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Wyświetlanie 1-15 z 33
Tytuł:
Implementation of contemporary technologies in naval sonars modernization
Autorzy:
Marszal, J.
Powiązania:
https://bibliotekanauki.pl/articles/331808.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
Today’s fast technological advancement in electronics and signal processing methods makes electronic systems, including sonars, obsolete very quickly. The Polish Navy seems to be particularly affected as its ships were built in the 1970s and 1980s. Researchers at the Gdansk University of Technology have developed a methodology for modernising Navy sonars which involves the use of new electronic sub-systems and modern, bespoke methods of digital signal processing. Thanks to that, the existing large and expensive ultrasonic transducers and their systems for deployment and stabilisation remain unchanged. Between 2001 and 2013 this methodology was used by the Gdansk University of Technology to modernise 26 sonars of different types for the Polish Navy. The projects have significantly improved the technical and utility parameters of the sonars, while keeping the expenditure at about 20% of the value of new equipment.
Źródło:
Hydroacoustics; 2013, 16; 167-180
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The numerical solution of boundary value problems of the theory of thermal stresses of isotropic plates
Autorzy:
Marszał, J.
Powiązania:
https://bibliotekanauki.pl/articles/748585.pdf
Data publikacji:
1976
Wydawca:
Polskie Towarzystwo Matematyczne
Opis:
Artykuł nie zawiera streszczenia
The article contains no abstract (see MR0452060)
Źródło:
Mathematica Applicanda; 1976, 4, 8
1730-2668
2299-4009
Pojawia się w:
Mathematica Applicanda
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Digital signal processing applied to the modernization of Polish Navy sonars
Autorzy:
Marszal, J.
Powiązania:
https://bibliotekanauki.pl/articles/260133.pdf
Data publikacji:
2014
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
sonar
anti-submarine warfare
mine countermeasure
digital signal processing
Opis:
The article presents the equipment and digital signal processing methods used for modernizing the Polish Navy’s sonars. With the rapid advancement of electronic technologies and digital signal processing methods, electronic systems, including sonars, become obsolete very quickly. In the late 1990s a team of researchers of the Department of Marine Electronics Systems, Faculty of Electronics, Telecommunications and Informatics, Gdansk University of Technology, began work on modernizing existing sonar systems for the Polish Navy. As part of the effort, a methodology of sonar modernization was implemented involving a complete replacement of existing electronic components with newly designed ones by using bespoke systems and methods of digital signal processing. Large and expensive systems of ultrasound transducers and their dipping and stabilisation systems underwent necessary repairs but were otherwise left unchanged. As a result, between 2001 and 2014 the Gdansk University of Technology helped to modernize 30 sonars of different types.
Źródło:
Polish Maritime Research; 2014, 2; 65-75
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental Study of Silent Sonar
Autorzy:
Marszal, J.
Powiązania:
https://bibliotekanauki.pl/articles/177418.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
silent sonar
wideband signal
detection
distance measurements
accuracy
Opis:
Stealth is a frequent requirement in military applications and involves the use of devices whose signals are difficult to intercept or identify by the enemy. The silent sonar concept was studied and developed at the Department of Marine Electronic Systems of the Gdansk University of Technology. The work included a detailed theoretical analysis, computer simulations and some experimental research. The results of the theoretical analysis and computer simulation suggested that target detection and positioning accuracy deteriorate as the speed of the target increases, a consequence of the Doppler effect. As a result, more research and measurements had to be conducted to verify the initial findings. To ensure that the results can be compared with those from the experimental silent sonar model, the target’s actual position and speed had to be precisely controlled. The article presents the measurement results of a silent sonar model looking at its detection, range resolution and problems of incorrect positioning of moving targets as a consequence of the Doppler effect. The results were compared with those from the theoretical studies and computer simulations.
Źródło:
Archives of Acoustics; 2014, 39, 1; 103-115
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Detection Range of Intercept Sonar for CWFM Signals
Autorzy:
Marszal, J.
Salamon, R.
Powiązania:
https://bibliotekanauki.pl/articles/176394.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
intercept sonar
silent sonar
CWFM signal
detection
detection range
Opis:
Stealth in military sonars applications may be ensured through the use of low power signals making them difficult to intercept by the enemy. In recent years, silent sonar design has been investigated by the Department of Marine Electronic Systems of the Gdansk University of Technology. This article provides an analysis of how an intercept sonar operated by the enemy can detect silent sonar signals. To that end a theoretical intercept sonar model was developed with formulas that can numerically determine the intercept ranges of silent sonar sounding signals. This was tested for a variety of applications and water salinities. Because they are also presented in charts, the results can be used to compare the intercept ranges of silent sonar and traditional pulse sonar.
