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The Study of Externally Modulated AM Video Lightwave TransmitterLin, Hsien-Sheng 27 June 2000 (has links)
Abstract
In this thesis, we use a high power 1550 nm DFB laser and
a Ti:LiNbO3 Mach-Zehnder modulator to construct an externally
modulated trensmitter for CATV lightwave system. We use two
methods to reduce the problem caused by stimulated Brillouin
scattering (SBS) effect in externally modulated AM video system
by using high-frequency phase modulation and low-frequency
dithering techniques. In this experiment, the SBS threshold can
be increased by 6 dB. We also design a automatic gain control
(AGC) circuit with a 10 dB dynamic range in our transmitter.
After addition with a home-made predistortion linearized circuit,
the system performance of this transmitter in a 20 km single-mode
fiber link carrying 60 NTSC channels can be achieved with a
CNR¡Ù46~52 dB¡BCSO¡Ø-68~-73 dBc¡BCTB¡Ø-59~-63 dBc. As the number of
channels increased from 60 to 80, we can obtain CNR¡Ù46~51 dB,
CSO¡Ø-65.5~-71 dBc, and CTB¡Ø-55~-60.4 dBc. According to preceding
description, we know that our trensmitter can carry 60 ~ 80 NTSC
channels.
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Amplificador óptico híbrido Raman/EDFA com controle automático de ganho para redes DWDM reconfiguráveis / Raman/EDFA hybrid optical amplifier with automatic gain control for reconfigurable DWDM networksJuliano Rodrigues Fernandes de Oliveira 27 May 2014 (has links)
Visando atender a massificação das tecnologias da informação e comunicação (TIC) por meio de um aproveitamento mais eficiente da infra-estrutura de fibras ópticas, as redes ópticas DWDM vem passando por significativa evolução de capacidade, com base no uso de formatos de modulação avançados, para canais operando em taxas de 100 Gb/s e superiores, bem como no emprego de topologias dinâmicas e reconfiguráveis. Estas redes ópticas de nova geração impõe novos requisitos de desempenho aos amplificadores ópticos. Especificamente, as características dinâmicas da rede tornam obrigatório o uso de esquemas de controle que assegurem estrita planicidade espectral de ganho enquanto o emprego de formatos de modulação avançados e de alta ordem requer margens mais estreitas em termos da relação sinal-ruído aceitável para detecção dos sinais recebidos. Neste contexto, esta tese propõe e avalia experimentalmente uma topologia de amplificação óptica híbrida Raman/EDFA, introduzindo um novo esquema de controle automático de ganho e apresentando desempenho superior aos amplificadores atualmente usados em redes DWDM reconfiguráveis. O amplificador óptico híbrido desenvolvido baseia-se em um estágio Raman distribuído contra-propagante, com excelente desempenho de figura de ruído (porém com baixa eficiência de conversão de bombeio em amplificação - PCE) seguido de um estágio EDFA, que assegura alta potência de saída, devido a sua elevada PCE. Ganho espectral plano foi obtido por meio de uma técnica de controle automático de ganho inovadora, baseada na atuação paralela e independente de duas malhas de controle automático de ganho, uma primeira aplicada ao estágio de amplificação Raman visando ganho-alvo variável com baixa variação espectral, enquanto outra malha de controle de ganho visa fornecer ganho alvo fixo ao estágio EDFA, com alta potência de saída. / Seeking to support the massive deployment of information and communication technologies (ICTs) by means of a more efficient usage of the optical fiber infrastructure, DWDM optical networks have been undergoing a significant capacity evolution, by using advanced modulation formats for optical channels operating at data rates of 100 Gb/s and beyond, as well as by employing dynamic and reconfigurable network topologies. These new generation optical networks impose new performance benchmarks on the optical amplifiers. Specifically, the dynamic characteristics of the network make mandatory the deployment of control schemes which assure stringent optical gain spectral flatness while the usage of high-order advanced modulation formats translate into more strict margins of signal-to-noise ratios for the detected signals. In this context, this thesis proposes and experimentally evaluates an hybrid Raman/ EDFA optical amplifier topology, introducing a novel automatic gain control scheme and demonstrating improved performance over the optical amplifiers already in use in DWDM reconfigurable networks. The developed hybrid optical amplifier is based on a distributed counter-propagating Raman stage, displaying excellent noise figure performance (albeit presenting low conversion efficiency - PCE) followed by an EDFA stage, which assures high output power, due to its high PCE. Flat spectral gain was achieved by means of a novel gain control technique, based on the parallel and independently acting of two control schemes, the first applied over the Raman amplifying stage, aiming at a variable target gain and low spectral gain ripple, while the other seeks to attain a fixed target gain at the EDFA, assuring a high output power.
