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Dissertations / Theses on the topic 'Radio Electrical engineering'
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1
Manley, Jason Ryan. "A scalable packetised radio astronomy imager." Doctoral thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/15573.
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Includes bibliographical referencesModern radio astronomy telescopes the world over require digital back-ends. The complexity of these systems depends on many site-specific factors, including the number of antennas, beams and frequency channels and the bandwidth to be processed. With the increasing popularity for ever larger interferometric arrays, the processing requirements for these back-ends have increased significantly. While the techniques for building these back-ends are well understood, every installation typically still takes many years to develop as the instruments use highly specialised, custom hardware in order to cope with the demanding engineering requirements. Modern technology has enabled reprogrammable FPGA-based processing boards, together with packet-based switching techniques, to perform all the digital signal processing requirements of a modern radio telescope array. The various instruments used by radio telescopes are functionally very different, but the component operations remain remarkably similar and many share core functionalities. Generic processing platforms are thus able to share signal processing libraries and can acquire different personalities to perform different functions simply by reprogramming them and rerouting the data appropriately. Furthermore, Ethernet-based packet-switched networks are highly flexible and scalable, enabling the same instrument design to be scaled to larger installations simply by adding additional processing nodes and larger network switches. The ability of a packetised network to transfer data to arbitrary processing nodes, along with these nodes' reconfigurability, allows for unrestrained partitioning of designs and resource allocation. This thesis describes the design and construction of the first working radio astronomy imaging instrument hosted on Ethernet-interconnected re- programmable FPGA hardware. I attempt to establish an optimal packetised architecture for the most popular instruments with particular attention to the core array functions of correlation and beamforming. Emphasis is placed on requirements for South Africa's MeerKAT array. A demonstration system is constructed and deployed on the KAT-7 array, MeerKAT's prototype. This research promises reduced instrument development time, lower costs, improved reliability and closer collaboration between telescope design teams.
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Tsoeunyane, Lekhobola Joachim. "RHINO software-defined radio processing blocks." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/20102.
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This MSc project focuses on the design and implementation of a library of parameterizable, modular and reusable Digital IP blocks designed around use in Software-Defined Radio (SDR) applications and compatibility with the RHINO platform. The RHINO platform has commonalities with the better known ROACH platform, but it is a significantly cut-down and lowercost alternative which has similarities in the interfacing and FPGA/Processor interconnects of ROACH. The purpose of the library and design framework presented in this work aims to alleviate some of the commercial, high cost and static structure concerns about IP cores provided by FPGA manufactures and third-party IP vendors. It will also work around the lack of parameters and bus compatibility issues often encountered when using the freely available open resources. The RHINO hardware platform will be used for running practical applications and testing of the blocks. The HDL library that is being constructed is targeted towards both novice and experienced low-level HDL developers who can download and use it for free, and it will provide them experience of using IP Cores that support open bus interfaces in order to exploit SoC design without commercial, parameter and bus compatibility limitations. The provided modules will be of particularly benefit to the novice developers in providing ready-made examples of processing blocks, as well as parameterization settings for the interfacing blocks and associated RF receiver side configuration settings; all together these examples will help new developers establish effective ways to build their own SDR prototypes using RHINO.
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Ngongoni, Chipo Nancy. "Neural cross-correlation for radio astronomy." Master's thesis, University of Cape Town, 2010. http://hdl.handle.net/11427/11427.
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Includes abstract.Includes bibliographical references (leaves 56-62).
Correlation engines are essential elements of most signal processing systems. Areas of applicability include image processing, speech synthesis and analysis, high energy physics, wireless and mobile communication systems, spread spectrum communication systems and even prosthetics. Finding cost effective and computationally less intensive engines is the thrust of most research. Neural networks have also been used as aids in making complex tasks relatively easy to process.
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Balakrishnan, Gautam. "Cognitive radio cooperative spectrum sensing." Thesis, California State University, Long Beach, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10252432.
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The effectiveness of a cognitive radio (CR) system depends mainly on involved spectrum sensing techniques. The main aim of CR is for effective utilization of the spectrum opportunistically by sharing it with secondary users (SUs), when the primary user (PU) is absent. In this project, cooperative spectrum sensing using weights based on the distance measures from the PU and Multitaper Method (MTM) method is briefly explained. The results show that MTM method provides more accurate threshold value compared to other methods for low signal to noise ratios (SNRs), hence improving the spectrum sensing technique. The results also show that MTM method requires a lesser number of Orthogonal Frequency Division Multiplexing (OFDM) sub-blocks compared to Periodogram (PE) for the same performance.
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Starrs, Gerard. "Measurement of the electrical properties of concrete at radio frequencies." Thesis, Edinburgh Napier University, 1994. http://researchrepository.napier.ac.uk/Output/6573.
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This thesis is a presentation of research into the elecrical properties of concrete at radio frequencies (1-1000 MHz). The physical properties of concrete are examined and found to be profoundly influenced by water both at gauging and at later stages of development. The merits of currently used test methods for quality assessment of concrete are discussed. The theory of polarization in dielectric materials is examined and a range of formulae suitable for frequency dispersion calculations in homogeneous and heterogeneous materials is presented. A review of previous research into the electrical properties of concrete at frequencies in and below the RF range, including a brief description of Ground Probe Radar techniques, is presented and the results discussed. A distinct shortage of data is found in the 100-1000 MHz range. The electrochemical properties of concrete are considered and their influence on the electrical properties is examined. A previous hypothesis in this area, based on the behaviour of ions in the mix water, is shown to be incorrect, but a new hypothesis relating the dielectric dispersion of fresh concrete to ionic effects at the surface of hydrating cement grains is proposed. The results from calculations based on the hypothesis are compared with available data at 1-1000 MHz and found to be in agreement. A geophysical explanation, previously derived for sedimentary rocks, is proposed as an influencing factor on the electrical properties of hardening concrete in the same frequency range. Measurement techniques at radio frequencies are considered and the application of these to concrete measurements is discussed with reference to two particular electrode systems at 1-100 MHz and 100-1000 MHz. A technique for calibrating out the effects of connector distortion is described and the results of tests presented. The results from a range of experiments on various concrete mixes in the 1-1000 MHz range are presented and discussed. The data obtained for fresh concrete agree very well with the hypothesis. The data for hardening concrete show a qualitative agreement with the relevant hypothesis. The probable effects on Ground Probe Radar signals of the dispersion observed for hardening concrete in the 100-1000 MHz range are discussed. Suggestions for further research are given.
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Harrison, Kyle. "Machine Learning for Radio Frequency Interference Flagging." Master's thesis, Faculty of Engineering and the Built Environment, 2021. http://hdl.handle.net/11427/33777.
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The field of radio frequency interference (RFI) flagging involves the identification of corrupted data within radio astronomy measurements. This work explores the application of supervised machine learning algorithms for RFI flagging, trained on real measurement data and simulated data with simulated RFI. The goal of this work is to investigate the prediction of RFI using specific machine learning algorithms; Naive Bayes Classifier, K-Nearest Neighbours Classifier, Random Forest Classifier, the U-Net convolution neural network and the Multilayer Perceptron. These algorithms are trained on real data, in which the ground truth includes inherent false positives, and simulated data where the ground truth positions of RFI are absolute. This is done through the use of time/frequency spectrogram data, relating to radio astronomy measurements, using the magnitudes and phases of each available polarization. Predictions for unseen test data are compared between algorithms, different implementations of those algorithms and each dataset. A specific implementation for data pre-processing is designed and implemented, utilizing a two dimensional filtering technique for feature construction. The goal of this method is intended to implement a means of injecting a form of spatial information of nearby time/frequency samples for each sample in a spectrogram. The inclusion of this spacial information, which is relevant to broadband bursts and narrowband persistent RFI, is hypothesised to increase the level of information present in the processed dataset. The use of feature construction using filtering techniques, demonstrates a noticeable improvement in the machine learning methods where each sample is treated individually during training and inference.
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Khalil, Karim. "Cooperation and Competition in Cognitive Radio Networks." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1398771432.
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Zhang, Yan. "Patch Antenna for 1420MHz Radio Telescope." Thesis, Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-1151.
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Patch antenna is one of the most rapidly popular topics in the antenna field in the past twenty years. In high-performance aircraft, spacecraft, satellite and missile applications, where size, weight, cost, performance, ease of installation, and aerodynamic profile are constraints, low profile antennas may be required. [7].
The project is to develop a single patch antenna operating on a specific frequency 1420MHz. The frequencies near to 1420MHz are worth to observe because the hydrogen in throughout of the space can be mapped by the observation of the 21 – cm wavelength line which is corresponding to 1420 MHz radiation. The final product antenna will be used in a radio telescope as a part of the signal receiving system.
