Spelling suggestions: "subject:"[een] INTERMODULATION PRODUCTS"" "subject:"[enn] INTERMODULATION PRODUCTS""
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[en] CALCULATING INTERMODULATION PRODUCTS BY REPRESENTING CONTIGUOUS NARROW BAND CARRIES AS BANDPASS NOISE / [pt] CÁLCULO DE INTERMODULAÇÃO ATRAVÉS DA REPRESENTAÇÃO DE PORTADORAS DE FAIXA ESTREITA CONTIGUAS POR UMA BANDA DE RUÍDOOLAVO ALVES DIOGO 29 October 2009 (has links)
[pt] A representação de várias portadoras SCPC/ FM contiguas por uma banda de ruído não permite obter com exatidão a densidade espectral de potência de intermodulação na saída de uma amplificador não-linear. No entanto, este trabalho mostra que, usada adequadamente, a representação por uma banda de ruído oferece uma solução para o problema de determinação dos efeitos da intermodução, na medida em que permite calcular com grande precisão a potência de intermodulação em RF dentro da faixa de qualquer portadora, o ruído em banda básica pode ser calculado de maneira adequada. Um programa de computador utilizando essa técnica para transponders ocupados por portadoras SCPC/ FM de diferentes níveis foi desenvolvido e como validação do procedimento proposto foram feitas comparações com os resultados obtidos a partir de uma técnica de contagem rápida de produtos de intermodulação recentemente desenvolvida. A representação por bandas de ruído é também útil quando portadoras com diferentes densidades espectrais de potência normalizadas compõem o transponder. / [en] Replacing several contiguous SCPC/ FM carriers by na equivalent band of thermal noise does not lead to the exact intermodulation power spectral density at the output of a nonlinear amplifier. However, this work shows that an appropriate use of the results following from this approach can still lead to a solution for the problem of evaluating intermodulation impairments, since a precise computation of the RF intermodulation power inside the frequency bandwidth of any carrier is indeed performed. Furthermore, if the spectrum shape is taken into account the baseband noise can be found in a proper way. A computer program using this technique for transponders accessed by SCPC/ FM carriers of different levels has been developed. In order to validate the proposed procedure, comparisons have been performed with the results based on another recently developed technique, involving a fast algorithm for counting intermodulation products. Replacing contiguous narrow-band carriers by thermal noise is also useful when carriers with different normalized power spectral densities are accessing the transponder.
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[en] A PERFORMANCE ANALYSIS OF PSK SYSTEMS WITH SEVERAL CARRIERS SHARING A CAMMON LINEAR CHANNEL / [pt] ANÁLISE DE DESEMPENHO DE SISTEMAS PSK COM MÚLTIPLAS PORTADORAS COMPARTILHANDO UM MESMO CANAL NÃO LINEARRAFAEL CIRIGLIANO SAMPAIO NETO 07 May 2007 (has links)
[pt] A análise de desempenho de sistemas de comunicações nos
quais um grande número de portadoras, de diferentes tipos
e níveis de potência, acessam uma mesma não-linearidade,
esbarra, inicialmente, na dificuldade de se determinar,
com precisão e tempo de computação aceitável, a
distribuição de potência do ruído de intermodulação
gerado. O problema torna-se ainda mais complexo nos casos
em que as portadoras têm envoltória variável no tempo,
quando, além de se tornar mais difícil a determinação do
espectro de intermodulção, há o aparecimento adicional da
transferência de modulação das demais portadoras para a
portadora desejada.
Com o enfoque voltado para o desempenho de sistemas
digitais, mostra-se que, utilizando-se determinados
algoritmos e aproximações, o tratamento analítico torna-se
factível. Com base na teoria apresentada, foi desenvolvido
um programa de computador que permite avaliação de
desempenho em situações bastante gerais. / [en] One of the difficulties arising in a theoretical
performance evaluation of communication systems in which
several carriers of various types are transmitted through
a cammon nonlinear amplifier, is related to the problem of
calculating, with good precision and within reasonable
computer time, the power spectrum of the intermodulation
noise generated at the output of the nonlinear device. The
analysis becomes more complex when the carriers have time-
varyng envelopes, since in such situations, besides the
difficulty involved in determining the power and spectrum
shape of the output signals and intermodulation products,
an extra system impairment should be taken into account.
Namely, the performance degradation due to modulation
transfer from all the other carriers into the desired
carrier.
With focus on digital systems, it is shoun that, by using
certain algorithms and approximations, theoretical
performance analysis is feasible. Based on the results
presented, a computer program was developed to evaluate
performance in fairly general situations.
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Koexistence mobilních komunikačních systémů GSM-EDGE a UMTS / GSM-EDGE and UMTS Systems CoexistenceGleissner, Filip January 2009 (has links)
The dissertation thesis deals with the investigation of the coexistence of GSM–EDGE and UMTS systems with focus on the physical layer of the systems. The aim is to provide a set of recommendations for practical cooperation while the systems operate in both the separated and the common radio bands. A detailed description of signal processing of both the systems on the physical layer is presented. On the basis of this description, models of both systems were created and implemented in the MATLAB environment. The simulations are focused on the physical layer quality parameters, especially the bit error ratio evaluation for various ratios of useful signal power to noise power during the transmission over the radio channel. Simulation is also used to examine the quality of received useful signal while it is interfered by signals from the same and adjacent channels. The purpose is to determine the isolation between these adjacent channels, when the bit error ratio of the useful signal does not exceed a certain reference value. The simulation results are subsequently subjected to comparison with the results of the experimental measurements in laboratory conditions. Before the measurements are carried out, a study of possible interference types is performed. Consequently, the crucial parameters of the measuring equipment used are verified. From the results of simulations and measurements, the proposal of a minimum and recommended carrier separation between both the systems is presented in order to efficiently utilize the assigned frequency spectrum. Furthermore, for the cooperation in both the separated and the common radio bands, the necessary precautions are given for reaching the required isolation and thereby inter-system interference minimization.
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