Tesi sul tema "Radio"
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1
Zhao, Youping. "Enabling Cognitive Radios through Radio Environment Maps". Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/27826.
Testo completoAbstract (sommario):
In recent years, cognitive radios and cognitive wireless networks have been introduced as a new paradigm for enabling much higher spectrum utilization, providing more reliable and personal radio services, reducing harmful interference, and facilitating the interoperability or convergence of different wireless communication networks. Cognitive radios are goal-oriented, autonomously learn from experience and adapt to changing operating conditions. Cognitive radios have the potential to drive the next generation of radio devices and wireless communication system design and to enable a variety of niche applications in demanding environments, such as spectrum-sharing networks, public safety, natural disasters, civil emergencies, and military operations.
This research first introduces an innovative approach to developing cognitive radios based on the Radio Environment Map (REM). The REM can be viewed as an integrated database that provides multi-domain environmental information and prior knowledge for cognitive radios, such as the geographical features, available services and networks, spectral regulations, locations and activities of neighboring radios, policies of the users and/or service providers, and past experience. The REM, serving as a vehicle of network support to cognitive radios, can be exploited by the cognitive engine for most cognitive functionalities, such as situation awareness, reasoning, learning, planning, and decision support. This research examines the role of the REM in cognitive radio development from a network point of view, and focuses on addressing three specific issues about the REM: how to design and populate the REM; how to exploit the REM with the cognitive engine algorithms; and how to evaluate the performance of the cognitive radios. Applications of the REM to wireless local area networks (WLAN) and wireless regional area networks (WRAN) are investigated, especially from the perspectives of interference management and radio resource management, which illustrate the significance of cognitive radios to the evolution of wireless communications and the revolution in spectral regulation. Network architecture for REM-enabled cognitive radios and framework for REM-enabled situation-aware cognitive engine learning algorithms have been proposed and formalized. As an example, the REM, including the data model and basic application programmer interfaces (API) to the cognitive engine, has been developed for cognitive WRAN systems. Furthermore, REM-enabled cognitive cooperative learning (REM-CCL) and REM-enabled case- and knowledge-based learning algorithms (REM-CKL) have been proposed and validated with link-level or network-level simulations and a WRAN base station cognitive engine testbed. Simulation results demonstrate that the WRAN CE can adapt orders of magnitude faster when using the REM-CKL than when using the genetic algorithms and achieve near-optimal global utility by leveraging the REM-CKL and a local search. Simulation results also suggest that exploiting the Global REM information can considerably improve the performance of both primary and secondary users and mitigate the hidden node (or hidden receiver) problem. REM dissemination schemes and the resulting overhead have been investigated and analyzed under various network scenarios. By extending the optimized link state routing protocol, the overhead of REM dissemination in wireless ad hoc networks via multipoint relays can be significantly reduced by orders of magnitude as compared to plain flooding. Performance metrics for various cognitive radio applications are also proposed. REM-based scenario-driven testing (REM-SDT) has been proposed and employed to evaluate the performances of the cognitive engine and cognitive wireless networks. This research shows that REM is a viable, cost-efficient approach to developing cognitive radios and cognitive wireless networks with significant potential in various applications. Future research recommendations are provided in the conclusion.Ph. D.
2
Navalekar, Abhijit C. "Distributed Digital Radios for Land Mobile Radio Applications". Digital WPI, 2010. https://digitalcommons.wpi.edu/etd-dissertations/4.
Testo completoAbstract (sommario):
The main objective of this dissertation is to develop the second generation of Distributed Digital Radio (DDR) technology. A DDR II modem provides an integrated voice/data service platform, higher data rates and better throughput performance as compared to a DDR I modem. In order to improve the physical layer performance of DDR modems an analytical framework is first developed to model the Bit Error Rate (BER) performance of Orthogonal Frequency Division Multiplexing over Frequency Modulation (OFDM/FM) systems. The use of OFDM provides a spectrally efficient method of transmitting data over LMR channels. However, the high Peak-to-Average (PAR) of OFDM signals results in either a low Signal-to-Noise Ratio (SNR) at FM receiver or a high non-linear distortion of baseband signal in the FM transmitter. This dissertation presents an analytical framework to highlight the impact of high PAR of OFDM signal on OFDM/FM systems. A novel technique for reduction of PAR of OFDM called Linear Scaling Technique (LST) is developed. The use of LST mitigates the signal distortion occurring in OFDM over FM systems. Another important factor which affects the throughput of LMR networks is the Push-to-Talk (PTT) delay. A PTT delay refers to the delay between the instant when a PTT switch on a conventional LMR radio is keyed/unkeyed and a response is observed at the radio output. It can be separated into a Receive-To-Transmit Switch Interval (RTSI) or a Transmit-To-Receive Switch Interval (TRSI). This dissertation presents the typical RTSI delay values, distributions and their impact on throughput performance of LMR networks. An analytical model is developed to highlight the asymmetric throughput problem and the unintentional denial of service (UDOS) occurring in heterogeneous LMR networks consisting of radios with different PTT delay profiles. This information will be useful in performance and capacity planning of LMR networks in future.
3
Ballena, Castillo Maria de Jesus. "Análisis de las temáticas desarrolladas por las radios comunitarias y educativas: Radio Cutivalú y Radio Vino". Bachelor's thesis, Universidad Católica Santo Toribio de Mogrovejo, 2019. http://hdl.handle.net/20.500.12423/2786.
Testo completoAbstract (sommario):
El presente trabajo de investigación tuvo como objetivo principal analizar las temáticas desarrolladas por las radios comunitarias y educativas: radio Cutivalú y radio Vino; y como objetivos específicos los siguientes: describir las características de las radios comunitarias y educativas: radio Cutivalú y radio Vino, identificar las temáticas que se desarrollan en radio Cutivalú y radio Vino, y señalar los aportes de las temáticas en el desarrollo de las comunidades en las que están establecidas radio Cutivalú y radio Vino. La metodología que se utilizó en la investigación fue cualitativa, con un enfoque hermenéutico, y los instrumentos aplicados fueron entrevistas a los habitantes de Piura y Jayanca, lugares donde se ubican las radios materia de estudio, para conocer los aportes que estas generan en ellos. El trabajo concluyó que, el aporte principal de radio Cutivalú y radio Vino, con la información que transmiten a la población, es la transmisión de valores y la concientización de los ciudadanos en temas de política, salud y educación, principalmente, y una reflexión dirigida a que estos se conviertan en agentes activos de la transformación de su entorno social.
4
Miller, Philip Geoffrey. "Radio-loud and radio-quiet quasars". Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260417.
Testo completo
5
Kim, Kyou Woong. "Exploiting Cyclostationarity for Radio Environmental Awareness in Cognitive Radios". Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/27928.
Testo completoAbstract (sommario):
The tremendous ongoing growth of wireless digital communications has raised spectrum shortage and security issues. In particular, the need for new spectrum is the main obstacle in continuing this growth. Recent studies on radio spectrum usage have shown that pre-allocation of spectrum bands to specific wireless communication applications leads to poor utilization of those allocated bands. Therefore, research into new techniques for efficient spectrum utilization is being aggressively pursued by academia, industry, and government. Such research efforts have given birth to two concepts: Cognitive Radio (CR) and Dynamic Spectrum Access (DSA) network. CR is believed to be the key enabling technology for DSA network implementation. CR based DSA (cDSA) networks utilizes white spectrum for its operational frequency bands. White spectrum is the set of frequency bands which are unoccupied temporarily by the users having first rights to the spectrum (called primary users). The main goal of cDSA networks is to access of white spectrum. For proper access, CR nodes must identify the right cDSA network and the absence of primary users before initiating radio transmission. To solve the cDSA network access problem, methods are proposed to design unique second-order cyclic features using Orthogonal Frequency Division Multiplexing (OFDM) pilots. By generating distinct OFDM pilot patterns and measuring spectral correlation characteristics of the cyclostationary OFDM signal, CR nodes can detect and uniquely identify cDSA networks. For this purpose, the second-order cyclic features of OFDM pilots are investigated analytically and through computer simulation. Based on analysis results, a general formula for estimating the dominant cycle frequencies is developed. This general formula is used extensively in cDSA network identification and OFDM signal detection, as well as pilot pattern estimation. CR spectrum awareness capability can be enhanced when it can classify the modulation type of incoming signals at low and varying signal-to-noise ratio. Signal classification allows CR to select a suitable demodulation process at the receiver and to establish a communication link. For this purpose, a threshold-based technique is proposed which utilizes cycle-frequency domain profile for signal detection and feature extraction. Hidden Markov Models (HMMs) are proposed for the signal classifier.
