- 13^ - 



4. Capability of the DPG System 



The DPG results shown in Table 6.3 were generated using 

 differential channels 2 and 3 and the absolute channel. These 

 results lend encouraging evidence that the DPG is capable of 

 accurately detecting wave direction. The radar pictures to which the 

 DPG results were compared are shown in Figure VI-11. One can 

 appreciate that it is often difficult to accurately resolve an 

 approximate direction from the radar images; in fact, it is 

 impossible during low wave activity or in the absence of capillary 

 waves of appropriate frequency. Hence, the small differences between 

 the reported wave direction from the DPG and the estimate from radar 

 is likely attributable to the poor resolution of the radar images. 

 It is instructive to note the accuracy of the visual estimates of 

 wave direction. Anyone who has tried to visually resolve the 

 direction of a wave train, especially that of short-crested waves, 

 appreciates the difficulty in making visual directional estimates. 



The significant height and period of greatest energy reported 

 by the DPG and the Baylor gauge near the end of the pier agree well. 

 Slight differences may be attributed to the different locations, 

 measurement techniques, and analysis details of each of the two 

 instruments. Analysis of the Baylor gauge data is carried out upon a 

 17 minute long record of one-quarter second sampling. 



