Demystifying EMC 2018 – Silverstone

Rohde & Schwarz held this years’s instance of their excellent Demystifying EMC seminar at the Silverstone race track in the Midlands. The venue was right in the middle of the racecourse with a great view of the start/finish straight.

It was good to see so many meaty sounding technical EMC presentations on offer and my only regret was that I couldn’t split myself into two or three and attend them all. Instead, I’m going to have to wait patiently for the PDFs of the slides to come through.

In the meantime here’s a quick rundown of some salient points from the presentations that I attended.

“Practical Probing Techniques for EMC Troubleshooting” – Lee Hill, Silent Solutions

Given the relatively short amount of time, Lee gave a very condensed presentation of basic EMI issues encountered, the need for probing and the merits of different types of probes available.

He included some good explanations on the figures of merit for RF current probes and gave a compelling argument for the use of a pre-amplifier with a near field probe: “it makes all the signals look important!”

The only small disagreement I’d have with his otherwise excellent talk was his recommendation against making one’s own near field probes. I think that, with some consideration and research, it is possible to make probe sets that are just as useful as ones you can buy. I frequently use a home made capacitive field probe for debugging and actually prefer it to the one from my purchased kit. However, having the luxury of an anechoic chamber, I’m usually using the probes to chase a known frequency. Therefore I’m more interested in relative sensitivity rather than absolute calibration as I’ll already have some comparable absolute levels from the chamber.

If you get the chance to see Lee present I can highly recommend attending.

“Technical Documentation for CE Marking” – Stuart Aust, Horiba Mira

Stuart gave a brief run down of the Technical File requirements and I was pleased to find out my understanding of the requirements was aligned with his.

“Risk Assessments Required by the EMC and RE Directives” – James Daniels, Element

The EMCD and RED come with a requirement for manufacturers to complete a Risk Assessment and James gave a thought provoking presentation on how one might go about this.

Interestingly in future harmonised product standards, the Annex ZA/ZZ part will give information on what Essential Requirements of the directives that the standard gives a presumption of conformity to. This will take a while to filter into the mainstream, especially given the sometimes glacial pace of standards publishing and vested interests within standards committees.

Again, it all hinges on how comfortable a particular manufacturer is with the concept of risk. Sometimes, as EMC and standards professionals we often apply things rigorously when such an approach might not be required from the manufacturers standpoint. This is an issue I’ll be coming back to in a future blog as its something that most people probably don’t already formally complete or even consider. I shall be advising my customers on how to best complete these requirements in the future.

“Assessment of modules and EMC testing of non-radio products which include a radio module” – Michael Derby, ACB

Michael gave a thorough and practised presentation into the requirements for integrating radio modules into existing products, from the perspective of the FCC and the RED. I was pleased to find out his talk confirming my understanding of the process.

 

After receiving copies of all the other presentations, some things that stood out as particularly interesting were:

  • Real time spectral analysis for EMI debugging. I miss the real time analyser from my previous employer when I could prise it out of the hands of the RF department. I’ve had some success with replicating this using a low cost pre-amplifier and Software Defined Radio (SDR) but its not a patch on a proper instrument. The usefulness of a large real time bandwidth and good user interface is not to be underestimated and I’ve found several intra-system (platform noise) based problems using this technique.
  • Langer presented a really good look at the physical basis for radiated emissions from PCBs. I’ll be studying these slides for future ideas into debugging emissions! They also had a demo in the exhibition hall of their miniature noise injection pens which I’d be very interested to trial in future.
  • Wurth have some dense and interesting looking info on filtering for DC/DC converters. The broadband noise from these can be quite pernicious and often ends up making its way out of poorly filtered unscreened power cables.
  • Albatross Projects gave an update from the CISPR committees responsible for various product standards. Points of interest were EN 55035 making onto the RED list of standards and some small changes to test equipment for EN 55015.
  • Rohde & Schwarz had a good primer on requirements for the Radio Equipment directive from the radio testing perspective. Given the vast range of radio test equipment they make it was no surprise that this featured and who can blame them!
  • Michael Derby (ACB) also had some slides on the RED and the state of various ETSI standards. There was a wealth of info in this presentation so I shall be going through it in some detail.

All in all I was most impressed with the technical content at the seminar and will certainly be attending future events. Thanks to the Rohde & Schwarz for putting on such a good event.