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Dissertations / Theses on the topic 'Digital communication'
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Maciejewski, Robert. "Privacy aspects of digital communication." St. Gallen, 2007. http://www.biblio.unisg.ch/org/biblio/edoc.nsf/wwwDisplayIdentifier/01665892002/$FILE/01665892002.pdf.
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Iyer, Gopal Balakrishnan. "Digital communication and control circuits for 60ghz fully integrated CMOS digital radio." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/39589.
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Emerging "bandwidth hungry" applications such as high definition video distribution and ultra fast multimedia side-loading have extended the need for multi-gigabit wireless solutions beyond the reach of conventional WLAN technology or even more recently emerging UWB and MIMO systems. The availability of 7GHz of unlicensed bandwidth in the 60GHz spectrum, represents a unique opportunity to address such data-throughput requirements. The 60GHz Integrated CMOS digital radio chipset comprises of PHY and MAC layers, RF transceiver, High-Speed Digital Interface and an underlying Serial Communication Fabric.
To have a complete communication solution compliant with the latest ECMA-369, ISO/DIS 13156 and IEEE 802.15.3c standards, we build a million gate digital implementation of MAC and PHY. The Serial Peripheral Interface (SPI) serves as the bridge between the higher layers in the communication stack (PAL-MAC) and the lower layers like PHY-RF Front End. The MAC module can setup the communication link on the fly by tuning parameters such as operating channel, channel bonding and bandwidth, data rates, error correction mechanisms, handshaking mechanisms, etc, by using the SPI to communicate with internal components. The SPI interface plays a crucial rule in not only this, but also during the testing and debug phase. Operation of each of the RF modules is monitored through the serial interface using local SPI slaves which are hooked up to the 4-wire serial bus running all through the chip. The SPI host controller emulates an embedded protocol analyzer. For calibration and fine tuning purposes, digital settings can also be loaded onto these modules through the SPI interface. R-2R DACs are used to convert these commands into analog voltages which then provide a tunable bias to the RF and mixed-signal modules. Other key functions of this serial communication and control interface are: Initialization of all of the RF and mixed signal modules, DC calibration of data converter, PLL and other mixed-signal modules, data acquisition, parametric tuning for digital modules such as linear equalizer, Gain Control loops (AGC, VGA), etc.
Ultra high speed digital Input-Output buffers are used to provide an external data interface to the radio chipset. These high speed I/Os are also used in the gbps (gigabit-per-second) link for data transfer between the RF transceiver chip and the PHY-MAC baseband chip. The IOs are expected to comply with different signaling standards such as LVDS, SLVS200, SLVS400, etc. A robust system involves a meticulous pad ring design with proper power domains and power cuts. Full-chip integration of the digital PHY, MAC, peripheral logic and IO ring is done in a semi-custom fashion.
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Rugbeer, Hemduth. "Communicating by ordering electrons : the development of electronic communication as part of a secondary school Communication Science curriculum in the Language, Literacy and Communication learning area." Thesis, University of Zululand, 2001. http://hdl.handle.net/10530/314.
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A thesis submitted in fulfilment of the requirements for the Degree of MA in Communication Science, University of Zululand, 2001.In this thesis I focus on the introduction of Electronic Cornmunication as part of an envisaged Communication Science curriculum in the Language, Literacy and Communication Learning area of the Further Education and Training band. In the course of my thesis I will show that the requisite elements of verbal and written cornmunication are dispersed throughout the Language, Literacy and Communication learning area in the General Education and Training band, and that they can be utilised as basis for formally introducing Communication Science, as a subject in the Language, literacy and Communication learning area in the Further Education and Train¬ing band. I also show that electronic communication will form a crucial area of study in such a Communication Science curriculum. I argue that due to the diversity of cultures in South Africa, cross-cultural cornmunication is required in such a curriculum. I also argue that by the very na¬ture of Outcomes-Based Education it is necessary to have a subject into our school curriculum that will form an interface with conceptual learning and experiential learning, that will contextu-alise language study within the more comprehensive scope of forms of human communication, and that will form an interface between the humanities and science to prevent the humanities from becoming soft options in Further Education and Training band learning programmes. To this effect I focus on the crucial role of Constructivism as integrating theory to account for vari¬ous approaches to motivational learning, the primary form of learning required in Outcomes-Based Education. I examine the principles of curriculum construction in OBE and its associated culture of learn¬ing against the backdrop of the theory of Situated Cognition. This presents a platform to argue the case for Electronic Communication as part of Communication Science in the Further Edu¬cation and Training band curricula in South African schools.
National Research Foundation
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Poirrier, Julien. "Electronic Mitigation of Polarization Mode Dispersion." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/34469.
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Polarization Mode Dispersion induces polarization dependent propagation. Consequently it generates a multiple imaging of the light pulse carrying the information. Its first order appears as a dual path fading channel of Maxwellian statistics. It results in harmful impairments that prevent the upgrade and installation of high bit-rate systems. The random process PMD exhibits a strong frequency dependence, so that its amelioration requires channel by channel, non-linear, adaptive mitigation. Electronic mitigation appears as a very attractive solution to overcome the limit set by the PMD.
Consequently, we considered the implementation of these solutions at the receiver in the electrical domain. We verified that these linear and non-linear equalization techniques can greatly reduce the power penalty due to PMD. Equalization's performance depends highly on the type of systems considered. For the two main types of systems: thermal noise limited systems and systems exhibiting ASE (systems using optical amplifiers), we demonstrated and quantified the induced improvement (measured as power penalty reduction). The most sophisticated technique that we considered (NLC+FDE) handles any kind of first order PMD within a 4 dB margin in the thermal noise limit. This extended to a 11 dB margin in the presence of ASE. This comes from the limitation set by the signal dependence of the noise. In fact, these DSP techniques do a better job at reducing very high penalty. Consequently, for a power and ISI limited link, it may be required to associate to electronic solutions optical compensation in order to reach acceptable performance. On the other hand, for links having large power margin or exhibiting reasonable PMD, electronic techniques appear as an easy, inexpensive and convenient solution.
We derived in this work the bounds to NLC performance in the presence of ASE. Therefore, we extended the usual results of the thermal noise limit to the particular case of signal dependent noise. We also made clear that optical systems, because of their noise specificities can not be studied or designed as others links. Notions such as eye opening, SNR and ISI need to be carefully defined and adapted to this case.
We have provided in this work PMD dependent power penalty map for known systems. Given the link's statistics and characteristics, one can determine, following our structure, which mitigation techniques allow upgrade.Master of Science
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Lashgari, Maryam. "Digital Marketing Strategy:B2B and Stakeholders Communication." Doctoral thesis, KTH, Skolan för industriell teknik och management (ITM), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-220144.
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Since digital media entered the business domain, many different tools and platforms have transformed the nature of business communications. This transformation has not been easy, since the journey has been accompanied by challenges from the marketers’ side against the adoption of the new platforms into the firm’s communication channels. Business to business marketers have also been engaged in such challenges by maintaining a slow adoption, which has motivated the researchers to study the adoption of different means and tools of digital communication in a business context. Through this research, I contribute by exploring the adoption strategies of digital platforms in the B2B supply chain including B2B firms, retailers and end users. By digital media, I mainly refer to social media and beacon technology. First, I begin this thesis by identifying the adoption and integration strategies of social media and digital marketing into traditional marketing channels in a B2B context. In this part, I identify the B2B firms’ target audience and propose a model facilitating a B2B firm’s practical social media adoption strategies. Second, to explore the benefits of different social media content sharing approaches derived from information accessibility resulted in the prior study of this thesis, I introduce and examine Public and Gated-Content sharing approaches. Thereafter, assisted by Social Power Theory and Resource Dependence Theory, I examine the effect of Public and Gated-Content sharing approaches on the target audience’s willingness to interact with the firm. The findings of this study reveal that Gated-Content approach can help the firms build closer relationship with the target audience and engage them in a co-creation process. Third, by studying proximity marketing through the adoption of beacon technology in the retail context, I explore the current methods of usage, as well as the benefits and challenges of in-store proximity marketing adoption for content sharing purposes. I complete the thesis by presenting the different challenges of such adoption, which consist technical, human behavior, managerial perception, resource and privacy factors. Finally, I identify the need to integrate the physical aspect of place and location back again into the online digital communication channels within a retail context.QC 20171219
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Qian, Xinben Garrison. "Adaptive systems in digital communication designs." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/38821.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996.Includes bibliographical references (leaves 98-100).
by Xinben Garrison Qian.
