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    Wyświetlanie 1-13 z 13
    Tytuł:
    Performance probability distribution function for modeling visibility for free space optical link in Nigeria
    Autorzy:
    Ojo, Joseph Sunday
    Olakunle Lawrence, Ojo
    Ibitola, Gilbert Akin
    Powiązania:
    https://bibliotekanauki.pl/articles/1163564.pdf
    Data publikacji:
    2018
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    Free Space Optical
    Nigeria
    distribution functions
    lognormal
    visibility
    Opis:
    This paper attempt to assess the performance of the most appropriate distribution function for modeling atmospheric visibility over five selected locations (Akure, Enugu, Ikeja, Jos and Port-Harcourt) in Nigeria. The distribution functions are tested based on 5-year (2010-2014) visibility data obtained from Nigeria Meteorological Agency (NIMET). Five distribution functions are tested to determine most suitable one based on four different metric measures. The associated parameters of the most suitable fitted distribution are estimated and the trends in the characteristic of the visibility are deduced. The result shows that lognormal distribution present the best probability distribution function for modeling visibility over the selected locations. A typical result for one of the locations (Akure) show that the lognormal distribution has Root Mean Square Error (RMSE) of 0.0766 km, Mean Absolute Error (MAE) of 0.0095 km, Mean Absolute Percentage Error (MAPE) of 17.8 % and coefficient of determination (R2) of 0.87. When compared with other distribution functions, the same trend could be seen in other locations although with different values of RMSE, MAE, MAPE and R2. The location and the scale parameters for the total distribution varies seasonal-wise and are location depended. The overall result will be useful for predicting future visibility over the locations. It will also be a good tool for free space optical link design in Nigeria.
    Źródło:
    World Scientific News; 2018, 109; 211-234
    2392-2192
    Pojawia się w:
    World Scientific News
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Average capacity analysis of FSO system with Airy beam as carrier over exponentiated Weibull channels
    Autorzy:
    Li, Yi
    Chu, Xingchun
    Han, Zhongxiang
    Tang, Hanling
    Song, Xinkang
    Powiązania:
    https://bibliotekanauki.pl/articles/2202763.pdf
    Data publikacji:
    2023
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    Airy beam
    free-space optical communication
    channel capacity
    exponentiated Weibull model
    Opis:
    Based on scintillation index of Airy beam and exponentiated Weibull channel model, analytical expressions of average channel capacity for free-space optical (FSO) communication links with Airy beam as signal carrier under weak atmospheric turbulence and on-off keying modulation scheme are derived. The average capacity at various propagation distances, transverse scale factors and exponential decay factors has been evaluated. And we compared the average capacity of FSO links with Airy beam and Gaussian beam as signal carrier. The results show that the average capacity of FSO links with Airy beam as carrier increases with the increase of mean signal-to-noise ratio and decreases uniformly with the increase of propagation distance. When the transverse scale factor of Airy beam is about 2 cm, a higher average capacity can be obtained. And the smaller the exponential decay factor of Airy beam, the larger the average capacity. Under the same source power or source width, the average capacity of FSO links with Airy beam as carrier is significantly higher than that of FSO links with Gaussian beam as carrier. The results of this research have some reference significance for the application of Airy beam in FSO communication system.