The work within the project contains simulation, fabrication and test of final antenna. The simulation work was carried out in advanced design system which is developed by Agilent technologies, USA. The most different feature of the project is that, comparing to normal patch antenna, usually 50 ohms is selected as the matching impedance, while in this project we made it conjugate to the input impedance of the LNA. In this way we can save extra components, as well as energy consuming.
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Periola, Ayodele Abiola. "Efficient spectrum-handoff schemes for cognitive radio networks." Doctoral thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/24443.
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Radio spectrum access is important for terrestrial wireless networks, commercial earth observations and terrestrial radio astronomy observations. The services offered by terrestrial wireless networks, commercial earth observations and terrestrial radio astronomy observations have evolved due to technological advances. They are expected to meet increasing users' demands which will require more spectrum. The increasing demand for high throughput by users necessitates allocating additional spectrum to terrestrial wireless networks. Terrestrial radio astronomy observations s require additional bandwidth to observe more spectral windows. Commercial earth observation requires more spectrum for enhanced transmission of earth observation data. The evolution of terrestrial wireless networks, commercial earth observations and terrestrial radio astronomy observations leads to the emergence of new interference scenarios. For instance, terrestrial wireless networks pose interference risks to mobile ground stations; while inter-satellite links can interfere with terrestrial radio astronomy observations. Terrestrial wireless networks, commercial earth observations and terrestrial radio astronomy observations also require mechanisms that will enhance the performance of their users. This thesis proposes a framework that prevents interference between terrestrial wireless networks, commercial earth observations and terrestrial radio astronomy observations when they co-exist; and enhance the performance of their users. The framework uses the cognitive radio; because it is capable of multi-context operation. In the thesis, two interference avoidance mechanisms are presented. The first mechanism prevents interference between terrestrial radio astronomy observations and inter-satellite links. The second mechanism prevent interference between terrestrial wireless networks and the commercial earth observation ground segment. The first interference reductionmechanism determines the inter-satellite link transmission duration. Analysis shows that interference-free inter-satellite links transmission is achievable during terrestrial radio astronomy observation switching for up to 50.7 seconds. The second mechanism enables the mobile ground station, with a trained neural network, to predict the terrestrial wireless network channel idle state. The prediction of the TWN channel idle state prevents interference between the terrestrial wireless network and the mobile ground station. Simulation shows that incorporating prediction in the mobile ground station enhances uplink throughput by 40.6% and reduces latency by 18.6%. In addition, the thesis also presents mechanisms to enhance the performance of the users in terrestrial wireless network, commercial earth observations and terrestrial radio astronomy observations. The thesis presents mechanisms that enhance user performance in homogeneous and heterogeneous terrestrial wireless networks. Mechanisms that enhance the performance of LTE-Advanced users with learning diversity are also presented. Furthermore, a future commercial earth observation network model that increases the accessible earth climatic data is presented. The performance of terrestrial radio astronomy observation users is enhanced by presenting mechanisms that improve angular resolution, power efficiency and reduce infrastructure costs.
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Abel, Ajibesin Adeyemi. "Adaptive radio resource management for mobile satellite systems." Master's thesis, University of Cape Town, 2007. http://hdl.handle.net/11427/5228.
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Word processed copy.Includes bibliographical references (leaves 89-99).
In this thesis, a set of unique strategies and enhanced schemes for adaptive CDMA modulation are devised. A graded resource system is proposed for better radio resource management. Subsequently, a successful adaptive CDMA algorithm is designed and a prioritised processing gain for adaptive CDMA algorithm in satellite system is introduced. The idea of the critical section in the downlink system when a user controller scheme has to be activated to improve the performance is initiated. The diversity technique and rate compatible punctured turbo-code (RCPT), which has been found to give improved throughput performance in a direct sequence (DS) CDMA, are exploited.
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Scott, Simon. "RHINO: reconfigurable hardware interface for computation and radio." Master's thesis, University of Cape Town, 2011. http://hdl.handle.net/11427/11428.
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Field-programmable gate arrays, or FPGAs, provide an attractive computing platform for software-defined radio applications. Their reconfigurable nature allows many digital signal processing (DSP) algorithms to be highly parallelised within the FPGA fabric, while their customisable I/O interfaces allow simple interfacing to analogue-to-digital converters (ADCs) and digital-to-analogue converters (DACs). However, FPGA boards that deliver sufficient performance to be useful in real-world applications are generally expensive. Rhino is an FPGA-based hardware processing platform that primarily supports software-defined radio applications. The final cost estimate for a complete Rhino system is under $1700, cheaper than similar FPGA boards that deliver much lower performance.
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Delport, Pierre. "Optimisation of UHF radio SCADA systems for electrical distribution networks." Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019.1/1905.
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Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2006.This thesis presents the results of an investigation to establish methods to improve the performance of area radio based communication systems for Supervisory Control and Data Acquisition (SCADA) systems. The considerable scale on which an area radio network is used as a telecommunication network is quite unique to South Africa due to a lack of high bandwidth telecommunication systems in rural areas. Research was done to establish Key Performance Indicators (KPIs) to measure the performance of the area radio telecommunication systems. Two KPIs were chosen, namely Remote Terminal Unit (RTU) availability and Control Success Rate (CSR). These KPIs were trended over a three-year period to measure the effectiveness of measures taken to improve the systems. Two measures were implemented, namely to change the RTU radios, antennas and coaxial feeder cables and to redesign the communication systems in such a way to restrict multiple RTU protocols on the same area radio telecommunication network. The installation of new digital radios together with low loss coaxial cable and specific antennas improved the RTU availability from 96.87 % for the year 2002 to 99.17 % for the year 2004, which realised in an increase of 2.83 % for 432 installed RTUs. This measure, however, did not influence the CSR. The implementation of the newly designed communication networks had a significant influence on the control success rate of the SCADA systems and the KPI increased from 77.65 % for the year 2002 to 78.76 % for the year 2003 and 80.88 % for the year 2004. A drastic increase in performance was observed after the restriction of multiple RTU protocols on the same network during May 2004, where the value for twelve months prior to September 2005 was measured at 84.38 %. The utilisation of area radio telecommunication networks was measured for two operational networks and it was found to be well within the specifications of international accepted standards. One of these networks comprised of three repeaters and 84 installed RTUs and an average utilisation of 17 % and a peak utilisation of 25 % was measured. The other network had an installed base of 4 repeaters and 15 installed RTUs’s and an average utilisation of 3 % and a peak utilisation of 8 % was measured. This compares favourable with the IEEE standard 999-1992 [20], which recommends a channel utilisation of between 40 % and 60 %. Keywords : Key performance indicators, Radio telecommunication networks, Remote terminal unit
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Ghafoor, Salman. "Radio over fiber systems." Thesis, University of Southampton, 2012. https://eprints.soton.ac.uk/340694/.
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The three main types of Radio Over Fiber (ROF)communication systems, namely analogue ROF, baseband ROF and digitized ROF are investigated. Optical fibers are increasingly replacing copper wires. In long-haul, high-bit-rate communication systems optical fiber has already become the dominant mode of transmission due to its enormous bandwidth and low loss. ROF facilitate the seamless integration of optical and wireless communication systems. Since the RF spectrum is limited, wireless systems rely on re-using the frequencies at different geographic locations, but the ever-increasing tele-traffic demands require ever-reduced cell-sizes. This enables wireless systems to provide high data rates for a reduced number of users by assigning each of them a larger fraction of the total bandwidth. Furthermore, higher frequencies, expanding to the microwave and mmwavelength bands are capable of supporting increased data rates. Since high-frequency signals travel shorter distances due to their higher path-loss, the cell sizes have to be further reduced. This reduction in cell size implies that more Radio Access Units (RAUs) are required for the increased number of cells, which are located close to each other. Conceiving these RAUs relying on complex signal processing is costly. Therefore, it is desirable to have simple RAUs that are connected to a central unit where all the signal processing tasks are carried out. In this scenario, ROF plays an important role in connecting these RAUs to the central unit. The major factors that makes ROF suitable is its transparency to the type of RF signal being transported, the large available bandwidth of fiber and its low attenuation. The first type of ROF communication investigated is baseband ROF (BROF), where electronic baseband data is directly transmitted over the fiber after Electronic-to-Optical (EO) conversion. Baseband optical communications generally transmit optical pulses that have a Gaussian timedomain profile associated with the most compact spectrum for transmitting baseband digital data. Optical pulsed laser sources are capable of generating narrow Gaussian pulses that may be used for high-rate systems relying on ON-OFF keying. All-optical regeneration of signals is investigated, where the signals transmitted over large distances may be regenerated at regular intervals. The second type of ROF communication is analogue ROF (AROF), where the analogue RF signal is transmitted over the fiber using an optical carrier. Finally, digitized ROF (DROF) communication is discussed, which digitizes the RF signal at the transmitter and after transmitting it over the fiber, it converts the digital signal back to analogue at the receiver. The thesis is concluded with the comparative study of the pros and cons of BROF, AROF and DROF techniques.
