Thèses sur le sujet « Modulation discrète »
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1
Tabaa, Mohamed. « Conception d'un système de transmission ultra-large bande par impulsions orthogonales ». Thesis, Université de Lorraine, 2014. http://www.theses.fr/2014LORR0375/document.
Texte intégralRésumé :
Dans cette thèse, nous proposons une méthodologie de conception d’architectures de communication dédiées aux réseaux de capteurs basées sur la technique de radio impulsionnelle pour les transmissions ultralarge bande (ULB). La technique impulsionnelle proposée ici repose sur la modulation de forme d’impulsion. L’approche de conception architecturale présentée dans cette thèse se focalise plus particulièrement sur la forme des impulsions et leur génération, qui revêt un intérêt majeur puisqu’elle constitue le support de l’information échangée. L’étude sur le choix de la forme d’impulsion nous a conduit à proposer deux architectures différentes. Une première architecture repose sur les polynômes orthogonaux, et plus particulièrement sur les polynômes d’Hermite, pour la génération des impulsions, et sur une architecture de corrélation pour la détection et la reconnaissance des trains d’impulsions transmis. La deuxième architecture est basée sur la transformée en paquets d’ondelettes discrète et peut être exploitée selon deux modes d’utilisation différents, mono et multiutilisateurs. L’utilisation d’une architecture de synthèse à l’émission et d’analyse à la réception ouvre une nouvelle orientation pour les communications numériques, permettant à la transformée en ondelettes d’assurer à la fois la génération des impulsions à l’émission et leur reconnaissance à la réception. Un intérêt immédiat de la technique proposée permet notamment de faciliter l’accès multiutilisateurs au canal ultralarge bande, et d’autoriser des communications simultanées (Many-to-one, des nœuds vers le puits) ou du broadcast (One-to-many, du puits vers les nœuds) sans surcharger la couche MAC. L’architecture proposée s’inscrit donc à l’interface des couches PHY et MAC et permet de relâcher les contraintes de conception spécifiques à ces couchesIn this thesis, we propose a design methodology for communication architectures dedicated to wireless sensor network based on impulse radio techniques for UWB communications. The impulse technique proposed in this work relies on pulse shape modulation. The architecture design approach proposed in this thesis focuses on pulses shape and their generation, which is of major interest as it constitutes the carrier of the information exchanged. The study on the choice of pulse shape led us to propose two different architectures. The first one is based on orthogonal polynomials, more especially on the Hermite polynomials, for impulse generation, and on a correlation architecture for detection and recognition of transmitted impulses. The second architecture is based on discrete wavelet packet transform and can be used according two different modes, mono and multi-users. The use of both synthesis and analysis architectures for emitter and receiver, respectively, offers a new way for digital communications and allows the wavelet transform to ensure the impulses generation on the transmitter and their recognition on the receiver. A major interest point of the proposed technique is to facilitate the multi-users access to the ultra-wideband channel and to allow simultaneous communications (many-to-one, from the sensors to the sink) or broadcast (one-to-many, from the coordinator to the nodes) but without overloading the MAC layer. Hence, the proposed architecture is part of the interface between both PHY and MAC layers, and allows to release their specific design constraints
2
Fang, Yi-chin. « Performance evaluation of discrete IR optical system ». Thesis, University of Reading, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270211.
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Bengtsson, Daniel, et Daniel Landström. « Coding in a discrete multitone modulation system ». Thesis, Luleå, 1996. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-62422.
Texte intégralRésumé :
Discrete Multitone (DMT) modulation is a multicarrier technique which makes efficient use of the channel, maximizing the htroughput by sending different numbers of bits on different subchannels. The number of bits on each subchannel depends in the Signal-to-Noise Ratio of the subchannel. The performance of a DMT system can be further increased by using powerful coding techniques. This thesis investigates an implementation of coding for a DMT system. The coding techniques considered are Ree-Solomon coding combined with interleaving, and Trellis Coded Modulation. Wei's 4-dimensional 16-state coder combined with trellis shaping is the suggested trellis code. A single encoder is used which codes across the tones of each DMT-symbol. At a bit error probability of 10 -7 the suggested codes gain 3-6 dB over uncoded transmission. Hardware complexity and algorithmic aspects of coding are covered, as well as simulations to verify it.
4
Jenkin, Robin Brian. « On the application of the modulation transfer function to discrete imaging systems ». Thesis, University of Westminster, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251647.
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Forbes, Jason. « Discrete signal processing techniques for power converters : multi-carrier modulation and efficient filtering techniques ». Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/45446.
Texte intégralRésumé :
Digital control has become ubiquitous in the field of power electronics due to the ease of implementation, reusability, and flexibility. Practical engineers have been hesitant to use digital control rather than the more traditional analog control methods due to the unfamiliar theory, relatively complicated implementation and various challenges associated with digital quantization. This thesis presents discrete signal processing theory to solve issues in digitally controlled power converters including reference generation and filtering.
First, this thesis presents advancements made in the field of digital control of dc-ac and ac-dc power converters. First, a multi-carrier PWM strategy is proposed for the accurate and computationally inexpensive generation of sinusoidal signals. This method aims to reduce the cost of implementing a sine-wave generator by reducing both memory and computational requirements. The technique, backed by theoretical and experimental evidence, is simple to implement, and does not rely on any specialized hardware. The method was simulated and experimentally implemented in a voltage-controlled PWM inverter and can be extended to any application involving the digital generation of periodic signals.
The second advancement described in this thesis is the use of simple digital filters to improve the response time of single-phase active rectifiers. Under traditional analog control strategies, the bandwidth of an active rectifier is unduly restricted in order to reduce any unwanted harmonic distortion. This work investigates digital filters as a proposed means to improve the bandwidth, and thereby create a faster, more efficient ac-dc power converter. Finally, a moving average filter is proposed, due to its simple implementation and minor computational burden, as an efficient means to expand the bandwidth. Since moving average filters are well known and widely understood in industry, this proposed filter is an attractive solution for practicing engineers.
The theory developed in this thesis is verified through simulations and experiments.
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Kuznetsov, Nikita A. « Modulation and Coordination of Respiratory Rhythm with Discrete Finger Movements in Manual Precision Aiming ». University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1291407910.
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Smecher, Graeme. « Discrete-time crossing-point estimation for switching power converters ». Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115995.
Texte intégralRésumé :
In a number of electrical engineering problems, so-called "crossing points" -- the instants at which two continuous-time signals cross each other -- are of interest. Often, particularly in applications using a Digital Signal Processor (DSP), only periodic samples along with a partial statistical characterization of the signals are available. In this situation, we are faced with the following problem: Given limited information about these signals, how can we efficiently and accurately estimate their crossing points?For example, an audio amplifier typically receives its input from a digital source decoded into regular samples (e.g. from MP3, DVD, or CD audio), or obtained from a continuous-time signal using an analog-to-digital converter (ADC). In a switching amplifier based on Pulse-Width Modulation (PWM) or Click Modulation (CM), a signal derived from the sampled audio is compared against a deterministic reference waveform; the crossing points of these signals control a switching power stage. Crossing-point estimates must be accurate in order to preserve audio quality. They must also be simple to calculate, in order to minimize processing requirements and delays.
We consider estimating the crossing points of a known function and a Gaussian random process, given uniformly-spaced, noisy samples of the random process for which the second-order statistics are assumed to be known. We derive the Maximum A-Posteriori (MAP) estimator, along with a Minimum Mean-Squared Error (MMSE) estimator which we show to be a computationally efficient approximation to the MAP estimator.
