Temperature drift and other environmental changes can lead to performance degradation for several PXIe-5840 specifications. Self-calibration adjusts the PXIe-5840 for variations in the module environment using an onboard high-precision calibration tone.

Perform self-calibration to compensate and optimize the performance of the PXIe-5840 for a given ambient temperature and operating environment.

The PXIe-5840 is calibrated at the factory; however, you should perform a self-calibration in any of the following situations:
  • After first installing your PXIe-5840 into your chassis
  • After any module in the chassis is added, moved, or removed
  • When the system is in an environment where the ambient temperature varies
  • If the module temperature has drifted more than ±5 °C from the last performed self-calibration

In addition to the preceding scenarios, performing proactive and regular self-calibration helps control the effects of aging-related drifts.

Note Allow the module to warm up for 30 minutes after the PXI Express chassis has been powered on and the operating system has completely loaded. If the temperature drifts significantly during self-calibration, the self-calibration exits with an error.
Note The onboard temperature may fluctuate despite consistent ambient operating temperature. For optimum performance, NI recommends that you periodically verify onboard temperature, especially after changes to the device configuration, and perform self-calibration as necessary. Refer to the PXIe-5840 Specifications for more information about operating temperature specifications.

Self-calibration adjusts the following parameters of the PXIe-5840 to facilitate temperature correction:

  • LO path gain
  • RF input gain
  • RF output gain
  • RF input residual LO power
  • RF output residual LO power
  • RF input residual sideband image
  • RF output residual sideband image
  • RF input flatness
  • RF output flatness
Note RF residual LO power and RF residual sideband images are only adjustable in self-calibration and cannot be corrected for during external adjustment. Self-calibration must be successfully executed after an external adjustment to ensure warranted performance.
Note NI recommends that no external signals are transmitted to the RF input port during the self-calibration.

Self-Calibrating the PXIe-5840 with InstrumentStudio

NI recommends you perform an initial self-calibration using InstrumentStudio.

Note Ensure that any connected external hardware is in an idle state and not transmitting during self-calibration. It is not recommended to perform self-calibration while connected in direct loopback configurations.

NI VSTs are represented in InstrumentStudio as a vector signal analyzer and a vector signal generator. Performing self-calibration with either representation of the PXIe-5840 accomplishes the same self-calibration, so it is not necessary to use both when you self-calibrate the PXIe-5840.

Complete the following steps to self-calibrate your VST with InstrumentStudio:

  1. To ensure specifications before you use the instrument or perform self-calibration, allow the instrument to warm up.
    1. If it is not powered already, provide power to the instrument:
      • : first provide power to the remote measurement module using the power adapter, and then power on the PXI Express chassis
      • All other PXIe-5840 instruments: power on the PXI Express chassis
    2. Wait for the operating system to completely load.
    3. Allow the instrument to warm up for 30 minutes.
  2. Launch InstrumentStudio by navigating to Start » National Instruments » InstrumentStudio.
  3. Click File » New » RF Signal Analyzer to create an analyzer panel for the PXIe-5840.
  4. Click the tab created for the PXIe-5840 and click the gear icon () in the upper right corner of the right sidebar.
  5. Hover over Device Slot » Calibration and click Self-Calibrate....
  6. Click Continue to proceed.
The PXIe-5840 stores the new calibration data in its nonvolatile memory if the self-calibration is performed successfully.

Partial Self-Calibration

The partial self-calibration feature self-calibrates all configurations within the specified frequency and reference level limits of the PXIe-5840.

For best results, NI recommends that you perform partial self-calibration without omitting any steps. However, if certain aspects of performance are less important for your application, you can omit the following steps for faster execution:

  • LO Self Cal—Omits the LO path gain adjustment.
  • Amplitude Accuracy—Omits the RF absolute amplitude accuracy adjustment.
  • Residual LO Power—Omits the RF residual LO power adjustment.
  • Image Suppression—Omits the RF residual sideband suppression adjustment.
Note The default partial self-calibration does not omit any steps.

Performing Partial Self-Calibration Using LabVIEW

To perform a partial self-calibration when using LabVIEW, use the niRFSA Self Calibrate Range VI or the niRFSG Self Calibrate Range VI.

Note The niRFSA Self Calibrate Range VI does not perform any RF output calibration steps and the niRFSG Self Calibrate Range VI does not perform any RF input calibration steps.
Note Do not access the RF input, RF output, or basecard clock circuitry while either of these VIs are executing.
Notice Resetting the driver results in the loss of any stored partial self-calibration data. Restarting the computer typically resets the driver.
Note NI recommends that no external signals are transmitted to the RF input port during the partial self-calibration.

For more information about calibration, contact NI or visit ni.com/calibration. You can obtain the calibration certificate for your product at ni.com/calibration.