M.S.
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Gomes, Rui Miguel Soares. "Intelligent peripherals with digital communication bus." Master's thesis, Universidade de Aveiro, 2009. http://hdl.handle.net/10773/5563.
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Mestrado em Engenharia Electrónica e TelecomunicaçõesEsta dissertação é parte integral do projecto ECU2010 e é focada no desenvolvimento de Periféricos Inteligentes que são conectados à ECU através de um Barramento Digital de Comunicação. O projecto ECU2010 está centrado no desenvolvimento de uma nova arquitectura da unidade de controlo electrónico (ECU) para desporto automóvel, focada no controlo de motores de combustão interna. A arquitectura proposta deverá ser ter a capacidade de controlar um motor de combustão interna usando os mais modernos modelos de controlo, mas sendo baseada numa modelo de processamento distribuído, composta por módulos de processamento auto-suficientes ao nível de comunicações e armazenamento e de sensores/actuadores com inteligência capazes de processamento prévio de dados. A ênfase desta dissertação será colocada apenas nos Periféricos Inteligentes e no Barramento Digital de Comunicação. Este documento irá analisar e propor uma solução para a inclusão de capacidades de processamento, armazenamento e diagnóstico nos periféricos, assim como o desenvolvimento de um Barramento Digital de Comunicação que permite aos periféricos comunicarem com a ECU e sincronizarem-se com a rotação do motor.
This dissertation is an integral part of the ECU2010 project and is focused on the development of Intelligent Peripherals which connect to the ECU by means of a Digital Communication Bus. The ECU2010 project is centered on developing a new architecture of electronic control units (ECU) for motor sport, focussing on control of internal combustion engines. The proposed new architecture should be capable of controlling an internal combustion engine using the state-of-the art control models, but based on a distributed processing model consisting on self-sufficient processing modules in terms of communications, storage and intelligent enabled sensors/actuators, which is able to produce low-level data processing. The focus of this dissertation will only be the Intelligent Peripherals and the Digital Communication Bus. This document will analyse and propose a solution for the incorporation of processing, storage and diagnostic capabilities into peripherals, as well as the development of a Digital Communication Bus which allows the peripherals to communicate with the ECU and synchronize them with the engine’s rotation.
FCT; FSE
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Hwang, Yong Goo. "Optimal configuration of digital communication network." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA243041.
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Thesis (M.S. in Computer Science)--Naval Postgraduate School, December 1990.Thesis Advisor(s): Suh, Myung W. Second Reader: Hamming, Richard W. "December 1990." Description based on title screen as viewed on March 30, 2010. DTIC Identifier(s): Program Listings, Lagrangian Relaxation. Author(s) subject terms: Network, Langrangian Relaxation, Subgradient Optimization. Includes bibliographical references (p. 66-67). Also available in print.
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Ramakonar, Visalakshi S. "Modulation classification of digital communication signals." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2002. https://ro.ecu.edu.au/theses/752.
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Modulation classification of digital communications signals plays an important role in both military and civilian sectors. It has the potential of replacing several receivers with one universal receiver. An automatic modulation classifier can be defined as a system that automatically identifies the modulation type of the received signal given that the signal exists and its parameters lie in a known range. This thesis addresses the need for a universal modulation classifier capable of classifying a comprehensive list of digital modulation schemes. Two classification approaches are presented: a decision-theoretic (DT) approach and a neural network (NN) approach. First classifiers are introduced that can classify ASK, PSK, and FSK signals. A decision tree is designed for the DT approach and a NN structure is formulated und trained to classify these signals. Both classifiers use the same key features derived from the intercepted signal. These features are based on the instantaneous amplitude, instantaneous phase, and instantaneous frequency of the intercepted signal, and the cumulates of its complex envelope. Threshold values for the DT approach are found from the minimum total error probabilities of the extracted key features at SNR of 20 to -5dB. The NN parameters are found by training the networks on the same data. The DT and NN classifiers are expanded to include CPM signals. Signals within the CPM class are also added to the classifiers and a separate decision tree and new NN structure are found far these signals. New key features to classify these signals are also introduced. The classifiers are then expanded further to include multiple access signals, followed by QAM, PSK8 and FSK8 signals. New features arc found to classify these signals. The final decision tree is able to accommodate a total of fifteen different modulation types. The NN structure is designed in a hierarchical fashion to optimise the classification performance of these fifteen digital modulation schemes. Both DT and NN classifiers are able to classify signals with more than 90% accuracy in the presence of additive white Gaussian within SNR ranging from 20 to 5dB. However, the performance of the NN classifier appears to be more robust as it degrades gradually at the SNRs of 0 and -5dB. At -5dB, the NN has an overall accuracy of 73.58%, whereas the DT classifier achieves only 47.3% accuracy. The overall accuracy of the NN classifier, over the combined SNR range of 20 to -5dB, is 90.7% compared to 84.56% for the DT classifier. Finally, the performances of these classifiers are tested in the presence of Rayleigh fading. The DT and NN classifier structures are modified to accommodate fading and again, new key features are introduced to accomplish this. With the modifications, the overall accuracy of the NN classifier, over the combined SNR range of 20 to -5dB and 120Hz Doppler shift, is 87.34% compared to 80.52% for the DT classifier.
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Ruiz, Svensson Erik, and Emma Rådhall. "Social responsibility in the digital era : Digital communication agencies social responsibility in digital channels." Thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH, Datateknik och informatik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-46404.
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Purpose and problem discussion: Nowadays, it is crucial to implement social responsibility to business operations to succeed as a business. Companies face increased demands from customers and stakeholders to show their actions regarding social responsibility. At the same time, digital development is shaping the communication industry, creating new communication platforms in the world. The purpose of this study is to explore digital communication agencies role in the production and implementation of digital products within digital channels to best understand digital social responsibility. The study aims to answer the research questions: What social responsibilities does a digital communication agency have in regard to the products and messages they produce for digital channels? and How do digital communication agencies become socially responsible when using digital channels? Method: An abductive analysis method was applied to semi-structured interviews with digital communication agencies in Jönköping, Sweden. The analysis of the empirical findings has resulted in deeper understanding of social responsibility in digital environments; a study area that has not been explored before. Four digital communication agencies represent the average digital social responsibility mindset and business culture in Jönköping, Sweden. This gave us the possibility to research social responsibility on digital channels. Results, discussion and conclusions: The results show that the digital communication agencies clients are entirely responsible for the digital material published on their own digital channels. Although, the agencies do need to make sure they produce the best possible material for their clients to avoid bad relationships with stakeholders and a bad reputation. The results also show that social responsibility is not first priority for any company; profitability always comes first. The key to digital social responsibility is to work with the right clients and thoroughly analyse the client’s business operations to bring out the best in each case and to be prepared for backlashes. The digital communication agencies could also benefit from a crisis plan, to minimise stress and optimize the problem solving if a crisis would occur. If doing this correctly,the agencies enable genuine and honest digital communication, which minimises the risk of being perceived unfairly on digital platforms. This is especially of importance on digital platforms, where the speed, great reach and two-way communication makes it even easier to receive negativity and face backlashes. A digital communication agency can become socially responsible by working with the right clients, as well as producing and publishing genuine and honest digital communication.
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Rockliff, Simon C. "Frequency hopping techniques for digital mobile radio /." Title page, contents and abstract only, 1990. http://web4.library.adelaide.edu.au/theses/09PH/09phr683.pdf.
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Lahey, Michael. "Soft control| Television's relationship to digital micromedia." Thesis, Indiana University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3607011.
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This dissertation explores the role soft control plays in the relationship between the television industry and short forms of digital media. Following James Beniger and Tizianna Terranova, I define soft control as the purposive movement by the television industry towards shaping audience attention toward predetermined goals through a range of interactions where development happens somewhat autonomously, while being interjected with commands over time. I define such things as media environment design, branding, and data collection as soft control practices. I focus on television as a way to understand how an industry historically patterned around more rigid forms of audience control deals with a digital media environment often cited for its lack of control features. And while there is already a robust discussion on the shifting strategies for the online distribution of shows, there is less of a focus on the increasing importance of shorter forms of digital media to the everyday operation of the television industry. Shorter forms of media include digitally circulated short videos, songs, casual digital games, and even social media, which is itself a platform for the distribution of shorter forms of media. I refer to all these forms of short media as "micromedia" and focus my interest on how various television companies are dealing with media environments saturated with it.
