Micro-controller communications module : an investigation into digital communications with emphasis on simplicity and practicality

Abstract

Advances in digital electronics have brought about the use of microprocessors and digital techniques in diverse fields once thought to be the exclusive domain of analog. Once such field is that of the telephone systems. Telephone companies are presently at work designing circuitry for use in ISDN (Integrated Services Digital Network) systems. In such a system, there is a need for simple modules capable of digitizing input signals and reproducing output signals, possibly with multiple channels. This thesis investigates the design and implementation of a four channel, full-duplex, digital communication module. Theory and techniques involved in the areas of analog-to-digital conversion, signal processing, serial communication, and digital-to-analog conversion are discussed and compared. Design goals are laid out with emphasis on simplicity and practicality. The entire design phase from concept to implementation is detailed. The final design successfully implements a simple yet practical module capable of performing simultaneous bi-directional digital communication on four channels. Each channel has a bandwidth of approximately 3kHz.