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Wyszukujesz frazę "Elminowicz, A." wg kryterium: Autor


Tytuł:
Broadband LFM signal source for a module-based diver detection sonar
Autorzy:
Zachariasz, K.
Lis, W.
Elminowicz, A.
Powiązania:
https://bibliotekanauki.pl/articles/332017.pdf
Data publikacji:
2010
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
A new approach to design of the diver detection sonar’s sounding pulse source is pre-sented. It is based on modules comprising 8 or 16 elements of the transducer grouped on the transmitting channel. The basic advantage of this solution is that it reduces significantly the number of group transmitters. The required output power and topology of the transmitters were determined through theoretical estimation and measurements in a four terminal network. Measurements were taken of the frequency characteristics in the transducer modules includ-ing the compensation system used. It is demonstrated that the source level is most irregular in the transducer under examination when the transducer’s voltage has a constant amplitude, i.e. with parallel compensation. It is also demonstrated that by appropriately selecting ele-ments for a series compensation of the transducer, the frequency characteristics becomes more regular and source level is increased at the extreme ends of the working bandwidth. The result is a compensated characteristics on the receiving side.
Źródło:
Hydroacoustics; 2010, 13; 269-278
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelling multistatic of target detection
Autorzy:
Klusek, Z.
Elminowicz, A.
Tęgowski, J.
Szczucka, J.
Dragan, A.
Powiązania:
https://bibliotekanauki.pl/articles/331565.pdf
Data publikacji:
2008
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
Gdansk Gulf
chirp signals
hydroacoustic
Opis:
The paper presents a numerical approach to modelling the detection of underwater targets with a bi- or multistatic active sonar systems in the shallow water areas using different waveform signals. The results of the numerical modelling of surface, bubble clouds and bottom reverberation for CW and using up and down time-varying instantaneous frequency of chirp signals are presented. Some suggestions are made on the basis of the development and practicality for the shallow sea modeling techniques and approaches to existing sonar models. The paper reports the literature of the model components required for active sonar modelling for different propagation conditions. Some examples of scattering of CW and chirp source signals at bubble clouds and corrugated surfaces, and coherence are given. Active propagation and the system performance are surveyed and modelled adaptable to the specific environmental condition of the shallow sea area of the Gdansk Gulf.
Źródło:
Hydroacoustics; 2008, 11; 131-138
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
System for bistatic measurements of reverberations in the shallow sea area
Autorzy:
Klusek, Z.
Elminowicz, A.
Majewski, P.
Dragan, A.
Powiązania:
https://bibliotekanauki.pl/articles/331817.pdf
Data publikacji:
2011
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
In the paper a system for measurements of reverberations in the shallow sea environment is presented. The setup operated in 40–80 kHz frequency range with pseudomonochromatic pulses or chirp signal and has possibility to acquire bistatic scattered data. The system is constructed in such manner that depending on an experiment configuration we could perform measurements of the local 3D scattering strength of the bottom and/or far range bistatic reverberations from the sea surface, volume inhomogeneities and sea bottom. The final objective of the system is to give prognosis for probability of target detections when using bior multistatic barriers. Details of the individual blocks are given in the following sections and the technicalities of the design are given. Furthermore, some examples of data gathered during test of the equipment concerning assessment of the reverberation and local bistatic scattering features are presented.
Źródło:
Hydroacoustics; 2011, 14; 83-90
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Data processing of broad-band signals received by multi-element cylindrical transducer
Autorzy:
Janowski, T.
Elminowicz, A.
Szworski, K.
Powiązania:
https://bibliotekanauki.pl/articles/331559.pdf
Data publikacji:
2008
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
data processing
multi-element cylindrical transducer
hydroacoustic
Opis:
The sonar based on cylindrical transducer compared with linear transducer has few advantages. Particularly its omni-directional central symmetry enables simplification of the echo signal Direction of Arrival (DOA) estimation. When the number of transducer staves is the power of two the efficient Fast Fourier Transformation can be used to calculate spatial convolution. The article presents theoretical and technological principles of the real time digital data processing of the wideband echo signals received by cylindrical hydroacoustic transducer. Described procedures enable high resolution underwater target location and precise data display. The implementation of effective broadband pulse compression technique with high range resolution will be presented. The results of signal processing modeling and examples of application will be also discussed.
Źródło:
Hydroacoustics; 2008, 11; 113-120
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ahead looking sonar with cylindrical array
Autorzy:
Elminowicz, A.
