Dissertations / Theses on the topic 'Broadband'
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Burghoff, David Patrick. "Broadband terahertz photonics." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92964.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2014.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 181-190).
In recent years, quantum cascade lasers have emerged as mature semiconductor sources of light in the terahertz range, the frequency range spanning 1 to 10 THz. Though technological development has pushed their operating temperatures up to 200 Kelvin and their power levels up to Watt-level, they have remained unsuitable for many applications as a result of their narrow spectral coverage. In particular, spectroscopic and tomographic applications require sources that are both powerful and broadband. Having said that, there is no fundamental reason why quantum cascade lasers should be restricted to narrowband outputs. In fact, they possess gain spectra that are intrinsically broad, and beyond that can even be tailored to cover an octave-spanning range. This thesis explores the development of broadband sources of terahertz radiation based on quantum cascade lasers (QCLs). The chief way this is done is through the development of compact frequency combs based on THz QCLs, which are able to continuously generate milliwatt levels of terahertz power covering a fractional bandwidth of 14% of their center frequency. These devices operate on principles similar to microresonator-based frequency combs, and make use of the quantum cascade laser's fundamentally large nonlinearity to phase-lock the cavity modes. These devices will enable the development of ultra-compact dual comb spectrometers based on QCLs, and will potentially even act as complete terahertz spectrometers on a chip. This thesis also uses broadband terahertz time-domain spectroscopy to analyze the behavior of THz QCLs. By using QCLs as photoconductive switches, the usual limitations imposed by optical coupling are circumvented, and properties of the laser previously inaccessible can be directly observed. These properties include the gain and absorption of the laser gain medium, the populations of the laser's subbands, and properties of the waveguide like its loss and dispersion. Knowledge of these properties were used to guide frequency comb design, and were also used to inform simulations for designing better lasers.
by David Patrick Burghoff.
Ph. D.
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Enabulele, Elizabeth Abimbola. "Bursting the broadband bubble." Thesis, Brunel University, 2008. http://bura.brunel.ac.uk/handle/2438/5368.
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Broadband has revolutionised the way the Internet is used and has become the critical enabling infrastructure of our modem and knowledge-based economy. Its widespread introduction has not only greatly enhanced the speed at which information online can be accessed, but also the range and sophistication of the content available. It is still penetrating the telecommunication market and is seen by some as the most significant evolutionary step since the emergence of the Internet. However in the rush to achieve market share, there is a risk that insufficient attention may be paid to quality issues, the central theme of this research. The research addresses the issues of broadband quality with a stated objective of assessing broadband quality by means of an integrated framework that encompasses factors beyond strict technical characteristics of broadband networks. Indeed, the concept of quality is a multi-facetted one, for which various perspectives can be distinguished. In this work, broadband quality as perceived by users, ISP and Government in the United Kingdom (UK) is looked at and a survey report is given and analysed. The aim of this doctoral research was to provide much needed empirical broadband quality framework that would guide the service provider as well as the UK government in the provision of quality broadband to its consumers. It will also stand as a benchmark to countries wanting to provide quality broadband to its citizens. A survey research approach was employed to achieve the overall aim and objective of this research. This was conducted using the response of 133 participants located in various boroughs in the UK. The results of the survey show that quality, though desired by many, has been short-changed by the desire to have access to the Internet via broadband at the lowest cost possible. However, this has not encouraged some consumers to switch to broadband from dial-up service despite continuous low prices being offered by service providers. Furthermore, the results also indicated that focusing on broadband quality will improve and promote investment in broadband capacity and decrease the uncertainty in consumer demand for applications such as multi-media content delivery, enhanced electronic commerce and telecommuting that exploit broadband access.
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Cabrera, George. "Broadband RF current detector." FIU Digital Commons, 1994. http://digitalcommons.fiu.edu/etd/1955.
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The problems to be solved in this thesis were 1) development of a broadband RF preamplifier to be used with non-ferrous current probes so that the amplified signal exceeds the errors due to cable pickup, no detection is needed in this application, and 2) development of a self-contained device that amplifies and detects the output from a nonferrous current probe, providing a digital readout of the current. These instruments have been completed and are being tested for use by the National Institutes of Occupational Safety and Health (NIOSH). The self-contained current meter operates at frequencies up to 600 MHz, and detects currents as low as 8 mA . At these current magnitudes, the probe (pick-up coil) will output a voltage of 500μV (-53 dBm on 50Ω) which will have to be raised above 0 dBm. The final circuit uses a RF mixer as a variable attenuator in order to increase the dynamic range, two Monolithic Microwave Integrated Circuits (MMIC) for preamplification, a final broadband amplifier to raise the output compression point, a Schottky diode detector, a sample and hold circuit, and a liquid crystal digital panel meter.
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Sparandara, Jennie. "Broadband and work habits." CONNECT TO ELECTRONIC THESIS, 2007. http://dspace.wrlc.org/handle/1961/4178.
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JIANG, YANYAN. "BROADBAND INVESTMENT AND REGULATION." Doctoral thesis, Università Cattolica del Sacro Cuore, 2010. http://hdl.handle.net/10280/693.
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La tesi è strutturata in 3 capitoli e analizza gli investimenti e la regolamentazione nel broadband market".
Il primo capitolo analizza la letteratura teorica ed empirica sul rapporto tra gli investimenti e la regolamentazione nel settore delle telecomunicazioni. Il secondo capitolo fornisce un'analisi teorica sullo "stepping-stone theory". La terza parte fornisce un'analisi sull'impatto dei diversi regimi normativi per la costruzione della Next Generation Networks.This dissertation is composed of three papers and discusses the issue of investment and regulation in broadband market. The first paper reviews the specialized but growing branch of the literature. It surveys the relevant theoretical and empirical literature on the relationship between regulation, at both retail and wholesale level, and investment in telecoms infrastructures. Theoretical analyses state that with respect to retail (incentive) regulation, the firm‘s incentive to invest is related to the level of price cap. As for access regulation, mandatory unbundling can possibly discourage firms‘ incentive to invest, but this is not the case for all circumstances because some studies have displayed an opposite (positive) effect on investment. The influence of regulators‘ limited ability to make credible commitment ex ante is not negligible either. Evidence in empirical findings exhibits a certain disunity. The majority concludes that local loop unbundling based on forward-looking cost methodology discourages both ILECs and CLECs from investing in networks, so that the stepping-stone theory is possibly not supported by the data; other findings support the non-negative effect of access regulation on investment. The second paper provides theoretical analysis on the stepping-stone theory. We dynamically model the competition between a vertically-integrated incumbent firm and a facilities-free new entrant in broadband market, where both firms are entitled with investment options: not only can the incumbent decide how much to spend in upgrading its existing network, but also the entrant can choose whether and when to invest on the construction of its own network. The analysis is conducted under three different kinds of competition: pure services-based, pure facilities-based and mixed competition. We find that the entrant's ability to provide value-added services affects the incumbent's investment choice. Our simulation results support the stepping-stone theory that access regulation provides an impetus for the entrant to invest in their own facilities after entering the market based on leased lines. It is also socially desirable because both the overall welfare and the consumer surplus are maximized in a regulated market under mixed competition. The third paper studies impacts of different regulatory regimes on the construction of Next Generation Networks (NGNs). We model the competition between a vertically-integrated incumbent firm and a facilities-free entrant firm in broadband market, where the incumbent has an investment option to upgrade its current network to the NGN. In order to analyze how policy settings affect the incumbent firm‘s investment choice, three kinds of regulatory regimes are discussed: no regulation, partial regulation (only the traditional network is regulated and the NGN is unregulated) and full regulation (both the traditional network and the NGN are regulated). We find that not only the entrant‘s ability to provide value-added services, but also the substitution factor that indexes the decrease in consumers‘ willingness to pay for the traditional service once the investment occurs, affect the incumbent‘s investment choice. Moreover, the comparison of results under different regimes shows that the incumbent invests the most under partial regulation, which sheds some light on impelling the deployment of Next Generation Networks.
