Spelling suggestions: "subject:"receiver"" "subject:"deceiver""
411 |
Low noise RF CMOS receiver integrated circuitsWoo, Sang Hyun 09 February 2012 (has links)
The objective of this research is to design and implement low-noise wideband RFIC components with CMOS technology for the direct-conversion architecture. This research proposes noise reduction techniques to improve the thermal noise and flicker noise contribution of a low noise amplifier (LNA) and a mixer. Of these techniques, the LNA is found to reduce noise, boost gain, and consume a relatively low amount of power without sacrificing the wideband and linearity advantages of a conventional common gate (CG) topology. The research concludes by investigating the proposed mixer topology, which senses and compensates local oscillator (LO) phase mismatches, the dominant cause of flicker noise.
|
412 |
Integrated Antennas and Active Beamformers Technology for mm-Wave Phased-Array SystemsBiglarbegian, Behzad 26 March 2012 (has links)
In this thesis, based on the indoor channel measurements and ray-tracing
modeling for the indoor mm-wave wireless communications, the challenges
of the design of the radio in this band is studied. Considering the recently developed standards such as IEEE 802.15.3c, ECMA and WiGig at 60 GHz, the link budget of the system design for different classes of operation is done and the requirement for the antenna and other RF sections are extracted. Based on radiation characteristics of mm-wave and the fundamental limits of low-cost Silicon technology, it is shown that phased-array is the ultimate solution for the radio and physical layer of the mobile millimeter wave multi-Gb/s wireless networks. Different phased-array configurations are studied and a low-cost single-receiver array architecture with RF phase-shifting is proposed. A systematic approach to the analysis of the overall noise-figure of the proposed architecture is presented and the component technical requirements are derived for the system level specifications. The proposed on-chip antennas and antenna-in-packages for various applications are designed and verified by the measurement results. The design of patch antennas on the low-cost RT/Duroid substrate and the slot antennas on the IPD technologies as well as the compact on-chip slot DRA antenna are explained in the antenna design section. The design of reflective-type phase shifters in CMOS and MEMS technologies is explained. Finally, the design details of two developed 60 GHz integrated phased-arrays in CMOS technology are discussed. Front-end circuit blocks such as LNA, continuous passive reflective-type phase shifters, power combiner and variable gain amplifiers are investigated, designed and developed for a 60 GHz phased-array radio in CMOS technology. In the first design, the two-element CMOS phased-array front-ends based on passive phase shifting architecture is proposed and developed. In the second phased-array, the recently developed on-chip dielectric resonator antenna in our group in lower frequency is scaled and integrated with the front-end. Read more
|
413 |
An investigation into the acoustic behaviour, ecology, biogeography, genetic relatedness and species limits within the Pauropsalta annulata Goding and Froggatt species complex (Hemiptera: Cicadidae)Lindsay Popple Unknown Date (has links)
This thesis investigates aspects of the ecology, morphology, bioacoustics, genetic relatedness, biogeography and taxonomy of cicadas in the Pauropsalta annulata Goding and Froggatt species complex, across their entire eastern Australian geographical distribution. These cicadas seem to emerge at the same sites annually, although the exact duration of their life cycle is not known. They are wary and mobile insects, with individuals generally taking flight at the first sign of disturbance, which makes them challenging to record, capture and observe. The males produce distinctive calling songs that have a consistent rhythmic structure, which is critically important for attracting females. In most cases, the songs are biphasic, with a penetrating introductory or "buzzing" component that apparently functions in mate attraction and a strongly structured cueing or "lilting" component for mate localisation. Initially Pauropsalta annulata was thought to comprise a single species with some degree of geographically structured variation in its calling song. Consequently, various "song types" had been recognised, but their precise relationship to one another had never been investigated. Therefore the structure of their calling songs were compared statistically across individuals of three song types, and this revealed four discrete clusters that were demonstrated to be independent of one another and consistent in their calling song structure. Plotting the geographical distributions of these cicadas revealed that each of the P. annulata song types is independently distributed geographically, with areas of overlap that are relatively small. Calling song structure is consistent for each song type across extensive geographical space and this structure holds even into areas of sympatry. One song type showed consistent differences from the others in male genitalia structure, and female ovipositor length differs significantly