We also derive the Cramer-Rao bound (CRB) on estimator variance for the problem, which allows practical estimators to be evaluated against a best-case performance limit. We investigate several comparison estimators chosen from the literature. The structure of the MMSE estimator and comparison estimators is shown to be very similar, making the difference in computational expense between each technique largely dependent on the cost of evaluating various (generally non-linear) functions.
Simulations for both Pulse-Width and Click Modulation scenarios show the MMSE estimator performs very near to the Cramer-Rao bound and outperforms the alternative estimators selected from the literature.
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Pham, Dang Kien Germain. « Conversion analogique-numérique Sigma-Delta large bande appliquée à la mesure des non-linéarités des amplificateurs de puissance ». Thesis, Paris, ENST, 2013. http://www.theses.fr/2013ENST0003/document.
Texte intégralRésumé :
Les amplificateurs de puissance, éléments constitutifs essentiels de tout système de télécommunication, vont jouer un rôle capital dans le développement des futurs systèmes de communication. Aujourd'hui l'amélioration des amplificateurs de puissance nécessite un progrès technologique au niveau du composant lui même mais doit aussi tenir compte d'une approche plus globale. En particulier, le progrès dans les traitements numériques permet aujourd'hui de corriger en amont certaines distorsions qui seront générées en aval de la chaîne de communication. La pré-distorsion numérique est une technique de correction des amplificateurs de puissance qui connaît un intérêt grandissant de par son intégration complètement numérique et par les gains en linéarité et en consommation. Cette technique nécessite une voie de retour dont un élément critique est le convertisseur analogique-numérique. Ce composant doit répondre à des contraintes de résolution, de bande passante et de linéarité élevées. Dans cette thèse, nous proposons une nouvelle architecture de convertisseur analogique-numérique à base de modulateurs Sigma-Delta passe-bande. Cette architecture tire partie du fonctionnement passe bande des modulateurs que nous faisons travailler en parallèle, chacun centré sur différentes fréquences, mais aussi d'un agencement en cascade particulier pour éliminer le signal utile, qui est de forte puissance, dans le but de diminuer les contraintes de dynamique.La conception haut niveau et les simulations ont été menées pour des systèmes à temps discret et aussi à temps continu et a nécessité le développement d'outils adaptés de simulation se basant sur la boîte à outils Delta Sigma Toolbox de Richard SchreierPower amplifiers, which are essential elements of any communication system, will play a crucial role in the development of future communication systems. Today improving power amplifiers requires technological advances at the circuit device level, but one also must consider a more global approach. In particular, advances in digital processing can now correct in the early stage of the communication chain some distortions that are generated downstream in the chain. Digital pre-distortion is a correction technique for power amplifiers that has a growing interest because of its completely digital implementation and of its gains in linearity and energy consumption. This technique requires a feedback path where the analog-to-digital converter is a critical element. This component must satisfy the constraints of high resolution , wide bandwidth, and high linearity. In this thesis, we propose a new architecture of analog-to-digital converter based on bandpass Delta-Sigma modulators. This architecture takes advantage of operating bandpass modulators that are designed to work in parallel, each focusing on different frequencies, but also of a particular cascading arrangement to eliminate the useful signal, which has a high power, in order to reduce dynamics constraints. High-level design and simulations were carried out for discrete time and continuous time systems and also required the development of appropriate simulation tools
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Nathany, Sumit Kumar. « Design of a 14-bit fully differential discrete time delta-sigma modulator / ». Online version of the thesis, 2006. https://ritdml.rit.edu/dspace/handle/1850/2799.
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Qu, Zhen, et Ivan B. Djordjevic. « Four-Dimensionally Multiplexed Eight-State Continuous-Variable Quantum Key Distribution Over Turbulent Channels ». IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2017. http://hdl.handle.net/10150/626439.
Texte intégralRésumé :
We experimentally demonstrate an eight-state continuous-variable quantum key distribution (CV-QKD) over atmospheric turbulence channels. The high secret key rate (SKR) is enabled by 4-D multiplexing of 96 channels, i.e., six-channel wavelength-division multiplexing, four-channel orbital angular momentum multiplexing, two-channel polarization multiplexing, and two-channel spatial-position multiplexing. The atmospheric turbulence channel is emulated by a spatial light modulator on which a series of azimuthal phase patterns yielding Andrews' spectrum are recorded. A commercial coherent receiver is implemented at Bob's side, followed by a phase noise cancellation stage, where channel transmittance can be monitored accurately and phase noise can be effectively eliminated. Compared to four-state CV-QKD, eight-state CV-QKD protocol potentially provides a better performance by offering higher SKR, better excess noise tolerance, and longer secure transmission distance. In our proposed CV-QKD system, the minimum transmittances of 0.24 and 0.26 are required for OAM states of 2 (or -2) and 6 (or -6), respectively, to guarantee the secure transmission. A maximum SKR of 3.744 Gb/s is experimentally achievable, while a total SKR of 960 Mb/s can be obtained in case of mean channel transmittances.
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Tao, Junbing [Verfasser]. « Half-cycle-sampled discrete model of series-parallel resonant converter with optimized modulation and its control design / Junbing Tao ». Paderborn : Universitätsbibliothek, 2018. http://d-nb.info/1155236297/34.
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Kemp, Pieter Stephanus. « The design of an analogue class-D audio amplifier using Z-domain methods ». Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/20084.
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Thesis (MScEng)--Stellenbosch University, 2012ENGLISH ABSTRACT: The class-D audio power amplifier has found widespread use in both the consumer and professional audio industry for one reason: efficiency. A higher efficiency leads to a smaller and cheaper design, and in the case of mobile devices, a longer battery life. Unfortunately, the basic class-D amplifier has some serious drawbacks. These include high distortion levels, a load dependent frequency response and the potential to radiate EMI. Except for EMI, the aforementioned issues can be mitigated by the proper implementation of global negative feedback. Negative feedback also has the potential to indirectly reduce EMI, since the timing requirements of the output devices can be relaxed. This thesis discusses the design of a clocked analogue controlled pulse-width modulated class-D audio amplifier with global negative feedback. The analogue control loop is converted to the z-domain by modelling the PWM comparator as a sampling operation. A method is implemented that improves clip recovery and ensures stability during over-modulation. Loop gain is shaped to provide a high gain across the audio band, and ripple compensation is implemented to minimize the negative effect of ripple feedback. Experimental results are presented.
AFRIKAANSE OPSOMMING: Die klas-D klankversterker geniet wydverspreide gebruik in beide die verbruiker en professionele oudio industrie vir een rede: benuttingsgraad. ’n Hoër benuttingsgraad lei tot ’n kleiner en goedkoper ontwerp, en in die geval van draagbare toestelle, tot langer batterylewe. Ongelukkig het die basiese klas-D klankversterker ernstige tekortkominge, naamlik hoë distorsievlakke, ’n lasafhanklike frekwensierespons en die vermoë om EMI te genereer. Behalwe vir EMI kan hierdie kwessies deur die korrekte toepassing van globale negatiewe terugvoer aangespreek word. Negatiewe terugvoer het ook die potensiaal om EMI indirek te verminder, aangesien die tydvereistes van die skakel stadium verlaag kan word. Hierdie tesis bespreek die ontwerp van ’n geklokte analoog-beheerde pulswydte-modulerende klas-D klankversterker met globale negatiewe terugvoer. Die analoogbeheerlus word omgeskakel na die z-vlak deur die PWM vlakvergelyker as ’n monster operasie te modelleer. ’n Metode word geïmplementeer wat die stabiliteit van die lus verseker tydens oormodulasie. Die lusaanwins word gevorm om ’n hoë aanwins in die oudioband te verseker en riffelkompensasie word geïmplementeer om die negatiewe effek van terugvoerriffel teen te werk. Eksperimentele resultate word voorgelê.
