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Wyświetlanie 1-15 z 232
Tytuł:
Resource allocation in MIMO systems specific to radio communication
Autorzy:
Ghaderi, Bahar
Parhizgar, Naser
Powiązania:
https://bibliotekanauki.pl/articles/140794.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
spatial modulation
multi quadrature amplitude modulation
modulation
Huffman coding
MIMO systems
Opis:
The performance of the multi-input multi-output (MIMO) systems can be improved by spatial modulation. By using spatial modulation, the transmitter can select the best transmit antenna based on the channel variations using channel state information (CSI). Also, the modulation helps the transmitter to select the best modulation level such that the system has the best performance in all situations. Hence, in this paper, two issues are considered including spatial modulation and information modulation selection. For the spatial modulation, an optimal solution for obtaining the probability of selecting antenna is calculated and then Huffman coding is used such that the transmitter can select the best transmit antenna to maximize the channel capacity. For the information modulation, a multi quadrature amplitude modulation (MQAM) strategy is used. In this modulation, the modulation size is changed based on the channel state variations; therefore, the best modulation index is used for transmitting data in all channel situations. In simulation results, the optimal method is compared with Huffman mapping. In addition, the effect of modulation on channel capacity and a bit error rate (BER) is shown.
Źródło:
Archives of Electrical Engineering; 2019, 68, 1; 91-100
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analog-based duobinary-4-PAM for electrical bandwidth limited optical fiber links
Autorzy:
Suhr, L.F.
Madsen, P.
Monroy, I. T.
Olmos, J. J. V.
Powiązania:
https://bibliotekanauki.pl/articles/173933.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
optical communications
advanced modulation formats
multilevel modulation
Opis:
This paper presents a demonstration of a seven level duobinary-4-PAM signal operating at 10.16 Gbit/s. The polybinary generation is achieved by a simple electrical Bessel filter of 5th order, with a frequency cut-off of 1.8 GHz. We assess the impact of the filter placement, either at the transmitter or the receiver, and find the impact is minimal in terms of bit error rate performance in transmissions of up to 40 km of single mode fiber.
Źródło:
Optica Applicata; 2016, 46, 1; 71-78
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Binaural masking of amplitude modulation
Autorzy:
Kordus, M.
Sęk, A.
Kociński, J.
Powiązania:
https://bibliotekanauki.pl/articles/177557.pdf
Data publikacji:
2005
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
masking
masking in the modulation domain
modulation filterbank
Opis:
A new concept concerned with the transformation of acoustic stimuli in the auditory system postulates the existence of a form of spectral analysis applied to the amplitude changes of the stimuli. It is assumed that this analysis takes place in the so-called modulation filters, i.e. bandpass linear filters tuned to different rates of the amplitude changes. The most striking argument supporting this idea is an effect of masking in the amplitude modulation domain whose nature can be easily explained basing on this concept. As the modulation filters are situated on the higher levels of the auditory system, it is also assumed that this form of masking is entirely a central process. However, most of the studies concerned with masking in the modulation domain used monaural listening only. Therefore, the main purpose of the presented here experiments was to investigate whether this type of masking is entirely a central process. Using a Three-Alternative Forced-Choice (3AFC) procedure the binaural and monaural masked thresholds of amplitude modulation were determined. A sinusoidal carrier at a frequency of 4 kHz was amplitude modulated by a specially designed band of noise characterized by a very low value of the crest factor, which was used as a masking signals. Different bandwidths of the modulating masking signals were used as well as different center frequencies to investigate whether the masking patterns in the modulation domain depend on the masker bandwidth and its center frequency. The modulating target (masked) signal was a pure tone at a frequency range from 2 to 256 Hz. Both modulating signals were applied to the same sinusoidal carrier signal. The most effective masking was noticed when the rate of the sinusoidal modulation was close to the center frequency of the masking signal or when it was in its spectral range and decreased outside of this range. The character of this dependence confirms the existence of some form of a frequency selectivity in the modulation rate domain similarly to the audible frequency domain. The thresholds for monaural and binaural listening were very close to each other. This implies that masking in the modulation domain is a central process.