Powiązania:
https://bibliotekanauki.pl/articles/332419.pdf
Data publikacji:
1999
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
Cylindrical arrays are widely used in omnidirectional or very wide sector sonars. These arrays utilise horizontal phasing for compensation of geometrical phase-delays, which form a narrow beam. The cylindrical symmetry of the array provides beam rofation around the array. The ahead looking sonar using the above method needs an array with a large number of staves and a larger number of receiver channels. This paper presents the design approach to ahead looking sonars with a cylindrical arc array using delay of the staves signals for equalising of the array and a beamforming processor for beam steering. This sonar performance is determined by array parameters and a processing method used to form the beams. There is no simple closed form of mathematical expression for a delayed signals and steered beam of such arrays so the array and method of beamforming have to be analysed by considering the elements spacing, weighting and directivity. The angular aperture and radius of array curvature are analysed. The results of a computer simulation of beam patterns for such sonars are presented. The indication for design of ahead looking sonars with cylindrical arc array using equalising and beam steering processing are presented.
Źródło:
Hydroacoustics; 1999, 2; 139-144
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An experimental study on transducer for the DDS technology demonstrator
Autorzy:
Elminowicz, A.
Lis, W.
Męciński, W.
Powiązania:
https://bibliotekanauki.pl/articles/332550.pdf
Data publikacji:
2009
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
transducer
DDS technology
sonar
Opis:
R&D MTC has began designing and building the next generation wideband Diver Detection Sonar (DDS, with cylindrical multielement piezocomposite transducer. The paper will focus on key features of DDS technology demonstrator, with special attention on technologies of the transducer. The new transducer is designed at the cooperation with the producer of the transducer - Materials Systems Inc. (Littleton, USA), remainder hardware and software solutions are designed in R&D MTC. In this article specific theoretical and technological principles of the wideband cylindrical piezocomposite transducer will be presented. The implementation of the transducer to the wideband Diver Detection Sonar (DDS) will be described. The results of transducer measurements, transmitter modules, matching circuits modeling and examples of application will be also presented.
Źródło:
Hydroacoustics; 2009, 12; 45-52
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of DDS and magnetic barrier cooperating with acoustic barriers and tethered sonobuoys for harbour and anchorage underwater protection
Autorzy:
Elminowicz, A.
Zajączkowski, L.
Powiązania:
https://bibliotekanauki.pl/articles/331708.pdf
Data publikacji:
2011
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
The underwater protection system that consists of wideband Acoustic Barriers (WAB) and wideband DDS (WDDS) is a very suitable acoustic device to operate in Littoral Water (LW) and Extremely Littoral Water (ELW). A new approach to underwater protection harbour and task group on the anchorage against AUV, DDV and torpedos is focused on designed stationary tethered sonobuoys with passive sonar, active multistatic sonar, intercept sonar and also possibility of jamming intercepted underwater objects. Passive omnidirectional sonar may be used for initial detection of intruder on the long distance (up to 5 km) and active multistatic sonar will be applied for detection and precise location of detected object. Intercept sonar is waiting for homing sonar signals generated by AUV, DDS, torpedos or submarines and received signals are basis generating jamming signals. The paper describes the WAB, WDDS and magnetic barrier integrated to short range (up to 1000 m) protection systems. The long range (up to 5000 m) sonobuoy – for various technical parameters and environmental conditions – has been studied.
Źródło:
Hydroacoustics; 2011, 14; 39-46
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Badanie przetwornika o nierównomiernie rozmieszczonych elementach
Autorzy:
Elminowicz, A.
Porosińska, E.
Powiązania:
https://bibliotekanauki.pl/articles/332235.pdf
Data publikacji:
2000
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
General object of nonuniform array design is the approximation of desired beam pattern with reduced number of elements which are required for uniform array of d/α=0,5. This work intends to study possibilities of design procedures lead to useful, nonuniform arrays with elements situated in raster d/α=0,5. Options of spacing elements for nonuniform arrays presented beneath are reduced to the raster d/α=0,5, which enable easier technical realisation of the beamformer. Arrays with equal excited elements have been used, what is highly practical, both for transmission and receiving. Many designs of arrays have been proposed and tested The beam patterns for steered beams are presented.
Źródło:
Hydroacoustics; 2000, 3; 135-140
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Correction of frequency distortion of the DDS signals
Autorzy:
Elminowicz, A.
Zajączkowski, L.
Powiązania:
https://bibliotekanauki.pl/articles/331959.pdf
Data publikacji:
2010
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
The Diver Detection Sonar (DDS) as a surveillance system has been designed to monitor the threat of underwater attacks against harbours, ships, naval bases, coastal industrial installations, oil platforms etc. This paper describes technical complexity of designing wideband DDS, with increased coverage effectiveness and following additional advantages: improved range resolution, high signal to noise and reverberation ratio and possibility operation of several sonars in the same frequency band using different type of modulation. The article presents technological principles and problems related to the wideband sig-nals transmitting and receiving by cylindrical piezocomposite transducer as well as implementation of the broadband compression technique for correction of frequency distortion.
Źródło:
Hydroacoustics; 2010, 13; 83-88
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Doppler effect in wideband sonars
Autorzy:
Elminowicz, A.