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Johnson, André Mark Allan. "Broadband feed antenna design." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/43532.
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This thesis describes the development of a log-periodic waveguide feed antenna from concept to design and finally to prototyping and testing. An electromagnetic simulator (CST) was used to evaluate different design concepts and a design based on a nested coaxial waveguide structure was selected. A design was developed that included a common excitation structure for all the waveguides and an aperture matching structure that scales periodically with frequency. In the design, each waveguide has a bandwidth ratio of 2:1 and the total bandwidth of the design is 1 GHz to 8 GHz. A physical model was created using the SolidWorks design software and a prototype was manufactured and tested. Simulation results were in good agreement with the experimental results over the majority of the antenna's bandwidth. The antenna design had good farfield patterns across most of the antenna's bandwidth with frequency-specific farfield issues. The return loss of the antenna varied greatly with frequency, being greater than 2 dB across the entire bandwidth of the antenna and greater than 6 dB for the majority of the bandwidth of the antenna. There were significant difficulties in achieving a good return loss at the aperture which limited the return loss of the antenna. This work demonstrates the potential of employing a nested coaxial waveguide structure for wideband feed applications.
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Reim, Klaus Franz. "Broadband optical quantum memory." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:d0d73ed2-32c2-4de9-8b3d-fcf8b88b22b4.
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This thesis is about the experimental implementation of a high-speed and robust quantum memory for light. A novel far off-resonant Raman approach to ensemble-based quantum memories in a room-temperature environment is developed and demonstrated. Storage and retrieval of sub-nanosecond, weak coherent light pulses at the single-photon-level with total efficiencies exceeding 30% and storage times of up to 4 μs are achieved. The coherence of the memory is shown by directly interfering a copy of the incident signal with the retrieved signal from the memory. The unconditional noise floor of the memory is found to be low enough to operate the memory in the quantum regime at room temperature. Multiple readout of a single stored excitation is demonstrated, suggesting that 100% readout is possible in different temporal modes. Furthermore, first results regarding the storage and retrieval of polarisation encoded qubits are obtained. This and the memory’s ability to operate in the quantum regime at room temperature with a low unconditional noise floor illustrate its potential usefulness for real world applications.
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Stock, Michael. "Broadband interferometry of lightning." Thesis, New Mexico Institute of Mining and Technology, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3684400.
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A lightning interferometer is an instrument which determines the direction to a lightning-produced radio point source by correlating the signal received at two or more antennas. Such instruments have been used with great success for several decades in the study of the physical processes present in a lightning flash. However, previous instruments have either been sensitive to only a narrow radio bandwidth so that the correlation can be done using analog hardware, or have been sensitive to a wide bandwidth but only recorded a short duration of the radiation produced by a lightning flash.
In this dissertation, a broad bandwidth interferometer is developed which is capable of recording the VHF radio emission over the entire duration of a lightning flash. In order to best utilize the additional data, the standard processing techniques have been redeveloped from scratch using a digital cross correlation algorithm. This algorithm can and does locate sources as faint as the noise level of the antennas, typically producing 100,000 or more point source locations over the course of a lightning flash.
At very low received power levels, the likelihood that a signal received at the antenna will be affected by the environmental noise is substantially higher. For this reason, the processing allows for the integration windows of the cross correlation to be heavily overlapped. In this way, the location of each event can be based on a distribution of windows. Further, noise identification techniques which leverage the heavily overlapped windows have been developed based on: the closure delay, the standard deviation, the correlation amplitude, and the number of contributing windows. The filtration techniques have proven to be very successful at identifying and removing mis-located sources, while removing the minimum number of low amplitude sources which are well located.
In the past, lightning interferometers have been limited to using only two perpendicular baselines to determine the direction to each point source. Additional techniques are developed in this dissertation for efficiently computing the image of a point source in the sky using an arbitrary number of antennas in an arbitrary configuration. The multiple baseline techniques further improves the sensitivity and accuracy of the locations provided by broadband interferometers.
To demonstrate the usefulness of broadband interferometers, the activity of 6 flashes spanning a diverse selection of lightning flash types are examined in this dissertation. This includes detailed analysis of negative stepped leaders, positive un-stepped leaders, K-changes, and fast positive breakdown. Initial breakdown pulses which are seen at the beginning of the flash are found to be no different than horizontal negative leader steps seen later in the flash. Evidence is found that positive leaders produce VHF radiation, as opposed to all of the radiation in the positive breakdown region being produced by retrograde negative breakdown. The time resolved three-dimensional velocity of 47 K-changes occurring in two flashes is measured. And finally, fast positive breakdown is characterized and found to be produced by a positive streamer process instead of a leader process.
Observations made with the instrument showcase the capabilities of a continuous sampling broadband interferometer. The instrument makes possible measurements which were difficult or impossible to obtain in the past, and the preliminary observations allude to many exciting scientific findings to come.
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Oni, Oluwasola. "Broadband adoption by SMES." Thesis, Brunel University, 2007. http://bura.brunel.ac.uk/handle/2438/5330.
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Because the benefits of broadband for businesses have been widely publicized, the UK government has tried to ensure that there is a wide and fast take-up of the technology. Initial figures showed that broadband adoption by SMEs was particularly slow and there has been little research on the use of broadband by businesses, particularly SMEs. An in-depth study into the roles and activities of the groups involved in broadband diffusion to SMEs was conducted. The innovation diffusion and social construction of technology theory were applied to develop a framework that addresses some of the issues not covered in previous literature. The research was carried out in two phases and the empirical data from these was obtained and analysed using a qualitative and interpretive approach. Whilst broadband adoption figures have picked up more recently the research results show that SMEs have not adopted broadband in its full capacity. The results show that factors including cost, quality of service, and lack of awareness might be a reason for this. Implications for policy makers and groups involved in broadband diffusion to SMEs have therefore been provided. The first phase of the research provides results that indicated that broadband has not necessarily changed the way the Internet is used by the SMEs. In the second phase, the results showed a wide if not incompatible difference among groups involved in the issues surrounding broadband diffusion to SMEs. Although the governi-nenht as provided funds for SMEs' adoption of information technology, the level of awareness displayed by SMEs is persistently low. A case is put that this may be because SMEs are unique as are their needs and so need to be targeted as individual businesses with individual needs as opposed to a 'one size fits all' solution.
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Shamsuddin, Shahril. "Positioning of wireless broadband." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/10967.
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Masood, Esa Han Hsien 1979. "Accessible broadband network analysis." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/87248.