among three of the other song types. Each song type was found to be strongly associated with a small number of tree species and these associations are maintained into areas of sympatry. The spatial ecological and morphological comparisons in song structure, plant associations and morphology made in this study demonstrate that the P. annulata song types actually represent a complex of cryptic species. Two of the song types appear to intergrade in areas of sympatric overlap in terms of calling songs, plant associations and morphology, and thus represent subspecies as defined in population genetics terms. The components of the male calling song were then investigated to determine their specific functions and thus how they could delimit species boundaries. Significant differences were found in dominant song frequency between three of the four species, and may contribute to differential mate attraction. Both components of the song of each species have the same dominant frequency. Consistent differences were also evident, among species and subspecies, in the rhythmic structure of the "lilting" component of the male calling song. This component contains repeated phrases and each one of these provides a cue to which the conspecific female may respond. Her response is timed for the brief silent interval between the phrases. At this point the calling song becomes a duet, which enables the male to locate the female, as he actively searches for her on the surrounding branches at this stage. The calling song is discussed in terms of random mating within gene pools of these cicadas and in terms of its role as part of their broader fertilisation mechanism. A molecular analysis of the P. annulata species complex was performed to examine the phylogenetic relationships across 12 species and four subspecies defined in this study, and estimate divergence times within the group. Individual specimens were sampled widely across the geographical distributions of the species and subspecies where possible to account for genetic variation across space. DNA sequences from two loci were amplified: mitochondrial CO1 ("barcoding region") and a large intron from the dynamin nuclear gene. Separate phylogenies were reconstructed for each locus using maximum parsimony procedures and Bayesian posterior sampling with implementation of a relaxed molecular clock. The phylogenies from both genes provided strong support for the monophyly of the P. annulata species complex, and nine of the species were monophyletic based on the CO1 gene. The remaining three emerged non-monophyletic. Based on a clock calibration of 0.0165s/s/myr, the monophyletic clades represented by extant P. annulata species diverged about 4.5-8.0 million years ago. Those species that emerged non-monophyletic had shallower divergences, with the exception of one species, which exhibited haplotype diversity that conferred up to 13.2% sequence divergence between allopatric populations in CO1. Dynamin produced a broadly similar phylogenetic pattern to that of CO1, but the relationships among individuals across the species and subspecies that emerged non-monophyletic differed substantially. This lack of congruence between the two genomes, in combination with the dominance of internal haplotypes in both loci, indicates an overall pattern of deep coalescence rather than interspecific hybridization. Therefore the molecular data do not provide an alternative definition of species limits in the P. annulata species complex, despite some emerging non-monophyletic in this analysis. Sound interpretation of the phylogenetic pattern discovered here would not have been possible without the acoustic, ecological and geographical investigations on species limits that preceded this work. To determine what biological and climatic factors influence the present day distributions of these cicadas, the distributions of two of the most closely related species in the P. annulata species complex were compared with the distributions of the tree species with which each is mainly associated. Because a large part of their life cycle is subterranean, soil texture, pH, electrical conductivity and force required for surface penetration were compared across sites where each of the cicadas occur in sympatry and allopatry. Finally, the influence of temperature and rainfall variables were investigated by testing 'predicted distribution' models (formed using positive distribution records) against negative records for both sets of variables, individually and in combination. The results show that the extent of the distribution of the cicada species is substantially less than that of the associated tree species. The geographical distributions of one of the species may be influenced more by rainfall, or a combination of temperature and rainfall, whereas the other species appears to be more influenced by temperature alone. Both species tolerate soils with a wide range of pH levels, electrical conductivity and forces required for surface penetration. They both showed a strong association with soils that had a silt loam texture, with only few records from sandy soils. However, none of the soils sampled where the cicadas occurred were heavy clays, which suggests that the physical properties of such soils