NI PXI-5404 Calibration Procedure
|
© National Instruments
|
17
To adjust the NI 5404, complete the following steps.
Note
You may also want to refer to the External Calibration examples in LabVIEW
or C, listed in Table 2.
1.
Open a session using the niHSSources Cal CalStart VI.
2.
Call
niHSSources_Cal_DeviceReset
to reset the module to the default state. Set the
following parameter:
•
sessionHandle
—The handle of the calibration session for the module
3.
Complete the following steps:
a.
Adjust the VXCO DAC for frequency accuracy as described in the
VCXO DAC for Frequency Accuracy
b.
Call
niHSSources_ApplySessionConstants()
(niHSSources Cal Apply
Session Constants VI).
c.
Adjust the GAIN DAC for sine amplitude accuracy and passband flatness accuracy as
described in the
Adjusting the SINE Out Amplitude
section.
d.
Call
niHSSources_ApplySessionConstants()
(niHSSources Cal Apply
Session Constants VI).
e.
Adjust the CLOCK out duty cycle accuracy and passband flatness accuracy as
described in the
Adjusting the CLOCK Out Duty Cycle
section.
4.
Call
niHSSources_CalEnd
(niHSSources Cal CalEnd VI) to close the session using the
following parameters:
•
sessionHandle
—A pointer to the handle of the calibration session for the module
•
action
—
niHSSources_ABORT
or
niHSSources_COMMIT_CONSTANTS
You can either save the constants you have calculated or abort the whole session. Aborting does
not save changes to the module.
Adjusting the VCXO DAC for Frequency Accuracy
The VCXO DAC controls the frequency accuracy of the onboard VCXO. Here you use a
calibration procedure that iteratively searches for the optimal VCXO DAC value by repeating a
measurement-adjustment loop 16 times. During each step in the loop,
niHSSources_CalAdjust
(niHSSources Cal CalAdjust VI) determines the next VCXO
DAC value by interrogating the measured frequency value passed to
niHSSources_CalAdjust
(niHSSources Cal CalAdjust VI) by the previous step. During this
process, the calibration session holds an internal variable for the VCXO DAC value. This
internal value is written to the VCXO DAC after you call
niHSSources_CalibrateVCXO
(niHSSources Cal CalibrateVCXO VI).