Toward the implementation of analog LDPC decoders for long codewords

Error control codes are used in virtually every digital communication system. Traditionally, decoders have been implemented digitally. Analog decoders have been recently shown to have the potential to outperform digital decoders in terms of area and power/speed ratio. Analog designers have attempted to fully understand and exploit this potential for large decoders. However, large codes are generally still implemented with digital circuits. Nevertheless, in this thesis a number of aspects of analog decoder implementation are investigated with the hope of enabling the design of large analog decoders. In this thesis, we study and modify analog circuits used in a decoding algorithm known as the sum-product algorithm for implementation in a CMOS 90 nm technology. We apply a current-mode approach at the input nodes of these circuits and show through simulations that the power/speed ratio will be improved. Interested in studying the dynamics of decoders, we model an LDPC code in MATLAB's Simulink. We then apply the linearization technique on the modeled LDPC code in order to linearize the decoder about an initial state as its solution point. Challenges associated with decoder linearization are discussed. We also design and implement a chip comprised of the sum-product circuits with different configurations and sizes in order to study the effect of mismatch on the accuracy of the outputs. Unfortunately, testing of the chip fails as a result of errors in either the packaging process or fabrication

On Coding and Detection Techniques for Two-Dimensional Magnetic Recording

Edited version embargoed until 15.04.2020 Full version: Access restricted permanently due to 3rd party copyright restrictions. Restriction set on 15/04/2019 by AS, Doctoral CollegeThe areal density growth of magnetic recording systems is fast approaching the superparamagnetic limit for conventional magnetic disks. This is due to the increasing demand for high data storage capacity. Two-dimensional Magnetic Recording (TDMR) is a new technology aimed at increasing the areal density of magnetic recording systems beyond the limit of current disk technology using conventional disk media. However, it relies on advanced coding and signal processing techniques to achieve areal density gains. Current state of the art signal processing for TDMR channel employed iterative decoding with Low Density Parity Check (LDPC) codes, coupled with 2D equalisers and full 2D Maximum Likelihood (ML) detectors. The shortcoming of these algorithms is their computation complexity especially with regards to the ML detectors which is exponential with respect to the number of bits involved. Therefore, robust low-complexity coding, equalisation and detection algorithms are crucial for successful future deployment of the TDMR scheme. This present work is aimed at finding efficient and low-complexity coding, equalisation, detection and decoding techniques for improving the performance of TDMR channel and magnetic recording channel in general. A forward error correction (FEC) scheme of two concatenated single parity bit systems along track separated by an interleaver has been presented for channel with perpendicular magnetic recording (PMR) media. Joint detection decoding algorithm using constrained MAP detector for simultaneous detection and decoding of data with single parity bit system has been proposed. It is shown that using the proposed FEC scheme with the constrained MAP detector/decoder can achieve a gain of up to 3dB over un-coded MAP decoder for 1D interference channel. A further gain of 1.5 dB was achieved by concatenating two interleavers with extra parity bit when data density along track is high. The use of single bit parity code as a run length limited code as well as an error correction code is demonstrated to simplify detection complexity and improve system performance. A low-complexity 2D detection technique for TDMR system with Shingled Magnetic Recording Media (SMR) was also proposed. The technique used the concatenation of 2D MAP detector along track with regular MAP detector across tracks to reduce the complexity order of using full 2D detection from exponential to linear. It is shown that using this technique can improve track density with limited complexity. Two methods of FEC for TDMR channel using two single parity bit systems have been discussed. One using two concatenated single parity bits along track only, separated by a Dithered Relative Prime (DRP) interleaver and the other use the single parity bits in both directions without the DRP interleaver. Consequent to the FEC coding on the channel, a 2D multi-track MAP joint detector decoder has been proposed for simultaneous detection and decoding of the coded single parity bit data. A gain of up to 5dB was achieved using the FEC scheme with the 2D multi-track MAP joint detector decoder over un-coded 2D multi-track MAP detector in TDMR channel. In a situation with high density in both directions, it is shown that FEC coding using two concatenated single parity bits along track separated by DRP interleaver performed better than when the single parity bits are used in both directions without the DRP interleaver.9mobile Nigeri

Design and construction of a laboratory system for neuromuscular stimulation of the lower extremities during cycling

Functional Neuromuscular Stimulation (FNS) is a method by which paralyzed muscles are stimulated electrically in order to produce a useful movement. The design and testing of a laboratory system for the modulated control of the lower extremities during FNS-induced cycling on an exercising device (Paracycle) is described. The system hardware, which is designed around a standard IBM compatible Personal Computer, features six independent stimulation channels. Waveform characteristics such as pulse frequency, width and amplitude are defined as a function of the crank position of the Paracycle for each channel. An extensive software package allows programmability of the waveform parameters and supports the user in the definition of stimulation sequences. The effective performance of the complete FNS-controller/ Paracycle system has been demonstrated during a controlled case study with two paraplegic subjects

Study of Various Motherboards

Not availabl

Modulation codes for mobile communications

M.Ing. (Electrical and Electronic Engineering)Please refer to full text to view abstrac

The Fifth NASA Symposium on VLSI Design

The fifth annual NASA Symposium on VLSI Design had 13 sessions including Radiation Effects, Architectures, Mixed Signal, Design Techniques, Fault Testing, Synthesis, Signal Processing, and other Featured Presentations. The symposium provides insights into developments in VLSI and digital systems which can be used to increase data systems performance. The presentations share insights into next generation advances that will serve as a basis for future VLSI design

LAN based Remote Access Multiple Users (RAMU) Voice Information Retrieval System.

