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NI 449
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Calibration Procedure
11. Repeat steps 1 through 10 for all input channels on the device. Connect the output of the
calibrator to the channel being verified during step 1. In step 3, replace
ai0
in the physical
channel parameter with the channel being verified.
AI DC Coupled Gain Accuracy Verification
Note
This section only applies to the NI 4492/4495/4497/4499. Skip this section if
you are verifying an NI 4496/4498.
Complete the following steps to verify DC coupled gain accuracy:
1.
Connect the output of the isolated voltage source to channel AI 0 on the device. Refer to
the documentation of the voltage source for its connector pinout information. Connect the
digital multimeter (voltage function) in parallel with the voltage source output.
2.
Configure the voltage source to generate a constant voltage with the amplitude listed in the
0 dB gain row of Table 15. Measure the actual voltage source value with the digital
multimeter.
Note
The actual source value must be 95% to 105% of the nominal value.
Table 13.
Maximum AI Flatness Specifications (Relative to 1 kHz)
Frequency Band
Flatness (dB)
20 Hz to 20 kHz
±0.005
20 kHz to 45 kHz
±0.016
45 kHz to 92.2 kHz
±0.08
Table 14.
AI Flatness Limits
Calibrator Output
Frequency (Hz)
Test Limit
Min
Max
20
0.99942 * V
1 kHz
1.00058 * V
1 kHz
20,000
0.99942 * V
1 kHz
1.00058 * V
1 kHz
45,000
0.99816 * V
1 kHz
1.00184 * V
1 kHz
92,200
0.99083 * V
1 kHz
1.00925 * V
1 kHz