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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.Includes bibliographical references (p. 126-127).
by Esa Han Haien Masood.
M.Eng.
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Chou, Thomas Clayton. "Broadband frequency-independent beamforming." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11854.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1995.Includes bibliographical references (p. 103-105).
by Thomas Clayton Chou.
M.S.
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Gordienko, Vladimir. "Broadband fibre parametric amplifiers." Thesis, Aston University, 2018. http://publications.aston.ac.uk/37690/.
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This thesis explores the broadband fibre optical parametric amplifiers (FOPAs) to develop the FOPA ability to provide broadband amplification anywhere in the low-loss transmission window and to make FOPA an enabling technology for future ultra-wide bandwidth high-speed optical communications. A number of techniques have been implemented to demonstrate an exceptionally wide and flat FOPA gain of 10.5±0.5 dB over 102 nm bandwidth on a single side of the FOPA pump. A flat gain spectrum is targeted here because FOPA is prone to large gain variation which has a particularly strong negative impact on amplified signals in FOPA. The FOPA dependence on gain fibre length, pump wavelength and pump power has been experimentally investigated. The parametric gain bandwidth enhancement by a forward Raman gain invoked by the same pump has been demonstrated. Gain spectrum shaping by pump polarisation tuning has been explored and has allowed for a significant gain spectrum flatness improvement. A concept of cascading low gain stages has been introduced as a way to achieve a high gain with low variation across a wide bandwidth. It is envisaged that gain of ~20±1.5 dB over >100 nm can be achieved using this approach. Additionally, a reliance of the FOPA on Erbium doped fibre amplifiers (EDFAs) for pump amplification, which restricts the FOPA operating range, has been addressed by demonstrating a high pump power (>1 W) EDFA-free FOPA for the first time. In this experiment a Raman amplification was used instead of an EDFA to amplify the FOPA pump and thus to grant a required flexibility for FOPA operation anywhere in the low-loss transmission window. In summary, this thesis has demonstrated the FOPA ability to provide an ultra-wide amplification and has highlighted a way towards obtaining an optical gain in arbitrary spectral regions.
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Mohd, Sultan Juwita. "Hybrid wireless broadband networks." Thesis, Lancaster University, 2016. http://eprints.lancs.ac.uk/78762/.
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A hybrid system is an integration of two or more different systems, particularly in this thesis referring to wireless broadband networks. However, to provide end-to-end quality of service (QoS) in a hybrid system is a challenging task due to different protocol in each system. In this thesis, we aim to improve the overall performance of hybrid networks in a disaster management by addressing the challenges as well as the problems in a homogeneous network. Such an approach allows more efficient multi-parameter optimization and significant improvements in the overall system performance. More specifically, we introduce two novel algorithms. The first is the novel end-to-end QoS algorithm for hybrid wireless broadband networks. We proposed the end-to-end QoS maps based on particular chosen parameters and analyse the simulation results. The QoS maps are applied to a few scenarios, and the performance evaluation of the constructed network is presented. Based on the results obtained by software simulation tools, the performance validation shows that the hybrid network has specific advantages and constraints in terms of number of users, preference, coverage and applications. The second algorithm presented is the novel in users’ application algorithm, the purpose of which is to optimize bandwidth for first responders applied in the PPDR project under grant agreement EU FP7 SEC PPDR-TC. This algorithm is responsible for incorporating more users and different levels of background load to a hybrid network. The proposed method analyses both positive and negative outcomes based on the results obtained. This algorithm has been presented in the PPDR project.
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Shreenath, Aparna Prasad. "Measuring broadband, ultraweak, ultrashort pulses." Diss., Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-07112005-171551/.
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Thesis (Ph. D.)--Physics, Georgia Institute of Technology, 2006.Trebino, Rick, Committee Chair ; First, Phillip, Committee Member ; Ralph, Stephen, Committee Member ; Kennedy, Brian, Committee Member ; Buck, John, Committee Member.
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Tozin, Samir Arvas Ercument Mautz Joseph R. "The broadband multifilar helical antenna." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2004. http://wwwlib.umi.com/cr/syr/main.
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Hansen, Lars-Petter Gunhildsberg, and Ivar Conradi Østhus. "NPT Online Broadband Test Tool." Thesis, Norwegian University of Science and Technology, Department of Telematics, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-8975.
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Many broadband subscribers suspect that they do not receive the data rate they are paying for. In order to verify that the broadband connection is compliant with the product purchased, subscribers can go on-line and choose between a myriad of available on-line broadband test tools with variable degree of precision. Today there exist no standardized methods to perform broadband evaluation for private subscribers. We review and benchmark a selection of the available broadband test tools to reveal their strengths and weaknesses. Different tools have different approaches in their evaluation of network performance. Our studies show that most of the tools achieve acceptable accuracy for common Internet access data rates in Norway today. But when the data rate is increasing, the results from the different tools start to deviate. This is apparent for the upload rates in particular. The test methodology and the implementation technology are crucial for high bandwidth measurements. The Norwegian Post and Telecommunications Authority will develop and release an on-line tool for evaluation of the end-users' Internet connections. We present the planned service and elaborate its possibilities and limitations. Network neutrality is a concept that is quite ambiguous, and there exist many different interpretations. Based on the principles of network neutrality, developed by the Norwegian Post and Telecommunications Authority, we evaluate if the planned service is able to reveal breaches of network neutrality. We conclude that this is not possible with the planned service, mainly because of the limitations in the planned architecture combined with the complexity of network neutrality. A broadband test tool should evaluate the quality of a broadband connection in context of its usage. We suggest a user profile scheme based on relevant services for different groups of users. Different services have requirements to different network characteristics, and this consequently determine what characteristics should be evaluated for each profile. Lastly, we make use of our gained knowledge and recommend possible extensions and future applications for broadband evaluation.
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Zubi, Hazem. "Lowpass Broadband Harmonic Filter Design." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606587/index.pdf.
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In this thesis an analytical design method of the improved broadband passive harmonic filter (IBF) for three phase diode rectifier front-end type adjustable speed drives is presented. The method is based on frequency domain modeling of the rectifier and filter. The success of the method involves accurate representation of the load harmonics. With the harmonics well defined, the harmonic and fundamental frequency equivalent circuits are utilized to analytically calculate the voltages/currents. Thus, the size and the performance of the filter can be optimized. The analytical method is verified via computer simulations and laboratory experiments.
Also a performance comparison of various passive harmonic filters for three-phase diode rectifier front-end type adjustable speed drives is provided. The comparison involves the input current total harmonic distortion, input power factor, rectifier voltage regulation, energy efficiency, size, and cost. The parallel/series harmonic resonance problem related issues are addressed and unbalanced operation performance investigated. The comparison is based on analysis and computer simulations and the results are validated by laboratory experiments.
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Sobbizadeh, Hibel. "Mobile Broadband: A Market Research." Thesis, Högskolan i Gävle, Avdelningen för ekonomi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-8727.
