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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Turbo-equalization for QAM constellations /

Petit, Paul F. Unknown Date (has links)
While the focus of this work is on turbo equalization, there is also an examination of equalization techniques including MMSE linear and DFE equalizers and Precoding. The losses and capacity associated with the ISI channel are also examined . Iterative decoding of concatenated codes is briefly reviewed and the MAP algorithm is explained. / Thesis (PhDTelecommunications)--University of South Australia, 2002.
22

High-performance RFID systems.

Jamali, Behnam January 2006 (has links)
Title page, abstract and table of contents only. The complete thesis in print form is available from the University of Adelaide Library. / In this thesis, I present and analyze two of the most fundamental constraints of Radio Frequency Identification Systems (RFID), power rectification and signaling. These two issues play an important role in the continuing development of RFID systems. A passive RFID tag draws power from the RF field created by an RFID reader and uses it to energize its circuitry. It does this by rectification of the reader's radiated RF field using rectifying circuitry. The power then available to the tag is dependent upon both the available field strength and the efficiency of the rectification process. One option for increasing the operating range of an RFID system without increasing the reader's field strength is to increase the efficiency of the tag's rectification structure. A major component of any rectification circuit is a diode type device and so, the first part of the thesis focuses on the design and implementation of a novel high efficiency Schottky Barrier Diode (SBD) on a standard CMOS process. The forward voltage drop of the SBD diode was investigated and analytic equations formulated considering the Schottky barrier drift region resistance and the contributions from the p⁺ guard-grid. A design procedure to minimize the drift region resistance for any blocking voltage was derived. The fundamental trade-off between the forward voltage and leakage current in the novel SBD concept was determined. Based on the critical review of the Schottky diodes fabricated in the first part, new structures of novel SBD were designed to address most of the open issues related to its reverse break-down voltage and series resistance. Detailed analysis of the important design parameters of the novel Schottky barrier diode were performed using HSPICE with the parameter set used in the calibration process. The novel structure was also compared to an alternative fabrication approach, specifically, a NMOS and PMOS gate-cross-connected bridge. The comparison shows that the novel structure provides a 10% higher figure of merit for power rectification. In the later part of the thesis, an analysis of circuit advantages enabled by the novel SBD is given. The circuit simulation showed that by utilizing the novel SBD the operating frequency of the circuit can be increased to the UHF region while maintaining approximately the same power efficiency as that achievable when using a discrete Schottky diode. This leads to the possibility of dramatic improvements in size, weight and cost of the RFID transponder circuits. Signaling also plays an important role in the development of RFID systems. The choice of signaling methods and protocols determines not only the spectrum bandwidth usage, but also the data throughput. Also with constantly changing standards and regulations, it is important to be able to characterize and optimize these issues. Therefore the second part of this dissertation presents the design, implementation and evaluation of a novel RFID data logging reader architecture based on software radio concepts. The system is designed to overcome the many challenges and exploit the advantages of performing real-time signal processing and data logging in an RFID environment. The proposed concept has a unique multi-band RFID tag reader platform and has been designed to read tags conforming to the Electronic Product Code (EPC ) specifications in both the HF and UHF frequency bands. The hardware architecture consists of a general purpose analogue front end up/down-converter for each band, followed by a software radio based architecture allowing easy adaptation to new frequencies and protocols if required. The last chapter presents the results of investigations conducted to determine the ability of the proposed reader architecture to communicate with tags in typical channel noise and environmental conditions present in an RFID operational environment. Studies of the effects of reader interference in multi-reader environments and the development of an anti-collision protocol signaling to address and mitigate those effects are also presented. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1222149 / Thesis (Ph.D.) -- University of Adelaide, School of Electrical and Electronic Engineering, 2006
23

High-performance RFID systems.

Jamali, Behnam January 2006 (has links)
Title page, abstract and table of contents only. The complete thesis in print form is available from the University of Adelaide Library. / In this thesis, I present and analyze two of the most fundamental constraints of Radio Frequency Identification Systems (RFID), power rectification and signaling. These two issues play an important role in the continuing development of RFID systems. A passive RFID tag draws power from the RF field created by an RFID reader and uses it to energize its circuitry. It does this by rectification of the reader's radiated RF field using rectifying circuitry. The power then available to the tag is dependent upon both the available field strength and the efficiency of the rectification process. One option for increasing the operating range of an RFID system without increasing the reader's field strength is to increase the efficiency of the tag's rectification structure. A major component of any rectification circuit is a diode type device and so, the first part of the thesis focuses on the design and implementation of a novel high efficiency Schottky Barrier Diode (SBD) on a standard CMOS process. The forward voltage drop of the SBD diode was investigated and analytic equations formulated considering the Schottky barrier drift region resistance and the contributions from the p⁺ guard-grid. A design procedure to minimize the drift region resistance for any blocking voltage was derived. The fundamental trade-off between the forward voltage and leakage current in the novel SBD concept was determined. Based on the critical review of the Schottky diodes fabricated in the first part, new structures of novel SBD were designed to address most of the open issues related to its reverse break-down voltage and series resistance. Detailed analysis of the important design parameters of the novel Schottky barrier diode were performed using HSPICE with the parameter set used in the calibration process. The novel structure was also compared to an alternative fabrication approach, specifically, a NMOS and PMOS gate-cross-connected bridge. The comparison shows that the novel structure provides a 10% higher figure of merit for power rectification. In the later part of the thesis, an analysis of circuit advantages enabled by the novel SBD is given. The circuit simulation showed that by utilizing the novel SBD the operating frequency of the circuit can be increased to the UHF region while maintaining approximately the same power efficiency as that achievable when using a discrete Schottky diode. This leads to the possibility of dramatic improvements in size, weight and cost of the RFID transponder circuits. Signaling also plays an important role in the development of RFID systems. The choice of signaling methods and protocols determines not only the spectrum bandwidth usage, but also the data throughput. Also with constantly changing standards and regulations, it is important to be able to characterize and optimize these issues. Therefore the second part of this dissertation presents the design, implementation and evaluation of a novel RFID data logging reader architecture based on software radio concepts. The system is designed to overcome the many challenges and exploit the advantages of performing real-time signal processing and data logging in an RFID environment. The proposed concept has a unique multi-band RFID tag reader platform and has been designed to read tags conforming to the Electronic Product Code (EPC ) specifications in both the HF and UHF frequency bands. The hardware architecture consists of a general purpose analogue front end up/down-converter for each band, followed by a software radio based architecture allowing easy adaptation to new frequencies and protocols if required. The last chapter presents the results of investigations conducted to determine the ability of the proposed reader architecture to communicate with tags in typical channel noise and environmental conditions present in an RFID operational environment. Studies of the effects of reader interference in multi-reader environments and the development of an anti-collision protocol signaling to address and mitigate those effects are also presented. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1222149 / Thesis (Ph.D.) -- University of Adelaide, School of Electrical and Electronic Engineering, 2006
24

