National Instruments NI PXI-5922, Руководство пользователя, Страница: 18 / 21

18 | ni.com | NI 5922 Calibration Procedure
9. Calculate the error in timing as parts per million (ppm) using the following formula:
where a = the measured frequency
Compare the result to the Calibration Test Limits or the Published Specifications listed in
Table 7. If the result is within the selected test limit, the device has passed this portion of
the verification.
Adjusting the NI 5922
If the NI 5922 successfully passed each of the verification procedures within the calibration test
limits, then an adjustment is recommended but not required to guarantee its published
specifications for the next two years. If the oscilloscope was not within the calibration test limits
for each of the verification procedures, you can perform the adjustment procedure to improve
the accuracy of the oscilloscope. Refer to the
External Calibration Options section to determine
which procedures to perform.
An adjustment is required only once every two years. Following the adjustment procedure
automatically updates the calibration date and temperature in the EEPROM of the oscilloscope.
Note
If the oscilloscope passed the entire verification procedure within the
calibration test limits and you do not want to perform an adjustment, you can update
the calibration date and onboard calibration temperature without making any
adjustments by completing
only steps 4 and 13 in this section.
Complete all of the following steps to externally adjust the NI 5922.
1.
Connect the scope calibrator to the channel 0 input of the oscilloscope. Configure the
calibrator to output an exact 1 MHz sine wave with 1 V peak-to-peak amplitude and 1 M
Ω
load impedance.
2. Connect the DC source calibrator to the channel 1 input of the oscilloscope. Configure the
DC source calibrator to output an exact 4 V DC signal into a 1 M
Ω load impedance
(channel 1).
3. Wait 3,000 ms for the calibrator to settle.
4. Call
niScope_CalStart
(niScope Cal Start VI) using the user password. The factory
default password for the NI 5922 is
NI
.
5. Call
niScope_CalSelfCalibrate
(niScope Cal Self Calibrate VI) with the following
parameters:
•
channelList :
VI_NULL
• option :
VI_NULL
Table 7.
NI 5922 Timing Accuracy
Calibration Test Limit Published Specification
±5.3 ppm ±50 ppm
error
a 2,000,000
–
 
2
------------------------------------- =