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Družicový přijímač s integrovaným anténním tunerem / Satellite Receiver with Integrated Antenna TunerMatoušek, Martin January 2018 (has links)
This work is focused on proposal of receiver with Integrated Antenna Tuner operating at 28 MHz. The design was primarily focused on simplicity and low power consumption. The receiver is adapted for SSB modulation. This work was realized for the transmission of audio signals. SSB modulation is far more efficient in terms of the radio spectrum used. First part of this thesis describes about the Antenna Tuner and block diagram of a receiver. Next parts are focused on proposal of individual blocks of the receiver, especially its most important parts. Finally, the overall evaluations of the design characteristics of SSB receivers with Integrated Antenna Tuner are discussed.
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Multi-Gain Control: Balancing Demands for Speed and PrecisionLemasters, Lucas Warner 05 June 2017 (has links)
No description available.
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Ranging airport pseudolite for local area augmentation using the global positioning systemBartone, Chris Gregory January 1998 (has links)
No description available.
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[en] PERFORMANCE OPTIMIZATION OF THE ERBIUM-DOPED FIBER AMPLIFIERS FOR OPERATION IN OPTICAL WDM NETWORKS / [pt] OTIMIZAÇÃO DO DESEMPENHO DE AMPLIFICADORES A FIBRA DOPADA COM ÉRBIO PARA OPERAÇÃO EM REDES ÓPTICAS WDMDJEISSON HOFFMANN THOMAS 20 December 2007 (has links)
[pt] Nas redes ópticas que contém EDFAs (amplificadores à fibra
dopada com
Érbio), a característica variável do tráfego faz com que a
potência de entrada do
amplificador oscile, causando rápidas flutuações de ganho
que podem inviabilizar
a transmissão de dados nos canais WDM (multiplexados por
divisão de
comprimento de onda) co-propagantes. As variações de
tráfego podem ser lentas,
quando originadas pela adição ou remoção de canais WDM em
qualquer nó da
rede (roteamento dos canais WDM), ou rápidas, quando
causadas pela
transmissão aleatória de pacotes ou rajadas de dados
através da rede. Logo, para
alcançar uma alta qualidade de transmissão é necessário
garantir a operação
estável do EDFA, independentemente da natureza das
variações de sua potência
de entrada. Por isto, nós otimizamos o desempenho da
técnica da oscilação laser
em anel para controlar o ganho do EDFA, empregando dois
comprimentos de
onda espectralmente opostos, um acima e outro abaixo da
banca C. A partir da
ótima estabilidade de ganho alcançada com o emprego desta
técnica de controle
em uma unidade amplificadora, implementamos um sistema de
armazenamento de
sinais ópticos com ótimo desempenho e mostramos como
minimizar as flutuações
de ganho acumuladas após muitos EDFAs em cascata, tornando
os enlaces ópticos
de longo alcance mais eficientes. / [en] In optical networks containing EDFAs (Erbium-Doped Fiber
Amplifiers),
the variable traffic characteristic lead the input power
to the amplifier to oscillate
and cause fast time-dependent gain fluctuations that can
impair the transmission
of data on co-propagating WDM (Wavelength Division
Multiplexing) channels.
Traffic variatons can be slow, when originated by add or
drop of WDM channels
at any network node (WDM routing), or fast, when come from
random
transmission of packet/burst data through the network.
Consequently, to reach a
high quality transmission it is necessary to ensure a
stable EDFA operation,
regardless the nature of its input power variations.
Therefore, we optimized the
performance of the ring-laser technique to clamp the EDFA
gain, using two
spectrally oposite lasing wavelengths, one above and
another below the C-band.
Based on the excellent gain stability reached with the
employment of this gain
control technique over one amplifier unit, we assembled a
high-performance alloptic
buffer memory and showed how to miminize the accumulated
gain
fluctuations after many cascaded EDFAs, enabling more
efficient long distance
optical links.
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High-Gain Transimpedance Amplifier With DC Photodiode Current RejectionOzbas, Halil I 05 May 2005 (has links)
This master's thesis deals with the design of a differential high-gain transimpedance amplifier in TSMC's 0.18 um mixed signal process that utilizes a DC photodiode current cancellation loop and a switching automatic gain control (AGC) with a bilinear gain curve. The amplifier is designed to satisfy the demands of Optical Coherence Tomography applications where the receiver is expected to measure the envelope power of an amplitude modulated sinusoidal optical signal that incorporates a large DC component. Methods of increasing dynamic range and gain linearity through the use of DC photodiode current cancellation and bilinear gain are explored. Effects of changing DC photodiode current on the overall system response is also demonstrated.