To do this I look at, for instance, how television companies use the data available on Twitter and appropriate the user-generated content of audiences, as well as how standard digital communication interfaces are utilized to more easily retrofit previous audience retention practices into new digital environments. Through the investigation of how television creates and appropriates micromedia as a way to reconfigure practices into the everyday lives of participatory audiences, I argue that we can see soft control elements at work in structuring the industry-audience relationship. These soft control features call into question the emancipatory role attributed to participatory audiences and digital technologies alike. If we think about media forms in their specific contexts, making sure to focus on their intermedial connections and their materiality, we can complicate ideas about what the categories of audience or industrial control mean.
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Lo, Chi-ming. "Analytical evaluation of wireless digital communication performance over fading channels." Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk/hkuto/record.jsp?B23295211.
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Pous, Solà Marc. "Radiated transient interferences in digital communication systems." Doctoral thesis, Universitat Politècnica de Catalunya, 2015. http://hdl.handle.net/10803/299210.
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In the Electromagnetic Compatibility research area, an unsolved interference problem is the measurement and evaluation of the distortion produced by radiated transient disturbances on digital communication systems. This impulsive noise, which is generated by switching devices or by sparks, is a broadband interference that covers the spectrum from DC to several hundreds of megahertz or some gigahertz. Additionally, this man-made noise is characterized by its short and random burst parameters, which make really challenging to measure it correctly. During the thesis, we have explained that impulsive noise is not properly measured and evaluated to prevent interference scenarios, when the EMC standard methodologies are applied. Detectors, such as the quasi-peak, frequency sweep measurements or signal-to-noise limiting evaluation described in the harmonized standards of the electromagnetic compatibility do not enable to determine beforehand the influence of transient interferences.
Our strategy to overcome the non-profit measurement has been to perform novel measurement and evaluation techniques beyond EMC standards. The measurement technique developed joins the capabilities of EMI receivers and oscilloscope instrumentations to capture accurately the radiated transient interference. To carry out the measurement, the input stage of the EMI receiver is used for filtering and pre-amplifying purposes, conducting the IF output towards the oscilloscope, which is used for triggering and storage. Furthermore, a final post-processing stage is needed to obtain in time-domain the in-phase and quadrature components of the transient interference.
Once the radiated transient interference has been measured properly, an accurate evaluation of the distortion produced to a digital communication system can be estimated. To evaluate the impact of the transient interference, a combination of the time-domain measurement with base-band simulation has been proposed to fulfil the thesis goal. The IQ time-domain measurement enables us to characterize the impulsive-noise present at the communication channel and determine the distortion produced to the digital communication system by means of base-band simulation. The procedure to determine the BER using the base-band simulation has been validated with experimental results, comparing the results reached with the developed methodology with the ones obtained when a communication system device is placed under radiated transient. Excellent results have been obtained employing the developed methodology, considering the interference produced by radiated transient to RFID or GSM communication systems
Additionally, a new measurement methodology to obtain the amplitude probability diagram (APD) has been developed, offering the possibility to determine the bit-error-rate including limit lines at the APD diagram. This measurement method, based on captures obtained from a general purpose oscilloscope, makes it possible to obtain the APD measurement at any frequency band with the same accuracy provided by an EMI receiver. Furthermore, the post-processing tools using mathematical software produce the APD results rapidly at any bandwidth, and this makes it more powerful than employing an EMI receiver.
The successful APD measurement system created is able to obtain the full-spectrum statistical measurement, employing several time-domain captures which can be acquired in practice immediately. In the final chapter of this thesis, the GSM system is interfered by radiated transients produced by sparks. The results provided by the APD diagram including the limit dots have been especially useful due to its fast capacity to interpret and quantify the degradation produced to the GSM system.En el camp de recerca de la compatibilitat electromagnètica, una de les problemàtiques no resoltes és la mesura i avaluació de les interferències produïdes per transitoris radiats sobre els equips de comunicació digitals. Aquest tipus de soroll impulsiu, que es genera per la commutació d' equips electrònics o guspires, és una interferència de banda ampla que ocupa l' espectre radioelèctric fins a diversos centenars de megahertz o algun gigahertz. A més, aquest soroll es caracteritza per la seva curta durada i l'aleatorietat dels seus paràmetres, i això fa que sigui molt complicat mesurar correctament la interferència. Al llarg de la tesi, hem explicat que el soroll impulsiu no es mesura ni s'avalua adequadament per evitar escenaris d'interferències si s'utilitzen les metodologies definides als estàndards d' EMC. Els detectors, com el de quasi-pic, l'escombratge en freqüència o l'avaluació basada en els límits relacionats amb la relació senyal a soroll no són vàlids per anticipar la influència de les interferències transitòries. La nostra estratègia per solucionar els problemes de les mesures normatives ha estat desenvolupar noves tècniques de mesura i avaluació fora dels estàndards d'EMC. La tècnica de mesura desenvolupada combina les capacitats dels receptors EMI i els oscil·loscopis per capturar la interferència transitòria radiada. Per realitzar les mesures, l'etapa d'entrada del receptor EMI s¿utilitza amb la finalitat de filtrar i preamplificar, enviant la sortida IF cap a l'oscil·loscopi, que es fa servir per detectar i emmagatzemar els transitoris. Per últim, en l'etapa de postprocessament, s'obtenen en el domini del temps els components en fase i en quadratura de la interferència transitòria. Una vegada s'ha mesurat adequadament la interferència radiada, es pot estimar correctament la distorsió produïda sobre els sistemes de comunicació digitals. Per avaluar l'impacte de la interferència transitòria i així complir amb l'objectiu de la tesi, s'ha proposat combinar les mesures en el domini del temps amb la simulació en banda base. La mesura IQ en el domini del temps ens permet caracteritzar el soroll impulsiu present al canal de comunicació i així determinar la distorsió produïda al sistema de comunicació digital mitjançant la simulació en banda base. El procediment per determinar el BER fent servir la simulació en banda base ha estat validat amb resultats experimentals, i s'han comparat els resultats obtinguts utilitzant la metodologia desenvolupada amb els resultats proporcionats directament col·locant un dispositiu sota la influència de transitoris radiats. Els excel¿lents resultats obtinguts considerant interferències produïdes sobre sistemes RFID i GSM han estat publicats. D'altra banda, també s'ha desenvolupat un nou mètode de mesura per adquirir el diagrama de probabilitat d¿amplitud (APD), oferint la possibilitat de determinar la probabilitat d'error en el bit incloent límits en el diagrama APD. Aquest mètode de mesura, basat en captures obtingudes mitjançant un oscil·loscopi de propòsit general, fa possible obtenir la mesura APD en qualsevol banda freqüencial amb la mateixa exactitud que proporciona un receptor EMI. A més, amb les eines de postprocessament desenvolupades és possible produir els resultats APD ràpidament i amb qualsevol amplada de banda, i això fa que sigui un mètode de mesura més potent que no pas utilitzar un receptor EMI. L'exitós sistema de mesura creat per obtenir l'APD és capaç d'obtenir la mesura estadística en tot l'espectre radiolèctric utilitzant poques captures en el domini del temps, les quals a la pràctica soón adquirides de forma inmediata. Al capítol final de la tesi, el sistema GMS és interferit per transistors radiats produïts per guspires. El resultat proporcionat pel diagrama APD, incloent-hi els límits, és especialment útil gràcies a la seva rapidesa per interpretar i quantificar la degradació produïda sobre el sistema GSM.
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Nilsson, Rickard. "Digital communication in wireline and wireless environments." Licentiate thesis, Luleå tekniska universitet, Signaler och system, 1999. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-17330.
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This thesis consists of an introduction and five parts dealing with digital communication. Three parts address Discrete Multi-Tone modulation (DMT), a wireline form of Orthogonal Frequency Division Multiplexing (OFDM). One part addresses channel estimation in wireless OFDM and one addresses multiuser detection in wireless Direct Sequence-Code Division Multiple Access (DS- CDMA).The first part presents a new duplex method, called Zipper, for Very High bit rate Digital Subscriber Lines (VDSL). It is a duplex method that offer high flexibility and compatibility with existing services in the access network. The second part presents a digital Radio Frequency Interference (RFI) suppression method. It is located in the frequency domain and it can be used by any DMT-based VDSL system. The third part presents a method to run Zipper in an asynchronous mode with only a small performance loss. This can be of interest for telecom operators when constructing a VDSL system. The fourth part examines the trade-off between pilot symbol spacing and symbol error rate in a wireless OFDM system using Pilot Symbol Assisted Modulation (PSAM). The last part presents a low complexity multiuser detector for wireless DS-CDMA. It consists of a pipelined detector structure that produces Maximum Likelihood Secence Detector (MLSD) decisions on some of the received bits in the sequence. The remaining, previously undetected bits, are fed to a secondary post-processor.Godkänd; 1999; 20070404 (ysko)
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Moussa, Badi M. S. "Adaptive transform coding for digital image communication." Thesis, Loughborough University, 1985. https://dspace.lboro.ac.uk/2134/27360.
