The Permanent Magnet Synchronous Motors (PMSM) have wide application in the robotics field due to its efficiency and reliability. As a servo system, it demands high precision in different control applications. Torque ripple is a critical issue resulting in mechanical vibrations and shortening the life of PMSMs, especially at low speeds. Because the magnitude of speed harmonics is proportional to the magnitude of the torque harmonics of the same order, methods to reduce speed harmonics can be utilized for torque ripple minimization. This thesis work proposes three methods for torque ripple reduction. One method is based on harmonic speed control (HSC) and harmonic current control (HCC). Another method uses the fuzzy to adjust PI parameters based on HSC-HCC. The third method utilizes torque ripple estimation (TRE) and HCC. In the proposed methods, torque ripples are estimated using a torque ripple model (TRM). At low speeds, speed harmonics and current harmonics are obtained based on an adaptive linear neural-based filter. The errors between the optimal harmonic current reference from HSC or TRE and the harmonic current from extraction are used to generate harmonic voltage in HCC. This harmonic voltage is fed back to compensate and reduce torque ripple. Furthermore, a feedforward compensation method is proposed to minimize torque ripple across a range of speeds based on the feedback compensation results. Finally, simulations and experiments are carried out to demonstrate the validity and performance of the proposed torque ripple reduction methods.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This work presents the development of a novel digital acceleration controller for sinusoidal vibration tests using switching-mode AC power source (ACPS) fed electrodynamic vibration machines. The proposed scheme is based on the interaction of two control loops: one for the shaker's acceleration regulation and another for the ACPS output voltage control. A robust model reference adaptive algorithm (RMRAC) is used in the voltage control loop. To reduce the effects caused by the plant's parameters variations as well harmonic vibrations and resonances of the test specimen, the acceleration feedback controller is augmented with a feedforward and a robust controller. Experimental results show that the proposed system is capable to achieve excellent acceleration reference tracking performance and robustness in the closed loop control from 20 Hz to 200 Hz. Investigations shall be performed to evaluate the response of this scheme when controlling vibrations as fast as 2000 Hz. A specific instrumentation system has been developed to feedback the electrodynamic vibration machine's acceleration. The proposed solution employs piezoelectric accelerometers, voltage mode preamplifiers, circuit for signal conditioning, analog to digital conversion and filtering. A study concerning the commonly used vibration measurement techniques and the design procedure, simulation, implementation and experimental results are described in detail. / Esse trabalho apresenta o desenvolvimento de um novo tipo de controlador digital de aceleração para ensaios com vibrações senoidais em máquinas de vibra ção eletrodinâmicas supridas por fontes de potência CA com comutação. O esquema proposto é baseado na interação entre duas malhas de controle: uma para regulação de aceleração da máquina de vibração e outra para ajuste da tensão de saída da fonte de potência CA. Um algoritmo adaptativo robusto por modelo de referência (RMRAC) é utilizado na malha de controle de tensão. Os efeitos de variações paramétricas existentes na planta bem como de vibrações harmônicas e ressonâncias do objeto ensaiado são minimizados com o uso de um controlador feedforward e um controlador feedforward robusto na malha de aceleração. Resultados experimentais demonstram que o sistema proposto é capaz de garantir excelente rastreamento da aceleração de referência e robustez em malha fechada entre 20 Hz e 200 Hz, necessitando ainda de investigação para controle de vibrações tão rápidas quanto 2000 Hz. A realimentação da aceleração da máquina é realizada com o desenvolvimento de uma instrumentação adequada a esse fim. A solução proposta utiliza acelerômetros piezoelétricos, pré-amplificadores modo tensão, circuito para condicionamento de sinais, conversão analógico-digital e filtragem. Um estudo sobre as principais técnicas utilizadas em medições de vibrações bem como a metodologia de projeto, simulação, implementação e testes experimentais são descritos detalhadamente.