Źródło:
Archives of Acoustics; 2005, 30, 1; 5-17
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Adaptive procedure for automatic modulation recognition
Autorzy:
Liedtke, F.
Powiązania:
https://bibliotekanauki.pl/articles/308334.pdf
Data publikacji:
2004
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
modulation recognition
modulation classification
signal analysis
radio monitoring
Opis:
An adaptive procedure for automatic modulation recognition is described. With it the automatic modulation classification and recognition of radio communication signals with a priori unknown parameters is possible effectively. The results of modulation recognition are important in the context of radio monitoring or electronic support measurements. The special features of the procedure are the possibility to adapt it dynamically to nearly all modulation types, and the capability to recognize continuous phase modulation (CPM) signals like Gaussian minimum-shift keying (GMSK) too. A time synchronization to the symbol rate is not necessary.
Źródło:
Journal of Telecommunications and Information Technology; 2004, 4; 91-97
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analytical Models for Distribution of the Envelope and Phase of Linearly Modulated Signals in AWGN Channel
Autorzy:
Moazzeni, T
Jiang, Y.
Selvaraj, H.
Chen, T.
Powiązania:
https://bibliotekanauki.pl/articles/226459.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
digital modulation
linear modulation
probability density function
phase
AWGN
Opis:
In this paper, analytical expressions for the distribution of the envelope and phase of linearly modulated signals such as BPSK, M-PSK, and M-QAM in AWGN are presented. We perform numerical simulations for different orders of signal constellations. The results show that the proposed theoretical models are in excellent agreement with the estimated distributions from various numerical experiments.
Źródło:
International Journal of Electronics and Telecommunications; 2014, 60, 1; 79-82
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Transmission Perspective on the Mechanism of Coarse and Fine Crackle Sounds
Autorzy:
Lu, Bing-Yuh
Hsueh, Meng-Lun
Wu, Huey-Dong
Powiązania:
https://bibliotekanauki.pl/articles/1953484.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
crackles
computer simulation
lung sound
respiration
amplitude modulation
frequency modulation
Opis:
The possibility of a normal distribution indicates that few particles are in the same phase during a breath and their reflections can be observed on the chest wall, then a few explosive waves with relatively large power occurr occasionally. Therefore, the one-cycle sine wave which is simulated as a single burst of the explosive effect phenomenon penetrates through the chest wall and was analysed to explore the reason of the crackle sounds. The results explain the differences between the definitions of crackle proposed by Sovijärvi et al. (2000a). The crackles in the lungs were synthesised by a computer simulation. When the coarse crackles occur, the results indicate that higher burst frequency carriers (greater than 100 Hz) directly penetrate the bandpass filter to simulate the chest wall. The simulated coarse crackle sounds were low pitched, with a high amplitude and long duration. The total duration was greater than 10 ms. However, for a lower frequency carrier (approximately 50 Hz), the fundamental frequency component was filtered out. Therefore, the second harmonic component of the lower frequency carrier, i.e., the fine crackle, penetrated the chest wall. Consequently, it is very possible that the normal lung sounds may contain many crackle-shaped waves with very small amplitudes because of the filtering effects of the chest wall, environment noises, electric devices, stethoscopes, and human ears, the small crackles disappear in the auscultations. In addition, our study pointed out that some unknown crackles of the very low frequency under the bandwidth of the human ears cannot penetrate the airways and be detected by medical doctors. Therefore, it might be necessary to focus advanced electronic instrumentation on them in order to analyse their possible characteristics for diagnosis and treatment of the respiration system.
Źródło:
Archives of Acoustics; 2021, 46, 2; 289-300
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pilot Based MMSE Channel Estimation for Spatial Modulated OFDM Systems
Autorzy:
Soman, Anetha Mary
Nakkeeran, R.