The spectrum awareness capability of CR can be undermined by spoofing radio nodes. Automatic identification of malicious or malfunctioning radio signal transmitters is a major concern for CR information assurance. To minimize the threat from spoofing radio devices, radio signal fingerprinting using second-order cyclic features is proposed as an approach for Specific Emitter Identification (SEI). The feasibility of this approach is demonstrated through the identification of IEEE 802.11a/g OFDM signals from different Wireless Local Area Network (WLAN) card manufactures using HMMs.Ph. D.
6
Poulain, Sebastien. "Les radios alternatives : l'exemple de Radio Ici et Maintenant". Thesis, Bordeaux 3, 2015. http://www.theses.fr/2015BOR30020/document.
Testo completoAbstract (sommario):
Dans cette thèse, nous nous demandons comment les mouvements contreculturels ont trouvé de nouveaux lieux d’expression grâce à la plus grande accessibilité de l’audiovisuel, grâce aussi au combat des « radios libres ». Plus précisément, nous cherchons à savoir pourquoi et comment la société et l’audiovisuel français ont permis la constitution d’un média alternatif radiophonique comme Radio Ici et Maintenant (RIM) et comment cette radio a trouvé un modèle économique viable pour diffuser son idéologie. Nous verrons que l’existence et la persistance de RIM est due à la conjonction de deux phénomènes : d’une part la diminution du coût d’entrée dans la radiophonie grâce au développement et au combat des « radios libres » qui ont donné naissance aux radios associatives (avec leur modèle juridico-économique spécifique), et d’autre part la diminution du coût d’entrée dans le marché religieux avec le développement de la contreculture New Age française issue de la contreculture américaine, elle-même issue des pensées religieuses alternatives occidentales (liées à l’ésotérisme, au médiumnisme) et des religions orientales (l’hindouisme et le bouddhisme). Ainsi, le modèle juridico-économique spécifique des radios associatives a permis de faire vivre puis persister l’idéologie « radiolibriste » et New Age au sein de RIM. Mais ajoutons que ce modèle n’aurait pas été possible s’il n’avait pas été porté par des animateurs bénévoles, des invités militants et des auditeurs actifs dont nous analysons ici le profil sociologique. L’intérêt scientifique de ce sujet provient du fait qu’il s’agit principalement d’étudier RIM qui est une ancienne « radio libre ». Elle a été l’une des radios les plus importantes au sein du mouvement. C’est la plus ancienne des radios locales privées parisiennes. C’est aujourd’hui une radio associative de catégorie A. Cette catégorie correspond à un grand nombre de radios (environ 600), mais celles-ci sont peu étudiées. Enfin, c’est une radio New Age et l’un des seuls médias audiovisuels français New Age. Croisant histoire et sociologie du religieux, des médias, de la communication, de la politique, des sciences, cette thèse repose sur une écoute assidue, sur de nombreux entretiens et discussions informelles, sur l’étude de différents fonds d’archives (papier, audio, numérique) et sur de nombreuses observations de type ethnographique. Nous donnons dans une première partie les outils scientifiques pour pouvoir analyser ce phénomène. Nous verrons ensuite dans quel contexte historique, radiophonique, économique, social, juridique et politique RIM fait son apparition et continue d’exister aujourd’hui. Enfin, nous nous focalisons sur le modèle radiophonique proposé, et sur les acteurs de cette radioIn this thesis, we wonder how countercultural movement found new places of expression through the increased accessibility of audiovisual, thanks to "free radio" fight. Specifically, we want to know why and how society and the French media have enabled the establishment of an alternative media like Radio Ici et Maintenant (RIM) and how this radio has found a viable business model to spread its ideology. We shall see that the existence and persistence of RIM is due to the combination of two factors: firstly the reduction in the cost of entry into the radio broadcasting through the development and struggle of "free radio" that gave birth to associative radios (with their specific legal and economic model) and also the decrease in the cost of entering the religious market with the development of the French New Age counterculture issue of the American counterculture, itself the result of religious thoughts Western alternatives (related to the esoteric, the mediumship) and Eastern religions (Hinduism and Buddhism). Thus, the specific legal and economic model of associative radios allowed to live and persist "radiolibriste" and New Age ideology within RIM. But add that this model would not have been possible if it had not been worn by volunteer facilitators, invited activists and active listeners which we analyze the sociological profile. The scientific interest of this subject is the fact that it is mainly to study RIM which is an old "free radio". She was one of the most important radio stations in the movement. It is the oldest Parisian private local radio station. Today, it is a community radio (category A). This category corresponds to a large number of radio stations (about 600), but these are little studied. Finally, this is a New Age radio and one of the only French audiovisual media New Age. Crossing history and sociology of religion, media, communication, politics, science, this thesis is based on a constant listening, on numerous interviews and informal discussions on the study of different archives (paper, audio, digital) and numerous ethnographic observations. We give in the first part scientific tools to analyze this phenomenon. We will then see in which historical, radio, economic, social, legal and political context RIM appeared and continues to exist today. Finally, we focus on the proposed radio model and the actors of this radio
7
Pirmoradian, Mahdi. "Radio resource management for cognitive radio networks". Thesis, Kingston University, 2012. http://eprints.kingston.ac.uk/23723/.
Testo completoAbstract (sommario):
Cognitive radio concept is a promising technology to cope with the spectrum scarcity issue in the emerging wireless technology. Practical cognitive radio as an intelligent radio is on the horizon, in which the system is able to observe radio environment, understanding its situation, and adapt its transceiver parameters without disruption to the licensed service. The main given functionality of the cognitive radio is dynamic spectrum management using underlay or overlay spectrum-sharing mechanisms. This thesis studies several objectives in cognitive radio networks namely; cumulative interference in multi-user overlay networks, effective capacity optimisation in time varying imperfect fading channels, and diverse spectrum decision schemes (i.e. Maximum Entropy Channel Access, MECA, and Adaptive Spectrum Opportunity Access, ASOA, schemes) in overlay networks. Also Green Cognitive Radio concept is introduced for enhancing energy efficiency in overlay networks. The cumulative interference at a cell-edge active primary receiver is estimated based on the two scenarios, the broadcast of receiver beacon signal and the broadcast of licensed transmitter beacon signal. In the proposed system topology, the cognitive users are distributed within and outside of the licensed coverage area with constant density. The results indicate that cumulative interference significantly gets low level through the broadcast of receiver beacon signal scenario in comparison with the licensed transmitter scenario. Additionally, optimising effective capacity of a secondary user subject to the interference constraint and transmission power constraint factors, in imperfect fading channels is studied. In this case, cross channel state information is a key factor in adapting transmission power and channel capacity accordingly. The numerical results show that effective capacity is influenced upon increasing cross channel error (secondary transmitter-primary receiver link), and QoS delay items. Moreover, the study is completed by proposing power control policy upon minimising interference level at the licensed receiver subject to the desired effective capacity level and transmission power constraint. Hence, performance of the proposed spectrum decision schemes (MECA, ASOA) is examined and explained by comparison with Random Channel Access (RCA), Minimum Channel Rate (MCR), and First Opportunity Channel Access (FOCA) schemes in the period of simulation time. MECA scheme uses weighted entropy function to assess usefulness of the remaining available idle channels, and so selects appropriate spectrum opportunity for secondary data delivery. The performance reveals that MECA and ASOA can potentially be considered as viable approaches in spectrum selection schemes. Additionally, in the case of GCR aspect an opportunistic power control policy using the remaining idle channel lifetime is proposed to mitigate interference power at the primary receiver. Overall, we develop and propose a unique technique in decreasing total interference in overlay networks; effective capacity optimisation in underlay networks, feasible spectrum selection schemes, and also green cognitive radio concept in the field of dynamic spectrum access networks.
8
Moy, Christophe. "Evolution de la conception radio : de la radio logicielle à la radio intelligente". Habilitation à diriger des recherches, Université Rennes 1, 2008. http://tel.archives-ouvertes.fr/tel-00354493.
