30 | ni.com | NI PXI-5650/5651/5652 Calibration Procedure
Adjusting Frequency Accuracy
This adjustment yields a more accurately tuned VCO frequency. Complete the following steps
to adjust the frequency accuracy of the PXI-5650/5651/5652 using a spectrum analyzer:
1. Connect the 6 dB precision attenuator to the PXI-5650/5651/5652 RF OUT front panel
connector.
2. Connect the spectrum analyzer RF INPUT connector to the 6 dB precision attenuator.
3. Connect any available rubidium frequency reference rear panel BNC connector to the
spectrum analyzer REF IN rear panel connector.
4. Configure the spectrum analyzer with the following settings:
• Reference Clock source: External
• Reference level: 10 dBm
• Center frequency: 400 MHz
5. Call the niRFSG Initialize External Calibration VI.
6. Call the niRFSG 5652 Initialize Reference Clock Calibration VI.
7. Call the niRFSG 5652 Configure Reference Clock Calibration VI.
8. Use the spectrum analyzer to measure the peak power using the following spectrum
analyzer settings:
• Frequency span: Value returned by the frequency span parameter of the niRFSG 5652
Configure Reference Clock Calibration VI
• Center frequency: Value returned by the center frequency parameter of the
niRFSG 5652 Configure Reference Clock Calibration VI
9. Use the spectrum analyzer frequency counter to measure the frequency of the peak.
10. Call the niRFSG 5652 Adjust Reference Clock Calibration VI. Wire the measured value
from step 8 to the measured REF OUT power parameter and wire the measured value
from step 9 to the measured REF OUT frequency parameter.
11. Repeat steps 7 through 10 until the reference clock calibration complete parameter of the
niRFSG 5652 Adjust Reference Clock Calibration VI returns a value of TRUE.
12. Call the niRFSG Close External Calibration VI to close the session. Set the write
calibration to hardware? parameter to TRUE to store the results to the EEPROM on the
PXI-5650/5651/5652.
You have finished adjusting the PXI-5650/5651/5652. Repeat the Verification section to reverify
the performance of the PXI-5650/5651/5652 after adjustments.
Updating Calibration Date and Time
This procedure updates the date and time of the last calibration of the PXI-5650/5651/5652.
1. Call the niRFSG Initialize External Calibration VI.
2. Call the niRFSG Update External Calibration Date and Time VI.
3. Call the niRFSG Close External Calibration VI to close the session. Set the write
calibration to hardware? parameter to TRUE to store the results to the EEPROM on the
PXI-5650/5651/5652.
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