Shinu, Mathew John
Powiązania:
https://bibliotekanauki.pl/articles/2055222.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
MIMO
multicarrier modulation
spatial modulation
channel estimation
channel model
interpolation
Opis:
Due to the multifold growth in demands of multimedia services and mobile data, the request for increased channel capacity in mobile and wireless communication has been quickly increasing. Developing a wireless system with more spectral efficiency under varying channel condition is a key challenge to provide more bit rates with limited spectrum. Multiple Input Multiple Output(MIMO) system with Orthogonal Frequency Division Multiplexing (OFDM) gives higher gain by using the direct and the reflected signals, thus facilitating the transmission at high data rate. An integration of Spatial Modulation (SM) with OFDM (SM OFDM) is a newly evolved transmission technique and has been suggested as a replacement for MIMO -OFDM transmission. In practical scenarios, channel estimation is significant for detecting transmitted data coherently. This paper proposes pilot based, Minimum Mean Square Error (MMSE) channel estimation for the SM OFDM communication system. We have focused on analyzing Symbol Error Rate (SER) and Mean Square error (MSE) under Rayleigh channel employing International Telecommunication Union (ITU) specified Vehicular model of Pilot based MMSE channel estimator using windowed Discrete Fourier Transform (DFT) and MMSE weighting function. Simulation output shows that proposed estimator’s SER performance lies close to that of the MMSE optimal estimator in minimizing aliasing error and suppressing channel noise by using frequency domain data windowing and time domain weighting function. Usage of the Hanning window eliminates error floor and has a compact side lobe level compared to Hamming window and Rectangular window. Hanning window has a larger MSE at low Signal to Noise Ratio (SNR) values and decreases with high SNR values. It is concluded that data windowing technique can minimize the side lobe level and accordingly minimize channel estimation error when interpolation is done. MMSE weighting suppresses channel noise and improves estimation performance. Since Inverse Discrete Fourier Transform(IDFT)/DFT transforms can be implemented with fast algorithms Inverse Fast Fourier Transform( IFFT)/Fast Fourier Transform(FFT) computational complexity can be remarkably reduced.
Źródło:
International Journal of Electronics and Telecommunications; 2021, 67, 4; 685--691
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Digital vector modulator with diagnostic circuit for particle accelerator
Autorzy:
Tarnowski, S.
Piotrowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/397924.pdf
Data publikacji:
2010
Wydawca:
Politechnika Łódzka. Wydział Mikroelektroniki i Informatyki
Tematy:
modulacja wektorowa
modulacja cyfrowa
diagnostyka
vector modulation
digital modulation
diagnostics
Opis:
Modern particle accelerators[8] have very strict requirements for controlling signal. To generate signal controlling field in cavities there is a possibility to use digital vector modulator and analog upconverter[6]. Hardware circuit consists of FPGA device, digital to analog converter and low pass filter. For experiments there is also a need to design and develop measurement circuit. Same circuit could be used in final application as diagnostics module. This enables an option for constant long term measurement and fault detection. This paper presents construction of such module.
Źródło:
International Journal of Microelectronics and Computer Science; 2010, 1, 1; 85-88
2080-8755
2353-9607
Pojawia się w:
International Journal of Microelectronics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental research of the AMWG algorithm for assessing amplitude modulation in wind turbine noise
Autorzy:
Czapla, Marcjanna
Wszołek, Tadeusz
Powiązania:
https://bibliotekanauki.pl/articles/24202008.pdf
Data publikacji:
2022
Wydawca:
Politechnika Poznańska. Instytut Mechaniki Stosowanej
Tematy:
wind turbine noise
amplitude modulation
modulation depth
modulation frequency
hałas turbin wiatrowych
modulacja amplitudy
głębokość modulacji
częstotliwość modulacji
Opis:
The operation of a wind turbine (WT) is characterized by fluctuations in sound pressure amplitude associated with the passage of the propeller blade through the tower. Amplitude Modulation (AM) is one of the factors that contributes to the increased annoyance of wind turbine noise. The phenomenon of AM is currently the subject of research in many research centers around the world in the context of a parametric assessment of its impact on annoyance. Despite the development of many methods to measure the AM of a WT noise, there is no commonly accepted method. This paper discusses the most crucial factors that stimulate the phenomenon of AM and the implementation in the MATLAB environment of the algorithm to find the frequency and depth of AM proposed by the Amplitude Modulation Working Group (AMWG). The results of verification of the developed algorithm as well as the measurement results of the frequency and depth of modulation for two measurement samples of a 2 MW wind turbine are presented.
