Finding Resonant Frequency with NI VNA Takes Too Long

Updated Sep 10, 2018

Reported In

Hardware

  • PXIe-5630
  • PXIe-8840

Software

  • LabVIEW 2016 Full

Operating System

  • Windows

Issue Details

I am trying to find the resonant frequency of an RF device by performing a frequency sweep input to the Device Under Test (DUT) and finding the minimum reflected power. 

The process of finding the minimum and thus identifying the resonant frequency takes too long in LabVIEW.

Solution

Make sure that the frequency step size of the frequency sweep is sufficiently large enough (lower frequency resolution) to facilitate faster array sorting.

Additionally, consider increasing the amount of RAM in your system to decrease processing time.

Additional Information

The high time requirement for this process is likely due to a high frequency resolution in the frequency sweep. When frequency resolution increases (which is a decrease in frequency step size), the output array increases in size. Thus the sorting algorithm used to find the minimum in the array takes longer to execute as the size of the array increases.

Example: Frequency sweep from 1GHz to 6GHz in increments of 1 kHz. The output array of this sweep would have five million samples. Sorting through that many samples would require considerable processing time.
 

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