Data Reduction
The time-mean component of the voltage signal has been obtained independently through
a  voltmeter, DANTEC 56N22. In order to achieve the best utilization of the
analog to digital converter resolution, the fluctuating component of the voltage signal
has been amplified by a gain factor of 10, prior to acquisition in the PC. This approach has the advantage that integration time constants can be applied unrestrictedly on the
time-mean and fluctuating component of the signal. A typical value of 100 s integration
constant has been used to measure the time-mean voltage. The fluctuation part was
acquired for 20 seconds duration with a gain setting of 10. The time-mean and the fluctuating voltage have been added during data processing to get the complete instantaneous
signal. It has been subsequently used with the calibration equation to calculate
the instantaneous velocity.
For the  -probes that are oriented at  to the incoming flow direction
and yaw coefficients  for each wire, the velocities  in the wire coordinate
system are related to the calibration velocity of each wire as
The above equations can be rearranged as:
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