Impacto da distorção não linear em sistemas wireless

Mestrado em Engenharia Electrónica e TelecomunicaçõesEsta tese esta inserida no domínio dos sistemas não lineares sendo direccionada para sistemas de micro ondas e radio frequência. Neste estudo pretende-se compreender o impacto da distorção não linear em sistemas wireless quando submetidos a sinais digitais modulados. Para fazer o estudo destes fenomenos é necessario efectuar uma correcta carcterização do sinal de excitação, contudo devido á sua natureza aleatoria este processo nem sempre é facil, o que originou simplificações, que no entanto são por vezes aplicadas de modo errado. Neste estudo é aboradado este problema sendo ilustradas as diferenças entre as aproximações e a estatistica real do sinal e ainda exposto o processo para o calculo analitico da estatistica real do sinal. Serão também estudados diversos fenomenos responsaveis pelo aparecimento de distorção não linear, estes fenomenos serão representados através de modelos, tais como, o modelo de Winner-Hammerstein e o modelo multi-slice. ABSTRACT: This thesis is performed under the non-linear electronic systems context, as radio frequency and microwave systems, this study is intended for the understanding of the impact of the non linear distortion in wireless systems when using complex digitally modulated signals. To evaluate it is necessary to make a correct characterization of the excitation signal. However, due to its random nature, these processes are not always easy, which leads to simplifications. Although this simplifications sometimes are used wrongly. These will be discussed and the differences between the real signal statistics and the approximations will be showed, moreover the analytical process to obtain the real signal statistics will be presented. Several non linear phenomena responsible for the non linear distortion will be studied. Each component will be represented by models as the Wiener- Hammerstein and the multi-slice model

Dual frequency receiver system for Mariner 1967 to Venus Final engineering report

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Research and technology highlights of the Lewis Research Center

Highlights of research accomplishments of the Lewis Research Center for fiscal year 1984 are presented. The report is divided into four major sections covering aeronautics, space communications, space technology, and materials and structures. Six articles on energy are included in the space technology section

CMOS SINGLE-PHOTON AVALANCHE DIODES AND MICROMACHINED OPTICAL FILTERS FOR INTEGRATED FLUORESCENCE SENSING

This dissertation presents a body of work that addresses the two most pressing challenges in the field of integrated fluorescence sensing, namely, the design of integrated optical sensors and the fabrication of high-rejection micro-scale optical filters. Two novel enabling technologies were introduced. They are: the perimeter-gated single-photon avalanche diode (PGSPAD), for on-chip photon counting, and the benzotriazole (BTA)-doped thin-film polymer filter, for on-chip ultraviolet light rejection. Experimental results revealed that the PGSPAD front-end, fabricated in a 0.5 μm standard mixed-signal CMOS process, had the capability of counting photons in the MHz regime. In addition, it was found that a perimeter gate, a structural feature used to suppress edge breakdown in the diode, also maximized the signal-to-noise-ratio in the high-count rate regime whereas it maximized sensitivity at low count rates. On the other hand, BTA-doped filters were demonstrated utilizing three commonly used polymers as hosts. The filters were patternable, utilizing the same procedures traditionally used to pattern the undoped polymer hosts, a key advantage for integration into microsystems. Filter performance was analyzed using a set of metrics developed for optoelectronic characterization of integrated fluorescence sensors; high rejection levels (nearing -40 dB) of UV light were observed in films of only 5 μm in thickness. Ultimately, BTA-doped filters were integrated into a portable sensor, and their use was demonstrated in two types of bioassays

Television broadcast from space systems: Technology, costs

Broadcast satellite systems are described. The technologies which are unique to both high power broadcast satellites and small TV receive-only earth terminals are also described. A cost assessment of both space and earth segments is included and appendices present both a computer model for satellite cost and the pertinent reported experience with the Japanese BSE

Research and Technology, 1994

This report selectively summarizes the NASA Lewis Research Center's research and technology accomplishments for the fiscal year 1994. It comprises approximately 200 short articles submitted by the staff members of the technical directorates. The report is organized into six major sections: Aeronautics, Aerospace Technology, Space Flight Systems, Engineering and Computational Support, Lewis Research Academy, and Technology Transfer. A table of contents and author index have been developed to assist the reader in finding articles of special interest. This report is not intended to be a comprehensive summary of all research and technology work done over the past fiscal year. Most of the work is reported in Lewis-published technical reports, journal articles, and presentations prepared by Lewis staff members and contractors. In addition, university grants have enabled faculty members and graduate students to engage in sponsored research that is reported at technical meetings or in journal articles. For each article in this report a Lewis contact person has been identified, and where possible, reference documents are listed so that additional information can be easily obtained. The diversity of topics attests to the breadth of research and technology being pursued and to the skill mix of the staff that makes it possible

Cellular and molecular investigations of undiagnosed neurometabolic disorders

Inborn errors of metabolism (IEM) affect 1 in 500 newborns causing significant disease-burden and mortality throughout childhood. However, despite extensive genetic and biochemical investigations the cause of disease remains unknown in up to 50% of patients with neurological symptoms; so-called neurometabolic disorders (NMD). The overarching aim of this thesis was to determine the cellular and molecular aetiologies for the clinical phenotypes seen in patients with undiagnosed NMD. In order to improve the diagnosis of these disorders in clinical practice, a comprehensive targeted gene panel of 614 genes known to cause IEM was designed and a cohort of 44 patients was analysed. A definitive or probable genetic diagnosis was achieved in 53% of patients without a prior genetic diagnosis. Method optimisation and validation, comparison to other diagnostic strategies and the advantages and disadvantages of targeted sequencing are reviewed. Case reports, novel mutations/phenotypes and their contribution to the expansion of the literature are described. Whole exome sequencing and functional characterisation was also undertaken for patients who had been extensively clinically investigated previously. Five patients identified with mutations in the mitochondrial glutamate transporter, SLC25A22, presenting with novel biochemical phenotypes are described and novel transporter functions are postulated. One patient diagnosed with a potassium channelopathy with biochemical abnormalities and anticonvulsant responses suggestive of an inborn error of vitmain B6 metabolism is documented and the mechanisms underlying the generalised anticonvulsant effects of vitamin B6 are postulated. Characterisation of a possible novel inborn error of lysine metabolism in a patient presenting with hyperlysinaemia and motor neuron disease is also discussed. These studies also demonstrate the complexity of unravelling the relationship between genotype and phenotype and highlight the need for novel functional assays to assess the pathogenicity of sequence variants. Mass spectrometry-based assays were developed to enable characterisation of disorders affecting vitamin B6 homeostasis, including pyridox(am)ine 5'-phosphate oxidase (PNPO), antiquitin and PROSC deficiency, the latter being a novel disorder. The differences between pyridoxine- and pyridoxal phosphate-responsive PNPO deficiency and fibroblast vitamer profiles in all patients were all investigated. Finally, multiple methodologies were employed with the aim of understanding the biological function of PROSC