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The performance of transform image coding schemes can be improved substantially by adapting to changes in image statistics. Essentially, this is accomplished through adaptation of the transform, bit allocation, and/or quantization parameters according to time-varying image statistics. Additionally adaptation can be used to achieve transmission rate reduction whilst maintaining a given picture quality.
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Sandberg, Sara. "Modulation and channel effects in digital communication /." Luleå : Luleå University of Technology, 2005. http://epubl.luth.se/1402-1757/2005/49.
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Bradley, Martin James. "Adaptive equalisation for fading digital communication channels." Thesis, Durham University, 1996. http://etheses.dur.ac.uk/5177/.
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This thesis considers the design of new adaptive equalisers for fading digital communication channels. The role of equalisation is discussed in the context of the functions of a digital radio communication system and both conventional and more recent novel equaliser designs are described. The application of recurrent neural networks to the problem of equalisation is developed from a theoretical study of a single node structure to the design of multinode structures. These neural networks are shown to cancel intersymbol interference in a manner mimicking conventional techniques and simulations demonstrate their sensitivity to symbol estimation errors. In addition the error mechanisms of conventional maximum likelihood equalisers operating on rapidly time-varying channels are investigated and highlight the problems of channel estimation using delayed and often incorrect symbol estimates. The relative sensitivity of Bayesian equalisation techniques to errors in the channel estimate is studied and demonstrates that the structure's equalisation capability is also susceptible to such errors. Applications of multiple channel estimator methods are developed, leading to reduced complexity structures which trade performance for a smaller computational load. These novel structures are shown to provide an improvement over the conventional techniques, especially for rapidly time-varying channels, by reducing the time delay in the channel estimation process. Finally, the use of confidence measures of the equaliser's symbol estimates in order to improve channel estimation is studied and isolates the critical areas in the development of the technique — the production of reliable confidence measures by the equalisers and the statistics of symbol estimation error bursts.
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Jalali, Sammuel. "Wireless Channel Equalization in Digital Communication Systems." Scholarship @ Claremont, 2012. http://scholarship.claremont.edu/cgu_etd/42.
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Our modern society has transformed to an information-demanding system, seeking voice, video, and data in quantities that could not be imagined even a decade ago. The mobility of communicators has added more challenges. One of the new challenges is to conceive highly reliable and fast communication system unaffected by the problems caused in the multipath fading wireless channels. Our quest is to remove one of the obstacles in the way of achieving ultimately fast and reliable wireless digital communication, namely Inter-Symbol Interference (ISI), the intensity of which makes the channel noise inconsequential.
The theoretical background for wireless channels modeling and adaptive signal processing are covered in first two chapters of dissertation.
The approach of this thesis is not based on one methodology but several algorithms and configurations that are proposed and examined to fight the ISI problem. There are two main categories of channel equalization techniques, supervised (training) and blind unsupervised (blind) modes. We have studied the application of a new and specially modified neural network requiring very short training period for the proper channel equalization in supervised mode. The promising performance in the graphs for this network is presented in chapter 4.
For blind modes two distinctive methodologies are presented and studied. Chapter 3 covers the concept of multiple "cooperative" algorithms for the cases of two and three cooperative algorithms. The "select absolutely larger equalized signal" and "majority vote" methods have been used in 2-and 3-algoirithm systems respectively. Many of the demonstrated results are encouraging for further research.
Chapter 5 involves the application of general concept of simulated annealing in blind mode equalization. A limited strategy of constant annealing noise is experimented for testing the simple algorithms used in multiple systems. Convergence to local stationary points of the cost function in parameter space is clearly demonstrated and that justifies the use of additional noise. The capability of the adding the random noise to release the algorithm from the local traps is established in several cases.
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Wong, Dennis Mou Ling. "Automatic classification of digital communication modulation schemes." Thesis, University of Liverpool, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.400128.
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Mokhtar, Makhfudzah. "Improved digital ternary performance in optical communication." Thesis, University of Essex, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438135.
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Goh, Cheh-Ngee. "Random multiple access in digital communication networks." Thesis, Imperial College London, 1988. http://hdl.handle.net/10044/1/47079.
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Zhu, Zhechen. "Automatic classification of digital communication signal modulations." Thesis, Brunel University, 2014. http://bura.brunel.ac.uk/handle/2438/9246.
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Automatic modulation classification detects the modulation type of received communication signals. It has important applications in military scenarios to facilitate jamming, intelligence, surveillance, and threat analysis. The renewed interest from civilian scenes has been fuelled by the development of intelligent communications systems such as cognitive radio and software defined radio. More specifically, it is complementary to adaptive modulation and coding where a modulation can be deployed from a set of candidates according to the channel condition and system specification for improved spectrum efficiency and link reliability. In this research, we started by improving some existing methods for higher classification accuracy but lower complexity. Machine learning techniques such as k-nearest neighbour and support vector machine have been adopted for simplified decision making using known features. Logistic regression, genetic algorithm and genetic programming have been incorporated for improved classification performance through feature selection and combination. We have also developed a new distribution test based classifier which is tailored for modulation classification with the inspiration from Kolmogorov-Smirnov test. The proposed classifier is shown to have improved accuracy and robustness over the standard distribution test. For blind classification in imperfect channels, we developed the combination of minimum distance centroid estimator and non-parametric likelihood function for blind modulation classification without the prior knowledge on channel noise. The centroid estimator provides joint estimation of channel gain and carrier phase o set where both can be compensated in the following nonparametric likelihood function. The non-parametric likelihood function, in the meantime, provide likelihood evaluation without a specifically assumed noise model. The combination has shown to have higher robustness when different noise types are considered. To push modulation classification techniques into a more timely setting, we also developed the principle for blind classification in MIMO systems. The classification is achieved through expectation maximization channel estimation and likelihood based classification. Early results have shown bright prospect for the method while more work is needed to further optimize the method and to provide a more thorough validation.
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Jamil, Izdihar Bt. "Communication patterns around multi-touch digital tabletops." Thesis, University of Bristol, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.633228.
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With advances in digital tabletop technology and increased levels of affordability in recent years, there has been growing interest in exploring multi-touch digital tabletops within educational contexts. Multi-touch digital tabletops offer simultaneous touch input facilities and a face-to-face communication platform- beneficial and attractive features for collaboration. This thesis focuses on understanding the communication patterns when children interact around digital tabletops within a learning environment. This thesis proposes three main contributions: 1) an analysis of the talk patterns between children when they collaborate around digital tabletops 2) the behavioural patterns of how children in India collaborate around digital tabletops and 3) the behavioural patterns of how children in multiple countries interact around digital tabletops. These findings highlight the importance of understanding the conversation styles and the behavioural patterns of children collaborating around multi-touch digital tabletops within an educational context. Moreover, understanding the communication patterns and interaction styles that occur within a multiple country setting provide an access such that any technological deployment can have a positive impact on their local users.
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Perez, Michael A. "Digital Public: Materializing the Space of Communication." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1423581096.
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Spiez, Michal Krzysztof. "Light communication - digital interface : USB - optical receiver." Master's thesis, Universidade de Aveiro, 2008. http://hdl.handle.net/10773/2038.
