an operator can leave the radar on a single range and view the return. 

 To measure the period, the operator would either select a stationary 

 radar scatterer, such as a tower or end of a pier shown in the radar 

 photo, or chose a point on the PPI and determine the time (with the aid 

 of the LED clock) for one wave (crest to crest) to pass the chosen point 

 on the scope. For better accuracy, the time is determined for the pass- 

 ing of 10 waves; the wave period would then be this time divided by 10. 

 From a radar picture, the wave period could be found by measuring the 

 wavelength at a location in the frame where the depth is known. Linear 

 wave theory could then be applied to give an estimate of the period. 



Information on wave height may be obtainable with the CERC radar. 

 The strength of the radar return is a function of the amplitude of the 

 capillary waves and the local grazing angle. Since the capillary waves 

 are modulated by the longer gravity waves, it would then appear that the 

 modulation of the radar return signal should contain information on the 

 long-wave heights. A complicating factor is that the capillary wave 

 development is influenced by the local winds. A complete theoretical 

 model is not now available to relate radar cross section or radar return 

 signal strength to wave height for radars such as the CERC radar. How- 

 ever, an empirical calibration of the radar return for wave height may 

 be possible. 



2. Future Plans . 



The main directions for further development are to increase resolu- 

 tion of the radar system and to develop automatic data reduction. The 

 CERC system has a 2.74-meter (9 feet) antenna array; however, a recently 

 available 3.66-meter (12 feet) array will give a slightly better angular 

 resolution of 0.6° instead of 0.9°. More importantly, it will give a 

 better signal-to-noise ratio. 



A shorter pulse width to improve resolution and perhaps provide better 

 radar wave images may be possible with only minor adjustments to the radar. 

 One drawback in shortening the pulse width is that this lowers the average 

 power transmitted. Weak scatters imaged when using the 0.05-microsecond 

 pulse, may be invisible with the shorter pulse. Tests are needed to de- 

 termine the conditions when the shorter pulse would be useful. 



An additional refinement is to modify the radar circuitry so that the 

 gain function more closely follows the decrease in radar return strength 

 with range to give a better image with a more even contrast across the 

 image and less saturation near the center of the PPI. This will also 

 give an image better suited to automatic analysis procedures. 



If a large quantity of data is collected with these radar systems, 

 then automated methods are needed for analysis. Suggested methods in- 

 clude (a) Fourier transforms of the radar film using either optical or 

 digital methods, (b) analytical means for obtaining wave direction from 

 the direct radar return signal, and (c) a TV recording system in lieu of 



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