The goal of this thesis work is to evaluate and quantify the advantages and disadvantages of Active Rear Steering (ARS). The evaluation is carried out through Multi-Body System (MBS) simulations. An analytical model has been developed to better understand the basic dynamics of vehicles equipped with rear steering. In parallel, a high fidelity MBS model is developed in Simpack. This model includes suspension kinematics and compliance, allowing for detailed analyses of steering hardware performance. Next, different control strategies aiming at improving manoeuvrability, stability and agility are implemented in Simulink. In order to assess their effectiveness, the high fidelity model is utilised by running co-simulation with Simulink. Manoeuvrability is assessed through constant steer, constant radius and ramp steer manoeuvres. Stability is assessed through transient manoeuvres such as step steer and sine with dwell. Agility is assessed through step steer and frequency response. Ultimately, also a subjective assessment is carried out by means of Volvo Cars' dynamic driving simulator. The conclusion from the assessment is that the drivers feel the all wheel steered vehicle more stable during evasive manoeuvres. It is concluded that for manoeuvrability the minimum turning radius is reduced by 19 % at low velocity; this implies that the steering angle request is reduced at low velocity, while it is increased at high velocity. A slightly higher steering angle request at high velocity might be beneficial since the driver would be able to control the vehicle in a wider range of steering wheel angles. For agility the results are contradicting: on the one hand, according to the step steer rise time difference between lateral acceleration and yaw rate, the controlled vehicles are performing worse than the passive vehicle; on the other hand, according to the frequency response analysis, both the delays between steering input and yaw rate and between lateral acceleration and yaw rate are reduced up to respectively 75 % and 46 % for the considered frequency range. Finally, for stability, the yaw rate overshoot from a step steer can be reduced up to 65 % at high velocity and the sideslip angle can always be reduced. The vehicle equipped with ARS outperforms the passive vehicle in the sine with dwell manoeuvre. / Målet med detta examensarbete är att utvärdera och kvantifiera fördelarna och nackdelarna med Active Rear Steer (ARS) för Volvo Cars. Utvärderingen utförs genom Multi-Body System (MBS) simuleringar. En analytisk modell har utvecklats för att bättre förstå den grundläggande dynamiken i fordon utrustade med bakhjulsstyrning. Parallelt utvecklades en MBS-modell med hög precision i Simpack. Denna modell inkluderar hjulupphängningens kinematik och eftergivlighet, vilket möjliggör detaljerade analyser av styrhårdvarans prestanda. Därefter implementeras olika kontrollstrategier som syftar till att förbättra manövrerbarhet, stabilitet och agilitet i Simulink. För att bedöma deras effektivitet används MBS-modellen för att köra co-simulering med Simulink.Manövrerbarhet bedöms genom konstant styrning, konstant radie och rampstyrning. Stabilitet bedöms genom transienta manövrar som stegstyrning och sinus med fördröjning. Agilitet bedöms genom stegstyrning och frekvensrespons. Slutligen görs också en subjektiv bedömning med hjälp av Volvo Cars dynamiska körsimulator. Slutsatsen från bedömningen är att förarna anser att fordonet upplevs vara mycket stabilare vid undanmanövrar. Vidare är slutsatsen att för manövrerbarhet minskar den minsta svängradien med 19 % vid mycket låg hastighet; detta innebär att styrvinkel reduceras vid låg hastighet, medan den ökar vid hög hastighet. En något högre styrvinkeln kan vara fördelaktig eftersom föraren skulle kunna styra fordonet i ett större rattvinkelområde. För agilitet är resultaten motsägelsefulla: å ena sidan, enligt stegstyrningstidsskillnaden mellan lateral acceleration och girhastighet, fungerar de aktiva fordonen sämre än det passiva fordonet; å andra sidan, enligt frekvensresponsanalysen, reduceras både fördröjningarna mellan girhastighet och styrvinkel och mellan lateral acceleration och girhastighet upp till ungefär 30 %. Slutligen, för stabilitet, kan girhastighetens översläng från en stegstyrning minskas upp till 65 % vid hög hastighet och avdriftsvinkeln kan alltid minskas. Fordonet som är utrustat med ARS överträffar det passiva fordonet i manövern sinus med fördröjning.