    Źródło:
    Optica Applicata; 2023, 53, 1; 35--48
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Variable antennas positions solution to reduce pointing errors due to wind speed and temperature coupled effects during free space optical link using matrix Rician pointing error model
    Autorzy:
    Teuma Mbezi, Michel
    Eke, Samuel
    Som, Idelette Hermine Judith
    Mouangue, Ruben Martin
    Powiązania:
    https://bibliotekanauki.pl/articles/27310098.pdf
    Data publikacji:
    2023
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    atmospheric turbulence
    pointing error
    free space optical transmission
    Rician pointing error model
    Opis:
    Pointing errors (PE) during free space optical (FSO) transmission can be caused by laser beam wander due to thermal and wind dynamic instability. The aim of this work is to study the coupled effects of temperature and wind speed on PE using matrix Rician pointing error (MRPE) model; then show how variable antennas height can reduce PE due to wind speed and temperature coupled effects. To achieve this purposes, average PE expression was established using MRPE model. Then considering a Gaussian beam wave and Monin–Obukhov similarity functions for the structure parameters of temperature, explicit relationship was established between average PE, temperature and wind speed. It comes out of this study that under dynamic turbulence, one can appropriately modify temperature to reduce PE due to dynamic instability and reciprocally. Depending on turbulence large cells or frozen turbulence eddies distribution, PE can be reduced by appropriately modified antennas height or the distance between transmitter and receiver. That is why this work suggests to install variable or dynamic antennas (rather than fixed ones) which could intelligently modify its positions according to laser beam wander created by atmospheric turbulence.
    Źródło:
    Optica Applicata; 2023, 53, 3; 393--406
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The improvement of fiber-detection method to enhance the output of amplify-received relaying on FSO communications
    Autorzy:
    Darusalam, Ucuk
    Priambodo, Purnomo Sidi
    Zulkifli, Fitri Yuli
    Rahardjo, Eko Tjipto
    Powiązania:
    https://bibliotekanauki.pl/articles/27311966.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    amplify-received relaying
    optical relaying network
    free-space optical communication
    noise suppression
    optical spatial filter
    scintillation
    Opis:
    The performance of free-space optical (FSO) communications that using an optical amplifier (OA) in the scheme of an amplify-received (AR)-relaying has a major drawback in the detection of input signal quality under the effects of turbulence. As an OA is based on a fiber-detection (FD) method to receive and delivers a signal at the amplification process stage, there is an opportunity to implement an optical spatial filter (OSF) to improve the quality of an input signal. In this paper, as the continuation of previous work on the direct-detection, the OSF is applied on the AR-relaying. The novelty proposed in this work is the improvement of FD method where the OSF is designed as the integration of cone reflector, pinhole and multi-mode fiber with an OA. The OSF produces an optical signal, the input of the OA, which minimizes the effects of turbulence, background noise and signal fluctuation. Thus, OA in AR-relaying produces signal output with high power and rise up below threshold level. Additionally, an OSF with a lower pinhole diameter produces the best quality of the signal spectral to be delivered into an EDFA. Through this implementation, the performance of optical relaying on FSO can be significantly improved.
    Źródło:
    International Journal of Electronics and Telecommunications; 2023, 69, 2; 325--333
    2300-1933
    Pojawia się w:
    International Journal of Electronics and Telecommunications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Indoor localization based on visible light communication and machine learning algorithms
    Autorzy:
    Ghonim, Alzahraa M.
    Salama, Wessam M.
    Khalaf, Ashraf A. M.
    Shalaby, Hossam M. H.
    Powiązania:
    https://bibliotekanauki.pl/articles/2063908.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
    Tematy:
    free-space optical communication
    visible light communication
    neural networks
    random forests
    machine learning
    Opis:
    An indoor localization system is proposed based on visible light communications, received signal strength, and machine learning algorithms. To acquire an accurate localization system, first, a dataset is collected. The dataset is then used with various machine learning algorithms for training purpose. Several evaluation metrics are used to estimate the robustness of the proposed system. Specifically, authors’ evaluation parameters are based on training time, testing time, classification accuracy, area under curve, F1-score, precision, recall, logloss, and specificity. It turned out that the proposed system is featured with high accuracy. The authors are able to achieve 99.5% for area under curve, 99.4% for classification accuracy, precision, F1, and recall. The logloss and precision are 4% and 99.7%, respectively. Moreover, root mean square error is used as an additional performance evaluation averaged to 0.136 cm.
    Źródło:
    Opto-Electronics Review; 2022, 30, 2; art. no. e140858
    1230-3402
    Pojawia się w:
    Opto-Electronics Review
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    SAC-OCDMA over Hybrid FTTx Free Space Optical Communication Networks
    Autorzy:
    Sahbudin, R. K. Z.
