Wave height and period data were collected on electrical capacitance wave
gauges calibrated daily with a computer-controlled procedure incorporating a
least-square fit of measurements at 11 steps. This averaging technique, involving
21 voltage samples per gauge, minimizes the error of slack in the gear drives and
hysteresis in the sensors. Typical calibration errors are less than 1 percent of full
scale for the capacitance wave gauges. Wave signal generation and data acquisi-
tion were controlled by a Digital Equipment Corporation (DEC) MicroVax I
computer.
Water velocity data were collected with a SonTek, Inc., two-dimensional
Acoustic-Doppler Velocimeter (ADV) with a side-looking probe oriented to col-
lect x-y velocity information in a horizontal plane. Samples were collected at
10 Hz, though the instrument makes 250 pings/sec and averages for each output
sample. Accuracy is 0.5 percent of the measured velocity, with resolution of
0.1 mm/sec and threshold of 0.1 cm/sec. The probe samples a 0.25-cm3 volume
located 5 cm from the sensor heads.
7
Chapter 2 Experiment Arrangement
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