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Umansky, Alec. « HIGH BANDWIDTH PORTABLE TRANSMISSION SYSTEMS USE OF xDSL TECHNOLOGY IN MILITARY, INDUSTRIAL AND TELEMETRIC APPLICATIONS ». International Foundation for Telemetering, 2001. http://hdl.handle.net/10150/606418.
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International Telemetering Conference Proceedings / October 22-25, 2001 / Riviera Hotel and Convention Center, Las Vegas, NevadaThis paper introduces new telemetry (communications) equipment based on Digital Subscriber Loop DSL technology (high speed transmission over copper cables) for defense and industrial applications. A brief xDSL technology overview is followed with introduction of the new ‘P3’ product and its application, reviewing advantages of using copper as a communications medium whenever rapidly deployed data and voice links are essential. An Australian Army report, detailing a specific equipment deployment’s findings is reproduced as an independent reference material.
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Umansky, Alec. « HIGH BANDWIDTH PORTABLE TRANSMISSION SYSTEMS USE OF xDSL TECHNOLOGY IN MILITARY AND INDUSTRIAL TELEMETRIC APPLICATIONS ». International Foundation for Telemetering, 2000. http://hdl.handle.net/10150/606792.
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International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, CaliforniaThis paper introduces new telemetry equipment based on Digital Subscriber Loop DSL technology (high speed transmission over copper cables) for military and industrial applications. A brief xDSL technology overview is followed with introduction of the new ‘P3’ product. A number of new applications for remote data transmission are presented and further highlighted in the Australian Army report detailing their recent equipment operational deployments.
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Khushk, Hasham Ahmed. « Modulateur ΣΔ passe-haut et application dans la réception multistandards ». Phd thesis, Télécom ParisTech, 2009. http://pastel.archives-ouvertes.fr/pastel-00006055.
Texte intégralRésumé :
Dans cette thèse, les recherches ont été menées à des niveaux d'abstraction différents pour optimiser le fonctionnement du modulateur ΣΔ passe-haut (PH). Une approche « top-down » est adoptée pour atteindre cet objectif. Au niveau de l'architecture du récepteur RF, le nouvellement créé récepteur Fs/2 est sélectionné pour sa grande compatibilité avec modulateur ΣΔ PH comparé aux architectures de réception: zéro-IF et faible-IF. Après avoir défini la topologie du récepteur, l'architecture du modulateur ΣΔ est adressée. Nous proposons une nouvelle architecture du deuxième ordre dont la fonction de transfert du signal est unitaire. Elle est plus avantageuse que d'autres topologies en termes de complexité et de performance. Puisque le modulateur de second ordre est incapable de fournir les performances requises, les structures en cascade ou MASH pour l'opération PH sont explorées. La topologie GMSCL (Generalized Multi-Stage Closed Loop) est choisie et une technique récemment proposée est appliquée pour linéariser le CNA de retour. En plus, cette technique augmente la plage dynamique du convertisseur. Ensuite, après une analyse comparative approfondie, le meilleur filtre HP est choisie pour ce modulateur. Il a les avantages d'avoir une basse consommation, une superficie réduite et un bruit moins important. Enfin, l'architecture GMSCL PH proposée est validée en CMOS 65nm. Les applications visées sont l'UMTS avec 3.84MHz bande de conversion à 80 dB de la plage dynamique et WiMAX avec 25MHz de bande passante à 52dB de dynamique.
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Krasňanský, Milan. « Radar Signal Processing for Radio Altimeter ». Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2017. http://www.nusl.cz/ntk/nusl-363816.
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Táto diplomová práca sa zaoberá návrhom a implementáciou algoritmu pre spracovaniu signálu z radaru využívajúceho frekvenčne modulovanú kontinuálnu vlnu. Cieľom je implementácia algoritmu, ktorý by bol dostatočne rýchly (výpočet v reálnom čase na cieľovej platforme) a dostatočne presný pre použitie v rádiovýškomere v ľahkom lietadle so zameraním na použitie počas pristávacieho manévru. Hlavnou metódou spracovania signálu, použitou v implementácii, je Diskrétna Fourierova transformácia. Vytvorený algoritmus bol otestovaný na reálnych letových dátach a pre pristávací manéver dosiahol uspokojivé výsledky.
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Surma, Dariusz. « Rekurencyjne metody ślizgającej analizy Wienera-Chinczyna ». Rozprawa doktorska, [Nakł.aut.], 2013. http://dlibra.utp.edu.pl/Content/602.
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Rozprawa poświęcona jest rozwojowi algorytmów analizy korelacyjnej, które wykorzystuje się w ślizgającej analizie Wienera-Chinczyna. Opracowano rekurencyjne algorytmy, które pozwalają na redukcję operacji matematycznych podczas obliczania estymat funkcji korelacji.
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Qu, Zhen, et Ivan B. Djordjevic. « High-speed continuous-variable quantum key distribution over atmospheric turbulent channels ». SPIE-INT SOC OPTICAL ENGINEERING, 2017. http://hdl.handle.net/10150/626486.
Texte intégralRésumé :
We experimentally demonstrate a RF-assisted four-state continuous-variable quantum key distribution (CV-QKD) system in the presence of turbulence. The atmospheric turbulence channel is emulated by two spatial light modulators (SLMs) on which two randomly generated azimuthal phase patterns are recorded yielding Andrews' azimuthal phase spectrum. Frequency and phase locking are not required in our system thanks to the proposed digital phase noise cancellation (PNC) stage. Besides, the transmittance fluctuation can be monitored accurately by the DC level in this PNC stage, which is free of post-processing noise. The mean excess noise is measured to be 0.014, and the maximum secret key rate of >20Mbit/s can be obtained with the transmittance of 0.85, while employing the commercial PIN photodetectors.
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Ouzzif, Meryem. « Etude comparative des performances des liaisons SCM-VDSL (Single Carrier Modulation- Very high bit-rate Digital Subscriber Line) et DMT-VDSL (Discrete MultiTone) en présence de bruits impulsifs ». Rennes, INSA, 2004. http://www.theses.fr/2004ISAR0002.
