Table Of Contents

Performing System Calibration

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    Last Modified: October 31, 2019

    Use the RF System Calibration Assistant to perform a full system calibration on all the mmWave OTA Validation Test Reference Architecture hardware components.

    NI recommends performing system calibration in any of the following situations:

    • After any module in the chassis is installed, uninstalled, or moved
    • After inter-module cabling has been changed, reconnected, or repositioned
    • After changing controllers, computers, or reinstalling software
    • After self-calibration is performed on the individual instruments

    The following equipment is required for the system calibration procedure:

    • PXIe-5831 Vector Signal Transceiver and mmRH-5582 mmWave Radio Head
    • Rohde & Schwarz NRP50S Power Meter
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    Note  

    The Rohde & Schwarz NRP50S Power Meter requires software that is not included with the mmWave OTA Validation Test Software. Install the power meter driver software before you complete the following steps.

    1. Connect the power meter USB cable to the PXI chassis USB port.
    2. Open the RF System Calibration Assistant and click Start Calibration.
    3. In the Load Configuration Dialog dialog box, click the file button and browse to C:\Users\Public\Public Documents\National Instruments\OTA Test\System Calibration Files.
    4. Select OTA-Test-Cal-Base.cfg and click Open.
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      Note  

      The calibration configuration assumes that the name of the PXIe-5831 in Measurement & Automation Explorer (MAX) is 3622. If you are not using 3622 as the name of the PXIe-5831, either change the name in the configuration file or change it in MAX.

    5. Select Use existing calibration configuration. The NI RF System Calibration Assistant Configurator window launches.
    6. In the Resources window, verify that all resources and resource settings are correct for the path loss characterization as shown in the following figure. Ensure the resource name for the power meter matches the name used in MAX.
      Figure 1. Resources Window

      By default, Self Calibrate Analyzer and Self Calibrate Generator are unchecked. NI recommends that you follow the calibration recommendations in the PXIe-5831 Specifications document and to perform self-calibration when the best accuracy numbers are desired.

    7. Click Next.
    8. In the De-Embedding Resources window, verify that the Resource Name and Resource Type are correct for the reference antenna.
      Figure 2. De-Embedding Resources Window
    9. In the Option String field, verify that the following string appears: Interpolate=true,FilePath=<createdpath>\antennadatafile.xml,PathName=VGain, where <createdpath> is the location of the reference antenna values XML file that you created.
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      Note  

      If you do not have the XML file, contact the NI services personnel contracted on your project. The calibration values are part of the reference antenna calibration data and are accessible through the embedded QR code on the antenna. The gain values are converted into an XML file that the software can read.

    10. To accept all calibration settings, click Calibrate.
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      Note  

      Refer to Advanced System Calibration Settings for more information about configuring advanced settings.

    11. When the Connect Power Meter Dialog box appears, complete the following steps:
      1. Disconnect the 2.4 mm (m)-to-2.4 mm (m) cable from the reference antenna and connect it to the power meter.
      2. Follow the onscreen prompts to connect the correct cables, then click Continue.
      3. When the calibration is complete, review the graphs and values to ensure the results are as expected. Click Accept Values or repeat the calibration if necessary.
      4. (Optional) For the second signal generator path, disconnect the 2.4 mm (m)-to-2.4 mm (m) cable from the power meter. Connect the opposite end of the 2.4 mm (m)-to-2.4 mm (m) cable connected to the interior chamber rear bulkhead 2A port to the power meter. Repeat steps 11b-11c.
    12. When the Connect VSA Dialog box appears, complete the following steps:
      1. Disconnect the power meter from all cables.
      2. Reconnect the opposite end of the 2.4 mm (m)-to-2.4 mm (m) cable connected to the interior chamber rear bulkhead 1A port to the reference antenna.
      3. In the mmWave OTA Test Positioner SFP, set the Azimuth to 90° and the Elevation to -90° to rotate the antenna as shown in the following figure. The calibration laser fixture should face the chamber door and the laser should point up toward the measurement antenna.
      4. Click Continue.
    13. When the MeasAntennaV dialog box appears, set the Azimuth to in the mmWave OTA Test Positioner SFP to rotate the antenna as shown in the following figure, then continue with calibration. This ensures that the correct polarization is measured.

      Once the signal analyzer and signal generator paths are complete, the Calibration Complete window appears with the file locations of the path loss results.

      The default location is expected by the TestStand sequences. If you changed the default location, update the proper configuration. You can set these values using the mmWave OTA Test Configuration UI. Note that if the file is not found, the sequence returns an error.

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      Tip  

      You can leave the Calibration Path field in the mmWave OTA Test Configuration UI empty if you don't want to use a calibration file or if you want to avoid receiving an error.


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