A study of the effects of linear networks on FM waves /

Johnson, Preston Benton, January 1966 (has links)
Thesis (Ph. D.)--Virginia Polytechnic Institute, 1966. / Vita. Abstract. Includes bibliographical references (leaves 113-116). Also available via the Internet.
25

Quasi-optimum receivers for analog FM signals over Rayleigh fading channels.

Le, Nguyen Huu. January 1977 (has links) (PDF)
Thesis (Ph.D. 1979) from the Department of Electrical Engineering, University of Adelaide.
26

Antenna positioning analysis and dual-frequency antenna design of high frequency ratio for advanced electronic code responding labels

Leong, Kin Seong. January 2008 (has links)
Thesis (Ph.D.) -- University of Adelaide, School of Electrical and Electronic Engineering, 2008. / "January 2008" Includes bibliography (p. 333-342) Also available in print form.
27

Implementation of an efficient algorithm to detect maximal cliques in a conflict graph

Bell, Kristi Jo. January 1990 (has links) (PDF)
Thesis (M.S. in Computer Science)--Naval Postgraduate School, June 1990. / Thesis Advisor(s): Hefner, Kim A. S. Second Reader: Shing, Man-Tak. "June 1990." Description based on title screen as viewed on October 19, 2009. DTIC Descriptor(s): Algorithms, input, military operations, detection, models, networks, real time, graphs, efficiency, solutions(general), limitations, command and control systems, communications networks, communication and radio systems, radio equipment, conflict, radiofrequency, paper, frequency allocation, frequency DTIC Indicator(s): Computerized simulation, radiofrequency, allocations, graphs, communications networks, theses, communications and radio systems, algorithms. Author(s) subject terms: Maximal clique, conflict graph, algorithm, heuristic, NP-complete. Includes bibliographical references (p. 119). Also available in print.
28

Theoretical studies of radio-frequency sheath

Xiang, Nong, Drummond, William E., Waelbroeck, F. January 2004 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisors: Bill Drummond and Frank Waelbroeck. Vita. Includes bibliographical references. Also available from UMI.
29

An investigation into filters utilising coupled transmission lines

Johnstone, G. G. January 1995 (has links)
This thesis addresses itself to the solution of a number of problems which arise in the development of Radio Frequency filters, particularly those involving coupled transmission lines as resonant elements. The text is divided into a number of sections dealing with individual topics. After a brief description of Darlington filter design principles, there is an account of the pivotal role of quarter wave sections and their vital part in the realisation of high frequency filters. This is followed by the development of new material relating to equivalent circuits of physical lines in terms of quarter wave sections, and its application to improvements in the design of wide-band filters. There follows an account of a new procedure for calculating the dimensions of comb-line and inter-digital filters. This section includes a new proposal for the inversion of Getsinger's procedure to permit the calculation of rectangular rod dimensions and spacings from given electrical data. There is also an algorithm for use with round rods which circumvents the tedious manual interpolation procedure devised by Cristal. There follows an investigation of and a proposed solution to a long-known but unexplained discrepancy existing between the calculated and measured pass-band width of the class of comb-line filters. With the new procedure the discrepancy reported previously to be of the order of 10% is eliminated. Finally, experimental evidence is adduced to verify the algorithms outlined in the preceding chapters.
30

OFDM/FM frame synchronization for mobile radio data communication

Warner, William D. January 1991 (has links)
A synchronization scheme enabling the use of OFDM/FM in a pure ALOHA environment over a mobile radio channel is proposed, implemented, and tested. The synchronization scheme encodes synchronization information in parallel with data in the same manner in which data is encoded in the OFDM/FM frame. The encoded synchronization information is in the form of tones, centered in reserved frequency sub-channels of the OFDM signal. The receiver uses a correlation detector, implemented in the frequency domain, to accurately acquire synchronization on a packet by packet basis. Experimental results indicate that BER performance with synchronization is achieved to within 1.5 dB of the performance achievable with ideal synchronization. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

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