NI Scope Frequency Accuracy Outside of Spec After External Calibration

Updated Mar 22, 2018

Reported In

Hardware

  • PXI-5152

Driver

  • NI-SCOPE

Issue Details

I performed an external calibration on my NI Scope, but when I re-verified my device the Measured Frequency Error is outside of my Calibration Test Limits (in ppm).

Solution

  • Double check the Calibration Procedure to ensure that all parameters and function calls are configured correctly and called in the right order.
  • Check the Calibration Test Limits calculation - temperature plays a large part in the calculation of these limits.
  • Ensure that the module under test and the last external cal temperature are close to room temperature. Use 25°C as a good rule of thumb.
  • After checking the above information, send the device in for repair.

Additional Information

  • You can generally find an indication about what temperature is good operating temperature in the Environment section of the specification sheet.
  • If the scope is close to the operating limits of the device, the time reference may not be as accurate due to the nature of the effect of temperature on oscillators.
  • Turning the PXI chassis fan on High or using a PXI Slot Blocker can help cool down the device.

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