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La technologie VDSL succède aux systèmes ADSL pour délivrer de l'information à des débits plus élevés (dizaines de Mbps) en utilisant également la paire téléphonique comme support de transmission. Sur le plan normatif, cette technologie donne lieu actuellement à une compétition entre deux types de modulation, monoporteuse SCM et multiporteuse DMT. Les performances des transmissions VDSL dépendent, en plus des caractéristiques de l'environnement de transmission, de la modulation mise en oeuvre. En particulier, les bruits impulsifs qui se couplent sur la ligne de transmission affectent différemment les systèmes SCM-VDSL et DMT-VDSL. Ce travail de thèse aborde l'étude comparative de l'impact des bruits impulsifs sur ces deux types de systèmes. La première partie décrit les caractéristiques de l'environnement de Transmission, à savoir la fonction de transfert du canal ainsi que les bruits stationnaires, Radio-Fréquences et impulsifs susceptibles de dégrader les performances de la liaison VDSL. Elle met en évidence également les fonctionnalités des systèmes SCM-VDSL et DMT-VDSL. La deuxième partie traite de l'impact du bruit impulsif sur le système monoporteuse SCM-VDSL qui nécessite l'implémentation d'une égalisation temporelle pour pallier les interférences entre symboles (IES). Pour évaluer l'effet du bruit impulsif sur la liaison SCM-VDSL, la chaîne de transmission dans sa globalité a été modélisée avec la fonction d'égalisation. La confrontation des résultats de simulations et expérimentaux obtenus par l'injection de bruits impulsifs a permis de valider le modèle développé. La modélisation de l'impact du bruit impulsif sur le système DMT-VDSL fait l'objet de la troisième partie. Elle repose sur les caractéristiques de la modulation DMT qui rendent l'égalisation triviale. La simulation s'affranchit donc de sa mise en oeuvre et s'effectue ainsi complètement dans le domaine fréquentiel. La méthode que nous proposons a été validée en comparant les résultats obtenus à ceux fournis par une approche de modélisation classique. La dernière partie présente une étude paramétrique ayant pour objet la comparaison de l'impact du bruit impulsif sur les deux systèmes monoporteuse et multiporteuse, pour différentes configurations des paramètres propres aux systèmes (débit, paramètres du codage Reed-Solomon et de l'entrelacement), et des paramètres liés aux caractéristiques du bruit impulsif. La comparaison est effectuée également pour les deux systèmes quand des puits de puissance sont implémentés dans les bandes radio-amateurs. Les résultats obtenus permettent d'évaluer leurs performances en terme de portée et de débit d'une part, et enterme de délai requis pour la correction des erreurs occasionnéespar la présence de bruit impulsif d'autre partThe latest DSL technology, called Very-high Digital Subscriber Line (VDSL), is intended to convey bit-rates up to 50 Mbps on the ordinary telephone access network. The standardization process is witnessing a competition between two modulation schemes: a single carrier modulation (SCM) and a multicarrier modulation (DMT). The VDSL transmissions performance depends on the electromagnetic environment as well as the implemented modulation. In particular, Impulse Noise, which is coupled on the copper lines, affects differently the SCM-VDSL and DMT-VDSL systems. The purpose of this thesis is to carry out a comparative study of the two systems in an Impulse Noise environment. First, the transmission environment characteristics are presented. The channel impulse response and the different noises liable to impair the VDSL transmission are detailed. The common transmission blocs to the two VDSL systems are explained. A second part is intended to the SCM-VDSL transmission modelling. The receiver of this system requires the implementation of an equalization structure to reduce the ISI. The consideration of Impulse Noise is carried out in the time domain. The developed simulation tool is validated through comparison with measurement results. A third part deals with the modelling of the Impulse Noise impact on DMT-VDSL transmissions. The modelling approach uses the characteristics of the DMT modulation and is led in the frequency domain. This method is simple to carry out since no equalization is needed. The two simulation tools are used in the last part to compare the two systems. First, the performance in terms of bit-rate of SCM-VDSL and DMT-VDSL is investigated for different line configurations (line length and presence of bridge taps) and for different transmission masks (with and without notches). The impact of Impulse Noise is examined for the two systems by considering the different parameters needed to optimize the robustness of the VDSL systems to this noise category
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Baltolu, Anthony. « Etude et conception analogique d’architectures d’acquisition acoustique très faible consommation pour applications mobiles ». Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0339/document.
Texte intégralRésumé :
Les récentes avancées technologiques des microphones de type microsystème électromécanique (MEMS) leurs permettent une utilisation sur une large gamme d’amplitudes sonores. Leur niveau de bruit ayant baissé, il devient possible de capter des sons provenant d’une distance plus lointaine, tandis que l’augmentation de leur pression acoustique maximale leur permet de ne pas saturer dans un environnement très bruyant de type concert ou évènement sportif. Ainsi le système électronique de conversion analogique-numérique connecté au microphone devient l’élément limitant les performances du système d’acquisition acoustique. Un besoin de nouvelles architectures de conversion analogique-numérique ayant une plage dynamique augmentée se fait donc ressentir. Par ailleurs, ces microphones étant de plus en plus utilisés dans des systèmes fonctionnant sur batterie, la contrainte de limitation de la consommation devient importante.Dans la bande de fréquences audio, les convertisseurs analogiques-numériques de type sigma-delta sont les plus aptes à obtenir une grande résolution combinée à une faible consommation. Ils sont divisés en deux grandes familles: ceux à temps discret utilisant principalement des circuits à capacités commutées, et ceux à temps continu utilisant des circuits classiques. Cette thèse se concentre sur l’étude et la conception de chacun des deux types de convertisseurs sigma delta, en insistant sur la faible consommation, le faible coût de production (surface occupée) et la robustesse du circuit, cela en vue d’une production de masse pour équipements portables.La conception d’un convertisseur analogique numérique de type sigma-delta à temps discret a été réalisé, ce dernier atteignant un rapport signal sur bruit de 100 décibels sur une bande de 24kHz, pour une puissance consommée de seulement 480μW. Pour limiter la consommation, de nouveaux amplificateurs à base d’inverseurs sont utilisés, et dont la robustesse contre les variations du procédé de fabrication ou de la température a été améliorée. Les spécifications ont été définies grâce au développement d’un modèle de haut-niveau précis, ce qui permet d’éviter le surdimensionnement tout en atteignant les performances voulues. Enfin, un grand ratio de suréchantillonnage a été choisi afin de réduire l’espace utilisé par les capacités commutées, minimisant le coût de fabrication.Après une étude théorique de l’équivalence entre les modulateurs sigma-delta à temps discret et à temps continu, ainsi que des spécificités propres aux modulateurs à temps continu, une réalisation de ces derniers a été effectuée. Celui-ci atteint un rapport signal sur bruit de 95 décibels sur une bande de fréquence de 24kHz, tout en consommant 142μW. Pour réduire la consommation ainsi que l’espace utilisé, un filtre de boucle du second-ordre a été réalisé avec un seul amplificateur, et le quantificateur fait aussi office d’intégrateur grâce à l’utilisation d’une structure d’oscillateurs contrôlés en tension. Ce quantificateur à base d’oscillateurs est réalisé par des cellules numériques, réduisant la consommation et l’espace utilisé, mais est hautement non-linéaire. Cette non-linéarité a été prise en compte par des choix architecturaux afin de ne pas réduire les performances finales du modulateurThe recent technological advances in microelectromechanical system (MEMS) microphones allow them to be used on a large sound amplitude range. Due to their lower noise level, it becomes possible to capture sound from a faraway distance, while their increased acoustic overload point gives them the ability to capture sound without saturation in a loud environment like a concert or a sport event. Thus, the electronic analog / digital conversion system connected to the microphone becomes the limiting element of the acoustic acquisition system performance. There is then a need for a new analog / digital conversion architecture which has an increased dynamic range. Furthermore, since more and more of these microphones are used in battery-powered devices, the power consumption limitation constraint becomes of high importance.In the audio frequency band, the sigma-delta analog / digital converters are the ones most able to provide a high dynamic range combined to a limited power consumption. They are split in two families: the discrete-time ones using switched-capacitors circuits and the continuous-time ones using more classical structures. This thesis concentrates on the study and the design of both of these two types of sigma-delta converters, with an emphasis on the low-power consumption, the low production cost (area occupied) and the circuit robustness, in sight of a mass production for portable devices.A discrete-time sigma-delta modulator design has been made, the latter reaching a signal to noise ratio of 100dB on a 24kHz frequency bandwidth, for a power consumption of only 480μW. To limit the power consumption, new inverter-based amplifiers are used, with an improved robustness against the variations of the fabrication process or the temperature. Amplifier specifications are obtained thanks to an accurate high-level model developed, which allows to avoid over-design while ensuring that the wanted performances are reached. Finally, a large oversampling ratio has been used to reduce the switched-capacitors area, lowering the modulator cost.After a theoretical study of the equivalence between discrete-time and continuous-time modulators, and of continuous-time modulators specificities, a design of the latter has been made too. It reaches a signal to noise ratio of 95dB on a 24kHz bandwidth, while consuming 142μW. To reduce the power consumption and the occupied area, a second-order loop filter is implemented using a single amplifier, and the quantizer uses a VCO-based structure that provides inherently an integrating stage. The VCO-based quantizer is made using digital cells, lowering the consumption and area, but is highly non-linear. This non-linearity has been handled by architectural choices to not influence the final modulator performances
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Dai, Min. « Control of power converters for distributed generation applications ». Connect to resource, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1124329850.