may provide an unsuitable environment for the nymphal stages of the life cycle of these particular cicadas. The resolution of species limits within the P. annulata species complex allowed the redescription of Pauropsalta annulata Goding and Froggatt sensu stricto and the description of 11 new species belonging to the P. annulata species group, all from eastern Australia. Two of these species comprise two subspecies each, also all new. New distribution records and calling song data are documented for the allied species, P. ayrensis Ewart, which is redescribed to include the characters newly recognised in the present study as significant taxonomically with respect to Pauropsalta cicadas. The treatment includes comprehensive descriptions of the morphology and calling songs of the species and subspecies, and separate descriptive keys are provided for both sets of characters. The new taxa comprise P. artatus sp. nov., P. corymbiae sp. nov., P. decorus sp. nov., P. graniticus sp. nov., P. inversus inversus subsp. nov., P. i. laboris subsp. nov., P. notialis notialis subsp. nov., P. notialis incitatus subsp. nov., P. simplex sp. nov., P. subtropicus sp. nov, P. torrensis sp. nov. and P. tremulus sp. nov. Areas of hybridization between P. n. notialis subsp. nov. and P. n. incitatus subsp. nov. are also documented, together with their calling songs and morphology, which justifies their subspecific status. The P. inversus subspecies are allopatric, but consistently differ in the duration between phrases of the calling song. Finally, the results and conclusions are amalgamated into a critical reassessment of what defines species limits and the most appropriate approaches to investigating species limits in sexual organisms. Some historical discussions are revisited, such as the question of the reality of species and how species are perceived under the premises of neoDarwinism. The realism of species demands that species limits are most realistically defined in terms of their fertilisation mechanism, for this delimits the gene pool and thus the distribution of adaptations (the calling song of cicadas, for example). Read more
|
414 |
A study of radio astronomy principles and SKA pathfinder system designs with pulsar scienceOtto, Sunelle 14 March 2011 (has links)
Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: The Square Kilometre Array (SKA) is an international project to build the world’s largest and most sensitive
radio telescope interferometer. It will consist of thousands of antennas distributed over many kilometers,
with the hosting country being either South Africa or Australia. Various pathfinders have been initiated to
demonstrate the technologies needed to implement the SKA. The astronomy community has defined five
Key Science Projects (KSP), which are the drivers for the SKA. The science goals determine the technical
requirements needed to design SKA systems. Many years of planning and development are still needed in
order to meet to the requirements of such a large and complex project.
This thesis aims to present the various SKA pathfinder systems in terms of their application to the SKA
key science projects, with main focus that of pulsar observations. In order to achieve this, a thorough overview
of basic radio astronomy principles and techniques is presented, followed by a detailed look at the various
pathfinders. Throughout the work, aspects of pulsar observations are given particular attention with the goal of
designing optimal systems for the SKA. / AFRIKAANSE OPSOMMING: Die Square Kilometre Array (SKA) is ’n internasionale projek om die wêreld se grootste en mees sensitiewe
radio teleskoop interferometer te bou. Dit sal bestaan uit duisende antennas versprei oor etlike kilometers, met
die gasheer land óf Suid-Afrika óf Australië. Verskeie koersbepalers is geïnisieer om die tegnologie te demonstreer
wat benodig is om die SKA te implementeer. Die astronomie gemeenskap het vyf sleutel wetenskap
projekte (KSP) gedefinieër wat dien as die drywers vir die SKA. Die wetenskap doelwitte bepaal die tegniese
vereistes wat nodig is om SKA stelsels to ontwerp. Talle jare van beplanning en ontwikkeling word steeds
benodig om te voldoen aan die vereistes van so ’n groot en komplekse projek.
Hierdie tesis het ten doel die aanbieding van verskeie SKA koersbepaler stelsels in terme van hulle aanwending
tot die SKA sleutel wetenskap projekte, met hoof fokus op die van pulsar waarnemings. Om dit te
behaal, word ’n deeglike oorsig van basiese radio astronomie beginsels en tegnieke aangebied, gevolg deur ’n
gedetailleerde kyk na die verskeie koersbepalers. Regdeur die werk word spesifieke aandag gegee aan aspekte
van pulsar waarnemings met die doel om optimale stelsels vir die SKA te ontwerp. Read more
|
415 |
IP mobile multicast over next generation satellite networks : design and evaluation of a seamless mobility framework for IP multicast communications over a multi-beam geostationary satellite networkJaff, Esua Kinyuy January 2016 (has links)