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Abstract Title: Mobile Broadband: A Market Research Level: Thesis for Master of Business Administration in Marketing Management Address: University of Gävle Department of Business Administration 801 76 Gävle Sweden Telephone (+46) 26 64 85 00 Telefax (+46) 26 64 85 89 Web site http://www.hig.se Author: Hibel Sobbizadeh Supervisor: Maria Fregidou-Malama Date: 2010-01 Aim: This research is performed in order to investigate about Mobile Broadband (MB) market and the evolution of mobile broadband modems in this market. The aim is to find out how the MB market is developing and which MB modems are dominating the market at present and future time. The study describes the history behind the MB market and its present and future state where an increase of “internet connected” devices is almost inevitable. It at the same time discusses how the MB modems are developing from today‟s PC data cards and USB dongles to integrated modules in different devices. Method: The research is based on published and unpublished articles and data found on internet. Different search engines and databases such as Google and Gävle University library-databases are used to find various data. This empirical data is then connected to theory containing Marketing analysis, planning, implementation and control. The analysis 3 part (PEST) gives a picture of the Political, Economic, Social and Technological factors of the MB market, while the planning, implementation and control parts of the work give an overview of the threats and opportunities of the market and the strategies to overcome the problems and embrace the opportunities. Result & Conclusions: The study demonstrates that MB market has potential of becoming a successful market where devices with embedded module will be connected to internet anywhere at anytime. This requires cooperation from all the players in the value chain. The companies that choose and implement the best marketing and value chain cooperation strategies will be leaders of this future market. Suggestion for future research: One of the biggest challenges and limitations during the work of this study due to its newness was to find empirical data about MB market. As the time passes new information and statistics will make it easier for further research. As the technology is developing rapidly it is recommended to use the latest articles and statistics on internet when gathering new research material. Contribution of the thesis: This study contains valuable input to people and organizations who would like to get an overview of the MB and MB modem markets‟ development in the coming years. Key words: Mobile Broadband, PEST analysis, marketing planning, marketing strategy, marketing implementation, marketing control, embedded modules.
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Tan, Zhijie. "The broadband ISDN source simulator /." Title page, abstract and contents only, 1991. http://web4.library.adelaide.edu.au/theses/09ENS/09enst1612.pdf.
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Sonawane, Jayesh Murlidhar. "Relay network under broadband jamming." Thesis, Wichita State University, 2010. http://hdl.handle.net/10057/3747.
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In this thesis, the bit error rate (BER) performance of a relay network using binary phase
shift keying (BPSK) and quadrature phase shift keying (QPSK) modulation was compared under
broadband jamming with a normalized maximum ratio combining (MRC) scheme at various
jamming locations. Results show that, among various jamming locations in the relay network,
jamming at the destination has more negative effects on BER than jamming at the relay. Other
observations show that increasing the jamming power will cause loss in the diversity order of the
relay network.Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Electrical Engineering and Computer Science.
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Lam, Jackson Chak Sang. "Policing in broadband ATM networks." Thesis, Imperial College London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309431.
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Patnam, H. R. "Broadband antennas for basestation applications." Thesis, Queen's University Belfast, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252595.
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Landman, Bennett (Bennett Allan) 1979. "Broadband nanosensing using heterodyne interferometry." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/87257.
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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.Includes bibliographical references (p. 103-105).
by Bennett Landman.
M.Eng.
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Shamir, Orit A. "Development of ultra-broadband modulators." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/46503.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2008.Includes bibliographical references (p. 129-132).
Optical signal modulation is a cornerstone of communication, allowing the transfer of information by electrically encoding data onto an optical carrier. Modulation with ultra-broadband capability enables the generation of arbitrary waveforms using the electro-optic effect. By separating an incoming pulsed optical source into a frequency comb through the use of arrayed waveguide gratings, and employing both phase and amplitude modulation using Mach Zehnder Interferometers, an arbitrary waveform is constructed following frequency channel recombination. Modulation of frequency combs centered at an operational frequency of 800nm requires the use of GaAs-based and InP-based materials that are transparent at 800nm. The design and growth of III-V structures, the fabrication of ultra-broadband modulators and the design of arrayed waveguide gratings are detailed in this work. Three distinct structures are presented along with a compatible fabrication procedure for the construction of discrete modulators. The work is culminated with a discussion of further steps in the realization of an optical arbitrary waveform generating system.
by Orit A. Shamir.
M.Eng.
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Neethling, M. (Marthinus). "A broadband microwave limiting amplifier." Thesis, Stellenbosch : University of Stellenbosch, 2004. http://hdl.handle.net/10019.1/16406.
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Thesis (MScIng)--University of Stellenbosch, 2004.ENGLISH ABSTRACT: Limiting amplifiers are employed in electronic warfare (EW) systems requiring a high measure of amplitude control. These EW systems employ sensitive signal processing components that are unable to accept the full dynamic range of input signals the system must face. The limiting amplifier, however, offers the unique capability of reducing the received signal spectrum to a suitable dynamic range. A typical application of the limiting amplifier is in the instantaneous frequency measurement (IFM) receiver where the limiting amplifier allows the receiver to accurately measure pulsed signals over a wide input dynamic range The aim of this study is the design and analysis of a broadband limiting amplifier. Focus is placed on the design of a socalled backbone limiting amplifier (BLA) which forms an integral part of a proposed modular design approach for realizing a design with improved input dynamic range. A designed BLA is discussed in this thesis while insight is given as to the intricacies associated with its mechanism of operation. Over its 45 dB (- 40 to + 5 dBm) input dynamic range, the designed 2-18 GHz limiting amplifier offers a typical saturated output power of 7.5 dBm while harmonic suppression of better than 8.6 dBc is achieved. The BLA design was based on an existing limiting amplifier design, the so-called baseline limiting amplifier, employing alternating amplifiers and attenuators. Evaluation of the baseline limiting amplifier design allowed for formulation of a design hypothesis for realizing the BLA design. Physical measurements on the BLA were then used to scrutinize and validate the formulated design hypothesis. The requirements for realizing the BLA design were the establishment of a thorough radio frequency (RF) amplifier design capability, an understanding of the nonlinear phenomena associated with the RF amplifier and the utilization and control thereof within the limiting amplifier. Different RF amplifier designs that were carried out are discussed in this thesis, while it is shown how they were used to further investigate important design considerations for application in the BLA design. The computer-aided design packages namely MultiMatch and Microwave Office (MWO) were successfully used in realizing the desired broadband RF amplifier designs and the eventual BLA design.