Źródło:
Archives of Acoustics; 2014, 39, 2; 215-230
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Signal conditioning for examination of shallow-water acoustic noise correlation properties
Autorzy:
Rudnicki, M.
Marszal, J.
Powiązania:
https://bibliotekanauki.pl/articles/331724.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
underwater acoustics
ambient noise
noise envelope
tetrahedral antenna
Opis:
The article describes the process of signal conditioning for examination of acoustic noise correlation properties in shallow water. Knowledge of these properties is very important for the design processes of passive and active hydroacoustic systems. This paper focuses on the above issue from the point of view of passive sonar. In sonar systems, signal processing algorithms operate on both useful acoustic signals, and accompanying noise. Quantitative estimation of the correlation properties of acoustic noise enables an accurate determination of detection conditions. This will verify the validity of certain commonly used simplified models in simulations of hydroacoustic systems. The article presents how the measurement system was constructed, and the structure of files for storing measurement data. It describes the processing algorithm developed for the measured signal conditioning. Research results are presented and discussed.
Źródło:
Hydroacoustics; 2016, 19; 335-340
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Doppler estimation method for moving target location
Autorzy:
Salamon, R.
Marszal, J.
Powiązania:
https://bibliotekanauki.pl/articles/331983.pdf
Data publikacji:
2010
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
The article presents an algorithm for target location based solely on Doppler shift of echo acoustic signals of a moving underwater object. The algorithm is designed for use in multi-static systems for protecting bodies of water from terrorist attacks by divers or submerged vehicles. The original source of signals is a transmitter emitting continuous acoustic waves. The echo signals from moving object are received by hydrophones located at fixed and known points in the water. Doppler shifts are determined from discrete Fourier transforms of hydrophone signals. The proposed iterative algorithm for target location calculates the approximate values of target speed vector and target coordinates which correspond to speed vectors as calculated previously.
Źródło:
Hydroacoustics; 2010, 13; 225-234
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Theoretical analysis of a new approach to order determination for a modified Prony method in swath mapping application
Autorzy:
Grall, P.
Marszal, J.
Powiązania:
https://bibliotekanauki.pl/articles/332107.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
swath bathymetry
interferometry
principal components
DOA
MBES
Opis:
This article presents a new approach to determine the model order (number of principal components) in the modified Prony method applied to swath acoustic mapping. Determination of the number of principal components is a crucial step in the modified Prony method. In the proposed approach the model order is chosen based on the underlying physical model of the underwater acoustic environment, and utilised signal processing operations. This data-driven approach, attempts to make use of all available information to assess the number of signals arriving at the receiver using pipeline processing in lieu of iterative processing.
Źródło:
Hydroacoustics; 2017, 20; 63-74
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Distance measurement errors in silent FM-CW sonar with matched filtering
Autorzy:
Marszal, J.
Salamon, R.
Powiązania:
https://bibliotekanauki.pl/articles/220637.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
silent sonar
frequency modulation
continuous wave
matched filtering
distance measurement
errors
Doppler effect
Opis:
The secretiveness of sonar operation can be achieved by using continuous frequency-modulated sounding signals with reduced power and significantly prolonged repeat time. The application of matched filtration in the sonar receiver provides optimal conditions for detection against the background of white noise and reverberation, and a very good resolution of distance measurements of motionless targets. The article shows that target movement causes large range measurement errors when linear and hyperbolic frequency modulations are used. The formulas for the calculation of these errors are given. It is shown that for signals with linear frequency modulation the range resolution and detection conditions deteriorate. The use of hyperbolic frequency modulation largely eliminates these adverse effects.
Źródło:
Metrology and Measurement Systems; 2012, 19, 2; 321-332
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation into interferometric sonar system accuracy
Autorzy:
Grall, G.
Marszal, J.
Powiązania:
https://bibliotekanauki.pl/articles/332610.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
bathymetry
phase differencing sonar
hydrographic standards
Opis:
The results of the accuracy measurements of phase differencing bathymetric sonar (PDBS) system in shallow waters are presented in the article. The measurement results were compared with the theoretical calculations for sonar system accuracy and international standards for hydrographic surveys. The proposed formulas enable to assess a priori sonar system performance using system quality factor (SQF), which takes into account influence of variable environmental conditions and auxiliary sensors on depth accuracy in a real-life scenario. The proposed SQF can be used in survey planning process to predict the swath width.
