A current meter similarly located at a depth s will record a 

 signal under waves such as: 



U(x,y,s;t) = — a K cos (kx + ky-at+e) /'')o^ 



2 u X y K^.S) 



where : j^ 



cosh ks 

 u sinh kh 



Although the magnitude of both the pressure and current 

 decreases steadily over increasing frequency, the differential 

 pressure signal reaches a maximum at an intermediate frequency. This 

 is illustrated graphically in Figure II-l, which depicts the dynamic 

 response of pressure and differential pressure gauges located near 

 the bottom with a wave crest of 2.5 foot amplitude. In the 

 upper-most curves, the differential gauge is assumed to sample two 

 points separated by three feet coincident with the wave ray. The 

 lower curve represents the difference in pressure monitored by two 

 absolute pressure gauges separated by twenty feet along the wave ray. 

 Each curve is normalized by typical values of the rated capacity of 

 the instruments, (35 psia for the pressure transducer, and +0.5 psid 

 for the differential transducers). Figure II-l represents a water 

 depth of fifteen feet, while Figures II-2 and II-3 represent twenty 

 and twenty-five feet water depths respectively. In each case, the 

 transducers are located three feet off the seafloor. It is clear 

 that the differential pressure signal utilizes a greater portion of 