Testo completoAbstract (sommario):
Le manuscrit de cette Habilitation à Diriger des Recherches reprend quelques thèmes de mon parcours de recherche depuis 10 ans, et que l'on peut résumer ainsi. De la conception radio classique pendant ma thèse (à base d'ASIC) j'ai vécu la transition vers la conception radio logicielle (dans un laboratoire de recherche d'un grand groupe industriel) et enfin j'étends désormais en parallèle mes travaux vers la conception radio intelligente (dans un laboratoire de recherche académique). Cinq travaux sont repris dans ce mémoire, portant sur la radio logicielle et la radio intelligente. Ils correspondent à cinq des thèses que j'ai encadrées. Ils portent tout d'abord sur la contribution à une approche de conception pragmatique pour la radio logicielle orientée composants. La radio logicielle en effet implique l'utilisation de ressources de traitements multiples et hétérogènes, générant ainsi des difficultés de conception non encore résolues dans leur ensemble par la communauté de l'architecture. L'un des principes repose sur l'indifférence qu'il doit y avoir entre traitements logiciels et matériels, quel que soit leur niveau de reconfigurabilité. Un effort de formalisation de la conception radio logicielle est proposé dans un deuxième temps, dans une approche orientée opérateurs communs. L'idée repose sur la description à différents niveaux de granularité des opérateurs de traitement du signal afin de bénéficier de la réutilisation de motifs de calcul. Le travail d'optimisation consiste à sélectionner le niveau de granularité adéquate suivant les besoins du concepteur. La gestion de reconfiguration, qui est un point central si ce n'est le point distinctif de la radio logicielle est le cœur du troisième travail présenté. Sa généralisation à la radio intelligente permet d'aboutir dans un quatrième cas d'étude à la proposition d'une architecture de gestion radio intelligente : HDCRAM. Une modélisation de cette architecture est proposée sous la forme d'un méta-modèle exécutable. Cela permet notamment de disposer d'un simulateur de scénarios du comportement de l'architecture de gestion d'une radio intelligente et de pouvoir la dimensionner pour chaque scénario. Enfin la dernière étude porte sur la définition du concept de bulle sensorielle radio intelligente qui porte particulièrement sur l'ensemble des capteurs d'un équipement de radio intelligente. Les perspectives de ces travaux sont notamment d'étudier le troisième et dernier élément du cercle cognitif simplifié (après la reconfiguration et les capteurs) qu'est la prise de décision.
9
Marlow, Ryan Lane. "Making Radios with GReasy: GNU Radio With FPGAs Made Easy". Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/50432.
Testo completoAbstract (sommario):
Radio technology is rapidly evolving and as processing capabilities and algorithms become more complex, the need for alternative compilation and user interface abstraction increases. Field Programmable Gate Array (FPGA) technology introduces unique reconfigurable hardware architectures that can aid in software defined radio (SDR) design. FPGAs have greater processing capability than traditional general purpose processors (GPP) found in desktop workstations. This work builds on an ongoing project, GReasy, that augments a Linux based open source SDR development platform, GNU Radio, with FPGA processing capabilities. By delegating processing intensive portions of a radio design to the Xilinx Zynq FPGA architecture, the domain of deployable radios by GNU Radio can be broadened.
Xilinx Zynq, integrates the FPGA fabric and CPU onto a single chip, which eliminates the need for a controlling host computer; thus, providing a single, portable, low-power, embedded platform. This thesis presents a Zynq capable version of GNU Radio -- an open-source rapid radio deployment tool -- with an enhanced flow that utilizes the processing capability of FPGAs. This work features TFlow -- an FPGA back-end compilation accelerator for instant FPGA assembly. GReasy generates a description of the hardware components that are used by TFlow for the instant FPGA assembly. Once the FPGA is programmed with a design based on the description generated by GReasy, modules and the target hardware can be parameterized to realize an even larger class of applications and further solidify the concept of rapid assembly of software defined radios.Master of Science
10
Ker, Louise Moira. "Radio AGN evolution with low frequency radio surveys". Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/7616.
Testo completoAbstract (sommario):
Supermassive black holes are leading candidates for the regulation of galaxy growth and evolution over cosmic time, via ‘feedback’ processes, whereby outflows from the Active Galactic Nuclei (AGN) halt star formation within the galaxy. AGN feedback is generally thought to occur in two modes, high-excitation (HERG, or ‘quasar-mode’) and low-excitation (LERG or ’radio-mode’) each having a different effect on the host galaxy. LERGs curtail the growth of the most massive galaxies, whereas HERGs are thought to be activated by mergers/interactions, switching off star formation at high redshift. A critical problem in current extragalactic astrophysics lies in understanding the precise physical mechanisms by which these feedback processes operate, and how they evolve over cosmic time. Radio-loud AGN are an essential tool for studying major feedback mechanisms, as they are found within the largest ellipticals, and hence are beacons for the most massive black holes across the bulk of cosmic time. In this thesis I develop and study existing complete radio samples with extensive new multi-wavelength data in the radio, optical and infrared, aiming to investigate the evolution of AGN feedback modes, and methods to locate and study such systems at the very highest redshifts. This will serve to inform further studies of radio-AGN planned with next generation radio instruments such as the LOw Frequency ARray (LOFAR). Very few radio-loud AGN systems are currently known at high redshifts, and the effectiveness of traditional high redshift selection techniques, such as selection based on steep spectral index, have not been well quantified. A purely evidence-based approach to determining the efficiency of various high redshift selection techniques is presented, using nine highly spectroscopically complete radio samples; although weak correlations are confirmed between spectral index and linear size and redshift, selection first of infrared-faint radio sources remains by far the most efficient method of selecting high-z radio galaxies from complete samples. Radio spectral curvature in four of the complete samples is analysed and the effect of radio spectral shape on the measurement of the radio luminosity function (RLF) of steep-spectrum radio sources is investigated. Below z=1, curvature has negligible effect on the measurement of the RLF, however at higher redshifts, where source numbers are low, the shape of the radio spectrum should be taken into account, as individual source luminosities can change up to 0.1-0.2 dex, and this can in some cases introduce errors in space density measurements of up to a factor of 2-3 where source numbers are low. Building upon these samples, the very first independent determinations of the separate RLFs for high and low excitation radio sources across the bulk of cosmic time are made, out to z=1. Here it is shown that HERGs show very clear signs of strong evolution, in line with theoretical predictions. LERGs also show some very weak evolution with redshift, showing increases in space density of typically around a factor of 2. These measurements are also used to estimate the contribution of LERGs, which typically show weak or no emission lines to the ‘missing redshift’ population, which are sources within the complete samples not identifiable spectroscopically. Complementary to this, a pilot study is presented in selecting ‘missing redshift’ sources which are classed as infra-red faint (IFRS), which show no optical or near-IR identification, and are compact in the radio. Follow up spectroscopy on these candidate high z sources detected no line emission. Finally, work carried out towards the testing and commissioning of the new LOFAR telescope is presented. The findings from this thesis will serve to both streamline and inform high redshift radio-AGN searches and studies planned to be carried out with LOFAR and other multi-wavelength complementary surveys in the near future, and help to open up an as yet unexplored epoch in radio-AGN formation and evolution.
11
Irick, Charles Robert. "Enhancing GNU Radio for Hardware Accelerated Radio Design". Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/33474.
Testo completoAbstract (sommario):
As technology evolves and new methods for designing radios arise, it becomes necessary
to continue the search for fast and flexible development environments. Some of these
new technologies include software defined radio (SDR), Field Programmable Gate Arrays
(FPGAs), and the open source project GNU Radio. Software defined radio is a concept
that GNU Radio has harnessed to allow developers to quickly create flexible radio designs.
In terms of hardware, the maturity of FPGAs give radio designers new opportunities to
develop high-speed radios having high-throughput and low-latency, yet the conventional
build-time for FPGAs is a limiting factor for productivity. Recent research has lead to
reductions in build-time by using FPGAs in a non-traditional manner, meaning produc-
tivity no longer has to be sacrificed. The AgileHW project demonstrated this concept and
will be used as a basis to develop an overlaying architecture that uses a combination of
the technologies mentioned to create a flexible, open, and efficient environment for radio
development. This thesis discusses the realization of this architecture with the use of
Xilinx FPGAs as a hardware accelerator for an enhanced GNU Radio.Master of Science
12
Finlay, Chris. "Radio Frequency Interference: Simulations for Radio Interferometry Arrays". Master's thesis, Faculty of Science, 2021. http://hdl.handle.net/11427/33716.
