NI 446X Calibration Procedure
32
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11. If you use C function calls, perform an FFT on the array of data. If you
use LabVIEW, use the Analog 1D Wfm 1chan Nsamp polymorphic VI
to acquire data in step 8. Measure the exact frequency of the peak
around 10 kHz using the Extract Single Tone Information VI with the
following inputs:
•
advanced search»approx freq.
: 10000
•
advanced search»search
: 1
•
export signals
: 0 (none)
12. Compare the detected frequency to the limits in Table 6.
NI 446
X
Adjustment Procedure
The NI 446
X
adjustment procedure adjusts the analog input, analog output,
and timebase frequency calibration constants. At the end of each
adjustment procedure, the new constants are stored in the external
calibration area of the device EEPROM, which ensures that you do not
accidentally access or modify any calibration constants adjusted by the
metrology laboratory while performing a self-calibration procedure. You
can adjust the NI 446
X
AI, AO, and timebase frequency independently.
The following sections describe the AI, AO, and timebase frequency
adjustment procedures.
Adjusting the Analog Input
Complete the following steps to adjust the analog input:
1.
Connect the output of the calibrator to all the analog input channels of
the device, using the BNC T-connectors to split the signal in a tree
formation to all the inputs.
2.
Use the calibrator to output 5.00 VDC.
Table 6.
Timebase Frequency Accuracy Limits
Function Generator Output
Device Input Frequency
Amplitude (V
p-p
)
Frequency (Hz)
Min (Hz)
Max (Hz)
9.0
10,000.00
9,999.8
10,000.2
