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    Tytuł:
    A new direct-sequence spread spectrum signal detection method for underwater acoustic communications in shallow-water channel
    Autorzy:
    Kochańska, Iwona
    Powiązania:
    https://bibliotekanauki.pl/articles/2146643.pdf
    Data publikacji:
    2021
    Wydawca:
    Politechnika Poznańska. Instytut Mechaniki Stosowanej
    Tematy:
    underwater acoustic communications
    UAC
    direct sequence spread spectrum
    DSSS
    akustyczna komunikacja podwodna
    bezpośrednie modulowanie nośnej sekwencją kodową
    Opis:
    Direct-Sequence Spread Spectrum (DSSS) is one of the modulation and coding techniques used in Underwater Acoustic Communication (UAC) systems for reliable data transmision even at low signal levels. However, in a shallow water channel, there is a strong multipath propagation which causes a phase fluctuation of the received signal, affecting the performance of the spread-spectrum system. The article presents a differential method for DSSS signal detection. It is based on the calculation of the correlation coefficient of adjacent segments of signal at the output of filter matched to the spreading sequence used in the transmitter. A positive value of the correlation coefficient means that a given modulation symbol carries the same information bit as the previous one; a negative value means that the opposite bit has been transmitted. The reliability of the proposed method has been compared to classical method of DSSS signal detection, which consists in detecting the information directly from the signal at the output of the matched filter. Simulation and measurement tests of underwater acoustic communications in strong multipath propagation conditions have shown that the proposed method allows obtaining lower values of the DSSS transmission Bit Error Rate (BER) than the classical detection technique while maintaining the same data transmission rate.
    Źródło:
    Vibrations in Physical Systems; 2021, 32, 1; art. no. 2021106
    0860-6897
    Pojawia się w:
    Vibrations in Physical Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Erratum: A new direct-sequence spread spectrum signal detection method for underwater acoustic communications in shallow-water channel (DOI: 10.21008/j.0860-6897.2021.1.06)
    Autorzy:
    Kochańska, Iwona
    Powiązania:
    https://bibliotekanauki.pl/articles/2146666.pdf
    Data publikacji:
    2022
    Wydawca:
    Politechnika Poznańska. Instytut Mechaniki Stosowanej
    Tematy:
    underwater acoustic communication
    UAC
    direct sequence spread spectrum
    DSSS
    akustyczna komunikacja podwodna
    bezpośrednie modulowanie nośnej sekwencją kodową
    Źródło:
    Vibrations in Physical Systems; 2022, 33, 1; art. no. 2022114
    0860-6897
    Pojawia się w:
    Vibrations in Physical Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Simulation of direct-sequence spread spectrum data transmission system for reliable underwater acoustic communications
    Autorzy:
    Kochańska, Iwona
    Schmidt, Jan H.
    Powiązania:
    https://bibliotekanauki.pl/articles/128008.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Poznańska. Instytut Mechaniki Stosowanej
    Tematy:
    underwater acoustic communications
    UAC
    direct sequence spread spectrum
    DSSS
    PRBS
    akustyczna komunikacja podwodna
    bezpośrednie modulowanie nośnej sekwencją kodową
    pseudolosowa sekwencja bitów
    Opis:
    Underwater acoustic communication (UAC) system designers tend to transmit as much information as possible, per unit of time, at as low as possible error rate. It is a particularly difficult task in a shallow underwater channel in which the signal suffers from strong time dispersion due to multipath propagation and refraction phenomena. The direct-sequence spread spectrum technique (DSSS) applied successfully in the latest standards of wireless communications, gives the chance of reliable data transmission with an acceptable error rate in a shallow underwater channel. It utilizes pseudo-random sequences to modulate data signals, and thus increases the transmitted signal resilience against the inter symbol interference (ISI) caused by multipath propagation. This paper presents the results of simulation tests of DSSS data transmission with the use of different UAC channel models using binary spreading sequences.
    Źródło:
    Vibrations in Physical Systems; 2019, 30, 1; 1-8
    0860-6897
    Pojawia się w:
    Vibrations in Physical Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Shallow Water Experiment of OFDM Underwater Acoustic Communications
    Autorzy:
    Kochańska, Iwona
    Schmidt, Jan H.
