SECONDARY CIRCULATION DATA ACQUISITION SYSTEM.

A computerized field data collection system was developed for a project investigating secondary circulation in natural rivers. The instrumentation includes a Commodore mini-computer with tape drive, a Marsh-McBirney electromagnetic current meter and an interface between the current meter and the computer. A computer program was developed for the Commodore to retrieve, process and store field data on cassette tapes. Once in the computer's memory space, the information is processed by a computer program to give velocity readings in ft/sec and directions in degrees. The velocity data can then be recorded onto cassette tapes either in a summary form with the mean velocities and their standard deviations or in detail with all the individual readings for every time interval during the sampling period.