A microcomputer-controlled digital acquisition and analysis system for the expendable bathythermograph

Abstract

For a number of years the expendable bathythermograph (XBT) has been an important tool for basic and applied oceanographic survey work. This has led to a significant body of work being done on the accuracy of the XBT system as a whole. One of the most important limitations has been the analogue recording and manual digitisation of the profiles. A digital interface is described that replaces the standard deck unit and removes this problem. The interface is controlled through an IEEE-488 interface bus by a microcomputer or a minicomputer. The data is stored with 12 bit precision 10 times a second. As many as 115 profiles, each recording to 450 m in depth, may be stored on a single cassette. The microcomputer and plotter may be used for a number of analytical tasks including isotherm following, contour plotting, and sound speed or density calculations. The profiles may also be automatically compressed by a "most reversible" algorithm and coded to standard format for radio transmission. The bibliography contains presently available research reports on the XBT.