The inherent broadcast nature of satellites, their global coverage and direct access to a large number of subscribers give satellites unrivalled advantages in supporting IP multicast applications. A new generation of satellite systems that support regenerative on-board processors and multiple spot beam technology have opened new possibilities of implementing IP multicast communication over satellites. These new features enable satellites to make efficient use of their allocated bandwidth resources and provide cost effective network services but equally, create new challenges for mobile satellite terminals. IP mobility support in general and IP mobile multicast support in particular on mobile satellite terminals like the ones mounted on continental flights, maritime vessels, etc., still remain big challenges that have received very little attention from the research community. Up till now, there are no proposed mechanisms to support IP multicast for mobile receivers/sources in multi-beam satellite networks in open literature. This study explores the suitability of IP multicast mobility support schemes defined for terrestrial networks in a satellite environment and proposes novel schemes based on the concepts of Home and Remote subscription-based approaches, multiple interface and PMIPv6 protocol. Detailed analysis and comparison of results obtained from the proposed schemes, Mobile IP (MIP) Home and Remote subscription-based approaches (for terrestrial networks) when implemented on a reference multi-beam satellite network are presented. From these results, the proposed schemes outperform the MIP Home and Remote subscription-based approaches in terms of gateway handover latency, number of multicast packets lost and signalling cost over the satellite air interface. Read more
|
416 |
Analysis of angular accuracy in the IFF Monopulse receiverBengtsson, Filip, Sköld, David January 2018 (has links)
This master thesis investigates how certain components error margin may affect the accuracy of a IFF monopulse receiver. The IFF monopulse receiver measures the angle of arrival of the incident signal by comparing sum and difference signals created in the receiver. The components of interest are phase shifters and attenuators, where both can give individual and different errors depending on the antenna steering angle. The project is conducted at Saab Aeronautics, based on a receiver in development for the Gripen E aircraft. The results of the thesis generated results showing that the angular accuracy decreases with the increase of steering angle. The angular deviation can for some cases be seen as sufficiently small for the receiver to work properly in the ideal case.
|
417 |
Essays on communication and information transmission / Essai sur la communication et la transmission d'informationsSchopohl, Simon 13 November 2017 (has links)
Cette thèse de doctorat traite de différentes questions concernant la communication et la transmission d’informations dans le cadre de la théorie des jeux. J’analyse différents dilemmes auxquels peut être confronté un joueur qui envoie des informations. Ces dilemmes correspondent aux questions suivantes: "Devrais-je investir dans un message vérifiable?", "Quand dois-je transmettre mon information?" et "Est-il préférable de ne pas envoyer mon information et uniquement de recueillir l’information des autres?". Cette thèse comprend une introduction et trois chapitres. L’introduction contient une motivation générale pour les trois problèmes que je présente dans cette thèse. Je donne une vue d’ensemble détaillée de tous les chapitres, j’examine la littérature relative au sujet et je la compare à mes résultats. / This Ph.D dissertation addresses different issues concerning communication and information transmission in a game theoretical framework. I analyze different dilemmas that a player who sends information has to deal with. These dilemmas correspond to the following questions: "Should I invest into a verifiable message?", "When should I pass my information?" and "Is it better if I do not send my information, but collect information from others?". This thesis includes an introduction and three chapters. The introduction contains a general motivation for the three different problems that I model in this thesis. I give a detailed overview of all the chapters, survey the related literature and compare it to my results. Read more
|
418 |
Intelligent computing applications to assist perceptual training in medical imagingDong, Leng January 2016 (has links)
The research presented in this thesis represents a body of work which addresses issues in medical imaging, primarily as it applies to breast cancer screening and laparoscopic surgery. The concern here is how computer based methods can aid medical practitioners in these tasks. Thus, research is presented which develops both new techniques of analysing radiologists performance data and also new approaches of examining surgeons visual behaviour when they are undertaking laparoscopic training. Initially a new chest X-Ray self-assessment application is described which has been developed to assess and improve radiologists performance in detecting lung cancer. Then, in breast cancer screening, a method of identifying potential poor performance outliers at an early stage in a national self-assessment scheme is demonstrated. Additionally, a method is presented to optimize whether a radiologist, in using this scheme, has correctly localised and identified an abnormality or made an error. One issue in appropriately measuring radiological performance in breast screening is that both the size of clinical monitors used and the difficulty in linking the medical image to the observer s line of sight hinders suitable eye tracking. Consequently, a new method is presented which links these two items. Laparoscopic surgeons have similar issues to radiologists in interpreting a medical display but with the added complications of hand-eye co-ordination. Work is presented which examines whether visual search feedback of surgeons operations can be useful training aids. Read more
