PXIe-5842 Had High Spurs ,How PXIe-5842 Specification Defined The Phase Noise As -145dBc

Updated Jun 6, 2023

Reported In

Hardware

  • PXIe-5842

Issue Details

Check the specification document  of PXIe-5842 , you will find one interesting thing that the RF IN non-harmonic spurs is higher about -66~-80 dBc and the RF IN phase noise is lower about -140dBc;
For example , When offset=10MHz, center frequency is 5.5GHz, we can find the Non-Harmonic Spurs is -66dBc, while the Phase Noise in the measured data is ~-145dBc.

non-harmonic spurs for 5842.jpg
phase noise for 5842.jpg


How did N measure the phase noise when spur is high?

Solution

NI use the R&S FSWP Phase Noise Analyzer to measure phase noise and like any other phase noise analyzer it supports spur removal as the spurs are NOT phase noise;Below is the excerpt from the R&S Manual for your reference;


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So you can see the interesting difference between non-harmonic spurs and phase noise;

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