Acquisition LO calibration is a required step for all RF Recording Software configurations that use LO star configuration. Acquisition LO calibration ensures the power level of the LO signal distribution is within the input power range of -4 dBm to 0 dBm. Successful calibration results in a calibration file being saved to disk on the PXIe controller.

This calibration setup requires additional SMA to SMA cabling to what is required for typical LO star configuration.
Table 39. Acquisition LO Calibration Additional SMA to SMA Cable Quantities
Channel CountAdditional SMA to SMA Cable Quantity
22
44
88
1616
Complete the following steps.
  1. Connect the cabling for acquisition LO calibration.
    1. Remove all MMPX to SMA cables connecting the VSTs and RF IN LO splitter(s).
    2. Use the SMA to SMA cables to connect each port of the RF IN LO Splitter to the RF IN connector of each VST in the system.
      Figure 1. Acquisition LO Calibration Cabling for 2-Channel Systems


      Figure 28. Acquisition LO Calibration Cabling for 4-Channel Systems


      Figure 29. Acquisition LO Calibration Cabling for 8-Channel Systems


      Figure 30. Acquisition LO Calibration Cabling for 16-Channel Systems


  2. Launch InstrumentStudio by navigating to Start » National Instruments » InstrumentStudio.
  3. In InstrumentStudio, click Manual layout.
  4. In the Edit Layout window that opens, under RPS Plugins, select System Calibration: LO Calibration and then select Create a large panel. Click OK.
    A panel opens.
    Figure 1. Acquisition LO Power Calibration Panel


  5. Ensure the IP address and port information are correct and click Connect to establish a connection to the RPS gRPC server.
  6. Set the parameters in the LO Power Calibration panel.
    • Calibration Instruments—Select the VSTs that will perform the power measurements.
    • LO Star Source and Port—Select the name and port number of the PXIe-5655 LO source.
    • Amplifier and Port—Select the name and port number of the SCT-2215 amplifier.
    • Path Loss—Set the estimated or measured path loss (in dB) of the splitter(s) used to distribute the LO from the amplifier to the calibration instruments.
    • Headroom—Set the margin (in dB) of the reference level used to make the power measurement.
    • Power Target—Change this value to account of magnitude imbalances of the splitter network in dBm, if the difference between outputs is greater than 1 dB. Refer to the PXIe-5841 Specifications for the supported LO ranges of the VST.
    • Frequency Start, End, and Delta—Set the frequency sweep parameters (in Hz) for the LO star configuration.
  7. Click Start.
    InstrumentStudio alerts you when calibration completes. If successful, the calibration process results in a calibration file saved within %Public%\Public Documents\National Instruments\ICsc\LO Power Calibration\.
    Note If calibration fails, check your cable connections and re-run the calibration.
  8. Click Disconnect.
  9. Reconnect the LO cabling for star configuration for RF recording applications.
    1. Remove all SMA to SMA cables connecting the VSTs and RF IN LO splitter(s).
    2. Use the MMPX to SMA cables to reconnect each port of the RF IN LO Splitter to the RF IN: LO IN connector of each VST in the system, as described in Cabling for Analyzer LO Star Configuration.