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Seabe, Phillip Sello. "Evaluation of microcontroller based packet radio modem." Thesis, Stellenbosch : University of Stellenbosch, 2007. http://hdl.handle.net/10019.1/2483.
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Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2007.The use of emerging microprocessors has become increasingly popular in packet radio communication equipment. This is mainly because of the improved performance and hardware simplicity they offer. The new generation field programmable gate arrays (FPGAs) and microcontrollers are now widely used in the development of terminal node controller (TNC) components. The aim of this thesis is to evaluate the use of these new generation FPGAs and microcontrollers in a TNC design, in order to utilise the software flexibility and hardware simplicity. The design process began with the selection of the available simple microcontroller-based modem that was just designed. Prior to its usage in a TNC, the software of the modem was modelled, in order to understand its signal processing functionality.
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Brady, Richard. "A Cross Platform Framework for Software Defined Radio." Thesis, Stellenbosch : University of Stellenbosch, 2007. http://hdl.handle.net/10019.1/2056.
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Thesis (MScEng (Electical and Electronic Engineering))--University of Stellenbosch, 2007.Software defined radios (SDRs) implement in software those parts of a radio which have traditionally been implemented in analogue hardware. We explain the importance of this definition and introduce reconfigurability and portability as two further goals. Reconfigurabilty is a property of the SDR platform, which may be a microprocessor, configurable hardware device, or combination of the two. We demonstrate that the field-programmable gate array is suficient for the implementation of practical SDR systems. Portability, on the other hand, is a property of the modulation and demodulation software, also known as waveform specification software. We evaluate techniques for achieving portability and show that waveforms can be specified in a generic form suitable for the autogeneration of implementations targetting both microprocessor- and FPGA-based architectures. The generated code is in C++ and VHDL respectively, and the tools used include formal models of computation and the XSLT language.
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Helman, Daniel Richard. "Packet radio simulation and protocols." Thesis, Massachusetts Institute of Technology, 1986. http://hdl.handle.net/1721.1/15074.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1986.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING
Includes bibliographical references.
by Daniel R. Helman.
Ph.D.
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Sakki, Kranthi Kumar. "A Radio Frequency Identification Multi-Sensor Health Monitoring System." Thesis, California State University, Long Beach, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10262351.
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Health Monitoring Systems (HMS) are used to monitor physiological signals such as the blood pressure, heart rate, and temperature of patients. The use of a HMS for continuous monitoring of the Vital Signs of patients requiring constant medical supervision, is particularly important. The current project presents the development and implementation of a multi-sensor HMS to track and record multiple parameters of a patient (Electrocardiogram, pulse, temperature, and body position). The project development uses biomedical sensor technology for monitoring the physiological signals, Radio Frequency Identification (RFID) technology for patient identification, and the Internet of Things (IoT) for information transmission. Sensors attached to a patient’s body collect data that alert users to abnormal values via smart devices, such as mobile phones or laptops. Experimental testing of the multi-sensor HMS developed and implemented for this project, demonstrates the system’s effectiveness in sensing, collecting, and transmitting accurate patient information for remote monitoring.
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Akeel, Hosam. "Remotely Operated VoIP Radio for Drones." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-290598.
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Nowadays, search and rescue organizations are considering using drones to aid in rescue missions. To ensure the drones work properly, we need to design a reliable and stable systems. One of these systems is the communication system, which creates a link between the drone and the operator. There are many communication technologies used in rescue missions, such as Voice over Internet Protocol (VoIP). VoIP uses the Internet to send and receive traditional telephony services such as voice, video, and other media sessions. In this project, we investigate the performance of Software Defined Radio (SDR) in implementing the VoIP technology on the drones to stream video by using Fourth Generation of Telecommunication Systems (4G) Long-Term Evolution (LTE). In addition, the SDR should also communicate in the sea using marine Very High Frequency (VHF) voice-radio for sea rescue missions. To verify and evaluate the system, we used BladeRF xA4 to run Qradiolink and srsLTE to simulate the communication system as the hardware platform. In this experiment, we use a BladeRF SDR as a base station. The test procedure is designed to evaluate the performance of the 4G LTE and marine VHF links. We conducted tests in three different environments to evaluate the performance of the system and show the impacts of different environments. In the 4G LTE measurements we evaluate the Signal to Noise Ratio (SNR), Reference Signal Received Power (RSRP), jitter, delay, and packet loss. In the marine VHF measurement we evaluate the Received Signal Strength Indicator (RSSI). The experimental result shows that it is possible to use SDR to implement the suggested communication system. However, there are some restrictions that are related to the power source and the BladeRF xA4 hardware design. Based on the experimental results, we create a scaling graph to show the baseline of the hardware specifications to achieve the desired performance. We also discussed in details the cost to implement this communication system. Finally, we conclude that it is cost-effective to use SDR as the communication system if there are no off-the-shelf products that cost 15000 SEK.Nu for tiden overvager sok- och raddningsorganisationer att anvanda dronare iraddningsuppdrag. For att sakerstalla att dronarna fungerar ordentligt maste videsigna palitliga och stabila system. Ett av dessa system ar kommunikationssystemet,som skapar en lank mellan dronaren och operatoren. Det finns mangakommunikationstekniker som anvands i raddningsuppdrag, sasom Rost overInternet Protokoll (VoIP). VoIP anvander Internet for att skicka och ta emottraditionella telefonitjanster som rost-, video- och andra mediasessioner. I dethar projektet undersoker vi prestanda for Mjukvara Definierade Radio (SDR)vid implementering av VoIP-teknik pa dronare for att stromma video med FjardeGenerationen av Telekommunikation System ( 4G) Langsiktig Utveckling(LTE). Dessutom bor SDR ocksa kommunicera i havet med hjalp av marineMycket Hog Frekvens (VHF) rostradio for sjoraddningsuppdrag. For att verifieraoch utvardera systemet anvande vi BladeRF xA4 for att kora Qradiolinkoch srsLTE for att simulera kommunikationssystemet som hardvaruplattform.I detta experiment anvander vi en BladeRF SDR som basstation. Testforfarandetar utformat for att utvardera prestanda for 4G LTE- och marineVHFlankar.Vi genomforde tester i tre olika miljoer for att utvardera systemets prestandaoch visa effekterna av olika miljoer. I 4G LTE-matningarna utvarderarvi signal brusforhallande (SNR), referenssignal mottagen effekt (RSRP), jitter,fordrojning och paketforlust. I VHF-matningen utvarderar vi mottagen signalstyrkaindikator (RSSI).Det experimentella resultatet visar att det ar mojligt att anvanda SDR for attimplementera det foreslagna kommunikationssystemet. Det finns dock vissabegransningar som ar relaterade till stromkallan och BladeRF xA4-maskinvarudesignen.Baserat pa experimentresultaten skapar vi en skalningsdiagram for att visa baslinjenfor hardvaruspecifikationerna for att uppna onskad prestanda. Vi diskuteradeocksa i detaljkostnaderna for att implementera detta kommunikationssystem.Slutligen drar vi slutsatsen att det ar kostnadseffektivt att anvanda SDRsom kommunikationssystem om det inte finns nagra hylla produkter som kostar15 000 SEK.
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Simard, François. "A packet radio network design for field, mobile multimedia communications, network configuration, radio channel access and network management." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ28459.pdf.
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Ghiaasi-Hafezi, Golsa. "Power efficient radio frequency transmitters for wireless digital mobile applications." The Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=osu1406883053.
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Vakili, Arash. "Adaptive spectrum sensing for cognitive radio networks." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=106425.