Źródło:
Vibrations in Physical Systems; 2022, 33, 3; art. no. 2022317
0860-6897
Pojawia się w:
Vibrations in Physical Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The diagnosis of onboard generators (alternators)
Autorzy:
Gębura, A.
Radoń, T.
Powiązania:
https://bibliotekanauki.pl/articles/258804.pdf
Data publikacji:
2009
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
technical diagnostics
frequency modulation
Opis:
In the paper selected problems related to diagnostics of onboard generators and alternators fitted with control systems are discussed. Problems refer to commutator generators and synchronous single- and threephase alternators. Special attention is paid to commutation effects. Results of incorrectness and possibility to detect them are discussed. There are also discussed effects associated with changes in a character of pulsation, which occur during shortings or insulation clearances in rotor or stator wiring. Possibility of diagnosis of generator’s or alternator’s parts by means of analysis of pulsation component parameters is indicated. In the case of alternators a number of diagnostic methods based on observation of changes in shape of voltage or frequency modulation, is discussed. This allows to detect many mechanical or electrical faults of generators, alternators or their control systems.
Źródło:
Polish Maritime Research; 2009, 3; 36-40
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Recognition of narrowband radio signals using autoregressive models and pattern comparison approach
Autorzy:
Łopatka, J.
Powiązania:
https://bibliotekanauki.pl/articles/308156.pdf
Data publikacji:
2002
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
signal models
modulation recognition
Opis:
This paper presents an improved spectral recognition method for digitally modulated radio signals. It is based on a signal autoregressive (AR) model. Model poles are used as signal features for neural network based on recognition process. To reduce an influence of the signal noise and distortions introduced by the digital receiver, a nonlinear Z plane transformation is proposed.
Źródło:
Journal of Telecommunications and Information Technology; 2002, 1; 56-59
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fuzzy logic classifier for radio signals recognition
Autorzy:
Łopatka, J.
Pędzisz, M.
Powiązania:
https://bibliotekanauki.pl/articles/308362.pdf
Data publikacji:
2001
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
modulation recognition
fuzzy logic
Opis:
This paper presents a new digital modulation recognition algorithm for classifying baseband signals in the presence of additive white Gaussian noise. Elaborated classification technique uses various statistical moments of the signal amplitude, phase and frequency applied to the fuzzy classifier. Classification results are given and it is found that the technique performs well at low SNR. The benefits of this technique are that it is simple to implement, has generalization property and requires no apriori knowledge of the SNR, carrier phase or baud rate of the signal for classification.
Źródło:
Journal of Telecommunications and Information Technology; 2001, 2; 31-34
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mодуляция как переводческая трансформация
Modulation as a translation transformation
Autorzy:
Гочев (Gochev), Гочо (Gocho)
Powiązania:
https://bibliotekanauki.pl/articles/967812.pdf
Data publikacji:
2012
Wydawca:
Uniwersytet Łódzki. Wydawnictwo Uniwersytetu Łódzkiego
Tematy:
translation
modulation
translation transformation
Opis:
Modulation is a process which involves changing the informative parameters of the source language word. The concrete manifestation of this transformation is the act of replacing the source language words with equivalents unrelated to the systematic regularities of lexis and as such they might a) have relevance to these regularities, i.e. the equivalent exhibits a semantic or associative link with the source language word, or b) not have relevance to these regularities, i.e. the equivalent does not exhibit a semantic or associative link with the source language word, but its use is justified by extralinguistic factors (e.g. logical reasoning or a concrete situation).