In the last decade acoustic noise has become more and more regarded as a problem. In cars, boats, trains and aircraft, low-frequency noise reduces comfort. Lightweight materials and more powerful engines are used in high-speed vehicles, resulting in a general increase in interior noise levels. Low-frequency noise is annoying and during periods of long exposure it causes fatigue and discomfort. The masking effect which low-frequency noise has on speech reduces speech intelligibility. Low-frequency noise is sought to be attenuated in a wide range of applications in order to improve comfort and speech intelligibility. The use of conventional passive methods to attenuate low-frequency noise is often impractical since considerable bulk and weight are required; in transportation large weight is associated with high fuel consumption. In order to overcome the problems of ineffective passive suppression of low-frequency noise, the technique of active noise control has become of considerable interest. The fundamental principle of active noise control is based on secondary sources producing ``anti-noise.'' Destructive interference between the generated and the primary sound fields results in noise attenuation. Active noise control systems significantly increase the capacity for attenuating low-frequency noise without major increase in volume and weight. This doctoral dissertation deals with the topic of active noise control within the passenger cabin in aircraft, and within headsets. The work focuses on methods, controller structures and adaptive algorithms for attenuating tonal low-frequency noise produced by synchronized or moderately synchronized propellers generating beating sound fields. The control algorithm is a central part of an active noise control system. A multiple-reference feedforward controller based on the novel actuator-individual normalized Filtered-X Least-Mean-Squares algorithm is introduced, yielding significant attenuation of such period noise. This algorithm is of the LMS-type, and owing to the novel normalization it can also be regarded as a Newton-type algorithm. The new algorithm combines low computational complexity with high performance. For that reason the algorithm is suitable for use in systems with a large number of control sources and control sensors in order to reduce the computional power required by the control system. The computational power of the DSP hardware is limited, and therefore algorithms with high computational complexity allow fewer control sources and sensors to be used, often with reduced noise attenuation as a result. In applications, such as controlling aircraft cabin noise, where a large multiple-channel system is needed to control the relative complex interior sound field, it is of great importance to keep down the computational complexity of the algorithm so that a large number of loudspeakers and microphones can be used. The dissertation presents theoretical work, off-line computer experiments and practical real-time experiments using the actuator-individual normalized algorithm. The computer experiments are principally based on real-life cabin noise data recorded during flight in a twin-engine propeller aircraft and in a helicopter. The practical experiments were carried out in a full-scale fuselage section from a propeller aircraft. / Buller i vår dagliga miljö kan ha en negativ inverkan på vår hälsa. I många sammanhang, i tex bilar, båtar och flygplan, förekommer lågfrekvent buller. Lågfrekvent buller är oftast inte skadligt för hörseln, men kan vara tröttande och försvåra konversationen mellan personer som vistas i en utsatt miljö. En dämpning av bullernivån medför en förbättrad taluppfattbarhet samt en komfortökning. Att dämpa lågfrekvent buller med traditionella passiva metoder, tex absorbenter och reflektorer, är oftast ineffektivt. Det krävs stora, skrymmande absorbenter för att dämpa denna typ av buller samt tunga skiljeväggar för att förhindra att bullret transmitteras vidare från ett utrymme till ett annat. Metoder som är mera lämpade vid dämpning av lågfrekvent buller är de aktiva. De aktiva metoderna baseras på att en vågrörelse som ligger i motfas med en annan överlagras och de släcker ut varandra. Bullerdämpningen erhålls genom att ett ljudfält genereras som är lika starkt som bullret men i motfas med detta. De aktiva bullerdämpningsmetoderna medför en effektiv dämpning av lågfrekvent buller samtidigt som volymen, tex hos bilkupen eller båt/flygplanskabinen ej påverkas nämnvärt. Dessutom kan fordonets/farkostens vikt reduceras vilket är tacksamt för bränsleförbrukningen. I de flesta tillämpningar varierar bullrets karaktär, dvs styrka och frekvensinnehåll. För att följa dessa variationer krävs ett adaptivt (självinställande) reglersystem som styr genereringen av motljudet. I propellerflygplan är de dominerande frekvenserna i kabinbullret relaterat till propellrarnas varvtal, man känner alltså till frekvenserna som skall dämpas. Man utnyttjar en varvtalssignal för att generera signaler, så kallade referenssignaler, med de frekvenser som skall dämpas. Dessa bearbetas av ett reglersystem som generar signaler till högtalarna som i sin tur generar motljudet. För att ställa in högtalarsignalerna så att en effektiv dämpning erhålls, används mikrofoner utplacerade i kabinen som mäter bullret. För att åstadkomma en effektiv bullerdämpning i ett rum, tex i en flygplanskabin, behövs flera högtalare och mikrofoner, vilket kräver ett avancerat reglersystem. I doktorsavhandlingen ''Active Control of Propeller-Induced Noise in Aircraft'' behandlas olika metoder för att reducera kabinbuller härrörande från propellrarna. Här presenteras olika strukturer på reglersystem samt beräkningsalgoritmer för att ställa in systemet. För stora system där många högtalare och mikrofoner används, samt flera frekvenser skall dämpas, är det viktigt att systemet inte behöver för stor beräkningskapacitet för att generera motljudet. Metoderna som behandlas ger en effektiv dämpning till låg beräkningskostnad. Delar av materialet som presenteras i avhandlingen har ingått i ett EU-projekt med inriktning mot bullerundertryckning i propellerflygplan. I projektet har flera europeiska flygplanstillverkare deltagit. Avhandlingen behandlar även aktiv bullerdämpning i headset, som används av helikopterpiloter. I denna tillämpning har aktiv bullerdämpning används för att öka taluppfattbarheten.