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Mestrado em Engenharia Electrónica e TelecomunicaçõesOs sistemas de comunicação por luz visível surgem como uma alternativa aos tradicionais sistemas de comunicação ópticos por raios infravermelhos. Esta alternativa tem por base a rápida evolução dos dispositivos de iluminação de estado sólido. Até há bem pouco tempo, as tradicionais lâmpadas incandescentes ou fluorescentes dominavam a tecnologia de iluminação. Recentemente, os dispositivos de estado sólido, como por exemplo, os LEDs (Light Emiting Diodes) de alta intensidade, tem evidenciado as suas vantagens neste domínio: maior eficiência, durabilidade e preço de fabrico. Adicionalmente estes dispositivos possibilitam outros domínios de aplicação, que não sejam exclusivamente a iluminação. A possibilidade de comutação rápida destes dispositivos torna-os adequados ao emprego em sistemas de comunicação tendo por base a luz visível. No âmbito deste trabalho pretendeu-se desenvolver um sistema de comunicação por luz visível capaz de servir o propósito de validação de conceito. Para tal, consideraram-se duas tarefas distintas: a concepção dos sistemas electrónicos de emissão-recepção de sinais ópticos, e o sistema de processamento de dados. O sistema de processamento de dados foi em particular o que definiu o tema desta dissertação. De forma a tornar o processo de geração e descodificação simples e eficiente, optou-se por recorrer ao protocolo USB. Desta forma tentou-se implementar uma solução que do ponto de vista do utilizador fosse tão simples como a utilização de um qualquer periférico plug-play num PC. Esta dissertação discute a implementação deste sistema de processamento de dados, tendo como recursos disponíveis uma placa de aquisição de dados em formato USB, e acessórios de electrónica digital reconfigurável. ABSTRACT: Visible light communication systems appear as a suitable alternative to the more traditional Infra-Red optical communication systems. This possibility is motivated by the fast evolution of solid-state lighting devices. Traditional incandescent and fluorescent light bulbs have been the unique solutions for the illumination purpose for years. Solid-state lighting devices, as for instance high brightness LEDs (Light Emitting Diodes), have become available. These devices present several advantages over the traditional light bulbs: they are more power efficient, they have lower production costs, and increased durability. Additionally, solid-state lighting devices present the useful property of fast switching, which makes them suitable for communication purposes, employing visible light. The main objective of this project was to develop a visible light communication system able to provide a practical demonstration test-bed for this new technology. In order to fulfill this objective, two separate tasks have been foreseen: The optical receiver-transmitter able to cope with the visible light requirements; and the data processing system. This dissertation was focused on the data processing system. USB protocol was chosen in order to simplify the processes of data generation and recovery. This would make the final systems as simple to use as any other USB plug-and-play device. This dissertation discusses the implementation of the data processing system, using one standard USB acquisition board plus digital reconfigurable electronic devices.
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Glass, Abdullatif M. "Digital communication networks incorporating mobile data terminals." Thesis, Aston University, 1989. http://publications.aston.ac.uk/8086/.
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The use of digital communication systems is increasing very rapidly. This is due to lower system implementation cost compared to analogue transmission and at the same time, the ease with which several types of data sources (data, digitised speech and video, etc.) can be mixed. The emergence of packet broadcast techniques as an efficient type of multiplexing, especially with the use of contention random multiple access protocols, has led to a wide-spread application of these distributed access protocols in local area networks (LANs) and a further extension of them to radio and mobile radio communication applications. In this research, a proposal for a modified version of the distributed access contention protocol which uses the packet broadcast switching technique has been achieved. The carrier sense multiple access with collision avoidance (CSMA/CA) is found to be the most appropriate protocol which has the ability to satisfy equally the operational requirements for local area networks as well as for radio and mobile radio applications. The suggested version of the protocol is designed in a way in which all desirable features of its precedents is maintained. However, all the shortcomings are eliminated and additional features have been added to strengthen its ability to work with radio and mobile radio channels. Operational performance evaluation of the protocol has been carried out for the two types of non-persistent and slotted non-persistent, through mathematical and simulation modelling of the protocol. The results obtained from the two modelling procedures validate the accuracy of both methods, which compares favourably with its precedent protocol CSMA/CD (with collision detection). A further extension of the protocol operation has been suggested to operate with multichannel systems. Two multichannel systems based on the CSMA/CA protocol for medium access are therefore proposed. These are; the dynamic multichannel system, which is based on two types of channel selection, the random choice (RC) and the idle choice (IC), and the sequential multichannel system. The latter has been proposed in order to supress the effect of the hidden terminal, which always represents a major problem with the usage of the contention random multiple access protocols with radio and mobile radio channels. Verification of their operation performance evaluation has been carried out using mathematical modelling for the dynamic system. However, simulation modelling has been chosen for the sequential system. Both systems are found to improve system operation and fault tolerance when compared to single channel operation.
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Dallmeier-Tiessen, Sünje. "Drivers and barriers in digital scholarly communication." Doctoral thesis, Humboldt-Universität zu Berlin, Philosophische Fakultät I, 2014. http://dx.doi.org/10.18452/16926.
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Zwei Innovationen innerhalb von Open Science werden in dieser Dissertation untersucht: Open Access und der Umgang mit Forschungsdaten. Die Ergebnisse zeigen ein positives Meinungsbild gegenüber beiden Innovationen, was sich allerdings nicht in einer übergreifenden Umsetzung in der Wissenschaft niederschlägt. Die disziplinären Unterschiede sind markant. Es lassen sich aber übergeordnete Ebenen herausarbeiten: Soziologische, technische & infrastrukturelle, sowie strategische & monetäre Aspekte gehören hierzu, wobei starke Interdependenzen zu verorten sind. Traditionell werden Qualität und Prestige von veröffentlichten wissenschaftlichen Ergebnissen als Maßgabe für die Reputation eines Wissenschaftlers angesehen, was klar in den Resultaten dieser Arbeit reflektiert ist. Sie präferieren die Nutzung von Publikationsorganen und Arbeitsabläufen, die in der Fachgemeinschaft etabliert sind. Daraus folgt ein zögerlicher Umgang mit Innovationen, z.B. dem offenem Zugang zu Forschungsdaten, wo es nur wenige etablierte Abläufe gibt. In der Diskussion dieser Arbeit wird die Notwendigkeit einer Verbindung zu heutigen Anreizsystemen und damit den Evaluierungssystemen in der Wissenschaft herausgestellt. Neue Strategien diesbezüglich sind im Aufbau, z.B. mit “zählbaren” Publikationen und Zitationen für Forschungsdaten. Die Kernthemen wurden in der Fallstudie der Hochenergiephysik genauer untersucht. Eine digitale Bibliothek erlaubte dort die praktische Implementierung von Open Science Werkzeugen. Die Ergebnisse unterstreichen das Potential: mit gezielten Diensten und Anreizen können Wissenschaftler für Open Science gewonnen werden; in diesem Fall zur Teilnahme in einem Crowdsourcingprojekt der digitalen Bibliothek und zur Umsetzung von „data sharing“. Dem Informationsmanagement kommt dabei eine neue Rolle zu, insbesondere bei einer engen Betreuung von Wissenschaftlern im digitalen Forschungsumfeld. Das kann parallel für die Serviceentwicklung und –begleitung genutzt werden.Two major Open Science innovations, Open Access and research data sharing, have been studied in detail in this thesis. A large-scale survey and personal interviews are used to gain detailed insights from a range of disciplines. In addition, a case study in the High Energy Physics (HEP) community was used to study the results in practice. The results show that a rather positive attitude towards both, Open Access and research data sharing is not reflected in the researchers’ practices. Disciplinary differences prevail and relate to the different publishing cultures and research workflows. The results indicate that quality and prestige of research output are perceived as very important in determining a researcher’s reputation. Researchers prefer community-approved publication outlets. They hesitate to explore new innovations, such as data sharing, for which only few established workflows exist in digital scholarly communication. Interviewees highlight the significance of a (missing) link between such approaches on the one hand and the current incentive system and the research assessment schemes on the other. The results indicate that barriers can be overcome. In the case study, a strong collaboration with the community facilitated enhanced feedback loops to develop tailored and targeted services for Open Science. Researchers in the case study were successfully engaged in new innovative workflows: a crowdsourcing tool and data sharing in a digital library. The results highlight that opportunities of Open Science are not yet explored widely. But with targeted support, it is possible to build on best practices and develop strategies that engage communities in new innovations. The results furthermore demand new strategies to establish links from Open Science services to the academic incentive system. It is needed to revisit the current research assessment scheme in regard to potential support mechanisms for Open Science.
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Frisch, Yannik Felix, and Jaakko Alarik Tawast. "Digital Sports Sponsorship : The Impact of Digital Communication Channels on Sponsorship Relationships." Thesis, Umeå universitet, Företagsekonomi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-164732.
