IoT Growth Brings Fresh EMI/EMC Challenges: Q&A with Tektronix



Taking on customers’ EMC/EMI compliance pain points led to a solution the provider has designed as all-in-one, so users can realize time and cost savings.

What the IoT brings to industrial, consumer, mobile and mil-aero connectivity does not have to include problems with electronic interference and unintentional radiators, as wired and wireless devices proliferate.

Editor’s Note: Unintended consequences are something to be avoided, with careful planning often the prescribed method for doing so. Recently Dylan Stinson, Product Marketing Manager at test, measurement, and monitoring solutions provider Tektronix, spoke with EECatalog.com about how designers and manufacturers can avoid interference that causes safety, regulatory, and performance issues, even as wireless “stuff” enters our lives at a relentless pace. Tektronix, says Stinson, “offers a complete solution, including pre-compliance software, accessories, and also the benefit of having a real-time spectrum analyzer.”  We spoke with Stinson at the time Tektronix announced its EMI/EMC Compliance Testing solution. Edited excerpts from our interview follow.

EECatalog: What is EMC and who needs to care about it?

Dylan Stinson, Tektronix

Dylan Stinson, Tektronix: EMC or electromagnetic compatibility is defined as the interaction of electrical and electronic equipment with its electromagnetic environment and with other equipment.

Anybody who designs, manufactures, or is importing products with electronics inside is definitely going to want to care about EMC compliance.

There have been several well published cases where because electromagnetic compatibility and EMC testing were not fully considered, companies have been fined and products have even had to be recalled or withdrawn from the market due to their emission levels exceeding regulated limits.[1]

EECatalog:  What have designers and manufacturers been doing to achieve compliance and what’s changed?

Stinson, Tektronix: To answer your second question first, we’re seeing new problems. For example, consider a lap top computer or a smartphone [see Figure 1]. It contains all the high-speed digital systems that are necessary in a digital computer or phone, combined with wireless transmitters or receivers for necessary connectivity and communication.

Figure 1: Multiple noise sources characterize today’s systems. (Courtesy Tektronix)

With the proliferation of all these wireless-enabled devices, where you have the proximity of unintended radiators, combined with sensitive receivers, you have an area that is rife with interference opportunities.

In the case illustrated in [Figure 1], each element of the design is operating within regulated limits, but EMI from the computer clocks or random hard drive access may be entering the receivers, reducing communication efficiency and overall performance. In some cases, it may work poorly, not work at all as an overall integrated system, or not be legal.

What we’d like to see change is the situation where designers and manufacturers have to go out of house to get EMC/EMI compliance testing done—and more than half of our spectrum analyzer users are testing for EMC and EMI issues. In doing so, they are having to do things like go to a test lab with an anechoic chamber to get a pre-scan. One customer told us, “We spend $1,250 per hour for a technician, lab equipment, and chamber. This adds up over time, as you can imagine. One time, we had a situation where we spent a year trying to figure out where the noise was coming from.”

As to your first question, the traditional method is: you have a design, you take it about 90 percent of the way, then you take it to an external test house that is licensed, but as just noted, this can be expensive, especially when multiple visits and design changes are required. In the U.S., designers have reported spending as much as $10,000 to get a product certified by an external compliance test house.

EECatalog: What should designers know about in-house pre-compliance testing?

Stinson, Tektronix: Performing basic pre-compliance testing in-house, the option Tektronix is providing, can help minimize product development time and expenses and help overall with the design. Pre-compliance allows issues to be caught early on, saving time, effort, and money.

We’ve introduced EMCVu as an all-in-one EMC pre-compliance solution. It is included as a license option for our existing SignalVu-PC software, a part of our Real-Time spectrum analyzer products.

This is for both radiated emission testing and conducted emission testing as well as EMI troubleshooting and debugging. It includes all the accessories—defined and characterized so you don’t have to spend the time doing it yourself—for EMC testing: two antennas, pre-amp, and tripod for radiated emissions testing, AC LISN, DC LISN, and transient limiter for conducted emissions testing, as well as near field probes and 20 dB amp for troubleshooting.

EECatalog: What opportunities to save time and effort does your solution make possible?

Stinson, Tektronix:  Some of the ways we accelerate EMC compliance are with our failure-targeting Quasi Peak detector. You specify the failure you want to test and spend less time having to test other failures outside that test. It includes an easy-to-learn wizard with built-in standards:  All the limit tables for the CISPR, and MIL standards, are included in the software.

You can populate limit lines based on the standards you select. In order to get higher accuracy as well as adding convenience, we have pre-defined the gains and losses of all our accessories, including antennas, cables, LISNs and pre-amplifiers. This pre-defining for gains and losses in the software means you don’t have to worry about the characterizing, and you get a higher level of accuracy.

Also, you can use our ambient noise comparison feature to measure the ambient noise in the test environment. Then you can compare that ambient noise to the actual measurement and apply trace math to remove it from the actual measurement. You can readily distinguish a failure caused by ambient noise from a failure caused by your test environment and equipment under test. This allows you to have the confidence to perform EMI/EMC pre-compliance testing in relatively noisy environments such as office areas, conference rooms, labs, and basements.

And you can get all of the notes, images, and result information to your manager and other engineers conveniently because the software is fully configurable for reporting in formats such as pdf and rtf. You can get any number of experiments and test results into this report.

EECatalog:  Do you anticipate any difficulties in getting folks to change what they’ve been doing, i.e., going to external test houses?

Stinson, Tektronix:  No, because we see it as not being much of an effort at all for somebody to get up and running on this. The software is easy to use. It has a set up wizard so even a junior engineer can get up and running on it and learn how to do EMI pre-compliance. We had customers going to the test house three or four times on a product. With proper in-house pre-compliance testing, customers can reduce it down to as little as one visit, so the potential cost savings here are huge.

EECatalog: Anything to add before we wrap up?

Stinson, Tektronix:  This solution plays well in many markets from IoT, medical devices, to military equipment and systems, and it also spans into non-traditional RF applications such as switching power supplies, DC to DC converters, and wireless chargers—these are all things requiring more attention to EMC and EMI compliance.

[1] http://www.fr.com/files/Uploads/attachments/fcc/2012_Q1_FCC-Enforcement-Matrix.pdf

 

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