Testo completoAbstract (sommario):
Radio Frequency Interference (RFI) is a massive problem for radio observatories around the world. Due to the growth of telecommunications and air travel RFI is increasing exactly when the world's radio telescopes are increasing significantly in sensitivity, making RFI one of the most pressing problems for astronomy in the era of the Square Kilometre Array (SKA). Traditionally RFI is dealt with through simple algorithms that remove unexpected rapid changes but the recent explosion of machine learning and artificial intelligence (AI) provides an exciting opportunity for pushing the state-of-the-art in RFI excision. Unfortunately, due to the lack of training data for which the true RFI contamination is known, it is impossible to reliably train and compare machine learning algorithms for RFI excision on radio telescope arrays currently. To address this stumbling block we present RFIsim, a radio interferometry simulator that includes the telescope properties of the MeerKAT array, a sky model based on previous radio surveys coupled with an RFI model designed to reproduce actual RFI seen at the MeerKAT site. We perform an indepth comparison of the simulator results with real observations using the MeerKAT telescope and show that RFIsim produces visibilities that mimic those produced by real observations very well. Finally, we describe how the data was key in the development of a new state-of-the-art deep learning RFI flagging algorithm in Vafaei et al. (2020.) [69] In particular, this work demonstrates that transfer learning from simulation to real data is an effective way to leverage the power of machine learning for RFI flagging in real-world observatories.
13
Lim, Christopher. "Optimizing access radio in multi-radio mesh network /". View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?CSED%202009%20LIM.
Testo completo
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Orth, Erika Elisabeth. "Ein Grundrecht auf Umweltschutz in Europa? : eine rechtsdogmatische Einordnung des Art. 37 GRC /". Frankfurt am Main ; New York : P. Lang, 2007. http://www.wdr.de/radio/wdr2/.
Testo completo
15
Mitola, Joseph. "Cognitive radio". Doctoral thesis, KTH, Teleinformatics, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-2987.
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16
Meyer, Jens-Uwe. "Radio-Strategie". Konstanz : UVK Verlagsgesellschaft, 2007. http://www.gbv.de/dms/ilmenau/toc/528374737.PDF.
Testo completo
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Maier, Benjamin. "Radio poetry". Thesis, Queen's University Belfast, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.675850.
Testo completoAbstract (sommario):
This thesis is a creative and critical exploration of "radio poetry" -poems commissioned and produced for radio transmission, which utilise a verse-script, sound effects, music and other sonic materials as part of their poetic make-up. It argues that radio poetry has been overlooked in both literary criticism and radio studies, because of the ephemerality and ubiquity of its medium, and on account of the absence of a fully developed critical framework for its analysis. The thesis is intended to redress such a lack, and to outline the potential of radio poetry as a mode of sono-poetic expression different from other forms of radio output, including radio drama. The creative component is a thirty-seven minute radio poem entitled Captain Swing. This concerns the 1830 "Swing Riots," an agricultural uprising in southern England. The poem employs a multitude of voices and minutely detailed sound design to create a heightened soundscape of Nineteenth Century England in turmoil. The main critical component provides a definition of the radio poem, before detailing a history of this idiosyncratic literary mode at the BBC, a pioneering organisation in the production of English-language radio poetry. It also develops a heuristic method for the analysis of radio poems, using examples from a wide range of broadcasts by contemporary poets. The final part of the thesis is a self-reflective essay, which examines Captain Swing through the prism of the radio poem tradition.
18
Egargo, Fernando Navidad. "Community radio strategies for participatory community building and development : a descriptive case study of selected community radio stations in the Philippines /". Roma : Pontifical Gregorian university, 2006. http://catalogue.bnf.fr/ark:/12148/cb411662241.
Testo completo
19
Müller, Sven Archibald Hubertus. "Dust in radio quiet quasars, ultra luminous infrared galaxies, radio galaxies and radio loud quasars". [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=962893366.
Testo completo
20
Jerbi, Amir. "Radio implementation of a testbed for cognitive radio source localization using USRPS and GNU radio". Thesis, Monterey, California: Naval Postgraduate School, 2014. http://hdl.handle.net/10945/43932.
Testo completoAbstract (sommario):
Approved for public release; distribution is unlimitedThe shift from wired to fully wireless communication is causing an increasing demand on the frequency spectrum. The cognitive radio was introduced to solve spectrum scarcity by allowing spectrum sharing between licensed and unlicensed users. This approach presents a challenge to source localization because of the cognitive radio’s capability to shift its spatial, frequency and temporal parameters. The extended semi-range-based (ESRB) and cooperative-received-signal-strength-based (CRSSB) localization schemes are proposed to overcome the challenge of identifying and locating a cognitive radio over time using a wireless sensor network. The objective of this thesis was to set up a testbed using GNU Radio and Universal Software Radio Peripherals (USRPs) to estimate the position of a cognitive radio device using the ESRB and CRSSB localization schemes. The ESRB algorithm does not provide accurate position estimates but the estimates are observed to be concentrated in the vicinity and converging toward the true position of the secondary user. The errors are believed to be caused by three factors: a limited number of sensor nodes used (four), an insufficient number of spectral scans per superframe (55), and the lack of synchronization among sensor nodes. The CRSSB localization scheme gave a more accurate position estimation.
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Stoneman, Timothy H. B. "Capturing Believers: American International Radio, Religion, and Reception, 1931-1975". Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/10415.
Testo completoAbstract (sommario):
Capturing Believers provides a history of the reception of American conservative evangelical missionary broadcasting from its inception in 1931 through the rise of the commercial era in 1970. The dissertation narrates accounts of two major Protestant stations, HCJB and ELWA, located in Ecuador and Liberia, respectively, as well as the U.S.-based project to build a custom transistor radio for the mission field. Employing a case-study approach, the thesis demonstrates the innovativeness of religious broadcasters who formulated a range of pragmatic responses to the drastic shortage of receiving sets in the southern hemisphere, including the use of social convention and the development of pretuned receiver technology. Missionary stations imported not only radios, but a constellation of American values into host countries through their reception activities. Overall, officials employed creative methods to construct a particular type of listener experience known as radio capture, characterized by regular listening in a domestic setting. By penetrating into the home or village and exposing listeners to proprietary broadcasts on a continual, even daily, basis, missionary receiver programs legitimized American conservative evangelicalism abroad and sowed seeds for a widespread revival of Protestantism in Latin America and Africa after 1970.
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Taylor, Randy Lyle. "Radio networks and the redefinition of local private radio". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0001/MQ37643.pdf.
Testo completo
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Pratt, Jason Michael. "A software defined radio for research into cognitive radio". Diss., Rolla, Mo. : University of Missouri-Rolla, 2007. http://scholarsmine.mst.edu/thesis/pdf/Pratt2_09007dcc8049b35e.pdf.
Testo completoAbstract (sommario):
Thesis (M.S.)--University of Missouri--Rolla, 2007.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed December 7, 2007) Includes bibliographical references (p. 171-173).
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Coley, Samuel John. "Freelance radio practices : producing music documentaries for commercial radio". Thesis, Birmingham City University, 2018. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.758576.
Testo completoAbstract (sommario):
This study considers the practice of freelance radio producers creating music documentaries for commercial radio audiences. Commercial radio is an underexplored field of study, while investigations into music documentary content for commercial broadcasters are even more uncommon. Previous inquiries into radio documentary production have focused on public service models of broadcasting. These studies often view the subject from a journalistic agenda, overlooking technical approaches and ignoring the commercial imperatives that inform freelance practices. I explore how advances in digital production tools and online technologies shape the work of radio producers. I address wider issues of debate surrounding freelance activities and question whether autonomous producers are capable of creating music documentary content of a calibre consistent with traditional team approaches to documentary production. As an experienced practitioner in the field of commercial radio, I use a practice-based approach to reveal the practices a freelance radio producer adopts to make music documentaries for commercial radio. I argue that this method is essential in order to capture an accurate, first-hand perspective of contemporary industry practice. It draws on a combination of data collection methods including iterative production research, industry interviews, and auto-ethnographic observations as a freelance radio producer across a five-year period of production. This data is interrogated using a theoretical framework that incorporates ideas of political economy, commercial broadcasting and documentary production. I find that the advances in digital production tools and online technologies have streamlined workflow processes and enabled the merging of a various duties into a single production role. I argue that political, economic and commercial considerations impact on the work of radio freelancers in the field by shaping their production output. I acknowledge this is a highly specialised field, as music documentaries are not commonly heard on commercial radio. Yet I assert the industry is favourable towards this form of programming, and recognises its ability to attract new audiences, strengthen listener loyalty and reinforce a station’s brand.
