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

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    Wyświetlanie 1-7 z 7
    Tytuł:
    Application of ofdm technique to underwater acoustic data transmission
    Autorzy:
    Kochańska, I.
    Lasota, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/331798.pdf
    Data publikacji:
    2011
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Opis:
    Performances of underwater acoustic communication (UAC) digital systems are strongly related to specific transmission properties of the underwater channel. Depending on the characteristics of the channel, an architecture and modulation techniques are usually implemented that are known as reliable solutions for data transmission in difficult radio channels. The OFDM technique seems to be the most promising nowadays. The parameters of the physical layer and data link layer of ISO/OSI model are adapted to the needs of underwater communications, so as to best protect the signal from distortions and interferences typical for the underwater environment. This paper compares the performance of UAC and wireless telecommunications systems working in channels of vary different transmission parameters. Based on these parameters, some physical and link layer configurations of OFDM data transmission systems are proposed for implementation in a laboratory model and testing at a lake.
    Źródło:
    Hydroacoustics; 2011, 14; 91-98
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Transmission parameters of underwater communication channels
    Autorzy:
    Lasota, H.
    Kochańska, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/331804.pdf
    Data publikacji:
    2011
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Opis:
    The underwater environment is tough and demanding as a communication channel for ultrasonic signals. The channel transmission characteristics in marine and inland waters depend much on local bathymetry and changing weather conditions. The architecture and performance of a reliable underwater acoustic communication (UAC) system should allow real-time adaptation of its transmission parameters to a large variety of possible channel characteristics. The paper presents an adaptation procedure based on the WSS-US statistical model developed for wireless telecommunication systems. The channel is there characterized by measurements of instantaneous channel impulse response being then a basis for estimation of the channel statistical characteristics and extraction of related parameters in the phase of communication handshake, and next used in the adaptive design of digital communication system transmission settings recorded at the physical and link layers of the communication protocol.
    Źródło:
    Hydroacoustics; 2011, 14; 119-126
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Measurements of transmission properties of acoustic communication channels
    Autorzy:
    Kochańska, I.
    Lasota, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/331858.pdf
    Data publikacji:
    2012
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Opis:
    Tough transmission properties of shallow water acoustic channels (SWAC) highly limit the use of underwater acoustic communication (UAC) systems. An adaptive matching of modulation and signaling schemes to instantaneous channel conditions is needed for reliable data communications. This creates, however, unique challenges for designers when compared to radio transmission systems. When communication system elements are in move, the accuracy of both the measurements of channel impulse responses and estimates of transmission characteristics is strongly limited, due to rapid variations of the channel performance. This paper describes communication tests of a model of the orthogonal frequency division multiplexing (OFDM) data transmission system. developed by the authors. The measurement procedures and signal processing algorithms were, first, tested in reverberant air-acoustic channels available in the laboratory, and, next, verified in natural conditions in a lake. The air acoustics trials prove to be effective and methodically correct.
    Źródło:
    Hydroacoustics; 2012, 15; 91-98
    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:
    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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