Expand Analyzer Dynamic Range While Taking a RFmx LTE PvT Measurements

Updated May 15, 2018

Reported In

Hardware

  • PXIe-5644
  • PXIe-5645
  • PXIe-5646
  • PXIe-5840
  • PXIe-5663
  • PXIe-5665
  • PXIe-5668

Software

  • NI-RFmx LTE TDD/FDD

Issue Details

I am using NI LTE Measurements Interactive Panel for testing LTE devices. My device fails the Power vs Time test due to the internal noise level of Analyzer. How can I reduce the Analyzer noises to meet the LTE PvT specification?
 

Solution

If you're using VST Device (NI PXIe-5644R/45R/46R or NI PXIe-5840)
There are few setting that may expand VST's Dynamic Range for PvT measurements:
  • Set Measurement Method to Dynamic Mode in PVT Settings section. 
  • ​Select Auto Level in Hardware Settings section.
  • Change LO Leakage Avoidance Enabled to True and de-select Use Default check box on Instrument Settings Tab.
Refer to Additional Information for technical details.

If you're using VSA Device (NI PXIe-5663/65/68R)
There is no quick solutions for VSA Devices within NI LTE Measurements Interactive Panel.
You may programm custom PvT measurement. Where to set up the measurement in steps, using a lower reference level for one acquisition (for OFF level) and a higher reference level for the next (ON level). 

Additional Information

Dynamic Mode
LTE PVT dynamic range mode provides a dual acquisition solution to achieve the required dynamic range. The first acquisition captures the I/Q with the user defined reference level, which will measure the ON power accurately. However, OFF power will not be represented adequately due to the limited dynamic range of the device, which leads to an inaccurate measurement of OFF power. To solve this, a second acquisition is done at a lower reference level which ensures the OFF power regions are represented adequately.

Auto Level
The RFmxLTE Auto Level method completes the following tasks:
  1. Resets the mixer level, mixer level offset, and IF output power offset.
  2. Sets the starting reference level to the maximum reference level supported by the device based on the current RF attenuation, mechanical attenuation, and preamplifier enabled settings.
  3. Iterates to adjust the reference level based on the input signal peak power.
  4. Uses immediate triggering and restores the trigger settings back to user setting after the execution.
LO Leakage Avoidance
Sets whether to reduce the effects of LO leakage by placing the LO outside the band of acquisition.

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