c. d. 



Fig. 6. Tests offshore from Bimini on 27 June 1962: (a) oscilloscope, 

 single sweep, 2 ms/cm, (b) Panoramic, 20 sweeps, ^-second tape 

 loop, (c) Panoramic, l6 sweeps, continuous segment and 

 (d) Panoramic, 60 sweeps, continuous segment. 



anchor a few feet from the current meter. Very 

 little Doppler was noted when the heads were 

 placed normal to the current flow. Magmeter 

 readings were reasonable compared to the current 

 velocity measured by timing a floating chip. 



CONCLUSIONS 



The Doppler current meter described will pro- 

 vide a sensitive and accurate sinusoidal output 

 for measurements of a unidirectional, turbulence- 

 free current containing particulate matter such 

 as would exist in a properly designed flow tube. 

 A meter based on the Doppler shift principle was 

 described in a paper by Chapulnik and Green. 3 

 Their experiments indicated that this instrument 



was well suited for measuring unidirectional, 

 constant-velocity current flow. 



Since this meter is non-inertial, it responds 

 to rapidly changing irregularities or turbulence 

 in the medium. Most mechanical meters read the 

 average or integrated gross water movement past 

 them and smooth out these irregularities . It 

 is possible by analytical or electronic means to 

 effect integration of the output Doppler mater; 

 however, to do so suppresses the capability of 

 this device to resolve instantaneous turbulent 

 flow. In a highly turbulent flow where complex 

 sidebands are produced, flow determination becomes 

 difficult, but there is reason to believe that 

 with a proper choice of integration time constants 



132 



