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It has been demonstrated that the differential pressure 

 transducer can be considered to be an inherently more effective 

 instrument for determining wave direction. The design is well suited 

 to the measurement of water surface slope and the response of surface 

 slope with depth is a maximum over frequencies that are more 

 representative of typical ocean gravity waves than the response of 

 conventional absolute pressure transducers. 



In the development of the DPG system, it was discovered that 

 careful attention must be given to the diameter of the tubing and to 

 the nature of the back-filling fluid used in the transducers' 

 sensors. This is to ensure a small response time for each 

 transducer. The DPG prototype, as installed at the CERC Field 

 Research Facility, utilizes gin and 1/8 inch I.D. flexible tubing in 

 its sensor systems. Ambient temperature changes induce differential 

 pressure changes as measured by the transducers since the tubing used 

 in the arm sensors is four times the length of that of the center 

 sensors . 



A simple bench-calibration device was developed to monitor 

 the response of the transducers and sensor systems to applied loads. 

 It is important that the load be distributed uniformly across the 

 sensor diaphragm. 