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Supporters and spectators of sports club matches are often exposed to advertising of sponsors of the respective club. The most common exposure is to billboard ads, such as, e.g. LED screens on the side of the football pitch, the logo of sponsors embedded in the ice of an ice hockey rink or the logo of the sponsor on the athletes' jerseys. However, exposure does not mean engagement and engagement is what sponsors seek as it can increase the purchase intention of the supporters and spectators engaging with the company. With classical sponsorship approaches, it is hard to measure the number of supporters that actually engage with and eventually purchase from the sponsoring companies. Furthermore, the engagement approach that companies choose besides classical offline sponsorship is limited to occasional news updates or - at the most - highlights of matches. Therefore, the distance between sponsors and supporters is perceived as very wide by the latter. Digital communication channels and especially social media generally poses a good way to engage with supporters, but many companies fail to implement a strategic approach to social media communication.This study is aimed at analysing sports sponsorship in the light of digitalisation and wants to contribute to the scarce literature in the field. Sponsorship is a generally widely investigated and researched topic, and so is digital marketing. In current literature, these topics rarely appear closely linked to each other. Although many companies recognise the importance of digital communication tools for their sponsorship agreements, many fail to integrate it properly. Also, sports clubs often neglect the strategic implementation of digital communication. To fill this research gap, the study at hand wants to answer the following research question.“How is sports sponsorship effectiveness enhanced by the use of digital communication channels and by restructuring the relationships among all three stakeholders within the respective agreement?”An exploratory mixed methods study, which includes 115 questionnaire respondents as well as six expert interviews, was conducted to address this research question as well as the novelty of the research topic. The research was undertaken with a focus on Swedish football and ice hockey teams in professional divisions as well as their sponsors. The study yielded several results which contribute to the literature and show relevance for practice. Firstly, the study showed that all the stakeholders lack the knowledge of the aspiration of each other as well as structured communication strategies in digital channels. Secondly, the communication between clubs and sponsors is insufficient, and wishes, ideas and assumptions concerning a sponsorship agreement remain hidden to the other parties. Thirdly, the clubs, as well as the sponsors, fail to integrate the supporters' wishes and needs into the sponsorship approach, which impedes the effectiveness and the success of this agreement. Fourthly, clubs and sponsors fail to implement precise indicators for the success of a sponsorship deal.
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Earnshaw, Rae A. "Digital media." IEEE, 2001. http://hdl.handle.net/10454/3507.
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YesDevelopments and advances in information and communications technology are boosting a convergence of computing, media, and telecommunications. This is dramatically affecting every aspect of society from technology designers and content creators to users. The design-to-product cycle time continues to decrease as new markets open up, and windows of opportunity exist for those who can move fast and make the right connections. Challenges and opportunities exist in each area of the convergence, but one thing is here to stay: being digital.
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Rintala, Maja. "Democratic participation on digital conditions : communication challenges and opportunities for collective action organizations." Thesis, Umeå universitet, Institutionen för kultur- och medievetenskaper, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-185462.
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This thesis examines how communication technology is used for creating a democratic and committed participation within collective action organizations (CAOs). This is achieved by illuminating how organizations' structure and culture relate to their communication. It’s done by in-depth interviews with network-based movements and association-based organizations, and analyses of their digital newsletters. The analysis is based on affordance-driven theory, capturing the interaction between organizations and their digital platforms. The focus lies on how internal democracy and collective action are afforded or constrained to some degrees. Degrees of deliberation for creating common ground and active participation are made visible by using the concept of communicative action. Theories within social movement studies, such as collective action, broaden the understanding of how the perception of digital tools shapes and is shaped by their structure and culture. The results show that the usage and coordination of communication channels is essential for the practice of internal democracy in everyday work, beyond annual meetings and board meetings. Independent chat-based platforms enable an increased control of conversations, cooperation and coordination, while information overload and effective decision- making processes can hinder democratic participation. Commercial social media platforms such as Facebook enables new flows of engagement and connectivity but constrains coordination and control of the framing process within Facebook groups. Additionally, unpredictable algorithms and advertising policy on Facebook makes it difficult to reach out. Overall, the study suggests a broadened view of communication, where communication and usage of digital media should not be considered as instrumental entities. Rather, it is strongly related to how channels are being coordinated, how organizations are organized and the view of participation. Formal structures can both hinder and enable increased communicative action that contributes to democratic participation.
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Söderström, Ulrik. "Very low bitrate video communication : a principal component analysis approach /." Umeå : Department of Applied Physics and Electronics, Umeå University, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1808.
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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.
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Spiniak, Juan (Spiniak Irarrazaval). "Digital help service opportunities for communication service providers in the convergent digital home." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/67570.
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Thesis (S.M. in Engineering and Management)--Massachusetts Institute of Technology, Engineering Systems Division, System Design and Management Program, February 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 97-100).
Homes are becoming increasingly connected as new technologies allow users to access media and information from any-device at anytime. Notebooks, HDTVs, smartphones, media servers, photo cameras, and video cameras, all form part of this new digital ecosystem where - the vision says - information and content will flow easily across devices, enabled by simple and intuitive user interfaces. These new home technologies are, however, often too complex for most users. Only "digital-natives" or technology savvy groups have the necessary skills, knowledge or confidence to adopt them and to use them effectively. For the rest, trying them becomes painful and frustrating. Moreover, the ecosystem itself adds confusion, given the large number of players involved and the many different kinds of relationships. Unless a dominant player gains enough power to establish a dominant digital home architecture, or this happens in some other way, most companies will continue to innovate around device-specific features that don't address the overall complexity of the complete systems that users have to work with. Digital help services can assist users by simplifying the selection, installation, learning and troubleshooting of new services and devices; facilitating the adoption of new convergent technologies. There is a broad range of potential services, including, for example, 'over the top' (OTT) television integration, smartphone mentoring services, WiFi network configuration and desktop support services. Communication service providers should pay close attention to digital help services as an opportunity to differentiate their offer, strengthen their relationship with end-customers, reduce customer support costs and simplify the adoption of bandwidth-intensive technologies. Moreover, digital help services can speed up the adoption of OTT television services, and companies can use them strategically. The technology help space is evolving and communication service providers need to figure out how they want to participate: offer help services themselves; partner or acquire a existing technology support company; and/or create an open marketplace for technology help services.
by Juan Spiniak.
S.M.in Engineering and Management
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Enqvist, Delia Ni Chiobhain. "Digital Maritime Sights : Digital visual documentation and communication in Scandinavian contract maritime archaeology." Licentiate thesis, Linnéuniversitetet, Institutionen för kulturvetenskaper (KV), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-77244.
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This licentiate thesis investigates the use of digital visualisations for knowledge production and communication of maritime heritage located underwater. The archaeological practice that takes place in response to development, contract archaeology, is the field that is being investigated. Much of the practical and administrative aspects of contract maritime work involves the survey, excavation and interpretation of archaeological remains. In addition, shifts in heritage policy emphasise that the results of this work move beyond their own value to provide access and democratic participation to heritage and be of benefit to society (e.g. Faro Convention, 2005). Since the inaccessibility of maritime archaeology underwater makes outreach especially challenging, digital, and in particular 3D, technologies have been recognised as having great potential to meet the needs of both maritime archaeological researchers and public audiences. Advances in methodologies for digitally documenting and visualising archaeological sites, both on land and underwater, are providing a range of innovative and multidisciplinary solutions for both archaeological analysis and outreach activities. The aim of this research is to understand current uses of digital visualisation for knowledge production and communication of maritime archaeology located underwater, in order to identify knowledge gaps that would benefit from future research. This aim is met through a study drawn primarily from the fields of digital archaeology, maritime archaeology and heritage studies, as well as discourse and thematic analysis of the factors that influence the use of these technologies in the sector. The case study is the contract maritime archaeology sector in Scandinavia, with a primary focus on the practice in Sweden and also including perspectives from the Danish and Norwegian sectors. The results show that an emphasis on efficiency within the contract sector shapes the understanding and use of digital technologies, in some instances limiting their potential for archaeological interpretation and communication. While the maritime sector was found to be partly defined and restricted by a distinct identity, at times operating independently from mainstream archaeology, it was also found to be open to innovation. This represents great potential for digital workflows aimed at enhancing both interpretation and communication to be applied to the maritime archaeological sector in the future.
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Westerlund, Nils. "Counteracting acoustic disturbances in human speech communication /." Karlskrona : Blekinge Institute of Technology, 2006. http://www.bth.se/fou/Forskinfo.nsf/Sok/343efb30a0905236c125715d002ec160!OpenDocument.
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Wang, Yan. "New advances in synchronization of digital communication receivers." Texas A&M University, 2003. http://hdl.handle.net/1969.1/1594.
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Synchronization is a challenging but very
important task in communications. In digital communication systems, a hierarchy of synchronization problems has to be considered: carrier synchronization, symbol timing synchronization and frame synchronization. For bandwidth efficiency and burst transmission reasons, the former two synchronization steps tend to favor non-data aided (NDA or blind) techniques, while in general, the last one is usually solved by inserting repetitively known
bits or words into the data sequence, and is referred to as a data-aided (DA) approach.
