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    Wyświetlanie 1-15 z 15
    Tytuł:
    Considerations of adaptive digital communiations in underwater acoustic channel
    Autorzy:
    Kochańska, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/985800.pdf
    Data publikacji:
    2013
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Opis:
    Down-link communication (DLC) and air transportable communication (ATAC) buoys as well as autonomous underwater vehicles (AUV) use acoustic links for gathering oceanographic data from underwater monitoring systems. The underwater channel propagation conditions are diverse in nature and require a special adaptive approach to the communication system design. The article presents a methodology for the communication systems design, combining modern radio standards experience, and hardware equipment to design and test the adaptive underwater data transmission systems. The testbed experiments should be preceded by the test being carried out under laboratory conditions using the underwater channel impulse responses collected at numerous measurement sessions in different reservoirs.
    Źródło:
    Hydroacoustics; 2013, 16; 113-120
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Adaptive identification of time-varying impulse response of underwater acoustic communication channel
    Autorzy:
    Kochańska, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/332081.pdf
    Data publikacji:
    2015
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Tematy:
    transmission properties
    time-varying impulse response
    Kalman filter
    Opis:
    The transmission properties of underwater acoustic communication channel can change dynamically due to the movement of acoustic system transmitter and receiver or underwater objects reflecting transmitted signal. The time-varying impulse response measurement and estimation are necessary to match the physical layer of data transmission to instantaneous channel propagation conditions. Using the correlative measurement method, impulse response estimate can be obtained no more than the duration of the measurement sequence. The paper proposes a joint correlative measurement and adaptive filtration approach, applying the Kalman filter algorithm to increase the time-domain resolution of the time-varying impulse response estimation.
    Źródło:
    Hydroacoustics; 2015, 18; 87-94
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Limitations of WSSUS modeling of stationary underwater acoustic communication channel
    Autorzy:
    Kochańska, I.
    Nissen, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/331730.pdf
    Data publikacji:
    2016
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Tematy:
    underwater communications
    impulse response
    stationary time
    stationary bandwidth
    adaptive communications
    WSSUS modeling
    Opis:
    Performances of underwater acoustic communication (UAC) systems are strongly related to specific propagation conditions of the underwater channel. Due to their large variability, there is a need for adaptive matching of the UAC systems signaling to the transmission properties of the channel. This requires a knowledge of instantaneous channel characteristics, in terms of the specific parameters of stochastic models. The wide-sense stationary uncorrelated scattering (WSSUS) assumption simplifies the estimation of terrestrial wireless channel transmission properties. Although UAC channels are hardly ever WSSUS, the rationale of such a stochastic modeling is that over a short period of time, and for a limited frequency range, this assumption is reasonably satisfied. The limits of application of the local-sense stationary uncorrelated scattering (LSSUS) model are determined by the stationary time and frequency. This paper presents the results of LSSUS model analysis for UAC channel measurements gathered by the former Research Department for Underwater Acoustics and Marine Geophysics (FWG), now part of the WTD71, during the SIMO experiment in the Bornholm Basin of the Baltic Sea.
    Źródło:
    Hydroacoustics; 2016, 19; 229-238
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    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:
    Stationary underwater channel experiment: Acoustic measurements and characteristics in the Bornholm area for model validations
    Autorzy:
    Nissen, I.
    Kochańska, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/332083.pdf
    Data publikacji:
    2016
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Tematy:
    underwater communications
    stationary time
    WSSUS indication
    Opis:
    The underwater acoustical channel is time-variant, and even on small time scales there is often existing no ‘acoustical frozen ocean’. Popular is the use of WSSUS-channel transmission modeling (Wide-Sense Stationary Uncorrelated Scattering) for the stochastic description of bandpass signals in GSM mobile phones with moving participants; since this results in a halved number of model parameters. For underwater sound applications such as detection, navigation and communication this approach provides limited a-priori-knowledge for adaptive algorithms with moving cooperative participants. The FWG of the WTD71 is collecting phase-accurate channel measurements from different sea areas in different time and application scenarios, with moving and stationary communication nodes since 2001. This paper presents a SIMO experiment from 2010, with a high precision continuous observation period of eleven hours using two stationary bottom nodes, mostly uncoupled from the influence of surface waves and from the sea floor. Transmitter and receiver node with a distance of two nautical miles between them were stationary installed on the bottom in shallow watersin the Bornholm Basin of the Baltic Sea. The sound speed has been measured continuously in the water column with a moving measurement chain. The question for this experiment was: Is the WSSUS-property fulfilled in water, when participants communicate motionless with negligible current, bottom influence and movements of the surface? The answer is: No, not in this experiment.
    Źródło:
    Hydroacoustics; 2016, 19; 285-296
    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:
    Measurement of impulse response of shallow water communication channel by correlation method
    Autorzy:
    Schmidt, J.
    Kochańska, I.