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Бекус, Ростислав Володимирович, et Rostislav Bekus. « Метод підвищення якості передачі сигналів в бездротових локальних мережах ». Master's thesis, Тернопільський національний технічний університет імені Івана Пулюя, 2020. http://elartu.tntu.edu.ua/handle/lib/34148.
Texte intégralRésumé :
У кваліфікаційній роботі магістра розкрито поняття основ передачі інформації в бездротової середовищі. Проведено дослідження роботи сучасного стандарту WI-Fi 802.11ac. Встановлено, що найактуальнішою проблемою локальний бездротових мереж на сьогоднішній день, є захист переданих даних. Тому розглянуті основні схеми шифрування і модуляції сигналу, проведено порівняння продуктивності актуального стандарту в порівнянні з попереднім. Виявлено перевагу в швидкості передачі інформації і зони покриття при багатоканальної роботі.
Досліджено основні стандарти бездротового зв'язку 802.11. Була розглянута гіпотеза про шкоду здоров'ю від використання Wi-Fi.In the qualification work of the master the concept of bases of information transfer in the wireless environment is opened. A study of the modern standard WI-Fi 802.11ac. It is established that the most pressing problem of local wireless networks today is the protection of transmitted data. Therefore, the main schemes of signal encryption and modulation are considered, the performance of the current standard is compared with the previous one. The advantage in the speed of information transmission and coverage area during multichannel operation is revealed. The basic standards of 802.11 wireless communication are investigated. The hypothesis of harm from health from the use of Wi-Fi was considered.
ВСТУП 8 РОЗДІ 1. АНАЛІТИЧНА ЧАСТИНА 10 1.1 Основи передачі ніформації в безпровідних технологіях 10 1.2 Класифікація безпровдіних технологій 14 1.2.1 Бездротові персональні мережі 15 1.2.2 Бездротові локальні мережі 16 1.2.3 Бездротові мережі масштабу міста 17 1.2.4 Бездротові глобальні мережі топологія 18 1.3 Порівняльний аналіз найбільш актуальних стандартів безпровідного зв'язку 18 1.4 Висновки до розділу 1 19 РОЗДІЛ 2. ОСНОВНА ЧАСТИНА 20 2.1. Основні терміни та елементи мережі 20 2.2. Актуальні стандарти безпровідних локальних мереж Wi-Fi 20 2.3. Актуальні стандарти бездротових мереж 21 2.3.1 IEEE 802.11g 22 2.3.2 IEEE 802.11n 23 2.3.3 IEEE 802.11ac 24 2.4 Об'єднання технологій безпеки Wi-Fi 26 2.4.1 Історія розвитку 26 2.4.2 Механізм аутентифікації WPA2 29 2.4.3 Механізм шифрування WPA2 35 2.4.4 Wardriving 37 2.4.5 Сніфери 38 2.4.6 Сніфери 39 2.5 Технології Wi-Fi які пливають на здоров'я людини 40 2.6. Висновки до розділу 2 41 РОЗДІЛ 3. НАУКОВО-ДОСЛІДНА ЧАСТИНА 42 7 3.1. Порівняння продуктивності 802.11 n і 802.11 ac 42 3.2 Висновки до розділу 3 45 РОЗДІЛ 4. СПЕЦІАЛЬНА ЧАСТИНА 46 4.1. Область застосування програмного забезпечення Microsoft Office Visio 46 4.2. Загальні принципи програми Microsoft Office Visio 48 4.3. Висновки до розділу 4 51 РОЗДІЛ 5. ОХОРОНА ПРАЦІ ТА БЕЗПЕКА В НАДЗВИЧАЙНИХ СИТУАЦІЯХ 52 5.1. Охорона праці 52 5.2. Безпека в надзвичайних ситуаціях 54 5.3. Висновки до розділу 5 56 ЗАГАЛЬНІ ВИСНОВКИ 57 ПЕРЕЛІК ПОСИЛАНЬ 58 Додаток А. Копія тези конференції 60
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Aimer, Younes. « Étude des performances d'un système de communication sans fil à haut débit ». Thesis, Poitiers, 2019. http://www.theses.fr/2019POIT2269.
Texte intégralRésumé :
La demande des usagers en termes de débit, de couverture et de qualité de service croît exponentiellement, avec une demande de plus en plus accrue en énergie électrique pour assurer les liaisons entre les réseaux. Dans ce contexte, les nouvelles formes d’ondes basées sur la modulation OFDM se sont répandues et sont utilisées dans les récentes architectures de radiocommunications. Cependant, ces signaux sont très sensibles aux non-linéarités des amplificateurs de puissance à cause des fortes fluctuations d’enveloppe caractérisées par un fort PAPR qui dégrade le bilan énergétique et le rendement de l’émetteur. Dans ce travail de thèse, nous avons tout d’abord dressé un état de l’art des techniques de réduction du PAPR. Cette présentation nous a permis de proposer une nouvelle méthodologie basée sur les techniques d’entrelacement et de codage. Cette première contribution consiste en l’utilisation de la technique d’entrelacement, en faisant appel aux sous porteuses nulles pour la transmission des informations auxiliaires, tout en respectant les spécifications fréquentielles du standard utilisé. La deuxième contribution est basée sur la combinaison des deux techniques de Shaping et de Transformée en Cosinus Discrète DCT, dans l’objectif d’améliorer davantage les performances du système. Les résultats de simulation ont montré que l’utilisation de ces deux techniques permet un gain significatif en termes de réduction du PAPR, qui se traduit par l’amélioration du rendement. Enfin, nous avons présenté une étude expérimentale pour l’ensemble des techniques proposées afin de confirmer les résultats obtenus en simulation. Ces évaluations sont réalisées avec un banc d'essais de radiocommunications pour le test d'un amplificateur de puissance commercial de technologie LDMOS de 20W, fonctionnant à 3.7 GHz en classe AB. Les résultats obtenus pour les standards IEEE 802.11 montrent que ces nouvelles approches permettent de garantir la robustesse de transmission, d’améliorer la qualité des liaisons et d’optimiser la consommation électriqueThe request of the users in terms of rate, coverage and quality of service is growing exponentially, with increasing demand for electrical energy, to ensure networks link. In this context, new waveforms based on the OFDM modulation become widely popular and used intensively in recent radio communications architectures. However, these signals are sensitive to the power amplifier nonlinearities because of their high envelope fluctuations characterized by a high PAPR, which degrades the energy consumption and the transmitter efficiency.In this thesis, we first began by a state art of the PAPR reduction techniques. This presentation allowed us to propose a new method based on interleaving and coding techniques. The first contribution consists on the use of the interleaving technique using null-subcarriers for the transmission of the side information, while respecting the frequency specifications of the used standard. The second one is based on the conjunction of the Shaping technique and the Discrete Cosine Transform (DCT), with the aim of improving the performance of the system. Simulation results show that the use of these two techniques allows a significant gain in terms of PAPR reduction, which results in the improvement of the system efficiency. Finally, we presented an experimental study of the proposed techniques using an RF test bench with a commercial LDMOS 20 W PA, class AB operating at 3.7 GHz. The results obtained for the IEEE 802.11 standards show that the proposed approaches allow the transmission robustness and quality, while optimizing the power consumption
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Rada, Dominik. « Přenosová technologie G.mgfast ». Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-442370.
