This thesis reports on the design and evaluation of a microprocessor-controlled, high-speed analog-to-digital converter. The processor supervises and manages the digital conversion, split-phase encoding (Manchester) and framing of the input signal. This converter is designed to be applied in an underwater package which will serially transmit sensor data over a fiber optic link to a shore station. This intelligent sensor will provide for ease of future system enhancements. An example would be the implementation of one package to multiplex several analog channels from a local sensor network over the single fiber optic link to the shore station. Keywords: Analog-to-Digital converter, Digital conversion, Split phase encoding, and Manchester. (r.h.) / http://archive.org/details/microprocessorco00schl / U.S. Coast Guard (U.S.C.G.) author.