    Chun, T. T. K.
    Anas, S. B. A.
    Hitam, S.
    Mokhtar, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/308402.pdf
    Data publikacji:
    2015
    Wydawca:
    Instytut Łączności - Państwowy Instytut Badawczy
    Tematy:
    Hybrid FTTx free space optical
    Khazani-Syed code
    SAC-OCDMA
    Spectral direct decoding
    Opis:
    This paper presents an investigation of Spectral Amplitude Coding Optical Code Division Multiple Access (SAC-OCDMA) over hybrid Fiber-to-the-x (FTTx) Free Space Optical (FSO) link under different weather conditions. FTTx and FSO are the last mile technologies that complement each other in delivering secure and high speed communication to customers' residence or office. SAC-OCDMA is one of the potential multiplexing techniques that has become a research area of interest in optical communications and considered a promising technique for FTTx access networks. It is based on Khazani-Syed (KS) code with Spectral Direct Decoding (SDD) technique. All the components involved in the network were specied according to the available market product in order to simulate the actual environment as close as possible. The result shows that for bit error rate (BER) of 10‾9, the network is able to perform with 20 km Single Mode Fiber (SMF) spanning from the central office (CO) and 1.48 km FSO range with transmission rate of 1.25 Gb/s during heavy rain.
    Źródło:
    Journal of Telecommunications and Information Technology; 2015, 2; 52-58
    1509-4553
    1899-8852
    Pojawia się w:
    Journal of Telecommunications and Information Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    An approach to investigating the feasibility of free-space optical communication technology deployment under scintillation effects
    Autorzy:
    Mahmood, Aras S.
    Powiązania:
    https://bibliotekanauki.pl/articles/27315698.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
    Tematy:
    free-space optical communication
    atmospheric turbulence
    scintillation attenuation
    refractive index structure parameter (Cn²)
    Opis:
    Local weather conditions have an impact on the availability of free-space optical (FSO) communication. The variation in meteorological parameters, such as temperature, humidity, and wind speed, leads to variations of the refractive index along the transmission path. These refractive index inhomogeneities produced by atmospheric turbulence induce optical turbulence which is responsible for random fluctuations in the intensity of the laser beam that carries the signal (irradiance) called scintillations that can significantly degrade the performance of FSO systems. This paper aims to investigate the feasibility of deploying FSO communication technology under scintillation effects in any urban region and atmospheric environment. To achieve that, firstly by utilizing the Hufnagel-Vally day with the Sadot and Kopeika models together, the scintillation strength for a specified region, Sulaimani City in north-eastern Iraq as an example, has been estimated through the calculation of the refractive index structure parameter (Cn²) over a period of 10 years and it was found to be at the strong turbulence level. Secondly, from the same estimated parameter, the scintillation attenuation of the signal carrying the laser beam intensity can be calculated to investigate the feasibility of FSO communication using Optysistem-7 software. The optimal link distance for northeastern Iraq (Sulaimani City) has been found to be within the limit of about 5.5 km. Analysing the max. Q-factor, bit-error rate and signal to noise ratio for an average of 120 months between 2013-2022 assessed the best and worst seasons for FSO.