Over the last two decades, extensive research work has been carried out to design nondata-aided timing recovery and carrier synchronization algorithms. Despite their importance and spread
use, most of the existing blind synchronization algorithms are derived in an ad-hoc manner without exploiting optimally the entire available statistical information. In most cases their
performance is evaluated by computer simulations, rigorous and complete performance analysis has not been performed yet. It turns out that a theoretical oriented approach is indispensable for
studying the limit or bound of algorithms and comparing different methods.
The main goal of this dissertation is to develop several novel signal processing frameworks that enable to analyze and improve
the performance of the existing timing recovery and carrier synchronization algorithms. As byproducts of this analysis, unified methods for designing new computationally and statistically efficient (i.e., minimum variance estimators)
blind feedforward synchronizers are developed.
Our work consists of three tightly coupled research directions. First, a general and unified framework is proposed to develop optimal nonlinear least-squares (NLS) carrier recovery scheme for burst transmissions. A family of
blind constellation-dependent optimal "matched" NLS carrier estimators is proposed for synchronization of burst transmissions fully modulated by PSK and QAM-constellations in additive white Gaussian noise
channels. Second, a cyclostationary statistics
based framework is proposed for designing computationally and statistically efficient robust blind symbol timing recovery for time-selective flat-fading channels. Lastly, dealing with the problem of frame synchronization, a simple and efficient data-aided approach is
proposed for jointly estimating the frame boundary, the frequency-selective channel and the carrier frequency offset.
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Groff, Wayne C. "Predetection filter design for practical digital communication systems." Thesis, University of Ottawa (Canada), 1989. http://hdl.handle.net/10393/5585.
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Hashimi, Seyed Bahauddin. "Coded modulation techniques for digital mobile communication systems." Thesis, Staffordshire University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321787.
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Mahmood, Intesar S. "Scientific communication in Libya in the digital age." Thesis, Manchester Metropolitan University, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.539404.
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Kaluarachchi, Eraj Dulip. "Digital pulse interval modulation for optical communication systems." Thesis, Sheffield Hallam University, 1997. http://shura.shu.ac.uk/9101/.
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Pulse time modulation (PTM) techniques have drawn considerable attention over the years as suitable schemes for transmission of information over optical fibres. PTM schemes are known to utilise the vast optical bandwidth to provide efficient transmission characteristics. Pulse code modulation is one such modulation scheme that has been used widely in various communication systems. In this thesis digital pulse interval modulation (DPIM), a form of PTM, is proposed as a suitable modulation scheme for optical communication systems. In this scheme the information is represented by means of varying the anisochronous frame interval between two successive pulses. Each pulse fulfils the dual role of representing the frame boundaries and initiation of the next sampling event within the modulator or sample reconstruction in the demodulator. In this study DPIM frame structure is proposed and sampling criteria, information capacity, bandwidth requirements are discussed in depth. The spectral behaviour of the scheme is investigated and a mathematical model is developed to represent the spectra. The model was numerically evaluated and verified with the practical measurements to prove its validity. Spectral predictions were made for random as well as periodic information signals showing the existence of the distinct slot frequency component, which is used for slot synchronisation. Frame synchronisation is not required as DPIM has self synchronised frame structure. For random signals, slot component is found to be about 15 dB and for periodic single tone sinusoidal signal this was at about 5 dB. Dependency of this component on the various system parameters such as bit resolution, pulse width, pulse shape are discussed. A detailed account of the receiver performance is given. Receiver analysis was carried out for narrow band as well as for wide band channels. Possible error sources are presented and the system performance degradation with these error sources is discussed and a comparison is made with isochronous DPPM and PCM. For performance evaluation of analogue systems, signal-to-noise ratio was mathematically modelled and compared with PCM. This analysis showed that DPIM SNRs shows three important regions as compared to PCM. That is when the SNR is inferior, superior and identical to PCM performance. Threshold levels corresponding to the above regions vary depending on the system bit resolution. A prototype DPIM system was designed and implemented to transmit low speed analogue signal (≈15 kHz) at bit resolutions of 4, 5 and 6 where the slot frequencies are at 510, 990 and 1950 kHz, respectively. Measurements were carried out in order to verify the predicted performance. This results showed close agreement with the predicted. Receiver sensitivity of the prototype at bit error rate of 10-9 was found to be about -45.5 dBm at all three cases with transmitted average power of -28.8 dBm allowing high optical power budget. The signal-to-noise ratio threshold level of the system was at -47 dBm. Finally, linearity measurements of the overall system were made at the above bit resolutions and the quantitative and qualitative results are presented.
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Goldfarb, Gilad. "DIGITAL SIGNAL PROCESSING TECHNIQUES FOR COHERENT OPTICAL COMMUNICATION." Doctoral diss., University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2893.
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Coherent detection with subsequent digital signal processing (DSP) is developed, analyzed theoretically and numerically and experimentally demonstrated in various fiber‐optic transmission scenarios. The use of DSP in conjunction with coherent detection unleashes the benefits of coherent detection which rely on the preservation of full information of the incoming field. These benefits include high receiver sensitivity, the ability to achieve high spectral‐efficiency and the use of advanced modulation formats. With the immense advancements in DSP speeds, many of the problems hindering the use of coherent detection in optical transmission systems have been eliminated. Most notably, DSP alleviates the need for hardware phase‐locking and polarization tracking, which can now be achieved in the digital domain. The complexity previously associated with coherent detection is hence significantly diminished and coherent detection is once again considered a feasible detection alternative. In this thesis, several aspects of coherent detection (with or without subsequent DSP) are addressed. Coherent detection is presented as a means to extend the dispersion limit of a duobinary signal using an analog decision‐directed phase‐lock loop. Analytical bit‐error ratio estimation for quadrature phase‐shift keying signals is derived. To validate the promise for high spectral efficiency, the orthogonal‐wavelength‐division multiplexing scheme is suggested. In this scheme the WDM channels are spaced at the symbol rate, thus achieving the spectral efficiency limit. Theory, simulation and experimental results demonstrate the feasibility of this approach. Infinite impulse response filtering is shown to be an efficient alternative to finite impulse response filtering for chromatic dispersion compensation. Theory, design considerations, simulation and experimental results relating to this topic are presented. Interaction between fiber dispersion and nonlinearity remains the last major challenge deterministic effects pose for long‐haul optical data transmission. Experimental results which demonstrate the possibility to digitally mitigate both dispersion and nonlinearity are presented. Impairment compensation is achieved using backward propagation by implementing the split‐step method. Efficient realizations of the dispersion compensation operator used in this implementation are considered. Infinite‐impulse response and wavelet‐based filtering are both investigated as a means to reduce the required computational load associated with signal backward‐propagation. Possible future research directions conclude this dissertation.Ph.D.
Optics and Photonics
Optics and Photonics
Optics PhD
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Wentzloff, David D. (David Dale) 1977. "Pulse-based ultra-wideband transmitters for digital communication." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40546.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.Includes bibliographical references (p. 113-123).
Ultra-wideband radio (UWB) is a rapidly developing wireless technology that promises unprecedented data rates for short-range commercial radios, combined with precise locationing and high energy efficiency. These benefits stem from the use of wide bandwidths and impulse signaling, implying high channel capacity and precise time resolution. UWB has been used for military radar and imaging since the 1950's; however, in 2002 the Federal Communications Commission approved the use of the 3.1-10.6GHz band for unlicensed UWB applications. The restriction on transmitted power spectral density in this band is equal to the noise emission limit of household digital electronics. This band is also shared with several existing services, therefore in-band interference is expected and presents a challenge to UWB system design. This thesis covers the aspects of pulse generation and transmitter implementation for pulsed-UWB communication by exploring tradeoffs that can be made in the pulse shaping in order to reduce power consumption in the transmitter electronics. A transmitter has been developed that exploits the exponential properties of a BJT to approximate a Gaussian shape. It generates BPSK modulated pulses at 100Mb/s in one of 14 channels in the 3.1-10.6GHz band, targeting high data rate applications. The transmitter has been fabricated in a 0.18pm SiGe BiCMOS process, and experimental results are presented. A second transmitter has been developed that uses an all-digital architecture.
(cont.) This architecture is made practical by relaxing the RF frequency tolerance, suitable for communication with an energy detection receiver using pulse position modulation. By using an all-digital architecture, energy is consumed only in CV2 switching losses and subthreshold leakage currents, and no RF oscillator or analog bias currents are required. This transmitter has been fabricated in a 90nm digital CMOS process, and demonstrated in a 16.7Mb/s wireless link.
by David D. Wentzloff.
