Landward 



Middle 



Seaward 



Gage 



Gage 



Gage 



<P 



(?) 



(3) 



Figure 4.5. Hume profile near structure with nearshore wave gage layout 



The gages were calibrated using the following automated technique. Each 

 gage was attached to a Jordan servo-controller and motor. The wave gage data 

 acquisition, control, and signal conditioning system consisted of a VAX PDP-1 1 

 microcomputer connected to 12-bit differential input analog-to-digital converters, 

 digital-to-analog converters, and analog filters. A program on the PDP-1 1 sent signals 

 to the Jordan controllers sending each through 10 calibration stops twice, covering a 

 range of motion in excess of the largest wave expected in the irregular time series. At 

 each stop, the voltage from each gage was recorded. For each gage, a calibration curve 

 was automatically tested for fit through the calibration points using linear, quadratic, or 

 cubic spline regression. The calibration program automatically chose the simplest 

 technique with less than 0.25 mm deviation from the regression curve, which 

 corresponds to approximately 0.1 -percent maximum deviation over the full calibration 



65 