    Marszal, Jacek
    Powiązania:
    https://bibliotekanauki.pl/articles/177592.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    underwater acoustic communications
    UAC
    orthogonal frequency-division multiplexing
    OFDM
    Opis:
    The large variability of communication properties of underwater acoustic channels, and especially the strongly varying instantaneous conditions in shallow waters, is a challenge for the designers of underwater acoustic communication (UAC) systems. The use of phase modulated signals does not allow reliable data transmission through such a tough communication channel. However, orthogonal frequency-division multiplexing (OFDM), being a multi-carrier amplitude and phase modulation technique applied successfully in the latest standards of wireless communications, gives the chance of reliable communication with an acceptable error rate. This paper describes communication tests conducted with the use of a laboratory model of an OFDM data transmission system in a shallow water environment in Wdzydze Lake.
    Źródło:
    Archives of Acoustics; 2020, 45, 1; 11-18
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Performance of the Direct Sequence Spread Spectrum Underwater Acoustic Communication System with Differential Detection in Strong Multipath Propagation Conditions
    Autorzy:
    Schmidt, Jan H.
    Kochańska, Iwona
    Schmidt, Aleksander M.
    Powiązania:
    https://bibliotekanauki.pl/articles/31339747.pdf
    Data publikacji:
    2024
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    direct sequence spread spectrum
    DSSS
    m-sequences
    Kasami codes
    shallow-water channel
    multipath propagation
    underwater acoustic communications
    UAC
    Opis:
    The underwater acoustic communication (UAC) operating in very shallow-water should ensure reliable transmission in conditions of strong multipath propagation, significantly disturbing the received signal. One of the techniques to achieve this goal is the direct sequence spread spectrum (DSSS) technique, which consists in binary phase shift keying (BPSK) according to a pseudo-random spreading sequence. This paper describes the DSSS data transmission tests in the simulation and experimental environment, using different types of pseudo-noise sequences: m-sequences and Kasami codes of the order 6 and 8. The transmitted signals are of different bandwidth and the detection at the receiver side was performed using two detection methods: non-differential and differential. The performed experiments allowed to draw important conclusions for the designing of a physical layer of the shallow-water UAC system. Both, m-sequences and Kasami codes allow to achieve a similar bit error rate, which at best was less than 10−3. At the same time, the 6th order sequences are not long enough to achieve an acceptable BER under strong multipath conditions. In the case of transmission of wideband signals the differential detection algorithm allows to achieve a significantly better BER (less than 10−2) than nondifferential one (BER not less than 10−1). In the case of narrowband signals the simulation tests have shown that the non-differential algorithm gives a better BER, but experimental tests under conditions of strong multipath propagation did not confirm it. The differential algorithm allowed to achieve a BER less than 10−2 in experimental tests, while the second algorithm allowed to obtain, at best, a BER less than 10−1. In addition, two indicators have been proposed for a rough assessment which of the detection algorithms under current propagation conditions in the channel will allow to obtain a better BER.
    Źródło:
    Archives of Acoustics; 2024, 49, 1; 129-140
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Underwater navigation system based on Doppler shift – measurements and error estimations
    Autorzy:
    Ostrowski, Zawisza
    Salamon, Roman
    Kochańska, Iwona
    Marszal, Jacek
    Powiązania:
    https://bibliotekanauki.pl/articles/260234.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    underwater acoustics
    navigation systems
    Doppler shifts
    Opis:
    A new acoustic navigation system was developed to determine the position and speed of moving underwater objects such as divers and underwater vehicles. The path of an object and its speed were determined by the Doppler shifts of acoustic signals emitted by a transmitter placed on the object and received by four hydrophones installed at the periphery of the monitored body of water. The position and speed measurements were affected by errors mainly caused by acoustic reflections (returns) from the water body boundaries and surface reverberations. This paper discusses the source of the disturbances with the results of a simulation test and experimental measurements. It was demonstrated that the magnitude of the errors could be acceptable in most of the potential applications of the acoustic navigation system.
    Źródło:
    Polish Maritime Research; 2020, 1; 180-187
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Performance of coherent modulation scheme used in acoustic underwater communication system
    Autorzy:
    Schmidt, Jan H.
    Schmidt, Aleksander M.
    Kochańska, Iwona
    Powiązania:
    https://bibliotekanauki.pl/articles/127757.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Poznańska. Instytut Mechaniki Stosowanej
    Tematy:
    underwater acoustic communications
    shallow underwater channel
    coherent modulation
    akustyczna komunikacja podwodna
    płytki kanał podwodny
    modulacja koherentna
    Opis:
    The development of an acoustic underwater communication system for shallow waters is still a big scientific and construction challenge. Currently, non-coherent modulations in combination with strong channel coding are used to achieve reliable communication with low rate in such a channel. To obtain transmission with a higher transmission rate, it is required to use coherent modulation. This paper presents the assumptions of such a transmission system and the results of data transmission carried out by this system in the channel with the Rician fading, which reflects the short range shallow water channel. A digital version of the carrier phase modulation known as Phase-Shift Keying was selected for simulation.