    Schmidt, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/331786.pdf
    Data publikacji:
    2017
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Tematy:
    underwater communications
    impulse response
    delay spread
    Doppler spread
    coherence time
    coherence bandwidth
    PRBS
    HFM
    Opis:
    Performances of underwater acoustic communication (UAC) systems are strongly related to specific propagation conditions of the underwater channel; conditions that can additionally change in time due to the movement of the acoustic system transmitter and receiver or to reflection by underwater objects of the transmitted signal. The time-varying impulse response is a comprehensive description of dynamically changing transmission properties of the UAC channel. It is a basis for estimation of stochastic parameters used for designing the signaling scheme of the communication system. The paper presents the results of a measurement experiment conducted in a shallow water environment. The channel impulse response was measured by the correlation method with the use of two kinds of broadband signals: pseudo-random binary sequence (PRBS) and hyperbolic frequency modulation chirp (HFM). For each measurement result statistical transmission parameters, namely delay spread, Doppler spread, coherence time, and coherence bandwidth were estimated.
    Źródło:
    Hydroacoustics; 2017, 20; 149-158
    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
    Tytuł:
    Mutual Clutter Suppression Techniques for FM Sonars
    Autorzy:
    Marszal, J.
    Rudnicki, M.
    Jedel, A.
    Salamon, R.
    Kochańska, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/176495.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    sonar
    signal processing
    FM
    LFM
    HFM
    clutter
    crosstalk
    Opis:
    The article presents methods that help in the elimination of mutual clutter as well as the consequences of two FM sounding signal sonars operating in the same body of water and frequency band. An in-depth analysis of mutual clutter was carried out. The effects of sounding signal differentiation were determined, as was the Doppler effect on mutual clutter suppression. One of the methods analysed is of particular interest in a situation in which collaborating sonars are operating in opposite frequency modulation directions. This method is effective for both linear and hyperbolic frequency modulations. A formula was derived, identifying exactly how much quantities of clutter may be lessened. The work included comprehensive computer simulations and measurements as well as tests in real-life conditions.
    Źródło:
    Archives of Acoustics; 2016, 41, 4; 721-729
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Good practice in information processing in networks of science and economy cooperation based on the paradigms of open innovation
    Autorzy:
    Kochańska, E.
    Adamkiewicz, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/105864.pdf
    Data publikacji:
    2013
    Wydawca:
    Centrum Badań i Innowacji Pro-Akademia
    Tematy:
    Open Innovation
    cluster
    bioenergy cluster for the region
    deENet Network
    otwarte innowacje
    klaster
    klaster bioenergetyczny dla regionu
    Opis:
    The article focuses on the phenomenon of open innovation (OI), which is a peculiar contrast to so-called closed innovations that assume that the process of creating new values requires control to guarantee success. The main assumptions of Open Innovation are the creation of multi-departmental capitals that bring together businesses, organizations, and research units dedicated to the common goal of creating and developing innovative products. The role of networks and stakeholders was discussed in the context of the introduction and use of external knowledge, access to new markets of skills, knowledge and others. The text focuses on the determinants of the implementation of open innovation and clusters as a source of innovation and synergy of benefit. In the context of the essence and assumptions of Open Innovation, the Bioenergy Cluster for the Region and the deENnet Network were analyzed.
    Źródło:
    Acta Innovations; 2013, 8; 10-16
    2300-5599
    Pojawia się w:
    Acta Innovations
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Determinants for development of cluster initiatives in Poland and Ukraine
    Autorzy:
    Kochanska, E.
    Kyzym, M.
    Khaustova, V.
    Klimek, A. R.
    Adamkiewicz, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/105788.pdf
    Data publikacji:
    2016
    Wydawca:
    Centrum Badań i Innowacji Pro-Akademia
    Tematy:
    cluster
    cluster initiative
    national policy of cluster development
    regional development
    Polish-Ukrainian cooperation of clusters
    klastry
    inicjatywa klastrowa
    polityka krajowa rozwoju klastrów
    rozwój regionalny
    polsko-ukraińska współpraca klastrów
    Opis:
    The article analyses the problems of cluster development in Poland and Ukraine in order to identify directions for possible cooperation between the countries. Specificity and priorities of the national policies of clusters development, regional systems of support and examples of good practices of clustering in the both countries were considered. The comparative analyses of prospects for clusters development in Poland and Ukraine were conducted, the basic determinants influencing the cluster development were identified and evaluated. There were recognized the areas and direction of Polish-Ukrainian clusters cooperation including: the opportunities to projects conducting within the European Funds, the possibilities of bilateral cooperation of cluster members with the support of cluster coordinators, the feasibility of joint Polish-Ukrainian projects run in third countries markets.
    Źródło:
    Acta Innovations; 2016, 21; 26-50
    2300-5599
    Pojawia się w:
    Acta Innovations
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-15 z 15

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