How To Avoid The Strange Noise Working On The IQ Wave When You Are Using PXIe-5663E

Updated Jun 26, 2023

Environment

Hardware

  • PXIe-5663E
  • PXIe-5663
  • PXIe-5668

When you used PXIe-5663E to capture the IQ data , you maybe find one strange noise issue working on the IQ wave. 
For example , first you used VSG PXIe-5673 to generate one CW signal (CF:2.001GHz) , then you used example "RFSA Acquire Continuous IQ.vi" with PXIe-5663E to capture IQ data (CF:2GHz) ; But you saw there were noise signal on the IQ wave;
5673.jpg

5663.png
Where is the noise from ? How could you avoid the noise effect ?


1. Try to decrease the IQ Rate , you can see the noise is decreasing ;
5663 -1.jpg
5663-2.jpg

2.Check the help document , found below information

help1.jpg

Above mentioned that the dither signal enabled is default setting for PXIe-5663E and the dither signal will affect one the IQ result with higher IQ rate.

3.Change the property of Digitizer Dither Enable as Disable , then re-run the example code with higher IQ Rate;

change dither disable.jpg
 

The noise dis-appeared after the digitizer dither disabled;
5663 with dither disable.jpg

Remark: When you disable the digitizer dither property , the accuracy will be decreased ;