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Spectrum sensing is an important functionality of cognitive radio as a means to detect the presence or absence of the primary user (PU) in a certain spectrum band. Energy detection is a widely used spectrum sensing technique based on the assumption that the PU is either present or absent during the whole sensing period. However, this assumption is not realistic in a dynamic environment where the PU could appear or disappear at any time. The performance of the conventional energy detector (ED) actually deteriorates in the scenario where the PU activity status changes during the sensing period.Therefore, it is crucial to design a detector which can adapt to such an environment and reliably detect a change in the PU activity. Several sequential change detection techniques already exist in the literature; however, change detection in a fixed sensing duration has not been given enough attention. In this dissertation, three adaptive EDs are proposed to improve the detection performance in dynamic environments, where there is a single change in the PU activity during a fixed sensing period. In particular, we address the change detection problem using an exponential weighting approach and two theoretical approaches based on the composite hypothesis testing. In the first case, an intuitive idea of exponential weighting of the received energies is applied to design an adaptive ED that aims to satisfy the Neyman-Pearson (NP) criterion. The performance analysis and simulation results prove that the proposed adaptive ED outperforms the conventional ED and also the only existing adaptive ED in the literature that deals with the aforementioned issue. In the second case, two theoretical approaches based on the composite hypothesis testing are used to design two additional adaptive EDs that improve the change detection during the sensing period. The first approach, known as the generalized likelihood ratio test (GLRT), uses the maximum likelihood estimation (MLE) of the unknown change location in a likelihood ratio test. In this case, an iterative method is proposed to reduce the computational complexity of the MLE process. The second approach, referred to as composite-Bayesian, assumes that the unknown change location is a discrete random variable whose probability mass function (PMF) is available. The PU channel access pattern is modelled as a two-state Markov chain to obtain the PMF of the change location and the probability of occurrence of the two hypotheses. The resultant adaptive ED based on the GLRT approach aims to satisfy the NP criterion while the adaptive ED based on the composite-Bayesian approach aims to minimize the probability of error. It is demonstrated through simulations that these two proposed adaptive EDs have superior performance over the conventional ED. Furthermore, the GLRT-based adaptive ED outperforms the first proposed adaptive ED based on the exponential weighting approach.La détection de spectre est une fonctionnalité importante de la radio cognitive car elle permet de vérifier la présence ou l'absence d'un utilisateur principal (PU) sur une bande de spectre donnée. La détection de l'énergie est une méthode fréquemment utilisée pour y parvenir.Cette dernière s'appuie sur l'hypothèse que le PU est présent ou absent pour la totalité de la période de mesure. Cependant, cette hypothèse n'est pas réaliste pour un environnement dynamique dans lequel le PU peut apparaître ou disparaître à n'importe quel instant. En effet, les performances d'un détecteur d'énergie conventionnel (ED) se détériorent lorsque l'état du PU varie au cours de la période durant laquelle les mesures sont effectuées. C'est donc pour cette raison qu'il est nécessaire de concevoir un détecteurqui s'adapte bien à ce genre d'environnement et qui permet de détecter de manière fiable tout changement dans l'activité du PU. Plusieurs techniques de détection de changements séquentiels existent dans la littérature mais la détection de changement pour une durée fixe n'a pas été explorée suffisamment en détails. Dans le cadre de ce mémoire, trois EDs adaptatifs sont proposés dans le but d'améliorer les performances dans un environnement dynamique au sein duquel il y a un seul changement au niveau de l'activité du PU et ce durant une période de mesure de durée fixe. Pour tenter de résoudre cette problématique, une approche à pondération exponentielle et deux approches théoriques en lien avec le test d'hypothèse composée sont proposées. Dans le premier cas, une approche intuitive exploitant la pondération exponentielle de l'énergie mesurée est utilisée afin de concevoir un ED adaptatif qui satisfait le critère de Neyman-Pearson (NP). L'analyse des performances et des résultats de simulation prouvent que cette stratégie offre de meilleures performances par rapport aux ED conventionnels. Il s'agit également du seul ED adaptatif présent dans la littérature qui tente de résoudre la problématique précédemment mentionnée. Dans le second cas, deux approches théoriques fondées sur le test d'hypothèse composée sont utilisées afin de concevoir deux nouveaux EDs adaptatifs qui améliorent la détection de changements durant la période de mesure. La première approche s'appuie sur le test généralisé de vraisemblance (GLRT) et utilise une estimation de la vraisemblance maximale (MLE) de la position inconnue du changement. Dans ce cas, une méthode itérative est proposée pour réduire la complexité de calcul du processus de MLE. La deuxième approche, dite composée bayésienne, prend pour acquis que la position inconnue du changement est une variable aléatoire discrète dont la loi de probabilité (PMF) est connue. Pour cette dernière approche, les accès au canal sont modélisés par un modèle de Markov à deux états afin d'obtenir la PMF de la position du changement et la probabilité d'occurrence des deux hypothèses. Le ED adaptatif utilisant le GLRT tente de satisfaire le critère de NP tandis que le ED adaptatif utilisant l'approche de la composée bayésienne tente de minimiser la probabilité d'une erreur. Il est démontré à l'aide de simulations que ces deux EDs adaptatifs offrent des performances supérieures à celles du ED conventionnel. En outre, le ED adaptatif utilisant le GLRT surpasse le ED adaptive utilisant l'approche pondération exponentielle.
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Chen, Xi. "Sequential Monte Carlo radio-frequency tomographic tracking." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104844.
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Target tracking in over a small-scale area using wireless sensor networks (WSNs) is a technique that can be used in applications ranging from emergency rescue after an earthquake to security protection in a building. Many target tracking systems rely on the presence of an electric device which must be carried by the target in order to reports back its location and status. This makes these systems unsuitable for many emergency applications; in such applications device-free tracking systems that where no devices are attached to the targets are needed. Radio-Frequency (RF) tomographic tracking is one such device-free tracking technique. This system tracks moving targets by analyzing changes in attenuation in wireless transmissions. The target can be tracked within the sensor network area without being required to carry an electric device.Some previously-proposed device-free tracking approaches require a time-consuming training phase before tracking can be carried out, which is time-consuming. Others perform tracking by sacrificing part of the estimation accuracy. In this thesis, we propose a novel sequential Monte Carlo (SMC) algorithm for RF tomographic tracking. It can track a single target moving in a wireless sensor network without the system needing to be trained. The algorithm adopts a particle filtering method to estimate the target position and incorporates on-line Expectation Maximization (EM) to estimate model parameters. Based on experimental measurements, the work also introduces a novel measurement model for the attenuation caused by a target with the goal of improving estimation accuracy. The performance of the algorithm is assessed through numerical simulations and field experiments carried out with a wireless sensor network testbed. Both simulated and experimental results demonstrate that our work outperforms previous RF tomographic tracking approaches for single target tracking.Suivi de cible dans la zone à petite échelle en utilisant les réseaux de capteurs sans fil est une technique qui peut être largement utilisé dans des applications telles que le sauvetage d'urgence après un tremblement de terre, ou la protection de la sécurité dans un bâtiment. Beaucoup de systèmes de poursuite de cibles nécessitent un dispositif électrique réalisée par l'objectif de faire rapport de ses localisation instantanée et le statut. L'inconvénient rend ces systèmes ne conviennent pas pour des applications nombreuses interventions d'urgence, dispositif sans systèmes de suivi qui ne les périphériques connectés sur les objectifs sont nécessaires. Radio-Fréquence (RF) suivi tomographique est l'une des techniques dispositif de suivi-libres. Il s'agit d'un processus de suivi des cibles mobiles en analysant l'évolution de l'atténuation dans les transmissions sans fil. La cible peut être suivi dans la zone de réseau de capteurs, tandis que les appareils électriques ne doivent être effectués. Cependant, certaines approches précédentes dispositif de suivi-libre nécessite une phase d'entraînement avant de suivi, ce qui prend beaucoup de temps. Autres effectuer un suivi par scarification partie de précision de l'estimation.Dans cette thèse, nous proposons une nouvelle Monte Carlo séquentielles (SMC) algorithme de suivi RF tomographique. Il peut suivre une cible unique sans formation du système dans un réseau de capteurs sans fil. L'algorithme de filtrage particulaire adopte la méthode pour estimer la position cible et intègre en ligne Expectation Maximization (EM) pour estimer les paramètres du modèle. Sur la base de mesures expérimentales, le travail introduit également un modèle de mesure de roman pour l'atténuation provoquée par une cible pour améliorer la précision d'estimation. La performance de l'algorithme est évaluée par des simulations numériques et expériences sur le terrain avec un réseau de capteurs sans fil banc d'essai. Les deux résultats simulés et expérimentaux démontrent que notre travail surpasse précédente approche RF suivi tomographique pour le suivi de cible unique.
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Wong, Chung Kit. "Resource allocation for multihop packet radio networks." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=68059.
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This thesis focuses on the routing, power control and channel allocation of Packet Radio Network (PRnet) with multiple channels. The Nearest Forward with Progress (NFP) routing policy is known to achieve higher throughput in the single channel setting than the Most Forward with Progress (MFP) strategy. This observation motivates our work on the variant of the Shacham/King model in which MFR is replaced by NFP in a multi-channel case. The resulting network shows that the superiority of NFP relative to MFP persists. Another way to improve network performance is to control the network topology by restricting the set of possible paths. Pairwise Channel Assignment (PCA), which assigns the different channels to the restricted paths, is modified so as to expand its applicability and reduce its computational burden without significant loss of throughput. The performance evaluations are based on a combination of analysis and simulation.
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Ngo, Duy. "Radio resource allocation for wireless heterogeneous networks." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=119622.