    Źródło:
    Vibrations in Physical Systems; 2019, 30, 1; 1-8
    0860-6897
    Pojawia się w:
    Vibrations in Physical Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Selected problems of water, electricity and waste management in Brazil in the context of its impact on climate change mitigation
    Autorzy:
    Kochańska, Ewa
    Adamkiewicz, Iwona
    Bertozo, Lais
    Powiązania:
    https://bibliotekanauki.pl/articles/105650.pdf
    Data publikacji:
    2019
    Wydawca:
    Centrum Badań i Innowacji Pro-Akademia
    Tematy:
    environmental protection
    climate change
    waste management
    water management
    Brazil
    ochrona środowiska
    zmiana klimatu
    gospodarowanie odpadami
    gospodarka wodna
    Brazylia
    Opis:
    The article discusses selected problems related to environmental protection in the context of climate change in the Ceara region of North-Eastern Brazil. The authors analyse the lack of water and negative impact of climate change on fish processing in the region. Also, the opportunity to use fish waste to increase profitability of the local fish processing SMEs thanks to implementation of climate-friendly technologies such as the production of fertilisers and energy for their own needs is discussed.
    Źródło:
    Acta Innovations; 2019, 32; 29-39
    2300-5599
    Pojawia się w:
    Acta Innovations
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Próba oceny programów europejskiej współpracy terytorialnej w Polsce w kontekście wspólnotowej polityki spójności – wnioski z badania
    The evaluation of the European Territorial Cooperation Programmes in Poland in the context of EU cohesion policy – research conclusions
    Autorzy:
    Adamkiewicz, Iwona
    Dorożyński, Tomasz
    Kochańska, Ewa
    Urbaniak, Wojciech
    Powiązania:
    https://bibliotekanauki.pl/articles/596876.pdf
    Data publikacji:
    2009
    Wydawca:
    Łódzkie Towarzystwo Naukowe
    Tematy:
    programy Europejskiej Współpracy Terytorialnej
    wspólnotowa polityka spójności Polska
    the European Territorial Cooperation Programmes
    EU Cohesion Policy
    Polska
    Opis:
    Nowadays Poland is one of the biggest beneficiaries of EU Cohesion Policy. One of its aims is European Territorial Cooperation although the share of Polish beneficiaries in the European Territorial Cooperation Programmes is insufficient, especially in transnational and interregional projects. The goal of the article is the evaluation of the role of the European Territorial Cooperation Programmes in Poland in the light of financial perspectives 2007-2013 and the next programming period. The first part of this article is devoted to the framework of the European Territorial Cooperation Programmes. The second part deals with the research methodology. The research involved beneficiaries and the institutions of the European Territorial Cooperation Programmes. The third part presents research results. In the final part of this article the authors point at the main conclusions and recommendations following the research.
    Źródło:
    Studia Prawno-Ekonomiczne; 2009, LXXX (80); 125-177
    0081-6841
    Pojawia się w:
    Studia Prawno-Ekonomiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    New concept of digital innovation ecosystem in boostering circularity development. Twilight of traditional brokerage of innovation
    Autorzy:
    Kochanska, Ewa
    Adamkiewicz, Iwona
    Wozniak, Katarzyna
    Podgórski, Marcin
    Przygodzki, Zbigniew
    Powiązania:
    https://bibliotekanauki.pl/articles/24201260.pdf
    Data publikacji:
    2023
    Wydawca:
    Centrum Badań i Innowacji Pro-Akademia
    Tematy:
    broker of innovation
    circularity
    megatrends
    interface
    broker innowacji
    obieg zamknięty
    megatrendy
    interfejs
    Opis:
    The aim of the paper is to identify the direction of evolution, the conditions of organisation and the impact of the new concept of digital innovation ecosystem in boostering circularity development. The traditional model of innovation brokerage and the new circularity broker paradigm in the development of the circular economy is presented. The authors discuss the circularity broker as an IT interface, equipped with wide range of IT tools, and above all, self-learning applications with AI elements. The circularity broker is accompanied by its watch dog, i.e. a set of IT tools used to search, process and transfer information dedicated to specific stakeholders, exactly when they need this information. The concept of circular brokerage is anchored in the area of the regional clusters dedicated to circular economy development.
    Źródło:
    Acta Innovations; 2023, 48; 92--106
    2300-5599
    Pojawia się w:
    Acta Innovations
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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