Texte intégralRésumé :
The master thesis deals with G.fast and G.mgfast transmission technologies, including their parameters. The work deals with the principle of vector DMT modulation and the possibility of time duplex TDD and full-duplex FDX in two-way communication used in these technologies. The following is a description of the line using the KHM model, which is suitable for simulations in the transmission band using G.fast and G.mgfast technologies. Subsequently, the disturbing effects of crosstalk at the near end of NEXT and the far end of FEXT and their elimination with these technologies are discussing. Part of the work explains supporting calculations to determine the SNR and bit allocation to calculate the baud rate. The work describes the methods of compensation of crosstalk FEXT and NEXT, which affect the resulting baud rate. The work also includes an application for simulation of transmission speed as a function of distance for G.fast and G.mgfast technologies, allowing changing input parameters and adjusting the transmission bandwidth based on G.9700 and G.9701 standards. Also, in work, an application is created to display the compensation of the influence of the transmitted signal crosstalk FEXT and NEXT, which allow the import of measured crosstalk between individual participants. The issue of influencing crosstalk for accurate measurements in the laboratory is also discussing. An application in the MATLAB environment is creating to display the measured characteristics.
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Jung, Jin Woo. « Modeling and control of fuel cell based distributed generation systems ». Connect to resource, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1116451881.
Texte intégralRésumé :
Thesis (Ph. D.)--Ohio State University, 2005.Title from first page of PDF file. Document formatted into pages; contains xvi, 209 p.; also includes graphics. Includes bibliographical references (p. 202-209). Available online via OhioLINK's ETD Center
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CHEN, JIAN-HUNG, et 陳建宏. « Wavelet-based Discrete Multitone Modulation ». Thesis, 1999. http://ndltd.ncl.edu.tw/handle/01521641416965102760.
Texte intégralRésumé :
碩士國立臺灣大學
電信工程學研究所
87
Discrete multitone modulation systems have been widely applied to various communication systems. Many high speed transmission techniques use this scheme to transmit data over digital subscriber loops. For a nonideal linear filter channel, inter-symbol interference degrades system’s performance. It is known that multichannel systems have many advantages in such channel. In DMT systems, the available channel is subdivided into a number of subchannels, and a wisely chosen bit allocation policy is used to optimize the total transmission rate. It can be shown that the DMT system can achieve within 8 to 9 dB of channel capacity. Traditional DMT systems use DFT matrices to divide the channel into a number of subchannels. When channel is not ideal, some degree of redundancy known as cyclic prefix is added to cancel ISI. However, the receiving filters in such systems have poor frequency separation and the performance degrades significantly in the existence of narrow band interference. Therefore it is important to design DMT systems using more general filter banks. We proposed the wavelet-based DMT system which has better frequency separation property. In this thesis, we provide a systematic study on DMT based on a polyphase approach. We analysis the traditional DFT-based DMT in detail ,including it’s polyphase representation. And a modified DFT DMT is proposed with the same complexity. The most general wavelet-based DMT solutions with ISI free property will be derived. Two design approaches will be introduced, and design examples are given. In our approach, when the channel is frequency dependent, perfect reconstruction can be achieved by padding zeros as redundancy. This system outperforms the DFT-based DMT when there is narrow band interference.
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Chou, Cheng-hsien, et 周政憲. « Integer modulation index CPM without discrete power component ». Thesis, 2012. http://ndltd.ncl.edu.tw/handle/81377811160634969336.
Texte intégralRésumé :
碩士國立高雄第一科技大學
電腦與通訊工程研究所
100
Continuous phase modulation (Continuous Phase Modulation, CPM) signal has the characteristic of constant envelope, bandwidth efficiency, power efficiency and low side-lobe. Nevertheless, CPM with integer modulation indexes usually do not with the above properties. In recent years, the foreign savant Huang suggested to decompose CPM signals with integer modulation indexes into a set of PAM (Pulse Amplitude Modulation, PAM) waveforms. The PAM waveforms can be classified into two parts of pulses, one is data-dependent PAM pulses and the other is data-independent. The data-independent PAM pulse is correspondent to the discrete power spectral that is a waste of power. Therefore, most CPM with integer modulation index is not useful and does not discuss by the researchers. In fact, only binary CPFSK with unity modulation index has been employed in the pager system. In this thesis, we study new modulator by removing the data-independent PAM waveform and the Euclidean distance and spectrum are calculated. Since this new modulation no longer has the constant envelope property, a limiter is constructed to recover the constant envelope. It is found that the novel modulator has better distance yet with bandwidth expansion, as compared to the original CPM signals.
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Milošević, Miloš. « Maximizing data rate of discrete multitone systems using time domain equalization design ». Thesis, 2003. http://hdl.handle.net/2152/791.
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Milošević, Milos̆. « Maximizing data rate of discrete multitone systems using time domain equalization design ». 2003. http://wwwlib.umi.com/cr/utexas/fullcit?p3116123.
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Tsai, Tsung Lin, et 蔡宗霖. « Proton radiography using Discrete Range Modulation method – A Monte Carlo study ». Thesis, 2017. http://ndltd.ncl.edu.tw/handle/3f77ra.
Texte intégralRésumé :
碩士長庚大學
醫學影像暨放射科學系
105
The advantages of the proton therapy are based on the characteristic proton Bragg peak. However, the proton range uncertainties which caused by many factors will lead to the dose deviation, even worse than photon therapy. This work has investigated the properties of proton radiography and water-equivalent path length (WEPL) to quantitatively assess the image quality and range uncertainties. We use Discrete Range Modulation (DRM) method for proton radiography benefited from CGMH wobbling and layer stacking techniques. We will report the advantages of DRM which compared to Continuous Range Modulation (CRM) method. In this study, we used MCNPX 2.7.0 to simulate the depth dose distribution by pencil beam geometry (PBG) on a water phantom of 40 x 40 x 40 cm2. According to ESS, beam energies from 70 to 230 MeV at 2.5MeV/step were obtained. In DRM method, we used the parameter based on Bragg Peak characteristics, R80. The mean proton range of different energies was obtained. DRM method to determine the WEPL is by using the relationship between the proton energy and energy deposition at 80% of the proximal fall off (E80) . The E80 will not vary while varying initial energy spread. For CRM method, a dose gradient plan was constructed to estimate relationship between WEPL and energy deposition. DRM and CRM were verified by different thickness of water phantoms, a step phantom and wedge phantoms. In DRM method, the difference of WEPL are < 2 mm, standard deviation in the images was found to be σ <0.5 mm . However, in CRM, difference of WEPL are >3mm, σ> 0.6 mm. SNR of DRM is more than three times of CRM. Proton radiography obtained using DRM method is more accurate and precise than those using CRM method. DRM method also can solve mixed beam problem owing to multiple Coulomb scattering.
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Ding, Ming Evans Brian L. « Channel equalization to achieve high bit rates in discrete multitone systems ». 2004. http://wwwlib.umi.com/cr/utexas/fullcit?p3142716.
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Chiu, Jih-Chin, et 邱日進. « Distributed Feedback and Feedforward of Discrete-Time Sigma-Delta Modulator ». Thesis, 2012. http://ndltd.ncl.edu.tw/handle/12358399977956662187.
