NI PXIe-4480/4481 Calibration Procedure
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© National Instruments
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15
7.
Calculate the RMS amplitude of the acquired fundamental harmonic. Compare this
amplitude to the appropriate voltage limits in Table 5. The calculated amplitude is used to
verify the gain accuracy of the measured analog input channels at the 10 V range setting.
As an example, you can use the Extract Single Tone Information VI to help calculate RMS.
Note that the output of this VI is peak amplitude, and you must divide the result by √2 to
convert to RMS.
8.
Stop and clear the task.
9.
Repeat steps 2 through 8 for each range setting of the device. When performing step 2,
configure the calibrator output to the amplitude and frequency indicated for the range to be
verified. When performing step 3, set the
range
parameter to 5, 1, and 0.5 as required.
10. If necessary, repeat steps 1 through 9 for all input channels of the device. In step 1, connect
the output of the calibrator to the channel being verified. In step 3, replace
ai0
in the
physical channel
parameter with the channel being verified.
Voltage Gain Flatness Verification
Note
This performance characteristic is not affected by adjustment. Consequently,
reverification after adjustment is not necessary.
Note
DC-coupled gain flatness is inherently better than AC-coupled gain flatness,
specifically at low frequencies. Consequently, the verification of AC-coupled gain
flatness covers both configurations.
Complete the following steps to verify the voltage gain flatness:
1.
Using the equipment described in Table 1 (PXIe-4480) or Table 2 (PXIe-4481), connect the
module to the calibrator as shown in Figure 2 (six channels) or Figure 3 (analog input
channel 0).
2.
Configure the calibrator to generate an output with the amplitude and frequency listed in
the 10 V row of Table 7.
Table 7.
Voltage Gain Flatness Inputs
Range (V)
Calibrator Output
Amplitude (V
rms
)
Frequency (Hz)
10
6.3
1,000
5
3.15
1,000
1
0.63
1,000
0.5
0.315
1,000