Zajączkowski, L.
Powiązania:
https://bibliotekanauki.pl/articles/332069.pdf
Data publikacji:
2004
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
To increase sonar range and to improve the range resolution and SNR, modern sonars use a matched filtration what corresponds to correlation between replica of transmitted sig-nal and received echoes. Motion of sound source or/and object causes frequency Doppler shift of received signals, thereby generating the distortion of the correlation processing of echo with signal replica. In the paper, the results of studies of sonar signals (CW, LFM and HFM) immunity to correlation distortions due to Doppler effect are presented. It has been demonstrated that only HFM signals are immune to adverse Doppler effect in correlation processing.
Źródło:
Hydroacoustics; 2004, 7; 31-36
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
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:
Multi-beam side-scan sonar
Autorzy:
Elminowicz, A.
Powiązania:
https://bibliotekanauki.pl/articles/332735.pdf
Data publikacji:
2001
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
Conventional single beam side-scan sonars with beams at about 1o are not well suited for the detection and identification of very small objects TS < -25 dB - e.g. minelike objects. Sonars of very high angular resolution at 0.1o - 0.2o operate in the nearfield and the speed of the sonar's transducer towing has to be reduced significantly. The paper presents a design approach to a multi-beam side-scan sonar where the above mentioned drawbacks have been removed. The sonar has several narrow parallel (not conical) beams simultaneously formed using the method of beam shaping in the nearfield. Two methods of beam shaping in the nearfield are presented. Thanks to them sonars of various quality and cost can be designed. Selected beam patterns for the two methods of beam forming in the nearfield are presented and compared.
Źródło:
Hydroacoustics; 2001, 4; 57-60
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multifrequency wideband sonar array
Autorzy:
Elminowicz, A.
Lis, W.
Zajączkowski, L.
Powiązania:
https://bibliotekanauki.pl/articles/332415.pdf
Data publikacji:
2012
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
This paper describes of new approach to Multifrequency Wideband Arrays (MWA), applied piezocomposite technologies of the array elements. MWA operating in transmitting (Tx) and receiving (Rx) mode on two or three bands, requires state-of-the-art technology and efficient array designing than conventional array in which separate arrays for every band or even separate Tx and Rx transducers/arrays are used. The new piezocomposite elements are designed at OBR Centrum Techniki Morskiej S.A., manufactured by Materials Systems Inc. (Littleton, USA) and tested at the cooperation with Gdansk University of Technology. The article presents research and development work at the multifrequency wideband piezocomposite arrays elements. An example of dual frequency wideband Tx/Rx array with design parameters and its implementation for the dual frequency wideband sonar will be presented. The results of array elements measurements: TVR, RVS, Impedance and Phase versus frequency from 50 kHz to 500 kHz as well as beam patterns, will be also presented.
Źródło:
Hydroacoustics; 2012, 15; 33-38
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multistatic systems
Autorzy:
Elminowicz, A.
Zajączkowski, L.
Powiązania:
https://bibliotekanauki.pl/articles/332386.pdf
Data publikacji:
2006
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
This paper describes key features of a multistatic operation in the littoral beginning from multistatic system (MS) configuration, his performance model and constraints imposed by environment of shallow water. The architecture of MS, features and requirements of MS basic subsystem has been presented. Essential role as during MS operation is fulfilled by data fusion and tracking methods as well a communication between MS units, has been protruded. The application of MS, especially for underwater protection systems, in the form of barriers protecting anchorage, harbour, straits or entries to the harbour has been presented. Other applications are connected with military operation, especially Anti–Submarine Warfare (ASW) in littoral areas. Attention was paid on possibility of cooperation among the different acoustics devices in MS.
Źródło:
Hydroacoustics; 2006, 9; 57-64
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mutual interferences reduction between sonars or barrier modules operating in the same area
Autorzy:
Elminowicz, A.
Zajączkowski, L.
Powiązania:
https://bibliotekanauki.pl/articles/332459.pdf
Data publikacji:
2007
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
This paper describes key features of a Mutual Interference Reduction (MIR) in sea area, especially in shallow water, where some acoustic devices may operate simultaneously. MIR is an essential problem in mono– and multistatic systems. Receivers of sonars or barrier modules, operating in these systems, can receive signals from other acoustic devices by direct track, as echoes from the targets or as reverberations. The mutual sonars interference level depends on many parameters, like: the transmitting signal parameters (modulation, SL, B, T) and bands aliasing, mutual sectors coverage, the distance and mutual localization of trans-mitting transducers and receiving arrays, as well as type of matched filtration. The degrada-tion of mutual interferences by matched filtration has been determined. Influence of modula-tion type, B and T parameters on MIR at the matched filtration output have been presented also.
Źródło:
Hydroacoustics; 2007, 10; 39-44
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł

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