Sum Wai Chun.Thesis (M.Sc.)--Chinese University of Hong Kong, 1992.Includes bibliographical references.AcknowledgementAbstractThesisChapter I --- Introduction --- p.P.1 - P.3Chapter II --- System Overview of RAMU --- p.P.3 - P.5Chapter III --- Hardware Implementation of VRU --- p.P.5 - P.8Chapter IV --- Software Design of RAMU --- p.P.8 - P.15Chapter V --- Software Support of RAMU --- p.P.15Chapter VI --- Potential Applications of RAMU --- p.P.16 - P.17Chapter VII --- Suggested Further Works --- p.P.17 - P.18Chapter VIII --- Demonstrated Applications Developed on RAMU --- p.P.18 - P.19Chapter IX --- Conclusion --- p.P.19BibliographyChapter Appendix 1 -- --- TIUChapter * --- Circuit layoutChapter * --- Circuit Operation of TIUChapter * --- DIP Switch Settings of TIUChapter * --- Data Sheets of8255Chapter * --- Data Sheets of MC145436Chapter Appendix 2 -- --- Application GeneratorChapter * --- User Guide of the Application Generator ProgramChapter * --- Program Listing of AppGen. Pas and its supporting unitsChapter - --- M__AppGen.PasChapter - --- DataStru. PasChapter - --- ColorDef. PasChapter Appendix 3 -- --- AEMChapter * --- Parameters of Running the AEMChapter * --- Program Listing of LAppExec.Pas and its supporting unitsChapter - --- ToneCard. PasChapter - --- VrpSupp. PasChapter - --- MiscUtil. PasChapter - --- DataStru. PasChapter - --- LanMStru. PasAppendix 4-- Manufacturer Manual of VRP-70 Voice Car

Development of a computer controlled multichannel potentiostat for applications with flowing solution analysis

A 16-channel computer controlled potentiostat has been designed for use with an amperometnc array for analysis in flowing streams The instrumentation developed to date has been used with both linear and radial flow cell configurations which have been constructed "m-house" Analogue and digital circuits for the independent control of 4 working electrodes have been fabricated, tested and integrated successfully to give an amperometnc array. The design is based on the utilisation of common reference and counter electrodes to reduce the complexity of the electrode arrangement Control of the purpose built instrumentation was effected with a 486-33 personal computer and Analog Devices RTI-815 and RTI-817 data acquisition/control cards, which are responsible for hardware control functions and data acquisition via digital and analogue control lmes. Software for instrumentation control, data display (2- or 3-dimensional formats), on-line and post-run data processmg and storage has been developed usmg the QuickBASIC software environment. The user interface utilises a Wmdows style display to achieve user friendliness with an on-lme help facility Data is stored in a spreadsheet compatible format ( ASCII with column delimiter) to facilitate post-run processmg with standard applications packages such as Microsoft EXCEL The system has been applied to the determination of well characterised electroactive compounds usmg flow-mjection analysis Linearity over the range 10"2- lO'^M has been obtamed with a detection limit of 2x 10'7m (S/N = 3 0) for potassium femcyamde The array has been applied to the simultaneous measurement o f both oxidation and reduction currents of femcyamde and hydroqumone

Thermion: Verification of a thermionic heat pipe in microgravity

The design and development is examined of a small excore heat pipe thermionic space nuclear reactor power system (SEHPTR). The need was identified for an in-space flight demonstration of a solar powered, thermionic heat pipe element. A demonstration would examine its performance and verify its operation in microgravity. The design of a microsatellite based technology demonstration experiment is proposed to measure the effects of microgravity on the performance of an integrated thermionic heat pipe device in low earth orbit. The specific objectives are to verify the operation of the liquid metal heat pipe and the cesium reservior in the space environment. Two design configurations are described; THERMION-I and THERMION-II. THERMION-I is designed for a long lifetime study of the operations of the thermionic heat pipe element in low earth orbit. Heat input to the element is furnished by a large mirror which collects solar energy and focuses it into a cavity containing the heat pipe device. THERMION-II is a much simpler device which is used for short term operation. This experiment remains attached to the Delta II second stage and uses energy from 500 lb of alkaline batteries to supply heat energy to the heat pipe device