A PULSE CODE MODULATION CODER/DECODER SUITABLE FOR LARGE SCALE INTEGRATION
Date
1979-05
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Type
Degree Level
Masters
Abstract
The need for an economical and reliable pulse code modulation encoder/decoder (PCM codec) has resulted from the increasing interest in digital methods for telecommun—ications transmission, switching and signal processing. This thesis presents a design of such a codec. The design uses a digitally adaptive delta modulator as the analog-to-digital interface. Accumulation of the delta code signals produces linear PCM and a recursive digital filter allows sample rate decimation without aliasing. The discussion continues with companding and code conversion which produces an industry standard eight—bit code. Decoding of PCM signals is also discussed.
The thesis concentrates on development of a suitable digital filter. The necessary theory is presented followed by an analysis of the various digital filter structures. A second-order recursive filter was chosen for experimentation. Circuit schematics and experimental results are included.
The thesis concludes that the proposed codec would be suitable for integration onto a set of three semiconductor chips. Anticipated advances in integrated circuit tech—nology should make a single chip codec possible in the near future.
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Degree
Master of Science (M.Sc.)
Department
Electrical Engineering