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Quadrature amplitude modulation (QAM) is a highly bandwidth efficient transmission technique for digital communications. It makes use of multiple signal phase and amplitude levels to carry multiple bits per symbol. This requires accurate and robust carrier phase and frequency estimation in the receiver. / Thesis (PhDElectronicEngineering)--University of South Australia, 2002

Wireless communication technologies are no longer limited for voice band applications, but have entered the era for multimedia data link. The IEEE802.11 family, which occupies a bandwidth in the multi-mega hertz region with the highest data rate of 54 Mbps, now has become the most widely deployed wireless LAN standards. The rapid adoption of IEEE802.11 for computer wireless networks and their growing popularity in mobile applications highlight the need for a low cost, low power consumption, and monolithic solution. To meet this challenge, traditional RF techniques, which revolved around the superheterodyne architecture can no longer be used. On the contrary, new receiver frontend architectures need to be developed to satisfy the demand of system level integration. Direct downconversion receivers directly translate the RF spectrum to the baseband by setting the LO frequency equal to the RF. Due to the single frequency translation, expensive and bulky off-chip filters and 50 ohm I/O matching networks at IF are no longer required. Also, the single-stage quadrature mixers further simplify the receiver design and reduce the power dissipation. Subsequent baseband components and ADCs are also possible to be integrated with the RF frontend to achieve a monolithic receiver chip. Despite the previously mentioned advantages, the implementation of a direct downconversion receiver has its own set of performance challenges. In particular, the performance is plagued by DC offset, flicker noise, linearity and mismatches etc. The main objective of this project is to investigate the feasibility of using direct downconversion architecture for the IEEE802.11a standard, and implement the design in a 0.18 µm CMOS technology. By approaching the design issue at a theoretic point of view, extensive modeling and simulations based on a SIMULINK IEEE802.11a physical layer theme have been carried out to evaluate the receiver performance. SER results of the receiver demonstrate that the impairments associated with zero IF can be minimised to an acceptable level. Under the guidance of the system level analysis, the circuit level design of a monolithic direct downconversion receiver has been implemented in a 0.18 µm RF CMOS process, including the building blocks of an LNA, mixer, baseband amplifier and a channel-selection filter. Particularly, a novel LNA design methodology with an improved noise figure and less power consumption has been developed. The mixer conversion gain and phase noise have been analysed by a novel approach. The combination topology of the highpass DC offset removal filter and the baseband amplifier provids the best linearity with a negligible noise figure degradation. Circuit simulations are performed using the foundry provided RF design kit with enhanced noise models to capture the extra noise of passive and deep submicron devices. Circuit level simulations show a qualified receiver frontend for the IEEE802.11a standard. As data converters are important building blocks in wireless receivers, research on high performance Sigma-Delta modulators is also included. MATLAB based programs have been developed for both the discrete and continuous time transfer function synthesis. A BPSDM chip with variable centre frequencies has been developed to verify the SDM transfer function algorithm and the design methodology. The design of an ultra fast continuous time SDM is particularly focused on for a broadband data conversion. To alleviate the challenge of the comparator speed limit, a novel noise transfer function with a unit clock delay has been synthesised. With such a delayed transfer function, a three-stage comparator can be acheieved that solves the comparator gain and speed tradeoff. The full chip simulation shows an acceptable performance for the IEEE802.11a standard. / Thesis (Ph.D.) -- University of Adelaide, School of Electrical and Electronic Engineering, 2008

<p>Technologies for position sensing and identification are important to have in ubiquitous computing environments. These technologies can be used to track users, devices, and artefacts in the physical milieu, for example, locating the position of a cellular phone in av physical environment. The aim of this thesis was to survey and classify available technologies for location sensing and identification. </p><p>We have made a literature study on both commercial and research-oriented systems and technologies for use in indoor and outdoor environments. We compared the characteristics of the underlying sensing technologies with respect to physical size, sensing method, cost, and accuracy. We conclude the thesis with a set of recommendations to developers and discuss the requirements on future sensing technologies and their use in mobile devices and environments.</p>

<p>The study of high power fusion plasmas at the JET tokamak has been further enhanced through the development of instrumentation for neutron emission spectroscopy (NES) measurements. This has involved the upgrade of the magnetic proton recoil (MPR) spectrometer used for deuterium-tritium plasmas earlier so that the MPRu can now be also employed for deuterium (D) plasmas. A neutron time-of-flight (TOF) spectrometer designed for optimized rate (TOFOR) has been constructed and put into operation. The MPRu and TOFOR spectrometers were carried out as part of the JET enhanced performance program and represent the most advanced instrumentation for NES diagnosis of both D and DT tokamak plasmas setting a central platform for R&D direct to the next step in fusion research to be carried out with ITER.</p><p>The MPRu work presented in this thesis concerns the development of a new focal plane detector based on the phoswich scintillator technique. The main objective of this sub-project was to increase the signal-to-background ratio to permit measurement of the 2.5-MeV neutron emission from d+d-->3He+n reactions and, hence, allow NES diagnosis of D plasmas. The objective was achieved as demonstrated in preliminary measurements at JET. </p><p>The development of TOFOR from concept to construction is presented in the thesis including, in particular, the commissioning of the instrument at JET. The objective of the TOFOR project was to achieve the same high performance in the NES diagnosis of D plasmas as had earlier been demonstrated by the MPR for DT plasmas. TOFOR has been used in the first plasma physics experiments reported in this thesis. These demonstrate that the performance objectives have been achieved as tested, in particular, in the observation of auxiliary heating effects on velocity distribution of the deuterium population.</p>

This thesis describes the design of a baseband digital predistortion architecture for radio frequency (RF) amplifier linearization. Existing amplifier linearization techniques are first examined. The nonlinearity of an amplifier can be characterized as amplitude-to-amplitude distortion and amplitude-to-phase distortion. The distortion can be corrected by providing a predistorted driver signal (both in amplitude and phase) to the amplifier. This counteracts the nonlinearity of the amplifier so that the overall system is more linear. A pipelined predistortion architecture is designed to allow fast processing speed, and is capable of providing linearization for a bandwidth of 25 Mhz. The simulation results show significant improvement in amplifier's performance using predistortion technique. The system bandwidth versus cost is examined by using commercially available components. / Graduation date: 1996

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L.B. Arguimbau ... [et al.]. / "September 20, 1954." / Bibliography: p. 49. / Army Signal Corps Contract DA36-039 sc-42607 Project 132B Dept. of the Army Project 3-99-12-022

R.D. Stuart ... [et al.]. / "July 6, 1953." / Bibliography: p. 10. / Army Signal Corps Contract No. DA36-039 sc-100 Project No. 8-102B-0 Dept. of the Army Project No. 3-99-10-022

Elie J. Baghdady. / "September 24, 1956." "This report is based on a thesis submitted to the Department of Electrical Engineering, M.I.T., May 16, 1956, in partial fulfillment of the requirements for the degree of Doctor of Science." / Bibliography: p. 106. / Army Signal Corps Contract DA36-039-sc-64637 Dept. of the Army Task 3-99-06-108 Project 3-99-00-100