    Źródło:
    Opto-Electronics Review; 2023, 31, 3; art. no. e147037
    1230-3402
    Pojawia się w:
    Opto-Electronics Review
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Investigation of optical short pulse generation using intensity modulation for LiDAR and free-space communications
    Autorzy:
    Wang, Fei
    Kang, Wen
    Powiązania:
    https://bibliotekanauki.pl/articles/1835768.pdf
    Data publikacji:
    2021
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    intensity modulator
    optical pulse generator
    pulsed LiDAR
    free-space communication
    Opis:
    A simple optical pulse generation scheme for pulsed light detection and ranging (LiDAR) and free-space communications is proposed and experimentally and numerically demonstrated, in which continuous-wave light emitted by a distributed feedback-laser diode (DFB-LD) is modulated by a lithium-niobate Mach–Zehnder intensity modulator to generate optical short pulses, and an Er-doped fiber amplifier (EDFA) is used to boost transmitting light power. Possibilities of intensity modulators for high speed communications being used to generate optical short pulses for low speed pulsed LiDAR are investigated. The influences of bias voltage of intensity modulator and bit rate of modulation signal on the generated optical pulses are discussed. The pulse width obtained by using the return to zero signal with 33% duty cycle on bit rate of 2.5 and 5 Gbit/s is respectively 128.0 and 63.2 ps, and the corresponding nominal accuracy of pulsed LiDAR is respectively 19.2 and 9.5 mm, and low repetition frequency required by pulsed LiDAR is achieved by coding to high-speed modulation signal. The system performance for free-space communications and pulsed LiDAR is evaluated, respectively. We believe that the proposed scheme is suitable for the integrated system of pulsed LiDAR and free-space communications.
    Źródło:
    Optica Applicata; 2021, 51, 1; 97-107
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optical Wireless Communications Operated at Long-Wave Infrared Radiation
    Autorzy:
    Mikolajczyk, Janusz
    Szabra, Dariusz
    Prokopiuk, Artur
    Achtenberg, Krzysztof
    Wojtas, Jacek
    Bielecki, Zbigniew
    Powiązania:
    https://bibliotekanauki.pl/articles/226104.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    optical wireless communication
    free space optics
    quantum cascade lasers
    optoelectronics
    telecommunications
    Opis:
    This paper presents some construction analysis and test results of a Free Space Optics system operating at the wavelength of 9.35 μm. In the system, a quantum cascade laser and a photoreceiver with mercury cadmium telluride photodetectors were used. The main parameters of these elements were discussed taking into account a data link operation. It also provides to determine a data range for various weather conditions related to scattering and scintillation. The results of numerical analyses defined the properties of currently available FSO technologies working in the near infrared or in the short infrared range of spectrum versus the performances of the developed system. The operation of this system was verified in three different test environments. The obtained results may also contain important issues related to the practical application of any FSO system.
    Źródło:
    International Journal of Electronics and Telecommunications; 2020, 66, 2; 383-387
    2300-1933
    Pojawia się w:
    International Journal of Electronics and Telecommunications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analysis of Free-Space Optics Development
    Autorzy:
    Mikołajczyk, J.
    Bielecki, Z.
    Bugajski, M.
    Piotrowski, J.
    Wojtas, J.
    Gawron, W.
    Szabra, D.
    Prokopiuk, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/221245.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    optical communications
    open path laser communications
    line of sight communications
    free space optics
    Opis:
    The article presents state of work in technology of free-space optical communications (Free Space Optics - FSO). Both commercially available optical data links and their further development are described. The main elements and operation limiting factors of FSO systems have been identified. Additionally, analyses of FSO/RF hybrid systems application are included. The main aspects of LasBITer project related to such hybrid technology for security and defence applications are presented.
    Źródło:
    Metrology and Measurement Systems; 2017, 24, 4; 653-674
    0860-8229
    Pojawia się w:
    Metrology and Measurement Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Dwufalowe łącze optyczne
    Dual wavelength optical link
    Autorzy:
    Rajba, S.
    Lipiński-Kempys, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/155870.pdf
    Data publikacji:
    2012
    Wydawca:
    Stowarzyszenie Inżynierów i Techników Mechaników Polskich
    Tematy:
    FSO (Free Space Optics)
    bezprzewodowe łącza w podczerwieni
    transmisja optyczna
    optolinia
    wireless infrared links
    optical transmission
    optolink
    Opis:
    Przedmiotem pracy jest analiza warunków pracy łączy optycznych w otwartej przestrzeni. Przedstawiono podstawowe uwarunkowania poprawnej pracy takich łączy. W oparciu o pewne doświadczenia eksploatacyjne z tego zakresu i na podstawie przedstawionej analizy zaproponowano koncepcję łącza dwufalowego, wskazując na wybrane długości fal do pracy łącza. W podsumowaniu wskazano na właściwości tego typu rozwiązań komunikacyjnych i na pola ich zastosowań w technice przesyłania informacji.
