Visualize, Localize and Troubleshoot EMI Signals with Real-time Spectral Analysis

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Troubleshooting and localizing intermittent signals or multiple layers of broadband and narrowband signals can be frustrating even for the most seasoned RF engineer. In this webinar we will learn about the capabilities of different types of spectral analysis and demonstrate how real-time can literally make previously-hidden signals leap into plain view.

Who Should Attend?
This seminar is intended for engineers and technicians involved in the development, pre-compliance, testing and certification of printed circuit board assemblies, electronic products, and systems.

Lee HillSpeaker: Lee Hill
Lee Hill, Founding Partner of Silent Solutions LLC, is an industry expert in electromagnetic compatibility and provides EMC troubleshooting services, design reviews, and training to a wide variety of industries nationally and around the world. Lee also teaches graduate-level classes in EMC at Worcester Polytechnic Institute (WPI), University of Oxford (England), and for the IEEE EMC Society’s annual Global University and EMC Fundamentals program. He earned his MSEE in electromagnetics from the Missouri University of Science and Technology EMC Laboratory.

The following are questions presented to the speaker by the attendees during the webinar, along with answers to each.

For standards that specify such as RBW, sweep times, etc, how to show that real-time settings are equivalant?
Answer: The purpose of real-time is not to make EMC measurements with the parameters equivalent to the standards measurements, rather provide a revolutionary view of the spectrum to gain clues to the source or sources of emission. However, there are control settings in real-time to change the FFT bin width (RBW) and the equivalent of sweep times.

How does RT measurements compare to QP measurement?
Answer: RT is a type of measurement where all the input data is collected without gaps and processed as fast as the input data is collected. QP is a type of detector which specifies how the samples are processed to derive a measurement point. There is no need for the QP detector in real-time because the QP detector produced an measurement value to a standard, where RT gives insight for EMI diagnostics.

What is the probe type that you are using sir?
Answer: For measuring the common-mode current on the mouse and motor cables, a Fischer Custom Communications F-61.

What is price difference between FFT based and real time analyzers?
Answer: Many if not most analyzers are FFT based, but only a subset come with the RT option so perhaps the more relevant question is how much is the RT option on an FFT capable EMI receiver. The list price of RT can vary from 14k to 25K depending on the BW and manufacturer.

Hello! I’d like to ask why on the video about new vs old measurenment methods, the blue lines on the screen of the spectrum analyser were seen only ones and not multiple times, when there was a spark? Thanks!
Answer: In the video where the Real-Time mode was domonstrated, a unique corresponding continuous spectrum was displayed (blue line) was displaed by the analyzer each and every time a spark was created. I can only gues that the online webinar might have had insufficient video bandwith (specifically the frame rate) which affected the image that was available to some attnedees.

The technology of real-time FFT indeed seems to be too good to make our products more robust from an emissions perspective. But is the use of a real-time FFT EMI receiver mandated in the regulatory standards? Because many EMC test labs still use the swept tuned EMI receiver for formal compliance. Please share your views.
Answer: The use of real-time is not mandated in the standards, and in fact is not even meant for standards based compliance measurements. The purpose of real-time is for EMI diagnostics. Rohde & Schwarz has a great deal of material comparing and contrasting the different methods used by spectrum analyzers and EMI receivers, I suggest to contact R&S for more information.

I do know this is for “Real Time“ Spectrum Analysis. However, there is a new feature of “APD“ feature of Spectrum Analysis. Could you explain this one too?
Answer: APD is amplitude probability distribution and plots the probability of the signal at a certain amplitude. It does not provide the time varying characteristics of the signal like real-time and therefore is of limited value for EMI diagnostics.