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Abozariba, Raouf. "Generalised radio resource sharing framework for heterogeneous radio networks". Thesis, Staffordshire University, 2017. http://eprints.staffs.ac.uk/4197/.
Testo completoAbstract (sommario):
Recent years have seen a significant interest in quantitative measurements of licensed and unlicensed spectrum use. Several research groups, companies and regulatory bodies have conducted studies of varying times and locations with the aim to capture the over- all utilisation rate of spectrum. The studies have shown that large amount of allocated spectrum are under-utilised, and create the so called "spectrum holes", resulting in a waste of valuable frequency resources. In order to satisfy the requirements of increased demands of spectrum resources and to improve spectrum utilisation, dynamic spectrum sharing (DSS) is proposed in the literature along with cognitive radio networks (CRNs). DSS and CRNs have been studied from many perspectives, for example spectrum sensing to identify the idle channels has been under the microscope to improve detection proba- bility. As well as spectrum sensing, the DSS performance analysis remains an important topic moving towards better spectrum utilisation to meet the exponential growth of traffic demand. In this dissertation we have studied both techniques to achieve different objectives such as enhancing the probability of detection and spectrum utilisation. In order to improve spectrum sensing decisions we have proposed a cooperative spec- trum sensing scheme which takes the propagation conditions into consideration. The proposed location aware scheme shows an improved performance over conventional hard combination scheme, highlighting the requirements of location awareness in cognitive radio networks (CRNs). Due to the exponentially growing wireless applications and services, traffic demand is increasing rapidly. To cope with such growth wireless network operators seek radio resource cooperation strategies for their users with the highest possible grade of service (GoS). However, it is difficult to fathom the potential benefits of such cooperation, thus we propose a set of analytical models for DSS to analyse the blocking probability gain and degradation for operators. The thesis focuses on examining the performance gains that DSS can entail, in different scenarios. A number of dynamic spectrum sharing scenarios are proposed. The proposed models focus on measuring the blocking probability of secondary network operators as a trade-off with a marginal increase of the blocking probability of a primary network in return of monetary rewards. We derived the global balance equation and an explicit expression of the blocking probability for each model. The robustness of the proposed analytical models is evaluated under different scenarios by considering varying tra�c intensities, different network sizes and adding reserved resources (or pooled capacity). The results show that the blocking probabilities can be reduced significantly with the proposed analytical DSS models in comparison to the existing local spectrum access schemes. In addition to the sharing models, we further assume that the secondary operator aims to borrow spectrum bandwidths from primary operators when more spectrum resources available for borrowing than the actual demand considering a merchant mode. Two optimisation models are proposed using stochastic optimisation models in which the secondary operator (i) spends the minimum amount of money to achieve the target GoS assuming an unrestricted budget or (ii) gains the maximum amount of profit to achieve the target GoS assuming restricted budget. Results obtained from each model are then compared with results derived from algorithms in which spectrum borrowings were random. Comparisons showed that the gain in the results obtained from our proposed stochastic optimisation model is significantly higher than heuristic counterparts. A post-optimisation performance analysis of the operators in the form of analysis of blocking probability in various scenarios is investigated to determine the probable per- formance gain and degradation of the secondary and primary operators respectively. We mathematically model the sharing agreement scenario and derive the closed form solution of blocking probabilities for each operator. Results show how the secondary and primary operators perform in terms of blocking probability under various offered loads and sharing capacity. The simulation results demonstrate that at most trading windows, the proposed opti- mal algorithms outperforms their heuristic counterparts. When we consider 80 cells, the proposed profit maximisation algorithm results in 33.3% gain in net pro�t to the secondary operators as well as facilitating 2.35% more resources than the heuristic ap- proach. In addition, the cost minimisation algorithm results in 46.34% gain over the heuristic algorithm when considering the same number of cells (80).
26
Postlethwait, Ben C. "The New Radio: How Public Radio Became Journalistic Podcasting". Ohio University Honors Tutorial College / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ouhonors1462981143.
Testo completo
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Modiba, Benjamin Maboke. "Radio Turf as a community radio station :empowerment possibilities". Thesis, University of Limpopo, 2002. http://hdl.handle.net/10386/2965.
Testo completoAbstract (sommario):
Thesis (M.A.(Media Studies)) --University of the North, 2002This research report looks at Radio Turf as a radio station serving the university community as well af the neighbouring communities. It seeks to establish whether Radio Turf is indeed an empowering tool to the community it serves, looking at language usage, skills development, promotion of local music, gender issues and education. It further seeks to establish whether it is indeed a community radio station in the true sense of the word. The research report lso looks at ways and means of improving community radio stations in general as a way of empowering the communities they serve through participation and involvement. The report could be of assistance to the radio station in as far as knowing its weaknesses and strong points as a way of improving its service to the community it serves
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Mariani, Giulia. "Interpretare per la radio – il caso di Hollywood Party su Radio3". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/19560/.
Testo completoAbstract (sommario):
In questo elaborato sono state analizzate dieci interviste ad alcuni ospiti stranieri francofoni condotte nell’ambito della trasmissione Hollywood Party dell’emittente radiofonica Radio3. Il primo capitolo si apre con una breve descrizione delle caratteristiche inerenti all’attività dell’interprete, e dopo aver descritto le modalità interpretative, affronta alcuni concetti e principi di base dell’interpretazione per i mass media. Vengono descritti i particolari setting dell’interpretazione per i media e le specifiche competenze necessarie per garantire al pubblico un servizio fruibile e soddisfacente. Il secondo capitolo tratta il giornalismo radiofonico, prima ripercorrendo brevemente la storia della radio come strumento di comunicazione di massa, in seguito elencando le caratteristiche del linguaggio radiofonico e del genere dell’intervista, e in modo particolare di quella culturale. Infine, viene spiegato perché l’interpretazione consecutiva si adatti ad una situazione comunicativa radiofonica che richiede la mediazione di un interprete. Dopo aver introdotto la trasmissione radiofonica Hollywood Party, il terzo capitolo descrive le modalità di raccolta, selezione e trascrizione dei dati, nonché la metodologia adottata per analizzarli. Il quarto capitolo si concentra sull’analisi qualitativa delle trascrizioni delle interviste selezionate, effettuata sulla base dell’analisi della conversazione e dell’analisi del discorso. Vengono osservati i turni originali, le rese traduttive, la presenza verbale dei conduttori e la visibilità dell’interprete. Infine, viene discussa la peculiare figura del conduttore-interprete. Un’ultima sezione è dedicata alle conclusioni che riassumono le caratteristiche principali dell’interpretazione in un contesto radiofonico, le differenze tra le rese interpretative dell’interprete professionista e del conduttore-interprete e mettono in rilievo l’esigenza di professionalità e di formazione in un setting così peculiare.
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Scaperoth, David Alan. "Configurable SDR Operation for Cognitive Radio Applications using GNU Radio and the Universal Software Radio Peripheral". Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/32961.
Testo completoAbstract (sommario):
With interoperability issues plaguing emergency responders throughout the country, Cognitive Radio (CR) offers a unique solution to streamline communication between police, Emergency Medical Technicians (EMT), and military officers. Using Software Defined Radio (SDR) technology, a flexible radio platform can be potentially configured using a Cognitive Engine (CE) to transmit and receive many different incompatible radio standards. In this thesis, an interface between a Cognitive Engine and an SDR platform is described which modifies (i.e., configures) the radioâ s operation. The interface is based upon communicating information via eXtensible Markup Language (XML) data files that contain the radioâ s Physical (PHY) parameters. The XML data files have been designed such that more development can be made to its structure as this research develops. The GNU Radio and the Universal Software Radio Peripheral (USRP) serve as the SDR platform for an example implementation. The example implementation involves importing XML data files into the SDR for quick configuration. Three configuration examples are used to describe this process.Master of Science
30
Hall, Margaret A. "Radio after radio : redefining radio art in the light of new media technology through expanded practice". Thesis, University of the Arts London, 2015. http://ualresearchonline.arts.ac.uk/8748/.