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By deploying small cells (i.e., femtocells) within the same service area of regular macrocells, a much higher area spectral efficiency, better indoor coverage, and significant mobile data offloading can be achieved at low cost. Because femtocells reuse the radio spectrum already assigned to macrocells in an uncoordinated fashion, new cell boundaries are created and the signal interference situation becomes far more unpredictable than in conventional networks. In this heterogeneous network setting, adaptive power allocation and dynamic spectrum access are needed to ensure a harmonized coexistence of network entities with diverse design specifications. Since femtocells are deployed by end users without any network planning, autonomous solutions are desirable to effectively control the severe intra-tier and cross-tier interferences. In this study, we develop and evaluate distributed radio resource allocation algorithms for wireless heterogeneous networks employing code-division multiple access (CDMA) and orthogonal frequency division multiple access (OFDMA). Requiring no central coordination, the devised solutions robustly protect the ongoing operation of all existing macrocell users, while optimally exploiting the residual network capacity for femtocells. In CDMA-based networks, we propose a dynamic pricing scheme combined with femtocell user admission control to indirectly manage the cross-tier interference. The proposed joint power and admission control algorithms can be locally executed at each link to offer a maximum utility to individual users. For the total network utility maximization, we develop joint Pareto-optimal power control and signal-to-interference-plus-noise ratio (SINR) assignment algorithms that can fairly share radio resources among users. Upon applying convex optimization methods, the minimum SINRs prescribed by macrocell users are effectively enforced, whereas the sum network utility is globally maximized. In OFDMA-based networks, to resolve the highly nonconvex and combinatorial problem of joint power and subchannel allocation, we propose a dynamic spectrum management scheme that alternatively optimizes the powers and assigns the subchannels. With the adopted successive convex approximation approach, the total throughput of all femtocells is maximized whilst the macrocell network capacity is always protected. In cognitive femtocells where femtocell users opportunistically access the spectrum licensed to macrocells, we apply Lagrangian duality to devise jointly optimal power and subchannel allocation algorithms. The distributed solutions are shown to achieve their global optimality with low complexity.En déployant de petites cellules (dénommées les femtocells) au sein de la même zone de service que les cellules de tailles régulières (dénommées cellules macro), une efficacité spectrale zone beaucoup plus élevé, une meilleure couverture à l'intérieur, et d'importantes données mobiles de déchargement entre les deux cellules peuvent être réalisé tout en gardant faible coût. Vu que les femtocells réutilisent le spectre de fréquence déjà consacré à la cellule macro, auxquelles ils sont assignés, d'une manière non-coordonnée, de nouvelles limites de cellules sont créées et l'interférence devient beaucoup plus imprévisible que dans les réseaux traditionnels. Dans ce contexte réseau hétérogène, une allocation adaptative de puissance et des méthodes d'accès dynamiques au spectre sont nécessaires pour assurer une coexistence harmonisée des entités du réseau avec les nouvelles spécifications imposées par les femtocells. Depuis que les femtocells sont déployées par les terminaux sans aucune planification au préalable du réseau, des solutions qui s'adaptent automatiquement sont toujours désirable pour contrôler efficacement les sévères interférences entre les différents niveaux du réseau sans fil hétérogène.Dans cette étude, nous développons et évaluons des algorithmes distribués pour l'allocation de ressources radio dans les réseaux sans fil hétérogènes employant l accès multiple par répartition en code (CDMA) et Accès multiple par répartition en fréquence (OFDMA). En évitant une coordination centralisée, les solutions proposées protègent le fonctionnement de tous les utilisateurs de la cellule macro existantes, tout en exploitant de manière optimale la capacité résiduelle du réseau pour les utilisateurs du femtocells. Dans les réseaux CDMA, nous proposons un schéma de tarification dynamique associé à un contrôle d'admission des utilisateurs de la femtocell nous permettant de gérer indirectement l'interférence inter-niveaux (entre cellule macro et femtocell). Le contrôle simultané de la puissance et les algorithmes de contrôle d'admission proposés peut être exécuté localement sur chaque lien pour offrir un maximum d'utilité pour les utilisateurs individuels. Pour maximiser l'utilité totale du réseau, nous développons un algorithme de contrôle simultané de puissance basant sur l'optimalité de Pareto et le rapport signal sur interférence plus bruit (SINR) qui peut partager équitablement les ressources radio entre les utilisateurs. En appliquant d'une méthode d'optimisation, les SINR minimaux prescrits par les utilisateurs des cellules macro sont garantis, alors que le maximal global la somme de l'utilité du réseau est trouvé.Dans les réseaux OFDMA, afin de résoudre le problème non convexe et combinatoire de l'allocation conjointe de la puissance et des sous-porteuses, nous proposons un schéma alternatif de gestion dynamique du spectre qui optimise la distribution de puissance et des sous-porteuses. Avec l'approche par approximations successives convexe adoptée, le débit total de tous les femtocells est maximisé alors que la capacité du réseau de la cellule macro est toujours protégée. En femtocells cognitives où les utilisateurs du femtocell accèdent au spectre autorisé à la cellule macro d'une manière opportuniste, nous appliquons la dualité lagrangienne pour optimiser la distribution de la puissance et des sous-porteuses. Nous prouvons que les solutions distribuées proposées atteignent leur optimal global avec une faible complexité.
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Matarrese, Vincent D. "Tapered radio frequency transmission lines." PDXScholar, 1992. https://pdxscholar.library.pdx.edu/open_access_etds/4329.
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A transformation used to obtain solutions for the beam parameter equation of fiber optics is applied to the second order differential equation for nonuniform transmission lines. Methods are developed for deriving possible transmission line tapers from known solutions of the transformed equation. This study begins with a comprehensive overview of previous work done to obtain closed-form solutions for the transmission line equations. Limitations of the lumped parameter model are also discussed. As part of this thesis, a tapered transmission line is constructed, based on one of the solutions obtained from the fiber optics studies. A discussion of the design and measurement results are given in the final chapter.
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Madic, Jelena 1977. "Security Sphere : radio frequency subsampling receiver." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/87251.
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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, June 2002.Includes bibliographical references (p. 85-86).
by Jelena Madic.
M.Eng.
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Rivas, Juan 1976. "Radio frequency dc-dc power conversion." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/38691.
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Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, February 2007.Includes bibliographical references (p. 197-204).
THIS THESIS addresses the development of system architectures and circuit topologies for dc-dc power conversion at very high frequencies. The systems architectures that are developed are structured to overcome limitations associated with conventional designs. In particular, the new architectures described here structure the energy processing and control functions of the system in such a manner that high efficiency can be achieved across wide load range while regulating the output. Moreover, these architectures are amenable to circuit designs operating at fixed frequency and duty ratio, considerable easing the circuit design. The thesis also develops new circuit designs that are well suited to these new architectures. As part of this, two new gate drives and control methods are introduced that greatly reduce gating loss at VHF frequencies for fixed frequency, fixed duty ratio operation. One of these gating schemes provides near theoretical minimum loss by resonantly wave shaping the gate voltage to have a trapezoidal drive voltage. This waveshaping approach is then taken a step further, yielding a new class of dc-dc converter that archives a significant reduction in peak switch voltage stress, requires small passive components with low energy storage, and provides the capability for extremely rapid startup and shutdown. This new class of converter is well adapted to the architectures and gate drive methods proposed in the thesis. It is expected that the new architectures and circuit designs introduced here will contribute to the development of power converter having greatly reduced size and improved transient performance.
by Juan Rivas.
Sc.D.
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Powell, Johnna 1980. "Antenna design for ultra wideband radio." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28542.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, June 2004."May 2004."
Includes bibliographical references (p. 108-109).
The recent allocation of the 3.1-10.6 GHz spectrum by the Federal Communications Commission (FCC) for Ultra Wideband (UWB) radio applications has presented a myriad of exciting opportunities and challenges for design in the communications arena, including antenna design. Ultra Wideband Radio requires operating bandwidths up to greater than 100% of the center frequency. Successful transmission and reception of an Ultra Wideband pulse that occupies the entire 3.1-10.6 GHz spectrum require an antenna that has linear phase, low dispersion and VSWR [< or =] 2 throughout the entire band. Linear phase and low dispersion ensure low values of group delay, which is imperative for transmitting and receiving a pulse with minimal distortion. VSWR [< or =] 2 is required for proper impedance matching throughout the band, ensuring at least 90% total power radiation. Compatibility with an integrated circuit also requires an unobtrusive, electrically small design. The focus of this thesis is to develop an antenna for the UWB 3.1-10.6 GHz band that achieves a physically compact, planar profile, sufficient impedance bandwidth, high radiation pattern and near omnidirectional radiation pattern.
by Johnna Powell.
S.M.
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Luschas, Susan 1975. "Radio frequency digital to analog converter." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/28277.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.Includes bibliographical references (p. 124-126).