Texte intégralRésumé :
碩士國立中山大學
電機工程學系研究所
100
This paper presents a distributed feedback and feedforward of discrete-time delta sigma modulator applications in the radio. We know the delta-sigma modulator using oversampling and noise shaping technique, thus we can relax the specifications of the components. This paper described the architectural differences and compare, the in-band signal is less sensitive to noise interference, and improve the resolution of the circuit. In the resonator, a simple structure with a small number of capacitor in resonator circuit. This paper uses the TSMC 0.18μm process parameters to the simulation, implementation, and measurement. Our fourth-order discrete-time delta-sigma modulator specifications as follows: the input signal frequency is 10.7MHz, the sampling frequency is 42.8MHz, the signal bandwidth is 200kHz, oversampling rate is 107, and one bit quantizer.
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Yang, Dong-Sheng, et 楊東盛. « A Discrete-Time Lowpass Sigma-Delta Modulator for Voice Band Application ». Thesis, 2006. http://ndltd.ncl.edu.tw/handle/08911904882866438278.
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Chen, Kuan-Hung, et 陳冠宏. « Design and Implementation of a Cognitive Radio Baseband Transceiver using Discrete Wavelet Multi-Tone Modulation ». Thesis, 2007. http://ndltd.ncl.edu.tw/handle/92355331877538212842.
Texte intégralRésumé :
博士國立臺灣大學
電機工程學研究所
95
In this thesis, design and implementation of a discrete wavelet multi-tone (DWMT) based baseband transceiver for cognitive radio applications are presented. The proposed system aims to provide wireless local-area network (WLAN service similar to IEEE 802.11 WLAN by exploiting the unused GSM spectrum. The DWMT modulation scheme originally proposed for wireline digital subscriber loop (DSL) applications is adopted as the modulation scheme. This modulation has stronger side-lobes attenuation than the popular OFDM modulation and thus generates much lower adjacent channel leakage, making it suitable for applications with dynamically-allocated spectrum. Signal and interference analysis of the adopted DWMT modulation is presented and signal processing techniques that tackle synchronization, equalization, and detection are developed. The entire DWMT-based baseband receiver is integrated and implemented in 0.18μm CMOS technology. Techniques such as hardware sharing, common term extraction, subcarrier constant multiplications removal, etc., are applied for hardware reduction. In addition, novel bi-directional SRAM-based delaylines are designed for memory saving. Measurement results of the fabricated receiver IC show that it functions well at 25.6 MHz operating frequency while drawing 165 mW from a 1.8 V supply voltage. When the whole 25.6 MHz bandwidth is available, this receiver IC can provide up to 153.6 Mbps of data transmission.
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Chen, Kuan-Hung. « Design and Implementation of a Cognitive Radio Baseband Transceiver using Discrete Wavelet Multi-Tone Modulation ». 2006. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-2507200716212900.
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Hung, Yang-Cheng, et 洪揚程. « Generalization of Discrete-Time Sigma-Delta Modulator Non-Ideality Power Models to Various Sigma-Delta Modulator Architectures ». Thesis, 2011. http://ndltd.ncl.edu.tw/handle/68049481827279158962.
Texte intégralRésumé :
碩士國立交通大學
電控工程研究所
100
The conventional high-level ΣΔM synthesis is mainly based on behavior simulation which is very time-consuming. Thus we propose model-based high-level ΣΔM synthesis. Model-based approach can be at the order of 104 times faster than simulation-based approach. Model-based method employs only mathematical models, which is set of ΣΔM non-ideality power models. Thus, the completeness of non-ideal power models is a must when we use model-based method to design ΣΔM. In this paper, major non-ideality power models of 2nd-order ΣΔM are discussed, and generalizations of those non-ideality power models to various ΣΔM topologies are also discussed. In addition, continuous-time ΣΔM is discussed in this paper, which incorporates comparison between discrete-time, continuous-time ΣΔM and loop filter design of continuous-time ΣΔM, and continuous-time ΣΔM behavioral model in MATLAB-Simulink environment.
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Ding, Ming. « Channel equalization to achieve high bit rates in discrete multitone systems ». Thesis, 2004. http://hdl.handle.net/2152/1219.
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Yi, Ya-Wei, et 易亞維. « Design and Implementation of Predictive Current Controllers with Discrete-Space-Vector Modulation for Permanent Magnet Synchronous Motors ». Thesis, 2019. http://ndltd.ncl.edu.tw/handle/62tuge.
Texte intégralRésumé :
碩士國立臺灣海洋大學
電機工程學系
107
In this thesis, predictive current controllers with discrete space-vector modulation for surface-mounted permanent magnet synchronous motors are proposed. The proposed controllers can apply three fixed-time voltage vectors in one sampling period, thus obtaining 37 composited voltage vectors. The proposed method is to improve the existing model-free current prediction methods and make detailed experimental comparisons with the model-based current prediction methods. The experimental platform is based on the TMS320F28379D microcontroller as the control core. Finally, the experimental results show that the proposed method can effectively improve the current-tracking performance.
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Chang, Shing-Yun, et 張馨云. « A Seventh-Order Low-Noise Discrete-Time Delta-Sigma Modulator for Audio Applications ». Thesis, 2018. http://ndltd.ncl.edu.tw/handle/n82kac.
Texte intégralRésumé :
碩士國立交通大學
電機工程學系
107
Due to our ears’ high ability of sound distinction, the resolution demand of the audio applications is higher and higher, such as audio equipment or speech recognition. To obtain a well performed SNR, we usually use the delta-sigma modulator to implement the ADC. When the order of the system is higher, the ability of de-noise is stronger. However, it will be more unstable as the order gets higher, so most people choose the third-order system to avoid this problem. Thus, the goal of this research is to achieve a very low noise floor (in-band noise power) with a seventh-order delta-sigma modulator and still stay stable. In this thesis, the design of the seventh-order delta-sigma modulator will be presented. It is utilized as the ADC in the analog front end of MEMS microphones. The design has to be medium-low power, low frequency, high SNR, and low noise to fit the demand of hearing applications. Results show for a 24kHz signal bandwidth the ADC achieves a dynamic range of 79dB, a peak signal-to-noise and distortion ratio of 68.1dB, and a in-band noise of -90.2dBFS with an oversampling ratio of 32 (sample rate of 1.536MHz). It was fabricated in a TSMC 0.18-m CMOS process with a 2.306mm2 active area, and dissipates 7.5mW from a 1.8-V power supply.
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Wang, Sheng-Tsung, et 王聖琮. « A Discrete-Time 2-2 Sturdy-MASH Delta-Sigma Modulator with a Multi-bit Quantizer ». Thesis, 2018. http://ndltd.ncl.edu.tw/handle/q76z4b.
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Li, Chia-Hsun, et 李家勛. « Design of the Forth-Order 4-bit Discrete-Time Sigma-Delta Modulator for Audio Application ». Thesis, 2019. http://ndltd.ncl.edu.tw/handle/7h888e.
Texte intégralRésumé :
碩士國立交通大學
電機工程學系
108
Due to the development of speech recognition systems in recent years, the demand of resolution for audio applications is getting higher and higher. To obtain a well performed SNR, we usually use the delta-sigma modulator to implement the ADC. When the order of the system is higher, the ability of noise shaping is stronger. However, the consideration of stability is very important as the order gets higher. A common solution to improve stability is to use a multi-bit quantizer. The goal of this research is to obtain the best resolution through balance between stability and circuit complexity. In this thesis, the design of the forth-order 4-bit sigma-delta modulator will be presented. It is utilized as the ADC in the analog front end of MEMS microphones. The design has to be medium-low power, low frequency, and high SNR to fit the demand of audio applications. Results show for a 24kHz signal bandwidth the ADC achieves a dynamic range of 57dB and a peak signal-to-noise and distortion ratio of 49.3dB with an oversampling ratio of 32 (sample rate of 1.536MHz). The chip was fabricated in a TSMC 0.18-m CMOS process with a 3.992mm2 active area and dissipates 7.7mW from a 3.3V/1.8V power supply.