Ph.D.
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Curry, Elam, and Javier Perez-Ramirez. "LED Communication Using a High Speed Digital Camera." International Foundation for Telemetering, 2014. http://hdl.handle.net/10150/577452.
Full textAbstract:
ITC/USA 2014 Conference Proceedings / The Fiftieth Annual International Telemetering Conference and Technical Exhibition / October 20-23, 2014 / Town and Country Resort & Convention Center, San Diego, CAAn optical communication system using a light-emitting diode (LED) as a transmitter and a high speed digital camera as a receiver is considered. The camera collects data at a rate of 1,200 frames per second (FPS). The pixel values are then processed using equal gain combining (EGC), best pixel selection (BPS), and maximal ratio combining (MRC) techniques. The bit error rate (BER) performance of these techniques is analyzed, and the effect of using different numbers of pixels for receiver processing is considered. The effect of the camera's pixel grid being at an angle with respect to the LED's direct path is experimentally explored.
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Newborough, Darryl. "Underwater position-fixing using digital acoustic communication techniques." Thesis, Loughborough University, 2002. https://dspace.lboro.ac.uk/2134/36078.
Full textAbstract:
This thesis describes an intelligent underwater acoustic system that allows the positions of several divers or Remotely Operated Vehicles (ROV) to be tracked in three-dimensional space and to telemeter the co-ordinates to a remote receiver at the surface. The positions are fixed using three randomly deployed seabed transponders that may be described as intelligent. The transponders fix their own relative positions and the position of the surface receiver, usually a vessel, by an exchange of coded acoustic pulses. These positions can be related to a differential GPS system at the surface if absolute coordinates are required. An underwater acoustic positioning and communication system can provide a vital navigation aid for a diver and surface supervisor. Often underwater positioning systems only provide the surface supervisor with diver's positions, with the diver navigating from voiced instruction via an acoustic or wire link communication. In the system described the divers each know their own position from a wrist-worn computer with a backlit graphical/numerical display. As well as the current position, the display can show the track from the beginning of the dive, the location of the surface vessel and the instantaneous position of the other divers.
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Asaduzzaman, A. S. M. "Digital Bangladesh : information and communication technology for empowerment?" Thesis, Goldsmiths College (University of London), 2013. http://research.gold.ac.uk/9608/.
Full textAbstract:
This study critically investigates the concept of “digital Bangladesh” putting it in the wider debates surrounding ICT for Development (ICT4D). The original contribution of this thesis is that it problematizes empowerment in ICT4D approach within the human development paradigm in the context of Bangladesh. The main argument of the thesis is that digital Bangladesh as the local manifestation of ICT for Development is both outcome and facilitator of neoliberal globalization. Another argument is that digital Bangladesh promotes entrepreneurship-oriented personal empowerment which is consistent with the neoliberal ideologies. The thesis involves two types of empirical study: discursive and ethnographic. To be precise, it conducts a critical analysis of the National ICT Policy 2009 with the aim of investigating how digital Bangladesh is discursively constructed by it. The findings of the analysis show that the Policy constructs a positive discourse of digital Bangladesh. Most importantly, parroting ICT4D, the Policy propagates the idea that ICT can bring about progress in all areas of the lives of the citizenry, particularly social equity, education, healthcare and economic growth. The entire National ICT Policy is permeated by technological determinism. On the micro level, ethnographically designed fieldwork was conducted at three telecentres located at three districts. Findings show that the telecentres served predominantly the privileged sections of rural societies (i.e. literate, young men and women), by providing either services based on computer, the Internet and the Web, or computer-education. Peasants and other marginalized populations that form the majority of rural populations were invisible at the centres. Analysed from an empowerment approach based on social power, the findings suggest that the telecentres could hardly bring about empowerment and human development in the lives of the people involved with them in different ways. They at best contributed to the entrepreneurs’ achievement of self-reliance, which is consistent with neoliberalism.
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Weiss, Charles Tabor. "Use of Digital Technologies in Graphic Communication Education." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/27734.
Full textAbstract:
This study investigated the use of digital technologies in secondary and post-secondary graphic communication education. Specifically it investigated: 1) the extent to which graphic communication educators utilized digital technologies in conjunction with instruction; 2) how selected factors affected graphic communication teachersâ implementation of digital technologies in their instruction; and, 3) how selected factors affected teacher and learner-centered instructional practices.
The Levels of Technology Implementation (LoTi) and â Technology Use Surveyâ instruments were administered to secondary and post-secondary graphic communication educators via the Web to assess: 1) the frequency of use of 17 different digital technologies; 2) the nature and level of digital technology implementation; 3) current instructional practices; and 4) demographic characteristics.
Graphic communication educators (n = 191) responding to the survey utilized a wide variety of digital technologies as part of their instruction. The data indicated that most students in graphic communication classes use computers, page layout software, and the Internet (for accessing digital content) â almost daily.â Most graphic communication students were creating and/or editing vector and raster graphics â several times a week.â Most graphic communication teachers reported student use of digital still cameras, digital instructional tutorials and the Internet (to solve technical problems) was limited to â several times a month,â while most students were creating digital multimedia projects only â several times each year.â Most respondents chose â neverâ to describe studentsâ use of: digital video cameras, digital drawing tablets, creating and/or editing Web pages with a WYSIWYG or HTML editors, digital spreadsheets, digital databases, and digital animations. Findings from this study further indicate graphic communication educators demonstrate high to extremely high skill levels using computers for personal use and implement digital technologies in ways that begin to shift the learning environment from teacher-centered to student-centered, but may not be effectively updating their curriculum to reflect current graphic communication industry workforce needs.Ph. D.
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Ganz, Matthew W. "Performance of digital communication systems with adaptive arrays /." The Ohio State University, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487267024994974.
Full text
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Namprempre, Chanathip. "Simultaneously ensuring privacy and authenticity in digital communication /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2002. http://wwwlib.umi.com/cr/ucsd/fullcit?p3061642.
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Chalustowski, Jan Francis. "Digital video communication : interpretive frameworks of key stakeholders." Thesis, Queensland University of Technology, 1996. https://eprints.qut.edu.au/36280/1/36280_Chalustowski_1996.pdf.
Full textAbstract:
Digital Video Communication (DVC) is an emerging technology which ultimately extends to
include applications of "Virtual Reality" where both computers and participants interact in
created worlds: "worlds of information, hubs, data bases and networks," which overlay "the
physical manifestations of power, walls, boundaries, highways and cities" (Mulgan, 1991,
p.3). This new technology combines the power of the current visual media with the power of
the computer, creating an intelligent communication system with increased data capacity,
greater reliability and a greater potential for synergism.
The direction and development of DVC can be influenced by the key stakeholders with
interests in the business, industry service and entertainment sector of technology. Knowledge
of the interpretive frameworks that key stakeholders use to understand DVC may help to
clarify the present and future courses of DVC. In particular the possibility of public
influence on the emergence of DVC is examined.
This study, then, is an attempt to describe the ways in which key stakeholders understand the
emergence of DVC as revealed by their communication about DVC. The analysis therefore
emerges from the described experiences of the people who comprise the study group To achieve this, detailed secondary analyses of interviews with twenty of Australia's key
stakeholders in the emergence of DVC were conducted. Follow-up interviews were
conducted with twelve of the original respondents to review the original transcripts as well as
to establish a longitudinal perspective. Theoretically, the study is anchored in the debate
regarding technological determinism. The thesis takes the perspective that an extreme
determinist stance must be rejected as part of the process of making decisions and
implementation of this emerging technology.
The themes of analysis revealed in the study were:
• The Technological Mindset,
• The Economic Rationalist Mindset,
• Decision Making, Control and Knowledge,
• Participation and Consultation,
• New Technology and Information Access.
In place of a deterministic model for technology, DVC will be viewed as being socially
constructed. However, it is argued that a holistic, co-evolutionary approach be adopted for
introducing new technologies such as DVC where there is an emphasis on human values and
human actions which affect future systems outcomes (Stevenson, 1992). In sum, this thesis will argue that the process of technological development ought to be open
to the influence by the "collective will." This development should not assume the diffusion
of technology through society and thereby become a singular power of repressive interest to
enforce ownership and participation (Hill, 1988), but rather it should merge economic and
social goals with individual goals, and in doing so, recognise that different types of ends must
necessarily co-exist in any system of communication (Mulgan, 1991).