Dynamic performance of high speed, high resolution digital-to-analog converters (DACs) is limited by distortion at the data switching instants. Inter-symbol interference (ISI), imperfect timing synchronization and clock jitter are all culprits. A DAC output current controlled by an oscillating waveform is proposed to mitigate the effects of the switching distortion. The oscillating waveform should be a multiple (k*fs) of the sampling frequency (f), where k>l. The waveforms can be aligned so that the data switching occurs in the zero regions of the oscillating output. This makes the DAC insensitive to switch dynamics and jitter. The architecture has the additional benefit of mixing the DAC impulse response energy to a higher frequency. An image of a low IF input signal can therefore be output directly at a high IF or RF frequency for transmit communications applications. A narrow-band sigma-delta DAC with eight unit elements is chosen to demonstrate the radio frequency digital-to-analog converter (RF DAC) concept. A sigma-delta architecture allows the current source transistors to be smaller since mismatch shaping is employed. Smaller current source transistors have a lower drain capacitance, allowing large high frequency output impedance to be achieved without an extra cascode transistor. Elimination of the cascode reduces transistor headroom requirements and allows the DAC to be built with a 1.8V supply. The RF DAC prototype is targeted to GSM transmit specifications and implemented in 0.1 8ptm CMOS technology. Measured single-tone SFDR is -75dBc, SNR is 52dB, and IMD3 is -70.8dBc over a 17.5MHz bandwidth centered at 942.5MHz. Measured SNR has the predicted dependence on the phase alignment of the data clock and oscillating pulse.
by Susan Luschas.
Ph.D.
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Newport, Calvin (Calvin Charles). "Distributed computation on unreliable radio channels." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/55120.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 169-175).
An important topic in wireless networking is the development of reliable algorithms for environments suffering from adversarial interference. This term captures any type of channel disruption outside the control of the algorithm designer-from contention with unrelated devices to malicious jamming. In this thesis, we provide four contributions toward a comprehensive theoretical treatment of this topic. First, we detail a formal modeling framework. This framework is general enough to describe almost any radio network studied to date in the theory literature. It can also precisely capture the often subtle details of adversarial behavior. In addition, we prove a pair of composition results that allow a layered strategy for designing radio network algorithms The results can be used to combine an algorithm designed for a powerful channel with an implementation of this channel on a less powerful channel. Next, we formalize adversarial interference with the definition of the t-disrupted channel. We then define the more powerful (t, b, p)-feedback channel, and provide both a randomized and deterministic implementation of the latter using the former. To emphasize the utility of this layered approach, we provide solutions to the set agreement, gossip, and reliable broadcast problems using the powerful feedback channel. Combined with the implementation algorithms and composition results, this automatically generates solutions to these problems for the less powerful, but more realistic, t-disrupted channel. Finally, we define a variant of the modeling framework that captures the attributes of an ad hoc network, including asynchronous starts and the lack of advance knowledge of participating devices.
(cont.) Within this new framework, we solve the wireless synchronization problem on a t-disrupted channel. This problem requires devices to agree on a common round numbering scheme. We conclude by discussing how to use such a solution to adapt algorithms designed for the original model to work in the ad hoc variant.
by Calvin Newport.
Ph.D.
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Kabelac, Zachary (Zachary E. ). "3D tracking via body radio reflections." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/91834.
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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 65-66).
This thesis presents WiTrack, a system that tracks the 3D motion of a user from the radio signals reflected off her body. It works even if the person is occluded from the WiTrack device or in a different room. WiTrack does not require the user to carry any wireless device, yet its accuracy exceeds current RF localization systems, which require the user to hold a transceiver. Empirical measurements with a WiTrack prototype show that, on average, it localizes the center of a human body to within a median of 10 to 13 cm in the x and y dimensions, and 21 cm in the z dimension. It also provides coarse tracking of body parts, identifying the direction of a pointing hand with a median of 11.2°. WiTrack bridges a gap between RF-based localization systems which locate a user through walls and occlusions, and human-computer interaction systems like Kinect, which can track a user without instrumenting her body, but require the user to stay within the direct line of sight of the device.
by Zachary Kabelac.
M. Eng.
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Mian, Omer. "Intelligent Spectrum Sensor Radio." Wright State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=wright1215360432.
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Azmat, Freeha. "Machine learning and energy efficient cognitive radio." Thesis, University of Warwick, 2016. http://wrap.warwick.ac.uk/85990/.
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With an explosion of wireless mobile devices and services, system designers are facing a challenge of spectrum scarcity and high energy consumption. Cognitive radio (CR) is a promising solution for fulfilling the growing demand of radio spectrum using dynamic spectrum access. It has the ability of sensing, allocating, sharing and adapting to the radio environment. In this thesis, an analytical performance evaluation of the machine learning and energy efficient cognitive radio systems has been investigated while taking some realistic conditions into account. Firstly, bio-inspired techniques, including re y algorithm (FFA), fish school search (FSS) and particle swarm optimization (PSO), have been utilized in this thesis to evaluate the optimal weighting vectors for cooperative spectrum sensing (CSS) and spectrum allocation in the cognitive radio systems. This evaluation is performed for more realistic signals that suffer from the non-linear distortions, caused by the power amplifiers. The thesis then takes the investigation further by analysing the spectrum occupancy in the cognitive radio systems using different machine learning techniques. Four machine learning algorithms, including naive bayesian classifier (NBC), decision trees (DT), support vector machine (SVM) and hidden markov model (HMM) have been studied to find the best technique with the highest classification accuracy (CA). A detailed comparison of the supervised and unsupervised algorithms in terms of the computational time and classification accuracy has been presented. In addition to this, the thesis investigates the energy efficient cognitive radio systems because energy harvesting enables the perpetual operation of the wireless networks without the need of battery change. In particular, energy can be harvested from the radio waves in the radio frequency spectrum. For ensuring reliable performance, energy prediction has been proposed as a key component for optimizing the energy harvesting because it equips the harvesting nodes with adaptation to the energy availability. Two machine learning techniques, linear regression (LR) and decision trees (DT) have been utilized to predict the harvested energy using real-time power measurements in the radio spectrum. Furthermore, the conventional energy harvesting cognitive radios do not assume any energy harvesting capability at the primary users (PUs). However, this is not the case when primary users are wirelessly powered. In this thesis, a novel framework has been proposed where PUs possess the energy harvesting capabilities and can get benefit from the presence of the secondary user (SU) without any predetermined agreement. The performances of the wireless powered PUs and the SU has also been analysed. Numerical results have been presented to show the accuracy of the analysis. First, it has been observed that bio-inspired techniques outperform the conventional algorithms used for collaborative spectrum sensing and allocation. Second, it has been noticed that SVM is the best algorithm among all the supervised and unsupervised classifiers. Based on this, a new SVM algorithm has been proposed by combining SVM with FFA. It has also been observed that SVM+FFA outperform all other machine leaning classifiers Third, it has been noticed in the energy predictive modelling framework that LR outperforms DT by achieving smaller prediction error. It has also been shown that optimal time and frequency attained using energy predictive model can be used for defining the scheduling policies of the harvesting nodes. Last, it has been shown that wirelessly powered PUs having energy harvesting capabilities can attain energy gain from the transmission of SU and SU can attain the throughput gain from the extra transmission time allocated for energy harvesting PUs.
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MacDonald, Brennan A. "Surface charge characteristics of a radio-charged electret." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60430.
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Measurements of charge distributions across the face of isothermally, radio-charged polymer electrets are presented. The electret forming chamber is comprised of a parallel-plate ionization chamber in which the collecting electrode is covered by a dielectric (Teflon, Mylar). Charging is accomplished by the simultaneous application of electric potential and ionizing radiation to the chamber. The electret can be discharged by removing the external potential during further irradiation. For these studies the electrets are scanned with an electrostatic voltmeter probe yielding digitized maps of the surface charge as functions of time under various charging and discharge conditions. The results of numerical modelling of the charging process are compared with experimental data. Storage techniques for optimum charge retention are discussed. It is found that charge stability is comparable to that achieved through corona charging. These results allow us to design an optimum reusable, radio-charged electret-dosimeter.
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Kanu, Joseph. "Low bit-rate speech encoding for digital mobile radio." Thesis, Aston University, 1991. http://publications.aston.ac.uk/8089/.
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The need for low bit-rate speech coding is the result of growing demand on the available radio bandwidth for mobile communications both for military purposes and for the public sector. To meet this growing demand it is required that the available bandwidth be utilized in the most economic way to accommodate more services. Two low bit-rate speech coders have been built and tested in this project. The two coders combine predictive coding with delta modulation, a property which enables them to achieve simultaneously the low bit-rate and good speech quality requirements. To enhance their efficiency, the predictor coefficients and the quantizer step size are updated periodically in each coder. This enables the coders to keep up with changes in the characteristics of the speech signal with time and with changes in the dynamic range of the speech waveform. However, the two coders differ in the method of updating their predictor coefficients. One updates the coefficients once every one hundred sampling periods and extracts the coefficients from input speech samples. This is known in this project as the Forward Adaptive Coder. Since the coefficients are extracted from input speech samples, these must be transmitted to the receiver to reconstruct the transmitted speech sample, thus adding to the transmission bit rate. The other updates its coefficients every sampling period, based on information of output data. This coder is known as the Backward Adaptive Coder. Results of subjective tests showed both coders to be reasonably robust to quantization noise. Both were graded quite good, with the Forward Adaptive performing slightly better, but with a slightly higher transmission bit rate for the same speech quality, than its Backward counterpart. The coders yielded acceptable speech quality of 9.6kbps for the Forward Adaptive and 8kbps for the Backward Adaptive.