Źródło:
Acta Universitatis Lodziensis. Folia Linguistica Rossica; 2012, 08; 43-49
1731-8025
2353-9623
Pojawia się w:
Acta Universitatis Lodziensis. Folia Linguistica Rossica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Symulacyjna aproksymacja charakterystyki przetwarzania flickermetru dla modulacji amplitudy i częstotliwości
Simulation approximation of flickermeter conversion characteristic for amplitude and frequency modulation
Autorzy:
Majchrzak, J.
Wiczyński, G.
Powiązania:
https://bibliotekanauki.pl/articles/156720.pdf
Data publikacji:
2007
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
flikermetr
wskaźnik Pst
modulacja AM
modulacja FM
flickermeter
Pst indicator
FM modulation
AM modulation
Opis:
Flickermetr jest potoczną nazwą układu pomiarowego przeznaczonego do oceny odczuwania migotania światła wywołanego wahaniami napięcia. Normatywna charakterystyka przetwarzania flickermetru jest określona mało licznym zestawem par wartości głębokości modulacji i częstotliwości harmonicznego lub prostokątnego sygnału modulującego dla modulacji amplitudy napięcia wejściowego. Wielkością wyjściową jest wskaźnik krótkookresowego migotania światła Pst. W celu dokładniejszego odtworzenia charakterystyki przeprowadzono badania symulacyjne dla modulacji amplitudy i częstotliwości napięcia wejściowego. Zamodelowano elementy toru normatywnego flickermetru, tj. filtry o stałych parametrach zapisane w postaci operatorowej wraz z multiplikatorami, narzędzie do wyznaczania wartości Pst, źródło sygnału testowego oraz narzędzia do prezentacji i archiwizacji wyników badań. W artykule przedstawiono wyniki badań symulacyjnych zrealizowanych przy pomocy standardowych przebiegów testowych dla modulacji amplitudy AM oraz częstotliwości FM. Zamieszczono specyficzne fragmenty wyznaczonych charakterystyk oraz przykład wpływu ograniczenia pasma napięcia wejściowego na wynik pomiaru flickermetrem dla modulacji FM. Wyniki symulacji porównano z nielicznymi punktami normatywnymi. Sformułowano uwagi przydatne w diagnostyce flickermetru.
Flickermeter is a measurement system for estimation of the disturbances coming from flickering of light caused by the fluctuations of voltage. The disturbances are described on the basis of values of short-term coefficient Pst and long-term coefficient Plt of light flickers. The flickermeter system considered in the paper consists of two main components: a signal channel simulating perception processes in the chain: light source-eye-brain and a statistics module. Signal chains action is a map for bounded number of standard points of characteristic conversion. The simulation works with realization interpolation and extrapolation standard points was advisable. Presented results come from tests for AM and FM modulation.Before using the results, the verification was necessary. The conclusions formulated are useful in flickermeter's diagnostic.
Źródło:
Pomiary Automatyka Kontrola; 2007, R. 53, nr 9 bis, 9 bis; 629-632
0032-4140
Pojawia się w:
Pomiary Automatyka Kontrola
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Chaotic-based Orthogonal Frequency Division Multiplexing with Index Modulation
Autorzy:
Hussien, Sura H.
Abdullah, Hamsa A.
Powiązania:
https://bibliotekanauki.pl/articles/2174449.pdf
Data publikacji:
2022
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
AWGN
chaos communications
DCSK
index modulation
Opis:
Orthogonal frequency division multiplexing with index modulation (OFDM-IM), stands out among conventional communication technologies, as it uses the indices of the available transmit entities. Thanks to such an approach, it offers a novel method for the transmission of extra data bits. Recent years have seen a great interest in chaos-based communications. The spectrum-spreading signals used in chaotic signal modulation technologies are orthogonal to the existing mixed signals. This paper presents how well a non-coherent differential chaos shift keying communication system performs across an AWGN. Different types of detection methods are simulated, bit error rate and power spectral density are calculated and then compared with standard OFDM with index modulation. The results of simulations concerning the performance of a DCSK system, adding to the security of the proposed solution and offering a comparable bit error rate performance, are presented in the paper as well.
Źródło:
Journal of Telecommunications and Information Technology; 2022, 4; 33--38
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 232

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