Les canaux vocodés sont les canaux de communications dédiés à la voix et dans lesquels le signal traverse divers équipements destinés au transport de la voix tels que des codeurs de parole, des détecteurs d’activité vocale (VAD), des systèmes de transmission discontinue (DTX). Il peut s’agir de systèmes de communications téléphoniques filaires ou mobiles (réseaux cellulaires 2G/3G, satellites INMARSAT…) ou de voix sur IP. Les codeurs de parole dans les normes récentes pour les réseaux de téléphonie mobiles ou de voix sur IP font appel à des algorithmes de compression dérivés de la technique CELP (Code Excited Linear Prediction) qui permettent d’atteindre des débits de l’ordre de la dizaine de Kb/s bien inférieurs aux codeurs des réseaux téléphoniques filaires (typiquement 64 ou 32 Kb/s). Ces codeurs tirent leur efficacité de l’utilisation de caractéristiques spécifiques aux signaux de parole et à l’audition humaine. Aussi les signaux autres que la parole sont-ils généralement fortement distordus par ces codeurs. La transmission de données sur les canaux vocodés peut être intéressante pour des raisons liées à la grande disponibilité des canaux dédiés à la voix et pour des raisons de discrétion de la communication (sécurité). Mais le signal modulé transmis sur ces canaux vocodés est soumis aux dégradations causées par les codeurs de parole, ce qui impose des contraintes sur le type de modulation utilisé. Cette thèse a porté sur la conception et l’évaluation de modulations permettant la transmission de données sur les canaux vocodés. Deux approches de modulations ont été proposées pour des applications correspondant à des débits de transmission possibles assez différents. La principale application visée par la thèse concerne la transmission de parole chiffrée, transmission pour laquelle le signal de parole est numérisé, comprimé à bas débit par un codeur de parole puis sécurisé par un algorithme de cryptage. Pour cette application, nous nous sommes focalisés sur les réseaux de communications utilisant des codeurs CELP de débits supérieurs à la dizaine de Kb/s typiquement les canaux de communication mobiles de deuxième ou troisième génération. La première approche de modulation proposée concerne cette application. Elle consiste à utiliser des modulations numériques après optimisation de leurs paramètres de façon à prendre en compte les contraintes imposées par le canal et à permettre des débits et des performances en probabilité d’erreur compatibles avec la transmission de parole chiffrée (typiquement un débit supérieur à 1200 b/s avec un BER de l’ordre de 10-3). Nous avons montré que la modulation QPSK optimisée permet d’atteindre ces performances. Un système de synchronisation est aussi étudié et adapté aux besoins et aux contraintes du canal vocodé. Les performances atteintes par la modulation QPSK avec le système de synchronisation proposé, ainsi que la qualité de la parole sécurisée transmise ont été évalués par simulation et validés expérimentalement sur un canal GSM réel grâce à un banc de test développé dans la thèse.La deuxième approche de modulation a privilégié la robustesse du signal modulé lors de la transmission à travers un codeur de parole quelconque, même un codeur à bas débit tels que les codeurs MELP à 2400 ou 1200 b/s. Dans ce but, nous avons proposé une modulation effectuée par concaténation de segments de parole naturelle associée à une technique de démodulation qui segmente le signal reçu et identifie les segments de parole par programmation dynamique avec taux de reconnaissance élevé. Cette modulation a été évaluée par simulation sur différents codeurs de parole. Elle a aussi été testée sur des canaux GSM réels. Les résultats obtenus montrent une probabilité d’erreur très faible quelque soit le canal vocodé et le débit des codeurs de parole utilisés mais pour des débits possibles relativement faibles. Les applications envisageables sont restreintes à des débits typiquement inférieurs à 200 b/s.Enfin nous nous sommes intéressés aux détecteurs d’activité vocale dont l’effet peut-être très dommageable pour les signaux de données. Nous avons proposé une méthode permettant de contrer les VAD utilisés dans les réseaux GSM. Son principe consiste à rompre la stationnarité du spectre du signal modulé, stationnarité sur laquelle s’appuie le VAD pour décider que le signal n’est pas de la parole / Pas de résumé