AFRIKAANSE OPSOMMING: Beperker versterkers word gebruik in elektroniese oorlogvoering (EO) stelsels waar ’n redelike mate van amplitude beheer noodsaaklik is. Sensitiewe seinverwerking komponente, wat nie die volle dinamiese bereik van intreeseine kan hanteer nie, maak deel uit van hierdie EO stelsels. Die beperker versterker bied egter die unieke eienskap om die ontvangde seinspektra te reduseer tot ’n gepaste dinamiese bereik. ’n Tipiese toepassing vir die beperker versterker is as deel van die oombliksfrekwensie- meting ontvanger waar die beperker versterker die ontvanger toelaat om akkurate meting van gepulsde seine te doen oor ’n wye intree dinamiese bereik. Die doel van hierdie studie is die ontwerp en analise van ’n wye-band beperker versterker. Fokus word geplaas op die ontwerp van ’n sogenaamde kruks beperker versterker wat ’n integrale deel uitmaak van ’n voorgestelde modulêre ontwerpsbenadering, wat ten doel het om ’n verbeterde intree dinamiese bereik daar te stel. Oor die 45 dB (- 40 tot + 5 dBm) intree dinamiese bereik, bied die ontwerpte 2-18 GHz beperker versterker ’n tipiese versadigde uittreedrywing van 7.5 dBm terwyl harmonieke onderdrukking van beter as 8.6 dBc verkry is. Die ontwerp van hierdie komponent word in hierdie tesis bespreek terwyl belangrike aspekte oor die werking daarvan uitgelig word. Die ontwerp van die kruks beperker versterker is gebaseer op ’n bestaande beperker versterker ontwerp, of sogenaamde basis ontwerp, wat gebruik maak van afwisselende versterkers en attenuators. Evaluering van die basis ontwerp het toegelaat vir die formulering van 'n ontwerpshipotese om die kruks beperker versterker te realiseer. Fisiese metings op die kruks beperker versterker is gebruik om die ontwerpshipotese krities te evalueer. Om die kruks beperker versterker te realiseer moes die nodige RF versterker ontwerpsvaardigheid daargestel word, ’n begrip vir die nie-liniêere verskynsels in die RF versterker en die gebruik en beheer daarvan in die beperker versterker moes daargestel word. Verskeie RF versterkers wat ontwerp is word in hierdie tesis bespreek, terwyl getoon word hoe hierdie ontwerpe gebruik is om belangrike ontwerpsaspekte te ondersoek wat uiteindelik toegepas is in die kruks beperker versterker ontwerp. Die ontwerpspakkette naamlik MultiMatch en Microwave Office is suksesvol gebruik vir die realisering van die nodige wye-band RF versterkers en die uiteindelike kruks beperker versterker ontwerp.
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Tisdale, Neil. "Improved broadband adaptive beamformer performance." Thesis, University of Southampton, 2010. https://eprints.soton.ac.uk/158117/.
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The protection of wireless communications links against interference is a key concern in mission critical systems. In particular low probability of interception (LPI) systems which operate below the thermal noise floor of the receiver are particularly vulnerable. To protect against interference it is often necessary to include some form of active interference suppression. Broadband adaptive beamforming is one such technique which may be used to suppress interference by spatial and spectral filtering of the signals received by an array antenna. The hardware requirements of adaptive Beamforming systems are high in comparison to other approaches. As a result, the total number of adaptable weights realisable in the beamformer may be limited by the size, weight and power constraints of the system. This will limit the degrees of freedom in the beamformer and hence, the interference cancellation capability of the beamformer. The effectiveness of increasing the number of time-taps in space-time adaptive processors (STAP) as a method of increasing the number of interferers the beamformer can simultaneously cancel in an environment containing a mix of narrowband, partialband and broadband interference is studied. An alternative scheme to free up degrees of freedom in the beamformer is proposed based on frequency-domain excision to pre-filter narrowband interference before it reaches the beamformer. This approach frees up degrees of freedom in the beamformer, which would otherwise be consumed by the narrowband interference, for use in cancelling partialband and broadband interference. To enable the excision filters to identify narrowband interference while allowing partialband and broadband interference to pass through, a novel scheme is presented which produces a frequency mask that varies on a per-bin basis. Eigenanalysis of the beamformer's covariance matrix is used to explore the ability of frequency-domain excision to desensitise the beamformer to narrowband interference while bit error rate (BER) simulations demonstrate the enhanced interference protection the scheme affords an LPI communications link. Mismatches between the gain and phase responses of the radio-frequency (RF) front-end channels in broadband adaptive beamformers can limit their cancellation performance against higher power partialband and broadband interference. This performance limitation arises from the decorrelation experienced by the received signals across the array due to the interchannel mismatches. In STAP systems this performance limitation may be mitigated by increasing the number of taps per channel in the STAP. However, the computational complexity of adding additional time-taps tends to be high in STAP beamformers. Two new methods of interchannel mismatch compensation are proposed based on efficient frequency-domain methods. Simulations using software models and experiments using a hardware STAP system demonstrate the proposed techniques' ability to improve the cancellation performance where interchannel mismatches are limiting cancellation performance.
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Russell, Christopher. "Broadband on-chip terahertz spectroscopy." Thesis, University of Leeds, 2013. http://etheses.whiterose.ac.uk/5911/.
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An enhancement of on-chip terahertz time domain spectroscopy (THz-TDS) systems for the analysis of polycrystalline materials has been made. An in depth review of planar Goubau lines is presented for which there are no analytically defined terms for transmission line parameters such as characteristic impedance and effective permittivity. Using a simulation package, Ansoft HFSS, the transmission line is optimised for spectroscopy applications and the bandwidth enhanced using a variety of methods. The theory for calculating the effective permittivity of the transmission line is derived based on a two dimensional interpretation of electromagnetic field patterns and cross-section transmission line geometry. The resulting formulae have a significant impact on both bandwidth and resonant filter designs. The excitation of the planar Goubau line’s quasi transverse magnetic mode, which is typically excited using coplanar to planar Goubau line transition, has been modified in favour of a novel all-planar Goubau line on-chip spectroscopy system utilising photoconductive generation and detection methodologies. In doing so, the frequency resolution of the system is heightened enabling a narrow line width system to be resolved. The planar Goubau lines are fabricated on a quartz substrate with epitaxial transferred low-temperature-grown GaAs based photoconductive switches for both THz generation and detection. The bandwidth of the planar Goubau line is enhanced using a substrate thinning methodology to 2 THz for a 1-mm-long planar Goubau line. Using the enhanced bandwidth, THz-TDS spectroscopy using a planar Goubau line is demonstrated for the first time, where spectra of polycrystalline lactose monohydrate is obtained with a 3.75 GHz frequency-resolution over variable temperature range (4 – 298 K). The THz-TDS spectra are compared with spectra found using alternative THz spectroscopy systems to highlight the improved benefits of using this device. The theoretical development of a narrow bandstop filter design is presented, with the analytical terms defined. This novel filter enables the dielectric sensing of overlaid materials at a multiple of predefined frequencies to be pushed away from the transmission lines, which would otherwise reduce the bandwidth of the system. Results presented in this thesis present a strong candidacy for planar Goubau lines to be utilised in a broad range of applications which hold information in the THz regime.
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Kowalski, Marcio Antonio. "AUDIOVISUAL: DO BROADCAST À BROADBAND." Universidade Metodista de São Paulo, 2015. http://tede.metodista.br/jspui/handle/tede/708.
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Made available in DSpace on 2016-08-03T12:30:06Z (GMT). No. of bitstreams: 1
Marcio Antonio Kowalski.pdf: 822717 bytes, checksum: b07b1e8d6f79ff2b5c7ed45608b849df (MD5)
Previous issue date: 2015-04-27The digital society embraces us in all of the daily aspects and a significant part of the population lives connected on multi-platforms. With the instantaneity of the communication flows, we live in a routine where many accesses are from a click or a touch away. The television as a preponderant media for many decades, in its digital transition involves a function beyond the television that we knew, as an interactive display that connects and absorbs contents from many sources. The consecrated global models of audio-visual distribution, especially by Broadcast, suffer the changes consequences of its public behavior by the new opportunities of contents acquisition, now interactive and on demand. On this context, the Smart TVs models (connected televisions) in Broadcast shows differentiated options and they require an increasing space on the connection with other displays. With this scenery, the study seeks to provide and analyze the new content offerings, applications, possibility and trends in the hybridity of the sources for the future television.