|
419 |
Caractérisation et modélisation multiphysique de MEMS supraconducteurs pour une application en radioastronomie millimétrique / Multiphysic characterization and modelling of superconducting MEMS for radio astronomy applicationsAllouch, Nouha 28 November 2011 (has links)
Des MEMS supraconducteurs ont été développés par l’IRAM pour des besoins instrumentaux dans les récepteurs hétérodyne large bande en millimétrique. Dans ce mémoire, la caractérisation de ces MEMS capacitifs par des mesures profilométriques, vibrométriques, aux rayons X , électriques et thermiques est présentée. Ils ont en outre été modélisés avec un modèle analytique électromécanique simple. Ce modèle est complété par un schéma équivalent haute fréquence semi-distribué facilement implantable dans le simulateur multiphysique COMSOL pour prendre en compte la supraconductivité. Ce travail a permis de déterminer quelles géométries de ces MEMS sont satisfaisantes pour une utilisation dans les récepteurs hétérodyne large bande en hyperfréquence. / Superconducting MEMS were developed by IRAM for millimetre wave heterodyne receivers improvements. In this report, the characterization of these capacitive MEMS is presented (profilometry, vibrometry, X rays, electric and thermal). They were described with a simple analytical electromechanical model which can be easily implemented with an equivalent high frequency circuit in the COMSOL multiphysic software to take into account the superconductivity. This work answers to the question of what are the MEMS geometries well suited for broadband heterodyne receivers requirements. Read more
|
420 |
Dramaturgia do aqui e agora: presen?a, recep??o e sentido no corpo do atorToledo, Marina Madeira de 12 April 2013 (has links)
Made available in DSpace on 2014-12-17T14:00:17Z (GMT). No. of bitstreams: 1
MarinaMT_DISSERT.pdf: 1946161 bytes, checksum: fa78815b909d85267052422856f66700 (MD5)
Previous issue date: 2013-04-12 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The actor is an actor during all the phases of creation and development of his
character. (S) He goes beyond the moment of interpreting. In this sense, in her (his) daily life,
the actor may use her (his) potential to extract from reality the necessary elements for the
work of creation. This is a theoretical research which focus on the concept of presence in
the actor s work, stretching the concept beyond the scene, encompassing different
components such as the body, the word, the silence, the technique and the acting as the actor s
stance in regards to his own reality. The objective of such stance is to integrate him (her)
self in the environment, balancing his (hers) inner life with the outside life flow. To reach this
objective, the research drew theoretical resources from the concept of presence in the
actor s work according to BROOK, BARBA, GROTOWSKI and MNOUCHKINE and the
studies on reception theory in ISER, 1996; GUMBRECHT, 2010. Thus, the dialogue between
reader and actor high lights both as receivers in this work. A practical description of a street
theater Kamch?tka show, featured by the Kamch?tka Company is used as an example of the
research on the presence. The elements localized in this show are: play, listening, word,
silence, meaning, relationship with here and now and the effects of the said presence / O ator n?o ? ator somente no momento da cena, ? ator em todas as etapas de cria??o e
desenvolvimento de seu objeto est?tico. Nesse sentido, em seu cotidiano o ator pode procurar
utilizar suas potencialidades para captar e traduzir da realidade o material para seu trabalho
criativo. Esta pesquisa possui car?ter te?rico e aborda o conceito de presen?a no trabalho do
ator, colocando-o como conceito para al?m da cena, n?o isolado de outros componentes
entre eles o corpo, a palavra, o sil?ncio, a t?cnica, a representa??o como uma postura do ator
para com sua realidade, a fim de integrar-se ao meio ambiente que o cerca, equilibrando seu
conte?do interior com o conte?do exterior. Para tanto, utiliza como aporte te?rico
encenadores que abordam o conceito de presen?a no trabalho do ator (BROOK; BARBA;
GROTOWSKI; MNOUCHKINE) e os estudos da teoria da recep??o (ISER, 1996;
GUMBRECHT, 2010), tra?ando um paralelo dial?gico entre as fun??es de leitor e ator,
apontando ambos como receptores. Como exemplo pr?tico do estudo sobre a presen?a, ? feita
aqui uma descri??o do espet?culo de teatro de rua Kamch?tka, realizado pela Companhia
Kamch?tka, localizando nesse espet?culo os elementos: jogo, escuta, palavra, sil?ncio,
sentido, rela??o com o aqui e agora e efeitos de presen?a; citados ao longo da disserta??o Read more
|
Page generated in 0.0382 seconds