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NI PXI-5404 Calibration Procedure
Adjusting the SINE Out Amplitude
Calibrating for amplitude accuracy and passband flatness accuracy at the SINE out adjusts the
value written to the GAIN DAC, which adjusts the amplitude of the sine wave output, until the
amplitude reaches the desired value. You determine the correct value for SINE out amplitude
by iterating measurements and adjustments. The calibration session holds an internal variable
for the GAIN DAC value. The program writes this value to the hardware when you call
niHSSources
_
CalibrateAmplitude
(niHSSources Cal CalibrateAmplitude VI). When
the program calls
niHSSources
_
CalAdjust (
niHSSources Cal CalAdjust VI), this variable
is adjusted according to the measured amplitude passed in. By repeatedly measuring, adjusting,
and programming the variable value to the hardware, the output amplitude converges on the
desired value. The amplitude is calibrated at several frequencies to flatten the passband response.
For the first frequency, perform 16 adjustment iterations. For all other frequencies, perform only
eight iterations.
Figure 4 shows the programming flow for the SINE out amplitude and passband flatness
adjustments.