics; 2008, 11; 401-411
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Development of a high-resolution real-time-capable 3D SONAR camera for deep sea operation
Autorzy:
Ehrhardt, M.
Becker, F. J.
Speicher, D.
Fonfara, H.
Hewener, H.
Degel, C.
Tretbar, S.
Powiązania:
https://bibliotekanauki.pl/articles/332135.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
2D array
matrix array
3D imaging
beamforming
Opis:
Within this work we present a first experimental setup of a high-resolution real-timecapable 3D sonar camera system for deep sea operation. Since we are currently in the development process, the focus of this work is on the transmission aspects of the camera. Following publications will include the receiving aspects as well as the first phantom reconstructions. The system consists of a 1024 element matrix array antenna, together with a 128 channel beamforming system including a 1:8 multiplexing device for each channel. The camera is supposed to deliver volumetric images within a range of up to 15 m in a deep sea environment up to 6000 m depth. The antenna provides the advantage of an adjustable defocused transmitting sound field. This allows dynamic control of the field of view, and an increase of the image contrast for a specific region.
Źródło:
Hydroacoustics; 2016, 19; 101-110
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-5 z 5

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