Submitted by Rosivalda Pereira (mrs.pereira@ufma.br) on 2017-08-14T18:28:45Z No. of bitstreams: 1 FabioSilva.pdf: 1098466 bytes, checksum: a72dcced91748fe6c54f3cab86c19849 (MD5) / Made available in DSpace on 2017-08-14T18:28:45Z (GMT). No. of bitstreams: 1 FabioSilva.pdf: 1098466 bytes, checksum: a72dcced91748fe6c54f3cab86c19849 (MD5) Previous issue date: 2008-06-20 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPQ) / Fundação de Amparo à Pesquisa e ao Desenvolvimento Científico e Tecnológico do Maranhão (FAPEMA) / We present in this work the results about two neural networks methods to solve the algebraic Riccati(ARE), what are used in many applications, mainly in the Linear Quadratic Regulator (LQR), H2 and H1 controls. First is showed the real symmetric form of the ARE and two methods based on neural computation. One feedforward neural network (FNN), that de¯nes an error as function of the ARE and a recurrent neural network (RNN), which converts a constrain optimization problem, restricted to the state space model, into an unconstrained convex optimization problem de¯ning an energy as function of the ARE and Cholesky factor. A proposal to chose the learning parameters of the RNN used to solve the ARE, by making a surface of the parameters variations, thus we can tune the neural network for a better performance. Computational experiments related with the plant matrices perturbations of the tested systems in order to perform an analysis of the behavior of the presented methodologies, that are based on homotopies methods, where we chose a good initial condition and compare the results to the Schur method. Two 6th order systems were used, a Doubly Fed Induction Generator(DFIG) and an aircraft plant. The results showed the RNN a good alternative compared with the FNN and Schur methods. / Apresenta-se nesta dissertação os resultados a respeito de dois métodos neuronais para a resolução da equação algébrica de Riccati(EAR), que tem varias aplicações, sendo principalmente usada pelos Regulador Linear Quadrático(LQR), controle H2 e controle H1. É apresentado a EAR real e simétrica e dois métodos baseados em uma rede neuronal direta (RND) que tem a função de erro associada a EAR e uma rede neuronal recorrente (RNR) que converte um problema de otimização restrita ao modelo de espaço de estados em outro de otimização convexa em função da EAR e do fator de Cholesky de modo a usufruir das propriedades de convexidade e condições de otimalidade. Uma proposta para a escolha dos parâmetros da RNR usada para solucionar a EAR por meio da geração de superfícies com a variação paramétrica da RNR, podendo assim melhor sintonizar a rede neuronal para um melhor desempenho. Experimentos computacionais relacionados a perturbações nos sistemas foram realizados para analisar o comportamento das metodologias apresentadas, tendo como base o princípio dos métodos homotópicos, com uma boa condição inicial, a partir de uma ponto de operação estável e comparamos os resultados com o método de Schur. Foram usadas as plantas de dois sistemas: uma representando a dinâmica de uma aeronave e outra de um motor de indução eólico duplamente alimentado(DFIG), ambos sistemas de 6a ordem. Os resultados mostram que a RNR é uma boa alternativa se comparado com a RND e com o método de Schur.

Industrial robot manipulators are general-purpose machines used for industrial automation in order to increase productivity, flexibility, and quality. Other reasons for using industrial robots are cost saving, and elimination of heavy and health-hazardous work. Robot motion control is a key competence for robot manufacturers, and the current development is focused on increasing the robot performance, reducing the robot cost, improving safety, and introducing new functionalities. Therefore, there is a need to continuously improve the models and control methods in order to fulfil all conflicting requirements, such as increased performance for a robot with lower weight, and thus lower mechanical stiffness and more complicated vibration modes. One reason for this development of the robot mechanical structure is of course cost-reduction, but other benefits are lower power consumption, improved dexterity, safety issues, and low environmental impact. This thesis deals with three different aspects of modeling and control of flexible, i.e., elastic, manipulators. For an accurate description of a modern industrial manipulator, the traditional flexible joint model, described in literature, is not sufficient. An improved model where the elasticity is described by a number of localized multidimensional spring-damper pairs is therefore proposed. This model is called the extended flexible joint model. This work describes identification, feedforward control, and feedback control, using this model. The proposed identification method is a frequency-domain non-linear gray-box method, which is evaluated by the identification of a modern six-axes robot manipulator. The identified model gives a good description of the global behavior of this robot. The inverse dynamics control problem is discussed, and a solution methodology is proposed. This methodology is based on a differential algebraic equation (DAE) formulation of the problem. Feedforward control of a two-axes manipulator is then studied using this DAE approach. Finally, a benchmark problem for robust feedback control of a single-axis extended flexible joint model is presented and some proposed solutions are analyzed.