Testo completoAbstract (sommario):
I have been working in the field of radio art, and through creative practice have been considering how the convergence of new media technologies has redefined radio art, addressing the ways in which this has extended the boundaries of the art form. This practice-based research explores the rich history of radio as an artistic medium and the relationship between the artist and technology, emphasising the role of the artist as a mediator between broadcast institutions and a listening public. It considers how radio art might be defined in relation to sound art, music and media art, mapping its shifting parameters in the digital era and prompting a consideration of how radio appears to be moving from a dispersed „live‟ event to one consumed „on demand‟ by a segmented audience across multiple platforms. Exploring the implications of this transition through my radio practice focuses upon the productive tensions which characterise the artist‟s engagement with radio technology, specifically between the autonomous potentialities offered by the reappropriation of obsolete technology and the proliferation of new infrastructures and networks promised by the exponential development of new media. Switch Off takes as its overarching theme the possible futures for FM radio, incorporating elements from eight „trace‟ stations, produced as a series of radio actions investigating these tensions. Interviews have been conducted with case study subjects Vicki Bennett, Anna Friz, LIGNA, Hildegard Westerkamp and Gregory Whitehead, whose work was chosen as being exemplary of the five recurrent facets of radio arts practice I have identified: Appropriation, Transmission, Activism, Soundscape and Performance. These categories are derived from the genealogy of experimental radiophonic practice set out in Chapter One.
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Nono, Njepang Luidor. "Les radios communautaires au Cameroun". Thesis, Paris 2, 2012. http://www.theses.fr/2012PA020051.
Testo completoAbstract (sommario):
L’ouverture du secteur audiovisuel camerounais a consacré l’avancée du processus d’acquisition et de l’octroi des libertés individuelles commencé autour des années 1990. Le décret d’application d’avril 2003 a entériné une dizaine d’années plus tard, le dispositif enclenché par la loi n°90-052 du 19 décembre 1990 relative à la liberté de communication sociale. Depuis lors, organes de presse et audiovisuels se côtoient et se heurtent à des pesanteurs susceptibles de limiter leur efficacité, en tant qu’outils et moyens de communication de proximité. Leur jeunesse, les problèmes endogènes et exogènes au paysage médiatique camerounais justifierait une étude sur l’existence et la manière dont les organes de communication sociale produisent et diffusent informations et nouvelles en direction des populations ciblées. A ce sujet, la radio communautaire, tout en cherchant à les impliquer et à les faire participer à cet objectif de communication sociale, promeut par ses programmes, la propre image des populations à laquelle elle est destinée. Il ne reste qu’à garantir les modalités pratiques, les conditions nécessaires pour une participation transparente des différents acteurs à la gestion et au fonctionnement de la radio. Pour une grande part, les populations sont prêtes à soutenir les projets de radios communautaires qui s’installent dans les localités. Les différentes techniques d’appropriation et d’usage des médias permettent d’appréhender de l’extérieur les différents enjeux qui se tissent. Elles permettent d’observer les pratiques mises en place et les conditions d’engagement des acteurs sociaux pour garantir, une longue vie à la radioThe opening of the Cameroonian audiovisual sector dedicated the overhang of the process of acquisition and the granting of the personal freedoms begun around 1990s. The application decree of April, 2003 confirmed a decade later, the plan engaged by the law 90/052 of December 19th, 1990 relative to the freedom of social communication. Since then, newspapers and broadcasting mix and come up against gravities susceptible to limit their efficiency, as tools and means of communication of nearness. Their youth, the endogenous and exogenous problems in the Cameroonian media landscape justify a study on the existence and the way the organs of social communication produce and broadcast information and news in the direction of the targeted populations. For this subject, the community radio, while trying to imply them and to make them participate in this objective of social communication, promotes by its programs, the own image of the populations for which is intended. It remains only to guarantee the practical methods, the necessary conditions for a transparent participation of the various actors in the management and in the functioning of the radio. Mostly, the populations are ready of supporting the projects of community radios which settle down in villages. The various techniques of appropriation and uses of the media allow dreading from the outside the various stakes which weave. They allow observing the organized practices and the conditions of commitment of the civil society to guarantee, a long life on the radio
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Suliman, I. M. (Isameldin Mohammed). "Performance analysis of cognitive radio networks and radio resource allocation". Doctoral thesis, Oulun yliopisto, 2016. http://urn.fi/urn:isbn:9789526212753.
Testo completoAbstract (sommario):
Abstract Cognitive radio (CR) is becoming a promising tool for solving the problem of the scarce radio resource and spectrum inefficiency. Spectrum sensing (signal detection) enables real-time detection of spectrum holes by unlicensed secondary users (SUs) in cognitive radio networks (CRNs). In this thesis, performance analysis of CRNs and radio resource allocation are considered. A continuous time Markov chain (CTMC) based analytical model taking into account all relevant elements as well as addressing the issue of the false alarm rate (FAR) associated with the continuous sensing is developed. In some cases, the PU can be modeled as time-slotted with constant state (transmitting or not) in each slot. In this case, assuming SU can synchronize to the slots, its intuitive to use beginning of a slot for sensing and rest (possibly) for communication. For this model, M/D/1 priority queueing scheme has been applied in this thesis to find waiting time and queue length for PU and SU. Multiple access among SUs in a time-slotted channel is considered next. A conventional method is e.g. using a channel access probability ψ in each slot similar to the slotted ALOHA. A radically new idea is introduced in this thesis: why not increase the false alarm probability PFA of each SU and use it as a multiple access method? A game theoretic approach to radio resource allocation for the downlink capacity providing fair resource sharing among mobile nodes located along a multihop link is presented. Furthermore, the problem of resource allocations in heterogeneous wireless networks is also studied. Finally, device-to-device (D2D) communication - with localized distribution, where users tend to gather around some areas (clusters/hot-spots) within the cell such as buildings is studied. Theoretical analysis with two dimensional clustering is presented including cases with correlated clusters. Correlation in cluster selection is shown to significantly improve performanceTiivistelmä Kognitiivinen radio (CR) on nousemassa lupaavaksi työkaluksi niukkojen radioresurssien ja spektrin käytön tehottomuuden ratkaisemisessa. Spektrin nuuskiminen (signaalin ilmaisu) mahdollistaa spektriaukkojen reaaliaikaisen tunnistamisen toissijaisten käyttäjien (SU) toimesta kognitiivisissa radioverkoissa (CRN). Tässä väitöskirjassa painotus on CRN verkkojen suorituskykyanalyysissa ja radioresurssien hallinnassa. Työssä kehitetään jatkuva-aikaiseen Markov ketjuun (CTMC) perustuva analyyttinen malli joka ottaa huomioon kaikki olennaiset asiat mukaan lukien jatkuva-aikaiseen spektrin nuuskimiseen liittyvän väärien hälytysten tiheyden (FAR). Joissakin tapauksissa PU:ta voidaan mallintaa aikajaoteltuna siten että PU:n tila on vakio kussakin aikavälissä. Olettaen että SU voi synkronoitua aikaväleihin, on intuitiivista käyttää aikavälin alkua nuuskimiselle ja loppuosaa (mahdollisesti) viestintää varten. M/D/1:n ensisijaisuus-jonotus-suunnitelmaa soveltamalla tässä väitöskirjassa saadaan tuloksia odotusajalle ja jonon pituudelle sekä SU:lle että PU:lle. Seuraavaksi käsitellään monikäyttöä SU:den joukossa aikajaotellussa kanavassa. Tavanomainen menetelmä käyttää esimerkiksi kanavapääsytodennäköisyyttä ψ kussakin aikavälissä vastaten aikajaoteltua ALOHA protokollaa. Tässä väitöskirjassa esitetään radikaali uusi idea: miksei lisätä väärän hälytyksen todennäköisyyttä kussakin SU:ssa ja käytetä sitä moniliittymämenetelmänä? Työssä esitetään peliteoreettinen lähestymistapa radioresurssien allokointiin siten että resurssit jaetaan oikeudenmukaisesti monen yhteysvälin linkeissä. Lisäksi tutkitaan myös resursoinnin ongelmaa heterogeenisissa langattomissa verkoissa. Lopuksi tutkitaan laitteiden välistä suoraa viestintää (D2D) paikallisen jakauman kanssa, jossa käyttäjillä on tapana kasaantua solun sisällä esim. rakennuksiin. Esitetään teoreettinen analyysi kaksiulotteisella klusteroinnilla myös korreloitujen ryhmien kanssa. Osoitetaan että korrelaatio ryhmän valinnassa parantavaa merkittävästi suorituskykyä
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Vernstrom, Tessa. "Contribution to the diffuse radio background from extragalactic radio sources". Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/37898.
