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Wyszukujesz frazę "Lasota, R." wg kryterium: Autor


Wyświetlanie 1-7 z 7
Tytuł:
Application of maximum-length sequences to impulse response measurement of hydroacoustic communications systems
Autorzy:
Mazurek, R.
Lasota, H.
Powiązania:
https://bibliotekanauki.pl/articles/332528.pdf
Data publikacji:
2007
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
There is a growing interest in digital transmission of telemetry data on ultrasonic waves. The dependence of signal attenuation on squared frequency, specific to the hy-droacoustic systems, induces problems that do not exist in monochromatic, narrowband radio communications systems. For adapting the transmission parameters to current propagation conditions, a precise knowledge of instantaneous changes of channel performances is needed. Simulating and testing of broadband communications techniques require robust, reliable and efficient method of impulse response measurements in natural exploitation conditions. The paper presents the MLS (Maximum-Length Sequence) correlation method applied to impulse response measurements of electroacoustic transducers as elements of communication chain.
Źródło:
Hydroacoustics; 2007, 10; 123-130
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ultrawideband transmission in physical channels: a broadband interference view
Autorzy:
Lasota, H.
Kochańska, I.
Mazurek, R.
Powiązania:
https://bibliotekanauki.pl/articles/331525.pdf
Data publikacji:
2014
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
The superposition of multipath components (MPC) of an emitted wave, formed by reflections from limiting surfaces and obstacles in the propagation area, strongly affects communication signals. In the case of modern wideband systems, the effect should be seen as a broadband counterpart of classical interference which is the cause of fading in narrowband systems. This paper shows that in wideband communications, the time- and frequency-domain approach of the linear time-invariant (LTI) systems theory does not fully reveal the significance of channelinduced distortions. A survey of MPC interference phenomena is presented, with time-evolving impulse responses and space-dependent notransfer functions. Linear prediction technique based on the autoregressive model is successfully applied as a complementary tool for speech signal distortion analysis in public address systems.
Źródło:
Hydroacoustics; 2014, 17; 129-136
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Adaptive telecommunications modems techniques for use in underwater communication systems
Autorzy:
Budzińska, I.
Lasota, H.
Mazurek, R.
Powiązania:
https://bibliotekanauki.pl/articles/331551.pdf
Data publikacji:
2003
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
hydroacoustics
underwater communication systems
data transmission
Opis:
Underwater channel data transmission is one of telecommunications most difficult problems. One way to optimise the transmission may be by adapting transmission techniques used in telecommunications modems. The articles presents two ITU-T standards: V.34 and G.992.1, known as ADSL. The possibilities and limitations of these techniques for underwater communication systems are discussed. The ADSI standard using the DMT modulation seems to be the best.
Źródło:
Hydroacoustics; 2003, 6; 285-292
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Detection on broadband signals in the field of aperture and array systems
Autorzy:
Mazurek, R.
Lasota, H.
Budzińska, I.
Powiązania:
https://bibliotekanauki.pl/articles/332465.pdf
Data publikacji:
2003
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
acoustics
broadband signals
array systems
Opis:
Antennas and antenna arrays in low band underwater systems introduce significant linear distortions that affect the detection of broadband signals. The article gives an analysis of the distortions using the space-time impulse response method. The signal received at different directions is subjected to two types of filtration, one matched to the transmitted signal and another one matched to the distorted signal. For the purpose of the simulation the Matlab software was used. Detection performance can be greatly enhanced, if receiver design takes account of the distortions.
Źródło:
Hydroacoustics; 2003, 6; 275-284
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
OFDM modulation and adaptive equalization for underwater communications
Autorzy:
Kochańska, I.
Lasota, H.
Salamon, R.
Powiązania:
https://bibliotekanauki.pl/articles/332731.pdf
Data publikacji:
2005
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
Transmission performances of a shallow underwater channel are limited due to multiple reflections of sound waves off the bottom and water surface, and to the non-stationarity caused mainly by water surface movement. In traditional narrowband telecommunication modems complex Decision Feedback Equalizers are used for minimizing the influence of intersymbol interferences caused by multipath propagation of sound waves. The article proposes adapting OFDM modulation and adaptive equalization based on Kalman filtration techniques for use in underwater communications system. The OFDM modulation is used in wideband ADSL telecommunication modems. The Kalman filtration algorithm is used for time-varying processes identification. The techniques were tested in simulation environment with promising results.
Źródło:
Hydroacoustics; 2005, 8; 77-82
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Transmission properties of a shallow hydroacoustic channel
Autorzy:
Kochańska, I.
Lasota, H.
Mazurek, R.
Adamczyk, J.
Powiązania:
https://bibliotekanauki.pl/articles/332175.pdf
Data publikacji:
2004
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
Multiple acoustic wave reflections on environment boundaries significantly reduce transmission capacity of shallow hydroacoustic channels. The use of BNM channel model being among the results of the international research project PROSIM developed within the framework of the MAST-III initiative, allowed to calculate the channel impulse response functions and perform a simulation of a digital signal transmission. This article presents the results of test transmission of binary FSK and PSK signals in a sample channel.
Źródło:
Hydroacoustics; 2004, 7; 121-128
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Transmission of digital signals in a nonstationary hydroacoustic channel
Autorzy:
Kochańska, I.
Lasota, H.
Mazurek, R.
Adamczyk, J.
Powiązania:
https://bibliotekanauki.pl/articles/332179.pdf
Data publikacji:
2004
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
From the communication point of view, transmission performances of a hydroacoustic channel are strongly limited due to multiple reflections of sound waves on the bottom and water surface, and to the nonstationarity caused mainly by water surface movement. This article presents a model of channel transmission properties which introduces nonstationarity to the channel impulse responses by assuming random variability of arrival times and amplitudes of subsequent elements of the impulse response. Transmission properties of this kind of channel have been tested in a digital simulator, using binary PSK and FSK signals. The results indicate that transmission velocity in such channels is reduced.
Źródło:
Hydroacoustics; 2004, 7; 115-120
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-7 z 7

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