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A unified approach to the analysis and design of digital line codes

Petkov, G. P. (1992). A unified approach to the analysis and design of digital line codes. (Unpublished Doctoral thesis, City, University of London)


In most areas of research the variety of possible approaches to analysis and design problems is very large. This is particularly true in the case of digital signal transmission where various conflicting requirements exist (e.g. minimum bandwidth for maximum information capacity and reliability). The lack of universally adopted analysis and evaluation methods is not due to any uncertainties or deficiencies in theoretical fundamentals, rather it is a problem of diversity of criteria and therefore modes of specification that apply.

The work presented in the thesis is concerned with the creation and evaluation of a universal algorithm suitable for the assessment of digital codes together with a systematic approach to the comparative evaluation of essential structural and spectral features of coding schemes.

The thesis begins with an overview of the basic theoretical principles of line coding as an essential part of the process of channel coding for reliable and efficient digital signal transmission. A general spectral analysis procedure is derived from the finite-state sequential machine model of fixed-length block coders, and is implemented in the form of a computer program. A technique for the conversion of coder rules, given in descriptive form into table and matrix form, suitable for the universal specification format used in the general spectral analysis procedure, is developed.

A new method of general classification of codes into categories, according to their complexity levels, is proposed. A modification of the spectral analysis routine into a universal block-code generating scheme is then introduced. The virtually unlimited capabilities for the design and analysis of new code structures is demonstrated. Following from this, a new method for evaluation of the performance of block codes is suggested. It is based on the introduction of an integral parameter, the Information Capacity, which determines the degree of possible spectrum modification for a particular coder specification. Using this method, it is demonstrated how an optimal combination of a code structure, spectral features and information capacity can be achieved.

The thesis concludes with a practical example of the application of the generalised analysis procedure, demonstrating the possibility to combine code multiplexing with modification of the spectrum of the line signal. A novel technique, based on the principles of spread spectrum for multichannel transmission, is proposed. It involves a Binary-Multiplexed Coding (BMC) scheme which is implemented in a generalised circuit, the performance of which is investigated and evaluated.

Publication Type: Thesis (Doctoral)
Subjects: Q Science > QA Mathematics > QA75 Electronic computers. Computer science
Departments: School of Science & Technology > Computer Science
School of Science & Technology > School of Science & Technology Doctoral Theses
Doctoral Theses
Text - Accepted Version
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