High-speed real-time data acquisition for vector measuring current meters

The authors describe an integrated hardware and software approach used to provide real-time acquisition and display of vector measuring current meter (VMCM) data at high sample rates (0.5 Hz) with supporting data from other instruments of somewhat slower rates. The hardware component consisted of a new circuit board for the VMCM that captured the VMCM data output, stored it, and transmitted it at high speed in response to a request from the data acquisition computer. The data acquisition software ran on a Masscomp 5600 computer under the UNIX operating system. A central control program provided timing information to several software processes that handled serial data acquisition, display, and storage for one or more instruments. Deployed as a part of the Surface Waves Processes Program (SWAPP) experiment, the integrated data acquisition system successfully collected, processed, stored, and displayed data from 19 VMCMs and four other instruments over a 22-day period in February and March of 1990