- h - 



the pressure sensors, as in Figure I~2, one could imagine that one 

 sensor would report the passage of the crest before the other. The 

 difference in pressure over time between the sensors' records can be 

 analyzed by well-known techniques and a first estimate of the wave 

 direction calculated, (Longuet-Higgins ,Cartwright , and Smith, 1963). 

 There is, of course, a directional ambiguity with only two sensors 



since a wave approaching as in 

 Figure 1-3 would create the same 

 pressure record over time as in 

 Figure 1-2. Such ambiguities may 

 be resolved by additional 

 sensors . 



Presently, the analysis 

 of data from bottom-mounted 

 arrays of pressure sensors 

 usually develops pressure 

 differences through the sub- 

 traction of individually meas- 

 ured absolute pressures. 

 However, instantaneous differ- 

 ences in the transducers ' records 

 due to wave action are typically 

 very small when compared to the 

 large pressure values that they 



FIGURES 1-1,2,3: Approach of 

 a long-crested "wave to two 

 adjacent pressure sensors. 