    The demand for implementation of digital data transmission lines in various topographies and field conditions is increasing. Such diversity requires many original solutions. Certainly one of the solutions are links that use free space to transmit information on optical wavelengths. The idea is not new, but the new optical and electronic technologies make this possible. The subject of investigations is to analyze the working conditions of optical links in open spaces. The issue is known in the literature as Free Space Optics Communication (FSO). In this paper there are presented the basic conditions for correct work of such links. On a basis of certain operating experience in this field and the presented analysis there was proposed the concept of a dual wavelength link with indicating the selected length waves for the link work . In the summary there are described the properties of such solutions in the fields of communications and their applications to information transmission technology.
    Źródło:
    Pomiary Automatyka Kontrola; 2012, R. 58, nr 12, 12; 1105-1109
    0032-4140
    Pojawia się w:
    Pomiary Automatyka Kontrola
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Peak detection unit for Free-Space-Optics receiver
    Autorzy:
    Achtenberg, Krzysztof
    Mikołajczyk, Janusz
    Szabra, Dariusz
    Prokopiuk, Artur
    Bielecki, Zbigniew
    Powiązania:
    https://bibliotekanauki.pl/articles/221334.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    peak detection
    infrared receiver module for optical communications
    open path laser communications
    free space optics
    quantum cascade laser
    Opis:
    The paper presents verification of a peak detection method cooperating with infrared radiation detector module applications. The work has been divided into parts including SPICE simulations and presentation of results obtained with the constructed prototype. The design of the peak detector dedicated to applications with very short pulses requires a different approach than that for standard solutions. It is mainly caused due to the ratio of pulse width and time period. In the described application this ratio is less than 10%. The paper shows testing of an analogue circuit which is capable to be inserted in these applications.
    Źródło:
    Metrology and Measurement Systems; 2019, 26, 2; 377-385
    0860-8229
    Pojawia się w:
    Metrology and Measurement Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Space and High Energy Experiments Advanced Electronic Systems 2012
    Autorzy:
    Romaniuk, R. S.
    Powiązania:
    https://bibliotekanauki.pl/articles/226298.pdf
    Data publikacji:
    2012
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    astronomy
    optical observations
    telescopes
    space technology
    ccelerators
    free electron laser
    industrial standards for advanced electronics
    photonic and electronic systems
    Opis:
    This paper is a research survey of the WILGA Symposium work. It presents a digest of technical effort results shown by young researchers from different universities during the Jubilee XXXth SPIE-IEEE-Photonics Society of Poland Wilga 2012 symposium on Photonics and Internet Engineering. Topical tracks of the symposium embraced: nanomaterials and nanotechnologies for photonics, sensory and nonlinear optical fibers, object oriented design of hardware, photonic metrology, optoelectronics and photonics applications, photonics-electronics co-design, optoelectronic and electronic systems for astronomy and high energy physics experiments, JET tokamak and pi-of the sky experiments development. The symposium is an annual summary in the development of numerable Ph. D. theses carried out in this country in the area of advanced electronic and photonic systems. It is also a great occasion for SPIE, IEEE, OSA and PSP students to meet together in a large group spanning the whole country with guests from this part of Europe. A digest of Wilga references is presented [1]-[60]. This paper is the first part of the digest focused on astronomy, space, astroparticle physics, accelerators, and high energy physics experiments.
    Źródło:
    International Journal of Electronics and Telecommunications; 2012, 58, 4; 441-462
    2300-1933
    Pojawia się w:
    International Journal of Electronics and Telecommunications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-13 z 13

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