High-speed real-time data acquisition for vector measuring currentmeters     

Park  M.M. Singer  R.C. Plueddemann  A.J. Weller  R.A. 《Oceanic Engineering, IEEE Journal of》1991,16(4):360-367

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  相似文献   

Design and performance of a self-contained fan-beam ADCP     

Plueddemann  A.J. Terray  E.A. Merewether  R. 《Oceanic Engineering, IEEE Journal of》2001,26(2):252-258

Recent field studies have shown the utility of acoustic Doppler current profilers (ADCPs) with fan-shaped transducer beam patterns (narrow in azimuth and broad in elevation) for the measurement of oceanic surface currents. For wind speeds greater than about 3 m·s^-1, the acoustic backscatter is dominated by microbubbles in the upper few meters of the water column, and beams intersecting the surface from below effectively map out horizontal profiles of near-surface current. This paper describes the design and performance of a self-contained, fan-beam ADCP consisting of RD Instruments 300 kHz BroadBand electronics mated to a specially designed transducer head, and intended for long-term deployment on conventional oceanographic moorings. The instrument operated successfully during two field deployments, providing horizontal profiles of near-surface velocity with precision of about 1 cm·s^-1 and horizontal resolution of about 5 m. Profiles were obtained once per minute during 20 min “burst” samples each hour. The usable horizontal range varied with wind speed from about 100 to 200 m. Distinct convergence patterns indicative of Langmuir circulation were evident in the cross-wind velocity field during strong forcing events. Time-range maps and horizontal wavenumber spectra of velocity showed evolution of the strength and dominant scale of the circulation during these events  相似文献