Convert the shear probe data: Difference between revisions
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<math> s=\frac{N_s}{2\sqrt2SU^2G\gamma} </math> | <math> s=\frac{N_s}{2\sqrt2SU^2G\gamma} </math> | ||
where <math>s</math> is the shear signal in physical units of <math>\mathrm{s}^{-1}</math> , <math>N_s</math> are the raw numeric samples (the output of an analog-to-digital converter), <math>S</math> is the calibrated sensitivity of the shear-probe in units of <math>\mathrm{V/(m | where <math>s</math> is the shear signal in physical units of <math>\mathrm{s}^{-1}</math> , <math>N_s</math> are the raw numeric samples (the output of an analog-to-digital converter), <math>S</math> is the calibrated sensitivity of the shear-probe in units of <math>\mathrm{V/(m\,s^{-1})^2}</math>, <math>U</math> is the speed of profiling in <math>\mathrm{m\,s^{-1}}</math>, <math>G</math> is the gain of the electronics of the shear probe in units of <math>\mathrm{s}</math>, and <math>\gamma</math> is the gain of the analog-to-digital converter used to create the samples in units of <math>\mathrm{counts\, V^{-1}}</math>. | ||
The sensitivity of the shear probe to shear is proportional to the square of the speed of profiling. | The sensitivity of the shear probe to shear is proportional to the square of the speed of profiling. | ||
Thus, one should set a minimum speed for the conversion of the shear-probe data into physical units. Otherwise, the conversion may produce enormously large and quite unrealistic values. | Thus, one should set a minimum speed for the conversion of the shear-probe data into physical units. Otherwise, the conversion may produce enormously large and quite unrealistic values. | ||
Realistic minimum speeds for the conversion into physical units are <math>0.05</math> to <math>0.1\, \mathrm{m\,s^{-1}}</math> because the shear-probe signal is likely to be dominated by electronic noise and the angle of attack will be large (<math> >20^{\circ}</math>) even for low levels of dissipation. | Realistic minimum speeds for the conversion into physical units are <math>0.05</math> to <math>0.1\, \mathrm{m\,s^{-1}}</math> because the shear-probe signal is likely to be dominated by electronic noise and the angle of attack will be large (<math> >20^{\circ}</math>) even for low levels of dissipation. | ||
Revision as of 18:38, 13 July 2021
copy&paste from V1 docx
Convert the shear-probe data samples into physical units using the standard equation,
where is the shear signal in physical units of , are the raw numeric samples (the output of an analog-to-digital converter), is the calibrated sensitivity of the shear-probe in units of , is the speed of profiling in , is the gain of the electronics of the shear probe in units of , and is the gain of the analog-to-digital converter used to create the samples in units of .
The sensitivity of the shear probe to shear is proportional to the square of the speed of profiling. Thus, one should set a minimum speed for the conversion of the shear-probe data into physical units. Otherwise, the conversion may produce enormously large and quite unrealistic values. Realistic minimum speeds for the conversion into physical units are to because the shear-probe signal is likely to be dominated by electronic noise and the angle of attack will be large () even for low levels of dissipation.