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Decision making in field cricketsGabel, Eileen 18 November 2016 (has links)
Akustische Signale dienen vielen Tierarten als Mittel zur Partnerfindung. Diese Tiere müssen ihre Entscheidung für den besten Paarungspartner durch die Integration der Parameter verfügbarer Signale treffen. Das Wahlverhalten weiblicher Grillen basiert auf der Attraktivität des zeitlichen Musters des männlichen Gesangs und auf dessen Intensität. Diese Eigenschaften korrelieren nicht zwangsweise positiv, daher wird sich kein Männchen in einer Aggregation von singenden Männchen als überragend abheben und somit wird dem Weibchen die Entscheidung erschwert. Die vorliegende Arbeit beschäftigt sich mit der Frage wie die relevanten Merkmale des männlichen Gesangs während der Entscheidungsfindung des Weibchens integriert werden. 6 Arten von Feldgrillen wurden in nicht-Wahl- und Wahlexperimenten hinsichtlich ihrer Antworten und Präferenzen für männliche Signale, welche sich in Pulsrate, Modulationstiefe, Intensität, Anordnung der Chirps während der Wiedergabe und der zeitlichen Verschiebung zweier Signale zueinander unterschieden, getestet. Des Weiteren wurde durch Transitivitätstests untersucht, ob dem Wahlverhalten weiblicher Grillen rationale oder vergleichende Entscheidungsmechanismen zugrunde liegen. Zusammenfassend zeigen die Ergebnisse, dass die Verarbeitungsmechanismen, welche der Entscheidungsfindung bei weiblichen Feldgrillen zugrunde liegen, in den untersuchten Arten ähnlich sind. Die Lokalisierung des Signals ist nicht unabhängig von der Erkennung. Neben einem generellen Verarbeitungsschema wurden zwischen den einzelnen untersuchten Arten charakteristische Unterschiede in der Mustererkennung, der Verarbeitung der Signalintensität und der Intensitätsgewichtung festgestellt. Jedoch wiesen nah verwandte Arten ähnlichere Präferenzen auf, als nicht nah verwandte Arten. Die Tests zur Transitivität der Präferenzen weisen auf vergleichende Entscheidungs-mechanismen hin und widersprechen einer rationalen Partnerwahl. / In many animals acoustic signals serve for mate attraction. They thus need to make a decision about which is the best mating partner in a choice situation by integrating the cues of the available signals. Choice behaviour in female crickets is based on the attractiveness of the temporal pattern of a male’s calling song and on its intensity. The parameters of a calling song are not necessarily positively correlated and no male will emerge as superior in an aggregation of singing males. The present thesis addresses the question on which cues decision making is based and how these relevant cues of a male’s song are integrated during the decision process of a female. To this aim no-choice and choice experiments with 6 species of field crickets were conducted. Experiments systematically varied pulse rate, modulation depth, intensity, chirp/trill arrangement and temporal shifts of synchronously presented signals. Furthermore, tests for transitivity of preferences examined if female choice behavior is based on rational or comparative decision making mechanisms. In summary, the results reveal that sensory processing underlying female decisions is similar in the 6 species studied here. Incoming signals are analyzed separately in bilaterally paired networks with parallel pathways for signal attractiveness and signal intensity. A gain-control mechanism fuses the outcome of both pathways and signal intensity is weighted by pattern attractiveness. Thus localization is not independent from signal recognition. Despite this general scheme remarkable characteristic differences between species were observed in pattern recognition, processing of signal intensity and weighting of signal intensity. Closely related species exhibited more similar preferences than unrelated species. Furthermore the tests for transitivity of preferences indicated that females use comparative decision making mechanism and contradicted rational mate choice.
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Design of a High Speed AGC Amplifier for Multi-level CodingBhuiya, Iftekharul Karim January 2006 (has links)
<p>This thesis presents the design of a broadband and high speed dc-coupled AGC amplifier for multi-level (4-PAM) signaling with a symbol rate of 1-GS/s ( 2-Gb/s ) . It is a high frequency analog design with several design challenges such as high -3 dB bandwidth ( greater than 500 MHz ) and highly linear gain while accommodating a large input swing range ( 120 mVp-p to 1800 mVp-p diff.) and delivering constant</p><p>differential output swing of 1700 mVp-p to 50-ohm off-chip loads at high speed. Moreover, the gain control circuit has been designed in analog domain. The amplifier incorporates both active and passive feedback in shunt-shunt topology in order to achieve wide bandwidth. This standalone chip has been implemented in AMS 0.35 micron CMOS process. The post layout eye-diagrams seem to be quite satisfactory.</p>
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Wideband active-balun variable-gain low-noise amplifier for mobile-TV applicationsLo, Keng Wai January 2010 (has links)
University of Macau / Faculty of Science and Technology / Department of Electrical and Electronics Engineering
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