Testo completoAbstract (sommario):
We examine the brightness of the Cosmic Radio Background (CRB) by comparing the contribution from individual source counts to absolute measurements. We use a compilation of radio counts to estimate the contribution of detected sources to the CRB in several different frequency bands. Using a Monte Carlo Markov Chain technique, we estimate the brightness values and uncertainties, paying attention to various sources of systematic error. At n = 150MHz, 325MHz, 408MHz, 610MHz, 1:4GHz, 4:8GHz, and 8:4GHz our calculated contributions to the background
sky temperature are 18, 2.8, 1.6, 0.71, 0.11, 0.0032, 0.0059 K, respectively.
We then compare our results to absolute measurements from the ARCADE 2 experiment. If the ARCADE 2 measurements are correct and come from sources, then there must be an additional population of radio galaxies, fainter than where current data are probing. More specifically, the Euclidean-normalized counts at 1.4 GHz have to have an additional bump below about 10 μJy. We present preliminary results of investigating this new population by use of signal stacking. By stacking onto a very deep 1:4GHz radio map at source positions determined in the infrared and optical we hope to be able to see evidence of this population that would be too faint to be seen individually. Results are currently inconclusive. Future work will consist of modelling radio luminosity functions and new observations with the Extended VLA to continue to search for what may be causing this excess emission.
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Bracht, Roger, Jeff Dimsdle, Dave Rich e Frank Smith. "RADIO FREQUENCY OVERVIEW OF THE HIGH EXPLOSIVE RADIO TELEMETRY PROJECT". International Foundation for Telemetering, 1998. http://hdl.handle.net/10150/607352.
Testo completoAbstract (sommario):
International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, CaliforniaHigh explosive radio telemetry (HERT) is a project that is being developed jointly by Los Alamos National Laboratory and AlliedSignal FM&T. The ultimate goal is to develop a small, modular telemetry system capable of high-speed detection of explosive events, with an accuracy on the order of 10 nanoseconds. The reliable telemetry of this data, from a high-speed missile trajectory, is a very challenging opportunity. All captured data must be transmitted in less than 20 microseconds of time duration. This requires a high bits/Hertz microwave telemetry modulation code to insure transmission of the data within the limited time interval available.
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Nahra, Cintia Maria Leite. "Radio institucional e radio livre : rupturas no modelo comunicacional dominante". reponame:Repositório Institucional da UFSC, 1988. https://repositorio.ufsc.br/handle/123456789/111941.
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Hope-Hume, Bob. "Radio, community and the public : Community radio in Western Australia". Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 1997. https://ro.ecu.edu.au/theses/889.
Testo completoAbstract (sommario):
This thesis examines community radio in Western Australia and its relationship to "the public sphere". The public sphere is that field in which private. persons interact with other private. persons and in so doing construct a 11public". Public opinion is formed through this interaction in the public sphere. The media provide a major part of that interaction. Moreover, the media determine which voices are privileged within the communicative sphere. Drawing from Jurgen Habennas I explore theories of the public sphere arguing that community radio constructs a new form of public sphere in contemporary culture. I explore notions of democratic radio following the theories of Harold Innis to explore how elites have attempted to control communication. I argue that community radio provides a participatory medium which democratises the medium and allows for a more comprehensive formation of public opinion through the creation of informed rational discussion in the public sphere. This thesis provides an overview of broadcasting and the public in Western Australia with background on the history and development of community radio. It examines the notion of the public as a site of struggle and examines how community radio seeks to challenge the status quo in Western Australian culture. as well as seeking to facilitate- ideas on the role of radio as a democratic medium.
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Liu, Hexin. "Radio sur fibre : réseaux, couvertures radio, architectures et dimensionnements matériels". Télécom Bretagne, 2013. http://www.telecom-bretagne.eu/publications/publication.php?idpublication=13211.
Testo completoAbstract (sommario):
L'objectif de la thèse est d'étudier un système d'antennes distribuées radio sur fibre pour le WLAN IEEE802. 11g OFDM à 2. 45 GHz. A partir de modèles et de caractéristiques de la chaîne optique, nous avons déduit les limitations d'un tel système pour en déduire des solutions techniques. Le niveau du facteur de bruit de la liaison est élevé, tout comme son point de compression est assez faible, et cela entraîne une dynamique assez faible. Compte tenu que nous maîtrisons les niveaux des signaux, le lien descendant se comporte correctement. Pour le lien montant, et avec des circuits optoélectroniques disponibles, la dynamique du récepteur est fortement affectée. Compte tenu de la dynamique des signaux reçus, la norme radio ne peut être respectée sans un contrôle automatique de gain. Par simulation et mesure, nous avons analysé les performances du point d'accès ainsi amélioré, en étudiant la dynamique et l'EVM. Nous avons ensuite regardé l'effet de plusieurs antennes sur le système. De nouveau c'est le lien montant qui est pénalisant. Pour plusieurs architectures, nous avons étudié les performances et dimensionné le système total en fonction du nombre d'antennes à distribuer par fibres optiques. La sélection d'une antenne parmi toute semble nécessaireIn this thesis, we have studied a Radio-over-Fibre Distributed Antenna System for WLAN IEEE802. 11g OFDM at 2. 45 GHz. By analyzing the model and the characteristics of the optical link, we have studied the limitations of such system, and then proposed the technical solution. Because of the high noise figure and the low compression point of the optical link, the dynamic range of a Point to Point Radio-over-Fibre system could be very small, which does limit the performance of receiver (Access Point). Considering the received sensitivities defined by IEEE802. 11g OFDM, the uplink could only respect the specification with the automatic gain control (AGC) loops. With simulation and measurement, we have proved that, using the automatic gain control units, the uplink performance of the access point can be improved. Then, we have analyzed the performance of the system including several distributed antennas. The uplink performance is still limited. For several architectures, we have studied the link budget and system dimensioning with different number of antennas. The diversity reception seemed necessary
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Selma, Martín Fernando. "Radio Environment Improvement". Thesis, Linköping University, Department of Electrical Engineering, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-4746.
Testo completoAbstract (sommario):
Mobile communications are a changing and really competitive market. Companies try to release new products and upgrade the old ones as soon as possible. And in this context it is where Ericsson Test Environment makes available to its customer one of the most comprehensive GSM test environments in the world.
The test site at customer disposal provides a good environment for testing purpose and it allows them to improve and develop their products in really interesting time terms.
To make this possible, a huge GSM network is enclosed inside its facilities and this entails some problem, mainly in the radio environment.
The main aim of this thesis work is to study the radio network from an EMC point of view, how all this equipment interacts to each other and to propose possible improvements in order to make a test environment more competitive. Moreover, it will be valued electric magnetic field in the plant with the intention to find out if is possible to warrantee an operation free of disruption in the equipment.
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Manicka, Naveen. "GNU Radio testbed". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 104 p, 2007. http://proquest.umi.com/pqdweb?did=1338919411&sid=4&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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40
Cordey, R. A. "Nearby radio galaxies". Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356676.
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Shepherd, Mark. "Radio channel assignment". Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288047.
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Fraser, Simon G. "Fibre radio transceivers". Thesis, University of Leeds, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406200.
Testo completo
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Wassell, Ian J. "Digital mobile radio". Thesis, University of Southampton, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277683.
Testo completo
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Maciel, Tamela. "Radio source evolution". Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708637.
Testo completo
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Alhasan, Raghda. "Software defined radio". Thesis, Linnéuniversitetet, Institutionen för fysik och elektroteknik (IFE), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-53361.