A sociedade digital nos abraça em todos os aspectos do cotidiano e uma parte significativa da população vive conectada em multiplataformas. Com a instantaneidade dos fluxos de comunicação, vivemos uma rotina onde muitos acessos estão a um clique ou toque. A televisão como mídia preponderante durante várias décadas, na sua transição digital comporta uma função além da TV que conhecíamos, como display interativo que se conecta e absorve conteúdos provenientes de várias fontes. Os consagrados modelos mundiais de distribuição de audiovisual, especialmente pelo Broadcast, sofrem as consequências da mudança do comportamento do seu público pelas novas oportunidades de acesso aos conteúdos, agora interativos e sob demanda. Neste contexto, os modelos das SmartTVs (TVs conectadas) em Broadband (Banda Larga) apresentam opções diferenciadas e requerem um espaço cada vez maior na conexão com todos os outros displays. Com este cenário, o presente estudo busca descrever e analisar as novas ofertas de conteúdos, aplicativos, possibilidades e tendências do hibridismo das fontes para a futura TV.
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KOWALSKI, Marcio Antonio de. "AUDIOVISUAL: DO BROADCAST À BROADBAND." Universidade Metodista de Sao Paulo, 2015. http://tede.metodista.br/jspui/handle/tede/1498.
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Submitted by Noeme Timbo (noeme.timbo@metodista.br) on 2016-08-17T18:43:42Z
No. of bitstreams: 1
Marcio Antonio Kowalski.pdf: 822717 bytes, checksum: b07b1e8d6f79ff2b5c7ed45608b849df (MD5)Made available in DSpace on 2016-08-17T18:43:42Z (GMT). No. of bitstreams: 1 Marcio Antonio Kowalski.pdf: 822717 bytes, checksum: b07b1e8d6f79ff2b5c7ed45608b849df (MD5) Previous issue date: 2015-04-27
The digital society embraces us in all of the daily aspects and a significant part of the population lives connected on multi-platforms. With the instantaneity of the communication flows, we live in a routine where many accesses are from a “click” or a touch away. The television as a preponderant media for many decades, in its digital transition involves a function beyond the television that we knew, as an interactive display that connects and absorbs contents from many sources. The consecrated global models of audio-visual distribution, especially by Broadcast, suffer the changes consequences of its public behavior by the new opportunities of contents acquisition, now interactive and on demand. On this context, the Smart TVs models (connected televisions) in Broadcast shows differentiated options and they require an increasing space on the connection with other displays. With this scenery, the study seeks to provide and analyze the new content offerings, applications, possibility and trends in the hybridity of the sources for the future television.
A sociedade digital nos abraça em todos os aspectos do cotidiano e uma parte significativa da população vive conectada em multiplataformas. Com a instantaneidade dos fluxos de comunicação, vivemos uma rotina onde muitos acessos estão a um “clique” ou toque. A televisão como mídia preponderante durante várias décadas, na sua transição digital comporta uma função além da TV que conhecíamos, como display interativo que se conecta e absorve conteúdos provenientes de várias fontes. Os consagrados modelos mundiais de distribuição de audiovisual, especialmente pelo Broadcast, sofrem as consequências da mudança do comportamento do seu público pelas novas oportunidades de acesso aos conteúdos, agora interativos e sob demanda. Neste contexto, os modelos das SmartTVs (TVs conectadas) em Broadband (Banda Larga) apresentam opções diferenciadas e requerem um espaço cada vez maior na conexão com todos os outros displays. Com este cenário, o presente estudo busca descrever e analisar as novas ofertas de conteúdos, aplicativos, possibilidades e tendências do hibridismo das fontes para a futura TV.
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Dwivedi, Jogesh Kumar. "Investigating consumer adoption, usage and impact of broadband : UK households." Thesis, Brunel University, 2005. http://bura.brunel.ac.uk/handle/2438/5335.
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Despite a large investment, the majority of countries especially the UK demonstrate a slow adoption of broadband. In order to enhance the adoption and use of broadband this research examines the factors influencing the decisions of household consumers. This research aims to address the two main areas of concern: first, to investigate consumer-level factors affecting the adoption of broadband in UK households; and second, to understand the usage of broadband and its impact upon household consumers in the UK. This research adopted a quantitative approach that was executed in the following steps. First, it developed a conceptual model by selecting and justifying relevant constructs from appropriate theories and models related to technology adoption, usage and impact. Second, it operationalised the constructs by developing and validating the research instrument by employing the content validity, reliability and construct validity approach. Finally, it empirically validated and refined the conceptual model by employing a survey research approach. The findings suggested that all the constructs included in the conceptual model, except knowledge, significantly influence the consumers when adopting broadband in a UK household. The significant constructs include relative advantage, utilitarian outcomes, hedonic outcomes, primary influence, facilitating conditions resources and self-efficacy. The rate and variety of Internet usage is significantly higher for broadband consumers than narrowband ones. It was also found that significantly more numbers of broadband consumers perceived changes in time allocation patterns on various daily life activities than narrowband ones. This research contributes towards theory, practice and policy. The contribution of this research towards theory is that it integrates and determines the appropriate information systems (IS) literature in order to enhance knowledge of technology adoption from the consumers' perspectives. An added contribution to theory is the development and validation of a research instrument that future studies can utilise to examine broadband and other similar technologies in household context. Considering the slow adoption of broadband, this research also provides implications for policy makers and the providers of broadband in order to encourage and promote homogenous adoption and usage.
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Stevens, Irena. "Policy implications of municipal investment in Georgia's wireline broadband networks." Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/49081.
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The Community Broadband Investment Act, introduced in the Georgia legislature in 2012 and 2013 is a reflection of a broader national debate over the role of government investment in broadband infrastructure. The bill would limit local governments' ability to invest in broadband infrastructure for their communities because of arguments that government entry into the telecommunications sector crowds-out private competition, does not serve the public adequately, and lacks a comprehensive business model or best practices. A closer look at the history of utility regulation and various economic perspectives on the proper government role in utility provision reveals that government has had an extensive historical role in utility infrastructure investment and regulation, and several economic doctrines support the conclusion that government can be helpful in facilitating effective broadband service to their communities. Case studies of different models of municipal broadband networks in Georgia reveal that government entry can facilitate private sector competition, often provides quality service, and has a set of best practices. The success of municipal broadband reveals an evolution in the approach to telecommunications regulation from a regulated monopoly approach to a public-private cooperation approach which considers public participation with private entities on a dynamic scale. Government-entry into the broadband market was a rational decision for several Georgia communities due to their unique set of circumstances, and while municipal broadband may not be the answer to many communities' problems with meeting public demand, communities should be allowed to maintain flexibility in their decision-making about how to best serve their residents, effectively allowing them to decide which combination of public and private advantages they can leverage to meet the demand of their communities in relation to their unique local characteristics.
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Smith, Brian J. "CELLULAR BROADBAND TELEMETRY OPTIONS FOR THE 21st CENTURY: Looking at broadband cellular from a telemetry perspective." International Foundation for Telemetering, 2006. http://hdl.handle.net/10150/604482.
