The lack of availability of a single, complete paper on the analysis of a digital data acquisition system for in situ oceanographic measurements brought about the present work. In order to compile an accurate technical paper on such a complex system, it was necessary to design, construct, and calibrate a system for the in situ measurement of various physical and chemical properties of sea water. A unique digital encoding circuit was developed which utilizes the basic principles of null balance, resistance ratio bridge and potentiometer measurements. The circuit is a uniquely loaded binary ladder resistance network. Variation of the loading allows resistance ratio and potentiometric measurements to be made over different ranges with a constant high degree of resolution. The developed system has the capability of measuring any parameter which can be converted into a varying voltage, current, or resistance. The range over which the measurement can be made is adjustable; and the resolution equals ± 0.006% of the full range value. The resolution is constant over the full range, as a result of the analog-to- digital converter linearity characteristics. / Graduation date: 1968