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Tombak, Ali. "Radio Frequency Applications of Barium Strontium Titanate Thin Film Tunable Capacitors." NCSU, 2000. http://www.lib.ncsu.edu/theses/available/etd-20001129-002144.
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TOMBAK, Ali. Radio Frequency Applications of Barium Strontium Titanate Thin Film Tunable Capacitors. (Under the supervision of Amir S. Mortazawi).Properties of thin film barium strontium titanate (BST) based capacitors for RF and microwave components were studied. The capacitors were measured for their tunability, loss tangent, frequency dependence of dielectric permittivity, and behavior at large RF signal amplitudes. A nonlinear equivalent circuit model for tunable BST capacitors was developed. Analysis of a tunable low pass filter fabrication using BST capacitors along with its intermodulation distortion measurements was given. Several simulations for bandpass filters were performed. Furthermore, a periodically loaded coplanar waveguide phase shifter utilizing the BST capacitors was designed.
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Li, Xue. "Spectrally Modulated Spectrally Encoded Framework Based Cognitive Radio in Mobile Environment." Wright State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=wright1365964727.
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Oppel, Patrick. "Radio Emissions from Earth’s Foreshock and Bolides." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-302431.
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It is well understood that Earth’s foreshock radiation is due to the bow shock deflecting the solar wind and accelerating electrons upstream into the foreshock where they produce Langmuir waves and radio emissions. Recently, the Long Wavelength Array (LWA) in the USA observed radio waves from meteors and other bolides entering the ionosphere and atmosphere. Here we correct and generalise the model for Earth’s foreshock radiation by Kuncic et al. (2004) and adapt it to the bolide case. We also produce the first 2D source pictures of Earth’s foreshock radiation, confirming the prediction from Gurnett et al. (1993) that the radio source should be elongated perpendicular to the plane containing the magnetic field vector. For the bolide case, we show that our predicted fluxes are in the same range as observations by Obenberger and Taylor (2018) and therefore the theory is now a viable explanation for radio emissions from fireballs.Jordens förströmsstrålning beror på att bågchocken avböjer solvinden och accelererar elektroner uppströms in i förskotten där de producerar Langmuir- vågor och radioutsläpp. Nyligen observerade Long Wavelength Array (LWA) i USA radiovågor från meteorer och andra bolider som kom in i jonosfären och atmosfären. Här korrigerar och generaliserar vi modellen för jordens förströmsstrålning av Kuncic et al. (2004) och anpassar den till bolide- fallet. Vi producerar också de första 2Dkällbilderna av jordens förströmsstrålning, vilket bekräftar förutsägelsen från Gurnett et al. (1993): att radiokällan skulle vara utsträckt vinkelrätt mot planet som innehåller magnetfältvektorn. För bolide- fallet visar vi att våra förutspådda flöden ligger inom samma intervall som observationer från Obenberger och Taylor (2018), därav är teorin nu en gångbar förklaring till radioutsläpp från större meteorer.
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Kimpe, Marc. "Computerized estimation of the indoor wideband radio channel." Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=34747.
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Wireless telephone service providers must deploy their cellular networks with two main criteria in mind: radio coverage and traffic density. All areas where users expect a service must be covered and enough channels must be provided to accommodate the users. This thesis explores the problem of radio coverage prediction for indoor systems.The indoor radio channel contains a large number and variety of obstacles which scatter and attenuate electromagnetic waves. A transmitted signal reaches a receiver via multiple propagation paths after undergoing a series of reflection, transmission and possibly diffraction effects along each path. The sum of all path contributions, each characterized by an [attenuation, delay, carrier phase shift] vector, is called the impulse response, from which various channel quality measures can be derived. Given an environment over which an indoor wireless cellular network has to operate and the location of a base station, one must evaluate, for every point in that environment, the channel quality and hence compute the impulse response. Since measurements are too slow, there is a need for a computer tool that could evaluate the coverage of a base station from a representation of the environment.
Using a high frequency ray approximation of electromagnetic waves, the thesis first presents the two main ray tracing algorithms: ray shooting and the method of images. In both cases, the scene is represented as a series of panels with associated electromagnetic characteristics. Ray shooting consists of shooting rays in all directions from a transmitter location, tracking their interactions with obstacles until one or many reach a receiver location. The method of images reflects the transmitter about permutations of panels and checks which combinations lead to physically realizable reflection paths. Comparison with measurement results show good agreement in both cases although running times are high.
Better running times are obtained by considering two alternatives. A software alternative in the form of a faster algorithm called the method of regions is described. Spatial coherence is used to discard a priori image combinations which are not feasible and finding grid locations which belong together. The environment is divided into reflection, transmission and optionally diffraction regions and it is checked in which regions the various grid points belong. A hardware alternative in the form of a parallel machine is also demonstrated. A Multiple Instructions Multiple Data stream machine can provide linear speed-ups over a large range of processor numbers. The concept of a low level massively parallel machine in the form of a threshold logic network is also described.
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Barton, Taylor Wallis. "Phase manipulation for efficient radio frequency transmission." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78474.
Full textAbstract:
Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 109-112).
Power amplifiers (PAs) for microwave communications are generally the most power-hungry element of a transmitter. High linearity is required for modern digital communications standards, and often is achieved at the expense of efficiency. Outphasing architectures, which combine multiple nonlinear but efficient switching PAs into a system with an overall linear response, represent a promising strategy for breaking the efficiency/linearity tradeoff inherent to conventional PAs. This work explores methods for efficient PA design using outphasing techniques. Two aspects of outphasing design are considered. First, a wide-band phase modulator is introduced that uses a single current-steering digital to analog converter (DAC) structure and discrete clock prerotation. This topology takes advantage of specifications particular to outphasing architectures to reduce matching requirements as compared to a two-DAC phase modulator while providing wideband capability. The phase modulator is demonstrated in 65-nm CMOS, operates over a carrier frequency range of 1.2-4.2 GHz and has a 12-bit phase resolution and sample rate of 160 MSamples/second. The second technique is a novel four-way lossless power combiner and outphasing system which provides ideally lossless power combining along with resistive loading of switching power amplifiers over a wide output range. This work presents the first-ever demonstration of this system at microwave frequencies. Particular attention is paid to the microwave-specific aspects of implementation. A 60-W GaN prototype demonstrates the outphasing and dynamic performance, which closely matches the expected performance despite the challenges of operating at microwave frequencies.
by Taylor Wallis Barton.
Sc.D.
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Forbess, Jessica (Jessica Anne) 1975. "Medium frequency radio propagation in urban settings." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/86471.
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Hamed, Ezzeldin Omar Hussein. "LTE radio analytics made easy and accessible." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/97326.
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Thesis: S.M. in Computer Science and Engineering, Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 69-71).
Despite the rapid growth of next-generation cellular networks, researchers and end users today have limited visibility into the performance and problems of these networks. As LTE deployments move towards femto and pico cells, even operators struggle to fully understand the propagation and interference patterns affecting their service, particularly indoors. This thesis introduces LTEye, the first open platform to monitor and analyze LTE radio performance at a fine temporal and spatial granularity. LTEye accesses the LTE PHY layer without requiring private user information or provider support. It provides deep insights into the PHY-layer protocols deployed in these networks. LTEye's analytics enable researchers and policy makers to uncover serious deficiencies in these networks due to inefficient spectrum utilization and inter-cell interference. In addition, LTEye extends synthetic aperture radar (SAR), widely used for radar and backscatter signals, to operate over cellular signals. This enables businesses and end-users to localize mobile users and capture the distribution of LTE performance across spatial locations in their facility. As a result, they can diagnose problems and better plan deployment of repeaters or femto cells. We implement LTEye on USRP software radios, and present empirical insights and analytics from multiple AT&T and Verizon base stations in our locality.
by Ezzeldin Omar Hussein Hamed.
S.M. in Computer Science and Engineering
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Wilcoxson, Donald C. (Donald Craig). "Phase noise in low-power radio communications." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/38178.
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Thesis (Elec. E.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996.Includes bibliographical references (leaves 99-101).
by Donald C. Wilcoxson.
Elec.E.
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Ghaffari, Mohsen. "Bounds on contention management in radio networks." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/79227.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 79-82).