<p>Industrial robot manipulators are general-purpose machines used for industrial automation in order to increase productivity, flexibility, and quality. Other reasons for using industrial robots are cost saving, and elimination of heavy and health-hazardous work. Robot motion control is a key competence for robot manufacturers, and the current development is focused on increasing the robot performance, reducing the robot cost, improving safety, and introducing new functionalities. Therefore, there is a need to continuously improve the models and control methods in order to fulfil all conflicting requirements, such as increased performance for a robot with lower weight, and thus lower mechanical stiffness and more complicated vibration modes. One reason for this development of the robot mechanical structure is of course cost-reduction, but other benefits are lower power consumption, improved dexterity, safety issues, and low environmental impact.</p><p>This thesis deals with three different aspects of modeling and control of flexible, i.e., elastic, manipulators. For an accurate description of a modern industrial manipulator, the traditional flexible joint model, described in literature, is not sufficient. An improved model where the elasticity is described by a number of localized multidimensional spring-damper pairs is therefore proposed. This model is called the extended flexible joint model. This work describes identification, feedforward control, and feedback control, using this model.</p><p>The proposed identification method is a frequency-domain non-linear gray-box method, which is evaluated by the identification of a modern six-axes robot manipulator. The identified model gives a good description of the global behavior of this robot.</p><p>The inverse dynamics control problem is discussed, and a solution methodology is proposed. This methodology is based on a differential algebraic equation (DAE) formulation of the problem. Feedforward control of a two-axes manipulator is then studied using this DAE approach.</p><p>Finally, a benchmark problem for robust feedback control of a single-axis extended flexible joint model is presented and some proposed solutions are analyzed.</p>

Vast attention has been paid to active continuous-time filters over the years. Thus as the cheap, readily available integrated circuit OpAmps replaced their discrete circuit versions, it became feasible to consider active-RC filter circuits using large numbers of OpAmps. Similarly the development of integrated operational transconductance amplifier (OTA) led to new filter configurations. This gave rise to OTA-C filters, using only active devices and capacitors, making it more suitable for integration. The demands on filter circuits have become ever more stringent as the world of electronics and communications has advanced. In addition, the continuing increase in the operating frequencies of modern circuits and systems increases the need for active filters that can perform at these higher frequencies; an area where the LC active filter emerges. What mainly limits the performance of an analog circuit are the non-idealities of the used building blocks and the circuit architecture. This research concentrates on the design issues of high frequency continuous-time integrated filters. Several novel circuit building blocks are introduced. A novel pseudo-differential fully balanced fully symmetric CMOS OTA architecture with inherent common-mode detection is proposed. Through judicious arrangement, the common-mode feedback circuit can be economically implemented. On the level of system architectures, a novel filter low-voltage 4th order RF bandpass filter structure based on emulation of two magnetically coupled resonators is presented. A unique feature of the proposed architecture is using electric coupling to emulate the effect of the coupled-inductors, thus providing bandwidth tuning with small passband ripple. As part of a direct conversion dual-mode 802.11b/Bluetooth receiver, a BiCMOS 5th order low-pass channel selection filter is designed. The filter operated from a single 2.5V supply and achieves a 76dB of out-of-band SFDR. A digital automatic tuning system is also implemented to account for process and temperature variations. As part of a Bluetooth transmitter, a low-power quadrature direct digital frequency synthesizer (DDFS) is presented. Piecewise linear approximation is used to avoid using a ROM look-up table to store the sine values in a conventional DDFS. Significant saving in power consumption, due to the elimination of the ROM, renders the design more suitable for portable wireless communication applications.

In the presented master paper: Analysis of car number plate recognition, optical character recognition (OCR), OCR software, OCR devices and systems are reviewed. Image processing operators and artificial neural networks are presented. Analysis and application of image processing operators for detection of number plate is done. Experimental results of estimation of Kohonen and multilayer feedforward artificial neural network learning parameters are presented. Number plate recognition is performed by the use of multilayer feedforward artificial neural network. Model of number plate recognition system is created. Number plate recognition software works in Microsoft© Windows™ operating system. Software is written with C++ language. Experimental results of system model operation are presented.