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ITC/USA 2006 Conference Proceedings / The Forty-Second Annual International Telemetering Conference and Technical Exhibition / October 23-26, 2006 / Town and Country Resort & Convention Center, San Diego, CaliforniaWith the recent broadband upgrades to various cellular infrastructures and the myriad new emerging wireless broadband standards and services offered by carriers, it is often difficult to navigate this sea of technology. In deciding the best choice for broadband telemetry applications, one must look not only at the technology, but also at the economics, market timing, bandwidths, legacy issues, future expandability and coverage, security, protocols, and the requirements of the specific application. This paper reviews the technology roadmap of cellular providers keeping these issues in perspective as they apply to TCP/IP data for images, audio, video, and other broadband telemetry data using CDMA 1xRTT, EV-DO, and EV-DO Rev A systems as well as GSM GPRS/EDGE, UMTS/W-CDMA, HSDPA, and HSUPA networks. Lastly, issues seen by system integrators when using cellular channels for telemetry applications are examined, and a case is presented for overcoming many of these issues through the use of cellular routers.
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Balmelli, Pio. "Broadband Sigma-Delta A/D Converters /." [Zürich], 2003. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=15392.
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Apelqvist, Martha, and Anders Apelqvist. "Broadband business in the Colombian market." Thesis, Högskolan i Gävle, Avdelningen för ekonomi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-11093.
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Aim and problem: Our aim with this study is to understand the dynamics on Colombian broadband market and the business opportunities arising from it. For that purpose we have formulated the following 3 research questions: 1) What characterizes the Colombian broadband market? 2) How can broadband contribute to development in Colombia? 3) Who benefits from business opportunities on the Colombian broadband market? Method: The authors have chosen the qualitative study method in order to have better understanding, explanations and analysis of the problem. The collection of the empirical data has been conducted through interviews in Colombia. Result & Conclusions: Research has shown that broadband in Colombia is still under development and is present mainly in urban areas while rural areas still show a great lack of the service. Operators are offering triple play service which includes telephone, Internet and television at different speeds and prices. The development of Broadband has a positive economic impact on the Colombian society and contributes to increase competitiveness and is a driving force for economic by stimulating productivity. Suggestions for future research: The study has been limited to Colombian broadband market, the broadband technology and services based on broadband technology. The authors suggest for a future research to study how the expansion of broadband in rural areas in Colombia will affect the life and the businesses. Contribution of the thesis: This study contributes to the understanding of the present situation of the broadband market in Colombia and the business opportunities open for vendors, operators and end users.
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Pakravan, Mohammad M. Reza. "Broadband indoor wireless communications using infrared." Thesis, University of Ottawa (Canada), 1994. http://hdl.handle.net/10393/9534.
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In this thesis, we discuss the issue of using infrared light as a carrier for broadband indoor wireless networks. We discuss the infrared channel and show how it differs from conventional radio frequency channel. Noise sources for this environment and the practical ways of reducing their harmful effects are discussed. We determine the safety levels for the radiated power of an IR transmitter and we show how the system should be designed to operate within the safety limits. We introduce a computer-simulation algorithm to find the impulse response of an indoor infrared channel and discuss several implementation issues for the algorithm. Using the simulation software, we investigate temporal and spatial distributions of the channel, e.g., the delay spread of impulse response and the total received optical power. We use the results of the simulations to investigate the effects of receiver rotation on the channel properties. We propose an angular diversity as a mean for performance improvement in an infrared receiver. Simulating the noise sources and signal sources in a typical indoor environment, we see how diversity improves the signal-to-noise ratio in a receiver with the angular diversity reception.
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Jiyapanichkul, Prasit, and jiyapanichkul@yahoo com. "Resource management in broadband multimedia networks." Swinburne University of Technology. Laboratory for Telecommunication Research, 1999. http://adt.lib.swin.edu.au./public/adt-VSWT20050610.100950.
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This research deals with optimal resource management in an overloaded broadband
multimedia network. Optimisation is with respect to user satisfaction, where user
satisfaction reflects both the quality of service experienced by connected users and the
dissatisfaction of users blocked from access to the network.
The research focuses on Asynchronous Transfer Mode (ATM) networks and the Internet, because these are the dominant emerging broadband networks which present some fundamental unsolved problems, related to the sharing of resources between mixed traffic types. ATM networks use conservative admission control, which protects
network resources and ensures a high level of service for those admitted to the network, but results in low network efficiency because of low utilisation of resources due to blocking of many potential users. The Internet does not use admission control, with the result that performance degrades progressively as load increases. This causes frustration among users, and lowers the network efficiency due to high levels of congestion.
We propose an optimisation model for each network (ATM networks and the Internet)which is intended to represent the distribution and consumption of key network resources by different traffic types. The model is aimed at maximising performance such that users admitted to the network are offered no less than some minimum acceptable level of quality of service (QoS). The solution is a set of traffic flow rates on each path which results in maximising an objective function value (revenue based on network operator interest or throughput based on customer interest) for a given network
configuration with given user demand. As an example using the ATM network model, we illustrate the application of the model to an ATM network carrying both connection oriented and connectionless traffic. We explore the optimal response to a link failure which in turn causes node overload. As an example using the Internet model, we consider an overloaded network with link bottlenecks and an overloaded Web server, and explore the effect of transferring some server capacity to a mirror site and a proxy server.
For real-time traffic control, the optimisation model is used to assign quotas for bandwidth or connections to selected paths. A control algorithm is implemented to provide maximum performance by admitting requests within the quotas which are obtained from the optimisation model. In an ATM network simulation, the algorithm is used to manage the virtual path (VP) pool in a network which suffers a link failure. A comparison is made between fixed virtual path management (FVPM) and dynamic
virtual path management (DVPM), comparing the revenue achieved by each. This illustrates how DVPM adapts the VP pool in a robust fashion to achieve maximum revenue in the face of a link failure. However, the transient response suggests that benefit could be obtained using non-steady-state solutions. The model is extended by taking network state and traffic parameters into account to control changes in the VP pool to recognise limits to the rate at which traffic can be moved (through the natural
birth-death processes). This scheme is called state dependent virtual path management (SDVPM). Performance evaluation of the new model shows that SDVPM achieves higher revenue than DVPM when the network suffers a link failure that requires a major change to the VP pool. In an Internet simulation, two algorithms are compared for control of access to a proxy server and a set of primary servers. An algorithm based on
optimal flow solutions provides substantially better network performance than a localised heuristic algorithm. In each simulation case (ATM and Internet examples), the performance using a control system based on the steady state optimum flow model is close to the ideal optimal result.
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Stickel, Micah. "Broadband high-fidelity directional transient couplers." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0018/MQ54214.pdf.
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Uzarski, Joel S. "Analysis of United States' broadband policy." Thesis, Monterey, Calif. : Naval Postgraduate School, 2007. http://bosun.nps.edu/uhtbin/hyperion.exe/07Mar%5FUzarski.pdf.
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Thesis (M.S. in Computer Science)--Naval Postgraduate School, March 2007.Thesis Advisor(s): Bert M. Lundy. "March 2007." Includes bibliographical references (p. 139-142). Also available in print.
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Sandberg, Pontus. "Mobile Broadband Service Experience and Evaluation." Thesis, Linköpings universitet, Institutionen för teknik och naturvetenskap, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-96304.