Źródło:
Hydroacoustics; 2015, 18; 69-76
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of distance measurement errors in CW FM sonar with MLS code modulation
Autorzy:
Jedel, A.
Marszal, J.
Salamon, R.
Powiązania:
https://bibliotekanauki.pl/articles/331626.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
CW FM sonar
pseudorandom sequence
Doppler effect
sonar parameters
Opis:
Although used in the classic silent sonar, the CW FM sounding signal has a major flaw which is its inaccuracy in determining the distance to a target. The authors of the article have developed a concept of silent sonar using frequency modulation signals switched by pseudorandom codes, already discussed in their previous work. This article presents a detailed analysis of errors in CW FM sonar with pseudo-random sequence code modulation confronted with errors which occur in similar sonar without code modulation.
Źródło:
Hydroacoustics; 2017, 20; 75-84
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Continuous wave sonar with hyperbolic frequency modulation keyed by pseudo-random sequence
Autorzy:
Jedel, A.
Marszal, J.
Salamon, R.
Powiązania:
https://bibliotekanauki.pl/articles/331999.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
CW FM
pseudorandom sequence
Doppler effect
matched filtering
Opis:
A CW FM type sounding signal is used in the classical solution of silent sonar. While the signal provides a relatively simple implementation of digital signal processing, and ensures good detection conditions, unfortunately, in the presence of the Doppler effect, distance measurement results tend to be wrong. This is due to the fact that the received signal’s instantaneous frequency value is dependent both on the distance to the object, and its speed. Sounding signal, as patented by the authors, is a combination of Pseudo-Random Sequences (PRS), and elementary signals of Hyperbolic Frequency Modulation (HFM) type. The structure of this signal is aimed at minimizing measurement error. The article presents the idea of a sounding signal of HFM+PRS type, and the results of computer simulations.
Źródło:
Hydroacoustics; 2016, 19; 185-196
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Small antenna for a dipping sonar
Autorzy:
Marszal, J.
Jedel, A.
Ostrowski, Z.
Powiązania:
https://bibliotekanauki.pl/articles/332487.pdf
Data publikacji:
2001
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
The dome enclosing the antenna of dipping sonar should be of the smallest possible size. Presented in the paper is a concept of hydroacoustic antennas of active and passive sonar. The active antenna performs mechanical scanning while the passive antenna uses the orthogonal array of gradient hydrophones. In addition to that the antenna array includes ultrasonic transducers of a sound velocity profiler, a pressure sensor for measuring the depth of antenna submergence. With that many sources of signal in the sonar's ease, a multiple fibre cable is required or signal modulation to transmit the signals over a limited number of wires. The sonar in question uses distribution over time and an original modulation method for simultaneous transmission of several signals using a cable channel. Block diagram and formulas describing the entire signal from the sonar's antenna are included.
Źródło:
Hydroacoustics; 2001, 4; 169-172
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of maximum length sequence in silent sonar
Autorzy:
Marszal, J.
Salamon, R.
Kilian, L.
Powiązania:
https://bibliotekanauki.pl/articles/331898.pdf
Data publikacji:
2012
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
Silent sonars are designed to reduce the distance over which their sounding pulses can be detected by intercept sonars. In order to meet this objective, we can use periodical sounding signals that have low power, a very long duration and wide spectrum. If used in the silent sonar’s receiver, matched filtration ensures very good detection of motionless or slow moving targets. However, it is more difficult to detect echo signals of fast moving targets with Doppler effect causing significant error in target distance measurements. In an effort to find signals that can better resist Doppler effect, maximum length sequence was tested for its application in silent sonar. It has an elementary signal which includes linear frequency modulation. It was demonstrated that the signal produces much better results than those obtained with simple frequency modulation signals.
Źródło:
Hydroacoustics; 2012, 15; 143-152
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Silent sonar with matched filtration
Autorzy:
Salamon, R.
Marszal, J.
Schmidt, J.
Rudnicki, M.
Powiązania:
https://bibliotekanauki.pl/articles/331754.pdf
Data publikacji:
2011
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
Radars with continuous wave frequency (CW FM sonars) are used in radiolocation as ‘silent radars’. They determine the distance to target by measuring the difference between the frequency of the sounding signal and echo signal. The article presents the principle of operation and parameters of silent CW FM sonars. Target distance determined by these sonars is based on the signal at the output of the matched filter. The Doppler effect is studied in detail to identify its effect on the sonar’s parameters. The results of theoretical calculations are presented together with the results of the sonar’s computer simulation.
Źródło:
Hydroacoustics; 2011, 14; 199-208
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 33

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