In this thesis, we study the local broadcast problem in two well-studied wireless network models. The local broadcast problem is a theoretical approach for capturing the contention management issue in wireless networks; it assumes that processes are provided messages, one by one, that must be delivered to their neighbors. We study this problem in two theoretical models of wireless networks, the classical radio network model and its more recent generalization, the dual graph model which includes the possibility of unreliable time-changing links. Both these models are synchronous; the execution proceeds in lock-step rounds and in each round, each node either transmits a message or listens. In each round of the dual graph model, each unreliable link might be active or inactive, whereas in the classical model, all the links are always active. In each round, each node receives a message if and only if it is listening and exactly one of its neighbors, with respect to the the active links of that round, transmits. The time complexity of the local broadcast algorithms is measured by two bounds, the acknowledgment bound and the progress bound. Roughly speaking, the former bounds the time it takes each broadcasting node to deliver its message to all its neighbors and the latter bounds the time it takes a node to receive at least one message, assuming it has a broadcasting neighbor. Typically these bounds depend on the maximum contention and the network size. The standard local broadcast strategy is the Decay protocol introduced by Bar-Yehuda et al. [19] in 1987. During the 25-years period in which this strategy has been used, it has remained an open question whether it is optimal. In this paper, we resolve this long-standing question. We present lower bounds on progress and acknowledgment bounds in both the classical and the dual graph model and we show that, with a slight optimization, the Decay protocol matches these lower bounds in both models. However, the tight progress bound of the dual graph model is exponentially larger than the progress bound in the classical model, in its dependence on the maximum contention. This establishes a separation between the two models, proving that progress in the dual graph model is strictly and exponentially harder than its classical predecessor. Combined, our results provide an essentially complete characterization of the local broadcast problem in these two important models.
by Mohsen Ghaffari.
S.M.
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Bagchi, Amit G. (Amit Goutam) 1974. "Asynchronous receivers in narrowband packet radio applications." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/43515.
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Jurkov, Alexander S. "Techniques for efficient radio frequency power conversion." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122558.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2019Cataloged from PDF version of thesis.
Includes bibliographical references (pages 293-304).
A diverse range of radio-frequency (RF) power applications demand RF power generation systems that allow for dynamic output power control while having the capability to efficiently deliver power into a varying load. While some of these existing and emerging applications are characterized with narrowband or single-frequency operation, others require operation over a range of frequencies. In such applications, the system architecture typically comprises an RF power amplifier (PA) or inverter along with a tunable impedance matching network (TMN). Electronically-controlled TMNs offer substantial benefits when it comes to the implementability of such highly reconfigurable and adaptive RF systems as they allow for proper impedance termination of the PA or inverter over the operating load and frequency range. This work explores the design of TMNs based on a solid-state technique that allows for faster and more accurate impedance matching compared to traditional approaches. The performance and design of such TMNs is demonstrated for plasma driving applications at 13.56 MHz. In addition, this work proposes techniques for designing switched-mode RF inverters that can operate efficiently over a wide load impedance range. These techniques are applied to the design of class E and class [Phi]2 inverter prototypes at 27.12 MHz, and their ability to handle large load modulation while maintaining high operating efficiency is demonstrated. The techniques presented in this work can be further applied to the integration of an RF power amplifier/inverter and a TMN into a single multi-transistor architecture capable of efficiently operating across frequency and load variation while providing dynamic output power control.
by Alexander Jurkov.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science
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Collins, Steven John. "A radio frequency capacitive discharge digital to analogue converter." Thesis, University of Glasgow, 2012. http://theses.gla.ac.uk/3371/.
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As the communications revolution continues there is an ever increasing demand for integrated transmitters and receivers on silicon in devices such as mobile phones and networking products. The demand to integrate complete systems onto a single die has driven a need to minimise the area of transmitters which has led to research into combining digital to analogue converters and RF mixers to minimise their area. The drive for increasing speeds and smaller transistors has resulted in higher capacitance densities and lower operating voltages, the latter making it more difficult to implement conventional transmitter circuits. Therefore there is a need for passive transmitter systems that maximise the output power to the load by minimising the voltage overhead on the output signal. This thesis proposes and demonstrates that it is possible to use a digital to analogue converter that performs RF up conversion using direct capacitive discharge to the load, which takes advantage of the large capacitance densities of a modern 40nm CMOS process. The DAC uses charge sharing in a similar manner to a charge sharing DAC without the bandwidth limitations imposed by an output amplifier. The RF frequency up conversion at the DAC data clock rate is produced using two DACs that differentially output the complement of each other on different halves of the clock cycle (one outputting while the other is charging) thereby emulating a passive switched mixer. The thesis shows that an 8 bit capacitive discharge DAC of 0.16mm2 can output 3dBm into a 50Ω load at 2.15GHz using a clock rate of 2GHz with MTPR of greater than 30dBc.
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Latief, Tauriq. "The design of a two-element radio interferometer using satellite TV equipment." Master's thesis, Faculty of Engineering and the Built Environment, 2021. http://hdl.handle.net/11427/33756.
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This research presents the design of a two-element radio interferometer capable of performing complex correlation. With the development of sophisticated radio astronomy instruments, particularly in South Africa, there is a need to develop an affordable educational instrument which can be used to demonstrate the fundamental concepts of radio interferometry to university students. The mass production of satellite TV equipment has resulted in relatively sensitive radio frequency (RF) equipment such as parabolic reflector dishes and low-noise block down-converters (LNBs) being available at significantly reduced costs. This served as the front-end of the interferometer which was used to observe the sun between 10.70 GHz - 12.75 GHz (RF). The LNB then down-converted these to an intermediate frequency (IF) between 0.95 GHz - 2.15 GHz. The LNBs were modified to make use of a common 25 MHz reference, which ensured that the observed fringes were only as a result of the source's geometric time delay. A power detector was also designed since the adding interferometer architecture was chosen. This power detector included the Analog Devices LT 5534 power detector integrated circuit (IC) and a Teensy 3.6 microcontroller. The calibrated power detector could detect signals as weak as - 60 dBm and showed less than 21 mV error in output for input signals in the range [- 50 dBm, -30 dBm]. The modified LNBs experienced issues, in particular the presence of a spurious LO signal, which distorted initial observations of the sun. This was resolved by the design and manufacture of narrowband hairpin filters and quarterwavelength stub filters which were used to isolate the IF band between 1.05 GHz - 1.15 GHz (corresponding RF between 10.80 GHz - 10.90 GHz). This also improved the interferometer's resolution. A series of filter-integrated Wilkinson power dividers and branchline couplers were designed to filter and further separate signals into in-phase and quadrature-phase (I-Q) components - these were required for complex correlation. The integrated quarter-wavelength stub filter and Wilkinson power divider achieved a maximum amplitude imbalance of 0.13 dB and phase imbalance of 0.9◦ between output ports. The integrated quarter-wavelength stub filter and branchline coupler achieved a maximum amplitude imbalance of 0.13 dB and phase imbalance of 91.1◦ between output ports. These results closely agreed with the simulated performance. First light was observed on the 5th December 2020 when the sun was successfully detected using the coherent two-element interferometer along a 1.1 m baseline. Other tests included using the observed fringe phase to verify the physical baseline. A theoretical baseline of 1.11 m was calculated for a physical baseline of 1.3 m indicating an error of less than 0.2 m. The sun's fringe frequency and amplitude was also observed for varying baselines - the sun was resolved along a 3 m baseline. Finally, full-system observations of the sun were conducted. These included observing the sun's cosine and sine fringes, which indicated that the analogue complex correlator was operating correctly. Thus, the primary goal of this project had been fulfilled. Specifically, developing a low-cost, educational two-element radio interferometer capable of detecting the sun.
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Malan, Jocias A. "X-band digitization systems aspects and filters for MeerKAT radio astronomy receiver." Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/27969.
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The MeerKAT Radio Telescope is a 64 element antenna array under construction in South Africa. This array will be used to observe radiation from celestial sources at radio frequencies. Once completed, this radio telescope will be the largest and most sensitive radio telescope in the Southern hemisphere. MeerKAT is being designed to observe radio signals produced by celestial sources at UHF-, L-, S- and X-band frequencies. With the development of the X-band receivers for MeerKAT scheduled to start in the near future, research is required to determine an optimum receiver design for this frequency band. There are two architecture options available for digitization of this band namely direct digitization of the entire band or digitization of a portion of the frequency band using a heterodyne configuration. In this thesis, both these options are investigated to determine the feasibility of both these architectures. A key outcome of this investigation will be the derivation of the specifications of the anti-aliasing filter used in a direct digitization receiver as well as the image reject filter used in the heterodyne receiver. The design of a wideband microwave filter capable of meeting these specifications is also presented. To conclude this investigation, the impact of the designed filter on the performance of the system is presented.
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Volkwin, Aadil. "Suitability of a commercial software defined radio system for passive coherent location." Master's thesis, University of Cape Town, 2008. http://hdl.handle.net/11427/5090.
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