This thesis examines the design of a QPSK demodulator frontend for GPON transceiver at end user's side. Since lowering the cost of the terminal transceivers in an access network like GPON is a key requirement, CMOS technology is used and several area-saving design techniques are applied. The designed frontend circuit saved more than 80% area of the key components like the mixers and the QVCO than some published designs which can also fit the application. A measurement in frequency domain and a simulation in time domain verified that this frontend is able to demodulate a QPSK signal with a data rate as high as 5 Gbit/s. Two structures of quadrature oscillators are firstly presented and compared. One is an LC QVCO centered at 5 GHz, which has a tuning range of 3 GHz, a phase noise of -100.8 dBc/Hz at 1 MHz offset, and an area of 0.15 mm2 excluding pads. The other is a ring QVCO which only takes an area of 0.019 mm2. But it has a higher phase noise of -81 dBc/Hz at 1 MHz offset. Then two broadband mixers are described separately. The first one provides a high conversion gain, but its input linearity is insufficient to meet the input power requirement. The second mixer obtains required input linearity but with a trade-off of conversion gain. Both mixers have a broadband input impedance match from 2 GHz to 8 GHz. The first mixer has a conversion gain of 8.5 dB and an input 1 dB compresion point at -17 dBm. The second mixer has a conversion gain of -7 dB with an on-chip buffer or -2.1 dB without buffer, but an input 1 dB compresion point at -5 dBm. A frontend circuit is lastly presented. It integrates the compact ring QVCO, two broadband mixers with high input linearity, and two second-order LC ladder low pass filters. A Frequency domain measurement shows the expected spectrum down conversion of a 2.5 Gsym/s QPSK signal centered at 5 GHz. The whole frontend circuit including pads takes 1 mm2 area, and consumed 157 mW power. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2010-06-29 10:59:45.312

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Thesis (M. Phil.)--University of Hong Kong, 1999. / Includes bibliographical references (leaves 123-126).

Pyroelectric Detector (PED) models are developed considering the classical heat balance equation to simulate the detector’s response under specified radiation conditions. Studies on the behaviour of a PED are presented under the conditions of step function and a pulsed load. Finite Element Methods (FEMs) have been used to obtain 3D models of the resulting temperature field in a Lithium Tantalate (LiTaO3) pyroelectric crystal, incorporated in a complete commercial detector, taking into account details of its geometry and thermal connectivity. The novelty is the achieved facility to predict the response to pulsed radiation, which is valuable for the engineering of pulsed-source sensor systems requiring detection at room temperature. In this thesis, we present a signal processing (SP) algorithm, which combines the principle of Quadrature Synchronous Demodulation (QSD) and Gated Integration (GI), to achieve an improved signal-to-noise ratio (SNR) in pulsed signal measurements. As a first step, the pulse is bracketed by a gating window and the samples outside the window are discarded. The gate duration is calculated to ensure that the periodic signal at the output has an 'apparent' duty factor close to 0.5. This signal is then fed continuously for QSD to extract the magnitude and phase of its fundamental component, referenced to a sinusoidal signal with period defined by the gate length. An improved SNR performance results not only from the increase of the average signal energy, but also from the noise suppression inherent to the QSD principle. We introduce this method as Gated Quadrature Synchronous Demodulation (GQSD), emphasizing the synergy between GΙ and QSD.

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In this thesis, several computationally-efficient approximate soft demodulation schemes are developed for multiple-input multiple-output (MIMO) communication systems. These soft demodulators are designed to be deployed in the conventional iterative receiver ('turbo') architecture, and they are designed to provide good performance at substantially lower computational cost than that of the exact soft demodulator. The proposed demodulators are based on the principle of list demodulation and can be classified into two classes, according to the nature of the list-generation algorithm. One class is based on a tree-search algorithm and the other is based on insight generated from the analysis of semidefinite relaxation techniques for hard demodulation. The proposed tree-search demodulators are based on a multi-stack algorithm, developed herein, for efficiently traversing the tree structure that is inherent in the MIMO demodulation problem. The proposed scheme was inspired, in part, by the stack algorithm, which stores all the visited nodes in the tree in a single stack and chooses the next node to expand based on a 'best-first' selection scheme. The proposed algorithm partitions this global stack into a stack for each level of the tree. It examines the tree in the natural ordering of the levels and performs a best-first search in each of the stacks. By assigning appropriate priorities to the level at which the search for the next leaf node re-starts, the proposed demodulators can achieve performance-complexity trade-offs that dominate several existing soft demodulators, including those based on the stack algorithm and those based on 'sphere decoding' principles, especially in the low-complexity region. In the second part of this thesis it is shown that the randomization procedure that is inherent in the semidefinite relaxation (SDR) technique for hard demodulation can be exploited to generate the list members required for list-based soft demodulation. The direct application of this observation yields list-based soft demodulators that only require the solution of one SDP per demodulation-decoding iteration. By approximating the randomization procedure by a set of independent Bernoulli trials, this requirement can be reduced to just one semidefinite program (SDP) per channel use. An advantage of these demodulators over those based on optimal tree-search algorithms is that the computational cost of solving the SDP is a low-order polynomial in the problem size. The analysis and simulation experiments provided in the thesis show that the proposed SDR-based demodulators offer an attractive trade-off between performance and computational cost. The structure of the SDP in the proposed SDR-based demodulators depends on the signaling scheme, and the initial development focuses on the case of QPSK signaling. In the last chapter of this thesis, the extension to MIMO 16-QAM systems is developed, and some interesting observations regarding some existing SDR-based hard demodulation schemes for MIMO 16-QAM systems are derived. The simulation results reveal that the excellent performance-complexity trade-off of the proposed SDR-based schemes is preserved under the extension to 16-QAM signaling. / Thesis / Doctor of Philosophy (PhD)

Typescript (photocopy). / Digitized by Kansas Correctional Industries

International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, California / Combined with an example of digital telemetry receiver design, this paper mainly discusses the application of software radio in telemetry receiver. The paper begins with an introduction of applying high efficiency digital filter and math analysis in quadrature digital frequency modulation and demodulation to digital frequency conversion technique. Next, Simulink/Matlab is used to simulate digital telemetry receiver. The method of simulation, analysis and calculation of performance and result of simulation are all available. In the end, the paper discusses digital telemetry receiver design and implement by making use of software radio technique, the circuits apply HSP50214 chip of Intersil Co., CPLD implements of Altera Co. and PC Bus. The sample is an expansion card for personal computer. Result of test, performance of the receiver and conclusion are given out, which show fine performance of receiver and can be apply to practice. The lever of this technology has reached first class in the world.

ITC/USA 2009 Conference Proceedings / The Forty-Fifth Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2009 / Riviera Hotel & Convention Center, Las Vegas, Nevada / Multi-h Continuous Phase Modulation (CPM) is a promising waveform for aeronautical telemetry because it is a compact spectrally efficient constant amplitude modulation. It has been selected as the Advanced Range Telemetry (ARTM) tier II waveform owing to these qualities. However, it is also a complicated waveform that has the reputation of suffering from complex demodulation processing and high sensitivity to transmission impairments and in particular synchronization aspects. In this paper we review a set of complexity reduction techniques that intend to bring this waveform into the domain of operational telemetry waveform, by allowing low complexity hardware implementation without sacrificing performance or robustness. Most techniques are adjustments of recent literature results, concerning both demodulation and synchronization. Computer simulation of a receiver implementing theses techniques shows negligible performance loss compared to optimal coherent demodulation with perfect synchronization. Hardware implementation confirms that nearly optimal performance can be achieved with hardware resource currently available in middle range FPGAs.