Testo completoAbstract (sommario):
Software Defined Radio (SDR) technology is used to receive and transmit radio signals. Radio signals can be received using the SDR_sharp software that can be downloaded to a personal computer and combined with the RTL-SDR dongle hardware that is connected to the computer. This report gives a brief explanation of the SDR receiver, the supported software, and some applications that can be implemented with SDR. Moreover, it is shown how to install the SDR_sharp software and the hardware Zadig. After installation, wideband FM (WFM) reception and adjustment of RF gain and frequency error is illustrated. The reception of some national, regional and community/commercial stations that can be received in Växjö Sweden is presented. Keyword: Software defined radio, FM radio.
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Borén, P. (Pietu). "Radio-ohjattava nelikopteri". Bachelor's thesis, University of Oulu, 2016. http://urn.fi/URN:NBN:fi:oulu-201602101154.
Testo completoAbstract (sommario):
Tässä kandidaatintyössä tutkitaan ja esitetään radio-ohjattavan nelikopterin lentoteoriaa sekä teknistä toimintaa. Lisäksi työssä esitetään yhden radio-ohjattavan nelikopterin rakentaminen ja siihen liittyvien komponenttien ja materiaalien valinnat perusteluineen. Tutkimustietoa kerättiin kirjallisuuslähteistä sekä tehtiin empiiristä tutkimusta radio-ohjattavan nelikopterin rakentamisen yhteydessä. Työssä todetaan valitut komponentti ja materiaaliratkaisut toimiviksi ja radio-ohjattava nelikopteri lentokelpoiseksiThe purpose of this bachelor’s work is to study and present a flight theory and technical activity of radio controlled quadcopter. This work also presents a building process of one radio controlled quadcopter, including justifications for the selected components and materials. Research information was collected from literature sources and empirical research was made during the building process of radio controlled quadcopter. In this bachelor’s work, component and material choices were found to be functional and radio controlled quadcopter was deemed airworthy
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Preston, Jon. "Voice in radio". Thesis, Goldsmiths College (University of London), 2017. http://research.gold.ac.uk/20190/.
Testo completoAbstract (sommario):
“Voice in Radio” is a practice-based thesis. It reflects on a series of participatory media projects involving community groups and secondary school students working together to produce radio shows. The thesis offers an analysis of those projects through the academic prism of ‘voice’, a term defined in both the personal and socio-political senses. Further, it reflects on the possibilities for voice offered by Participatory Community Radio (PCR) practice. Having devised and led this practice, I occupy the position of a ‘reflexive practitioner’ in the study. The thesis is presented as a linear narrative: through PCR, a participant hears their own physical voice as others do, externally; they first become accustomed to and then comfortable with the sound of their own voice; they gain agency, becoming able to vocalise their stories through the radio project work; they gain further agency through socio-political Voice as their work is aired in a series of radio shows. The participant groups are from a selection of cohorts encompassing a ‘Senior Citizens West Indian Luncheon and Social club’, a boys’ secondary school, a hospice, an Arts school and a Pupil Referral Unit (PRU). The data presented were collected through a mixed methods strategy. Project work and participant reflections are offered, together with comments from associated professionals. This material features in both written and aural form. The ideas of authors including Berry, Chomsky, Couldry, Coyer, Dowmunt, Mayo and Rodenburg are drawn upon to establish the project work within a framework for discussion. Conclusions are offered on the possibilities of PCR in a neo-liberal economic and cultural climate specifically in relation to empowerment, voice and exchange. An hour-long audio CD accompanies the written thesis as an illustration of the PCR practice under review. Combined, these two elements offer an investigation into “Voice in Radio”.
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Silva, Mário Marques da. "Emergent Radio Systems". Doctoral thesis, Instituto Superior Técnico, 2005. http://hdl.handle.net/11144/350.
Testo completoAbstract (sommario):
Emergent services are demanding higher data rates, especially in the downlink. Wideband Code Division Multiple Access (WCDMA) is the key to reach this development in cellular communications. To obtain this, it is important to find schemes able to reduce Inter-Path Interference (IPI) and Multiple Access Interference (MAI), and to explore new types of diversity. These are the objectives of the present thesis.
Interference cancellation subject considers post-processing and pre-processing schemes. A new linear Multi-User Detector (MUD) is proposed and analyzed. As pre-processing schemes, the new Pre-distortion and the Precoder schemes are studied and analyzed.
New types of diversity are also presented and analyzed. A new post-processing detector for the Vertical Bell Laboratories Layered Space-Time (V-BLAST) Multiple Input Multiple Output (MIMO) scheme, optimized for WCDMA signals subject to frequency selective fading, is proposed and analyzed. Moreover, a new frequency domain pre-processing scheme for frequency-selective fading MIMO channels is also proposed and analyzed.
The new Beam-Selective Transmit Diversity (BSTD) can be seen as a composite scheme where the MAI reduction is performed jointly with the exploration of transmit diversity, without additional Mobile Station (MS) complexity.
It is shown that, in most conditions, the pre-processing scheme for MIMO channels tends to achieve the best performance in most scenarios, being followed by the BSTD which allows interference cancellation and provides diversity. Both schemes tend to lead to good performances and capacities, facing the requirements of the emergent cellular communication systems. Depending on the complexity and size constraints imposed to the MS, the present thesis suggests the scheme that should be selected to allow such improvements
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Hussain, Sajjad. "PEAK TO AVERAGE POWER RATIO ANALYSIS AND REDUCTION OF COGNITIVE RADIO SIGNALS". Phd thesis, Université Rennes 1, 2009. http://tel.archives-ouvertes.fr/tel-00426930.
Testo completoAbstract (sommario):
* La multiplication des standards de télécommunications fait apparaître la nécessité de disposer de terminaux multistandard et reconfigurables. Ces nouvelles fonctionnalités trouvent leurs réponses dans le domaine de la radio logicielle. De tels terminaux ne sont pas encore réalisables pour des raisons technologiques liées à la complexité nécessaire à leur réalisation (convertisseurs ultra rapides, processeurs reconfigurables, antennes et amplificateurs très large bande, ....). En se basant alors sur une véritable technologie radio logicielle, la radio intelligente va encore plus loin dans la prospective en dotant le terminal de capteurs qui lui permettront de s'adapter et de réagir vis à vis de son environnement. La radio devient alors décentralisée et flexible se détachant de la notion de standards et transmettant de façon opportuniste une communication dans une bande qui aura été détectée comme libre. Cette présentation s'inscrit dans le contexte présenté ci-dessus en se focalisant sur les conséquences de l'amplification de puissance d'un signal multistandard. En effet, l'amplication de puissance est un étage fondamental de tout système radio et certaines précautions doivent être prises avant d'amplifier un signal. En effet, les amplificateurs ont des caractéristiques non linéaires et de faibles rendements nécessitant un traitement du signal à amplifier afin de limiter d'une part les distorsions non linéaires et d'autre part la consommation des terminaux. Les signaux caractérisant les systèmes multistandard ayant des caractéristiques proches de celle d'un signal OFDM (connu pour les problèmes liés à l'amplification de puissance), ce travail apporte des réponses sur : * les niveaux de puissance d'un signal multistandard * les méthodes à développer pour en minimiser les fluctuations de puissance * les conséquences de l'accès opportuniste au spectre sur les fluctuations de puissance dans un contexte de radio intelligente
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Kunselman, Gary L. "Radio frequency power amplifiers for portable communication systems". Thesis, Virginia Tech, 1992. http://hdl.handle.net/10919/41493.
Testo completoAbstract (sommario):
Portable communication systems require, in part, high-efficiency radio frequency power amplifiers (RF PA) if battery lifetime is to be conserved. Conventional amplifier classifications and definitions are presented in a unified and concise format. The Bipolar Junction Transistor (BJT) and Metal-Semiconductor Field Effect Transistor (MESFET) are evaluated as active devices in high-efficiency RF PA designs. Two amplifier classes (class CE and class F) meet the system requirements of an 850 MHz operating frequency, a power output of 3 W, a battery supply voltage of 9 Vdc, and a sinusoidal-type signal to be amplified. Both classes are evaluated through recent research literature and simulated using the PSpice® computer simulation program. Class CE and class F are found to provide efficiencies exceeding 80 percent under the given system constraints.Master of Science