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EGDE manages Internet Radio streams up to 96kbit/s while WCDMA R99 delivers satisfactory quality for media streams up to 320 kbit/s. Internet Radio isnot possible to use over GPRS with satisfactory quality. The quality assessment for Internet Radio is highly dependent on the stream bit rate and a stream of 128 kbit/s delivers high user satisfaction. For online gaming other parameters than the well known latency, jitter and packet loss aects the session quality. High start up or map load times will cause premature game termination and poor quality grading. Shorter Counter- Strike sessions are playable over HSPA where it outperforms WCMDA R99 inboth network performance and user quality assessment. World of Warcraft has more limited network requirements and is playable over both WCDMA R99 and HSPA but suers from latency impairments when played over GPRS/EDGE. The developed objective quality prediction model for First Person Shooter (FPS) games, like CounterStrike, shows pretty good performance, despite a small number of test persons. The model predicts online gaming quality with an RMSE value of 0.609, prediction accuracy of 91.9% and correlation between predicted and subjective MOS of 0.8803.EDGE klarar att leverera Internet Radio-oden upp till bittakter av 96 kbit/s medan WCDMA R99 klarar bittakter upp till 320 kbit/s med tillfredstallande kvalitet. GPRS kan inte anvandas for Internet Radio sessioner med tillfredsstallande kvalitet. Kvalitetensbedomningen av ett Internet Radio ode ar strikt beroende av odets bithastighet och Internet Radio-oden pa 128 kbit/s och hogre levererar hog kvalitet och tillfredstallse bland anvandare. Kvalitetsbedomningen av online spel paverkars av andra parametrar an de typiskt val kanda latency, jitter och paketforluster. Hoga start- och kartladdningstider leder till lagt betyg pa sessionen och ett tidigt avslutande av spelet. HSPA klarar kortare spel sessioner av CounterStrike och levererar avsev art mycket battre prestanda och kvalitetsbedomning an for WCDMA R99. World of Warcraft har betydligt mindre krav pa accessnatverket och ar spelbart over bade WCDMA R99 och HSPA men lider av hoga latencynivaer for GPRS/EDGE. Den framtagna kvalitetsprediktionsmodellen for First Person Shooter (FPS) spel som CounterStrike visar pa bra prestanda, trots baserad pa ett begransat antal testpersoner. Modellen predikterar kvalitet pa online spel med ett RMSE varde pa 0.609, en prediktionssakerhet pa 91.9% och en korrelation pa 0.8803 mellan predikterat och subjektivt MOS.
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Adas, Abdelnaser M. "Supporting multimedia traffic in broadband networks." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/14849.
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Al-Yatama, Anwar. "Quantization and routing in broadband networks." Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/15374.
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Bean, Nigel Geoffrey. "Statistical multiplexing in broadband communication networks." Thesis, University of Cambridge, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282808.
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Qin, Yi. "Broadband high efficiency active integrated antenna." Thesis, Northumbria University, 2007. http://nrl.northumbria.ac.uk/79/.
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Active integrated antenna (MA) is a very popular topic of research during recent decades. This is mostly due to its advantages, such as compact size, multiple functions and low cost, etc. The MA system can be regarded as an active microwave circuit which the output or input port is free space instead of a conventional 50-ohm interface. The major drawbacks of the conventional MA include narrow bandwidth, low efficiency, etc. An experimental investigation on broadband slot-coupled antenna is carried out, which results an impedance bandwidth of 50 % is achieved by both a ring slot- coupled and square ring slot-coupled patch antenna. An improved design technique for broadband class-E power amplifier (PA) design, based on the theoretical analysis done by Mader [2], is introduced to calculate the circuit parameters. The technique is applied to a RF microwave class-E power amplifier design (PA) that results a bandwidth of 12 % power added efficiency (PAE) greater than 60 % is achieved. The aim of this work is to design broadband high efficiency linearly polarized (LP) and circularly polarized (CP) MA and arrays that will be useful for mobile communication system. The MA does not need conventional matching network between the amplifier and the antenna, because the antenna serves as both a harmonics-tuning network and a radiator. A novel high efficiency broadband LP MA is demonstrated using a ring slot-coupled patch antenna with a class-E PA. It exhibits a PAE over 50 % within a 14.6 % bandwidth. For the first time, a high efficiency broadband CP MA is designed using a class-E PA integrated with a broadband CP antenna. The CP AIA achieves a PAE over 50 % within a 14 % bandwidth. The axial ratio of the CP MA is below 3 dB over a 9 % bandwidth. For further improve the performance, a novel L-shaped slot-coupled broadband CP MA is employed in a 2x2 array. The array consists of four sequentially rotated broadband CP antenna elements with an element spacing of half a free space wavelength. The antenna was designed to operate in the 3G band around 2 GHz. A bandwidth of 22.7 % PAE greater than 50 % is achieved together with a peak PAE of 71.35%. A bandwidth of 27 % axial ratio below 3 dB is resulted.
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Xia, Bin, and 夏斌. "Enhanced techniques for broadband wireless communications." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B29144231.
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Sun, Fanglei, and 孫芳蕾. "Resource allocation in broadband wireless networks." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B40887868.
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Cole, Colin. "Broadband antireflection coatings for spaceflight optics." Thesis, University of Reading, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308025.
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iyer, vishwanath. "Broadband Impedance Matching of Antenna Radiators." Digital WPI, 2010. https://digitalcommons.wpi.edu/etd-dissertations/388.
Full textAbstract:
"In the design of any antenna radiator, single or multi-element, a significant amount of time and resources is spent on impedance matching. There are broadly two approaches to impedance matching; the first is the distributed impedance matching approach which leads to modifying the antenna geometry itself by identifying appropriate degrees of freedom within the structure. The second option is the lumped element approach to impedance matching. In this approach instead of modifying the antenna geometry a passive network attempts to equalize the impedance mismatch between the source and the antenna load. This thesis introduces a new technique of impedance matching using lumped circuits (passive, lossless) for electrically small (short) non-resonant dipole/monopole antennas. A closed form upper-bound on the achievable transducer gain (and therefore the reflection coefficient) is derived starting with the Bode-Fano criterion. A 5 element equalizer is proposed which can equalize all dipole/monopole like antennas. Simulation and experimental results confirm our hypothesis. The second contribution of this thesis is in the design of broadband, small size, modular arrays (2, 4, 8 or 16 elements) using the distributed approach to impedance matching. The design of arrays comprising a small number of elements cannot follow the infinite array design paradigm. Instead, the central idea is to find a single optimized radiator (unit cell) which if used to build the 2x1, 4x1, 2x2 arrays, etc. (up to a 4x4 array) will provide at least the 2:1 bandwidth with a VSWR of 2:1 and stable directive gain (not greater than 3 dB variation) in each configuration. Simulation and experimental results for a solution to the 2x1, 4x1 and 2x2 array configurations is presented. "
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Parker, Melahn Lyle 1979. "Broadband satellite constellation design & evaluation." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/81807.
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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2001.Pages 145-150 are folded and numbered as leaves.
Includes bibliographical references (p. 175-179).
by Melahn Lyle Parker.
M.Eng.
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Fludger, Christopher Ronald Stephen. "Raman amplification for broadband optical communications." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620474.
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