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1
Rozmieszczenie obszaru zaników w jednoczęstotliwościowej sieci SFN na przykładzie sieci DAB+
100%
Zieliński R. J.
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2018
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tom nr 8-9
581--584
PL
Przedstawiono sposób wyznaczania poziomu sygnału i wielkości zaników w sieci SFN, składającej się z dwóch pracujących nadajników. Z taką sytuacją można się spotkać wtedy, gdy w sieci z trzema nadajnikami jeden z nich utraci synchronizm i wyłączy się. Przedstawiono na wybranych trasach dla sieci SFN LokalDAB we Wrocławiu przebiegi poziomu natężenia pola elektrycznego wraz z zanikami.
EN
The article presents the method of determining the level of signal and magnitude of fading in the SFN network consisting of two working transmitters. This situation can happen when in a network with three transmitters one of them loses synchronism and turns off. The electric field strength along with the fades is presented on selected routes of the SFN LokalDAB network in Wrocław.
2
Szerokopasmowa akwizycja sygnałów w systemach ELINT
63%
Hibner R. , Zieliński R. J.
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tom nr 8-9
1089--1092, CD
PL
Rosnące wymagania stawiane systemom rozpoznania (ELINT) wymuszają zwiększanie pasma analizy z zachowaniem wysokiej dynamiki detekcji sygnałów. W artykule została przedstawiona analiza możliwych rozwiązań. Przestawione zostały również wyniki pomiarów sprzętowej implementacji szerokopasmowego systemu akwizycji opartego o równoległe kanały, z której wynika, że możliwe jest uzyskanie dynamiki przekraczającej 70dB w dowolnie szerokim paśmie analizy przy zastosowaniu równoległej struktury.
EN
Growing expectations for ELINT systems’ parameters lead to expansion of analysis bandwidth with high dynamic range requirements. This article presents an analysis of possible solutions of wideband acquisition systems. Additionally, experimental results of hardware implemented multichannel system are presented. Dynamic range exceeding 70dB was achieved in parallel architecture that allows unlimited bandwidth scalability.
3
Content available High Altitude Platform : Future of Infrastructure
63%
Malinowski A. , Zieliński R. J.
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tom Vol. 56, No. 2
191-196
EN
High Altitude Platform (HAP) concept and idea is presented in the article. Characteristics, advantages and disadvantages of HAPs are described. There is also the comparison available between HAPs and existing telecommunication infrastructure (terrestrial and satellite). Selected examples of the possible limitation and technological restrictions of HAP based systems are presented in the article.
4
Content available Frequency Dependent Mismatch Correction Scheme for Zero-IF Receivers
63%
Hibner R. , Zieliński R. J.
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tom Vol. 64, No. 1
13--18
EN
This paper shows effective method of linear distortions compensation in zero-IF receivers. With application of frequency domain processing a computation efficient method was developed that allows to correct quadrature mismatch in Zero-IF receiver along with gain and group delay independent of receiving signal type. Method was implemented and tested on hardware platform confirming its effectiveness. This method makes it possible to build high sensitivity devices to monitor spectrum in very wide frequency ranges.
5
Content available Measurement of Special Shielding Materials at S and C Band Using Improved Free-Space Transmission Technique
63%
Dvurechenskaya N. , Zieliński R. J.
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tom Vol. 57, No. 3
329-334
EN
In this paper we discuss state of the art in the field of shielding materials investigation. Two types of newly manufactured shielding materials (nonwoven and fabric) were measured using improved free-space transmission technique at 2-5 GHz depending on electromagnetic wave (EM) polarization and antenna to specimen distance. Results of shielding effectiveness (SE) evaluation based on measured complex transmission coefficients (S21) were presented and compared with SE measured using coaxial transmission line technique. Also results of surface resistance measurements with the four-probe technique for the test materials are shown.
6
Content available Operational characteristic of wireless WiMax and IEEE 802.11x systems in underground mine environments
51%
Kowal M. , Kubal S. , Piotrowski P. , Zieliński R. J.
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tom Vol. 56, No. 1
81-86
EN
The paper presents research results pertaining to transmission parameters of wireless communication systems, based on WiMax and IEEE 802.11x radio interfaces. Research was performed in severe operating conditions of an underground mine - testing various parameters, such as: throughput, delays and maximum range.
7
Content available Measurements of shielding effectiveness of textile materials containing metal by the free-space transmission technique with data processing in the time domain
51%
Dvurechenskaya N. , Bajurko P. R. , Zieliński R. J. , Yashchyshyn Y.
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tom Vol. 20, nr 2
217--228
EN
The results of shielding effectiveness (SE) measurements of textile materials containing metal by the free-space transmission technique (FSTT) in the 1-26.5 GHz frequency range are presented in the paper. It is shown that experimental data processing using time-domain gating (TDG) makes it possible to effectively remove diffracted and reflected components from the desired signal. The comparison with the results obtained by other techniques, namely modified FSTT with TDG and coaxial line probe technique (ASTM D4935-99) is given. The comparison shows that the proposed technique gives more reasonable results while the measurement set-up is simpler in realization.
8
Content available A Simulation Model of the Radio Frequency MIMO-OFDM System
51%
Kowal M. , Kubal S. , Piotrowski P. , Zieliński R. J.
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tom Vol. 57, No. 3
323-328
EN
The paper presents a simulation model of the radio frequency MIMO-OFDM system. The simulation model was made in Matlab Simulink environment. It contains the transmitter, the receiver and the telecommunication channel models. The telecommunication channel model consists of models used during development of technical documentation of IEEE 802.11n. Signals generated at the transmitter output are fully compatible with signals described in IEEE 802.11n [1]. Simulations are conducted on a radio frequency, so they can be compared with results of measurements of real systems.
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