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Hu, Chun Hsiang, et 胡竣翔. « Applying the Discrete Range Modulation Method to Proton Radiography for a Clinical Pencil Beam Delivery System - a Monte Carlo Study ». Thesis, 2019. http://ndltd.ncl.edu.tw/cgi-bin/gs32/gsweb.cgi/login?o=dnclcdr&s=id=%22107CGU05770004%22.&searchmode=basic.
Texte intégralRésumé :
碩士長庚大學
醫學影像暨放射科學系
107
Proton therapy provides the physical properties of the Bragg peak, and by adjusting the energy of the proton beam, the tumor has a good dose distribution. Proton beams for clinical treatment of patients may have range uncertainties, and if there is an incorrect safety margin for the proton therapy range, it will be worse than photon therapy. In this study has investigated whether the Discrete Range Modulation (DRM) method can be used in the clinic. We used PTSim to simulate the CGMH pencil beam scanning system. DRM method determine the WEPL by the different energy Bragg peak 80% range (R80) and calculate the WEPL from the energy deposition at 80% of the proximal fall off (E80) which without being affected by varying the initial energy spread. For the research, the effects of dose and fluence detectors for 1 x 106, 6 x 106, 3 x 107, particle numbers and different dose detector thicknesses for 0.5, 1, 2, 3, 5, 10 cm on the image quality of DRM proton radiography (pRG) by simulation of pure water phantom were investigated. A dose detector with a thickness of 2 mm and 6 x 106 particle numbers were selected as the setting for optimizing the simulation parameters. We also used DRM method to explain the WEPL of different thickness boundaries of the step phantom and pyramid phantom. The height of the X- and Y-axis magnets differs by the nozzle setting, which can increase the X and Y axis profile differently. Make sure DRM method is subject to beam divergence and cause the image enlargement. In the inhomogeneity phantom experiment, the smaller size of the phantom, the DRM pRG more blurred, that may cause by the proton passing through the phantom is insufficient. For DRM method, which can identify the WEPL distribution of various substances. Compared with the WEPL by the relative stopping power (RLSP), excluding titanium, all other materials have the range error less than 1 mm, proving that DRM method is better than the relative electron density (RED) to calculate the WEPL.
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Acharya, Anirudh B. « Integrated Common And Differential Mode Filters With Active Damping For Active Front End Motor Drives ». Thesis, 2011. https://etd.iisc.ac.in/handle/2005/2348.
Texte intégralRésumé :
IGBT based power converters acts as front end in the present day Adjustable Speed Drive (ASD). This offers many advantages and makes regenerative action possible. PWM rectifier operation produces electrically noisy DC bus on common mode basis. This results in higher ground current as compared to three phase diode bridge rectifier. Due to fast turn-ON and turn-OFF time of IGBT, the inverter output voltage dv/dt is high during switching transients and voltage waveform is rich in harmonics. As a result, in applications involving long cable the motor terminal voltage during the switching transient is as high as twice the applied voltage. This voltage stress reduces the life of insulation in motors. The high dv/dt output voltage applied at the motor terminal excites the parasitic capacitive coupling resulting in increased ground currents and causes Electric Discharge Machining (EDM) which reduces the life of motor bearings. The common mode voltage due to PWM rectifier and the inverter appear at the motor terminals exacerbating these problems.
The common mode voltage due to PWM inverter with PWM rectifier is analyzed. An integrated approach for filter design is proposed wherein the adverse effects due to common mode voltage of both AFE converter and the inverter is addressed. The proposed topology addresses the problems of common mode voltage, common mode current and voltage doubling due to ASD. The design procedure for proposed filter topology is discussed with experimental results that validate the effectiveness of the filter.
Inclusion of such higher order filter in the converter topology leads to problems such as resonance. Passive methods are investigated for damping the line resonance due to LCL filter and common mode resonance due to common mode filter. The need for active damping technique for resonance due to common mode filter is presented. State space based damping technique is proposed to effectively damp the resonance due to line filter and the common mode filter. Experimental results are presented that validate the effectiveness of active damping both on the line basis (differential mode) and line to ground basis (common mode) of the filter.
44
Acharya, Anirudh B. « Integrated Common And Differential Mode Filters With Active Damping For Active Front End Motor Drives ». Thesis, 2011. http://etd.iisc.ernet.in/handle/2005/2348.
Texte intégralRésumé :
IGBT based power converters acts as front end in the present day Adjustable Speed Drive (ASD). This offers many advantages and makes regenerative action possible. PWM rectifier operation produces electrically noisy DC bus on common mode basis. This results in higher ground current as compared to three phase diode bridge rectifier. Due to fast turn-ON and turn-OFF time of IGBT, the inverter output voltage dv/dt is high during switching transients and voltage waveform is rich in harmonics. As a result, in applications involving long cable the motor terminal voltage during the switching transient is as high as twice the applied voltage. This voltage stress reduces the life of insulation in motors. The high dv/dt output voltage applied at the motor terminal excites the parasitic capacitive coupling resulting in increased ground currents and causes Electric Discharge Machining (EDM) which reduces the life of motor bearings. The common mode voltage due to PWM rectifier and the inverter appear at the motor terminals exacerbating these problems.
The common mode voltage due to PWM inverter with PWM rectifier is analyzed. An integrated approach for filter design is proposed wherein the adverse effects due to common mode voltage of both AFE converter and the inverter is addressed. The proposed topology addresses the problems of common mode voltage, common mode current and voltage doubling due to ASD. The design procedure for proposed filter topology is discussed with experimental results that validate the effectiveness of the filter.
Inclusion of such higher order filter in the converter topology leads to problems such as resonance. Passive methods are investigated for damping the line resonance due to LCL filter and common mode resonance due to common mode filter. The need for active damping technique for resonance due to common mode filter is presented. State space based damping technique is proposed to effectively damp the resonance due to line filter and the common mode filter. Experimental results are presented that validate the effectiveness of active damping both on the line basis (differential mode) and line to ground basis (common mode) of the filter.
45
Wang, Tao. « Low-power high-resolution delta-sigma ADC design techniques ». Thesis, 2012. http://hdl.handle.net/1957/29740.
Texte intégralRésumé :
This dissertation presents a low-power high-resolution delta-sigma ADC. Two new architectural design techniques are proposed to reduce the power dissipation of the ADC. Compared to the conventional active adder, the direct charge transfer (DCT) adder greatly saves power by keeping the feedback factor of the active adder unity. However, the inherent delay originated from the DCT adder will cause instability to the modulator and complex additional branches are usually needed to stabilize the loop. A simple and power-efficient technique is proposed to absorb the delay from the DCT adder and the instability issue is therefore solved. Another proposed low-power design technique is to feed differentiated inverted quantization noise to the input of the last integrator. The modulator noise-shaping order with this proposed technique is effectively increased from two to three without adding additional active elements.
The delta-sigma ADC with the proposed architectural design techniques has been implemented in transistor-level and fabricated in 0.18 µm CMOS technology. Measurement results showed a SNDR of 99.3 dB, a DR of 101.3 dB and a SFDR of 112 dB over 20 kHz signal bandwidth, resulting in a very low figure-of-merit (FoM) in its application category. Finally, two new circuit ideas, low-power parasitic-insensitive switched-capacitor integrator for delta-sigma ADCs and switched-resistor tuning technique for highly linear Gm-C filter design are presented.Graduation date: 2012
Access restricted to the OSU Community at author's request from June 9, 2012 - June 9, 2014