Radiated Emissions Testing Gathers Bandwidth

State-of-the-art Bureau Veritas EMC testing lab helps keep electronic roles distinct, as growing automotive features share an ever-more-crowded spectrum.

The Bureau Veritas automotive lab in Auburn Hills, Michigan features a host of EMC testing facilities, including a reverberation/mode-tune chamber outfitted here with a transmit antenna and RF stirrer. (SAE)

In a non-descript business park in Auburn Hills, Michigan, Bureau Veritas is conducting tests to help prevent electronic havoc. With today’s vehicles chock full of wired and wireless devices – and tomorrow’s more automated machines destined to expand the complement – ensuring this burgeoning technology isn’t radiating disruptive frequencies will be crucial to expanding functions and features. For the coming electric/autonomous age, radiated frequencies will become the new emissions challenge.

Test chambers include semi-anechoic enclosures with RF absorbing iron-ferrite cores and ferrite-impregnated foam. When the door is closed, there is a 100:1 dB separation factor. (SAE)

Often summarized as electro-magnetic compatibility (EMC) testing, the Bureau Veritas (BV) facility (which sits in sight of the re-christened Stellantis North American HQ) provides a host of testing, inspection and certification services designed to simplify and speed vehicle development. The Motown BV crew does this by helping to ensure electronic components don’t radiate spurious electromagnetic interference known as radiated and conducted emissions, and that they remain functioning even when subjected to such fields.

Netting GM approval

Bureau Veritas Detroit Lab General Manager Jason Kanakry standing next to an EM test automotive transient rack capable of producing all ISO and standardized automotive electrical pulse with a 100A output. (SAE)
The Bureau Veritas lab in Auburn Hills, Michigan is replete with state-of-the-art testing gear from Rohde & Schwarz. (SAE)
Construction on the new Bureau Veritas EMC lab began in March 2019, and it announced GM W3097:2019 approval in May 2021. (SAE)
Bureau Veritas test engineer Ryan Phillips setting up a test bench inside one of 10 EMC test chambers on site. (SAE)
The Bureau Veritas lab is designed to accommodate busy engineers during testing, providing a low-key atmosphere, private workspaces and a comfortable lounge. (SAE)

In May 2021, BV announced its Detroit-area automotive lab had gained official approval from General Motors in respect to automotive EMC specification GM W3097:2019. What does this equate to in practical terms? “What that means is we're doing EMC testing – radiated immunity, radiated emissions, bulk current injection, transient immunity, and electrostatic discharge testing on behalf of General Motors to their specifications for Tier-1 suppliers,” explained Jason Kanakry, the Detroit lab general manager, and our host at the sparkling new facility.

“The easiest way to break it down is we're doing automotive RF EMC testing in this instance on automotive parts specifically for GM,” Kanakry said. “The lab is fully ISO 17025 accredited so we can do a whole other array of other tests. But in the U.S., OEMs require EMC approval before you can submit a report to them. We can still do the testing, but they will reject the report.”

According to Kanakry, the bulk of their testing hems along the old FCC saw about not interfering, and not getting interfered with. “For an emissions test, we look at how much RF energy a device is giving off and make sure that amount of energy isn't going to interfere with something else in the vehicle. One of the things you have to remember is almost all these products that we're testing are inside of a vehicle, whether in the engine bay or in the cabin,” he noted.

“We want to make sure this instrument cluster that we're testing doesn't produce so much RF noise that the key fob stops working, or anything in that range,” Kanakry said. “On the flip side, we also test to make sure that it always functions in an environment. Say you put your cell phone on the dash, the instrument cluster still continues to function.”

New asylum for electronics

Modern automotive features (now encompassing Wi-Fi, Bluetooth, V2X, radars, lidars, etc.) operate across an expansive frequency range. Though each component is designed to stay in its own lane of the spectrum, unintended EMC emissions can interfere with a host of functions. “In the automotive world for radiated emissions we have a couple individual bands that are very, very important, such as the 315 MHz range for TPMS sensors or 433 MHz for key fobs and other components – the FM-band range,” Kanakry said. “But on top of that we have ranges for full spectrum from 30 MHz to 6 GHz, and that's for broadband noise. So if you raised the whole noise floor inside of the vehicle, nothing’s going to function.”

The BV lab tests and certifies individual Tier-1 components (radios, key fobs, instrument clusters, ECUs), with full-vehicle EMC testing left to the OEMs. For each component, individual tests are managed in strictly controlled environments. Radiated emissions/immunity and conducted emissions are all done in an ALSE (absorber-lined shielded enclosure), a semi-anechoic chamber – essentially a two-layer metal box with an iron ferrite-inside core, with iron-impregnated polystyrene foam on the walls.

“If you've ever seen an insane asylum with padded walls, instead of keeping people safely inside we're keeping RF inside, or out in this case as well,” Kanakry said. “Inside of that room when we're doing emissions testing, it's 100:1 dB of separation from the outside world.”

The BV lab uses Rohde & Schwarz analyzing equipment, with racks of the latest devices forming a dream setup for bench testers. “Here in the lab we use strictly Rohde & Schwarz products. We have Rohde & Schwarz RF amplifiers, signal generators, and receivers with FFT [fast Fourier transform] capability, one of the newest things that's reduced test times and made it more accurate. Whereas before, we had to go in 4.5-KHz steps, and every single one of those frequencies had to dwell for 5 microseconds, and the test would take an hour to run. With the new receivers, we can do this testing sometimes in seven minutes.”

The state-of-the-art equipment also positions the BV lab to manage evolving hardware, much of it coming in the form of advancing ADAS equipment. “Because we started this from scratch and had a lot of Cap-Ex investment into this facility, the oldest piece of equipment in here is just over a year and a half old,” Kanakry noted of the lab that began construction in March 2019 with only a dirt floor. “For full emissions, you need to be able to go out now to 6 GHz. We're focusing on the automotive EMC side of stuff, but we built this lab to be able to do regulatory testing for the FCC. We have receivers that go up to 44 GHz, so the six-gig expansions weren't a problem for us because we're new.”

New spectrum territory

It’s those exponential climbs in frequencies that’s making EMC testing more vital. “Any electronic device creates an RF signature, whether there's an antenna attached to it or not,” Kanakry said. “The power that goes through most of these devices is actually pretty small, but when you're talking multiple gigahertz, the power needed to make that radiate into the open world could be as small as a bad solder joint. It'll use a solder joint or a pin inside of the device as an antenna.”

Being able to shrug off radiated environmental conditions is equally important in the automotive space. “One of the worst-case EMC scenarios that I've ever been a part of was cars were shutting down on the side of an expressway as they drove past the radar array for a local airport,” Kanakry recalled. “The instrument cluster housing the brains to say, ‘Yes, your key is good,’ all this was good. But as they were driving past the airport the radar was of such significant power that it reset the instrument cluster and the whole car shut off.

“We can do 600 volts per meter in radar, which is an insane amount of power for that range,” he said. “We've tested everything from automotive radar to lidar and V2X, and have the ability to prove that it can work in the environment that it's designed to be in. I wouldn't be surprised that in the next couple years, we start seeing stuff in the 10- to 12-GHz range.”

More features, same product timeline

Compared to just a decade ago, the number of electronic features available on vehicles has skyrocketed, but OEM production timelines have not grown, instead often getting tighter. Integrating these expanding suites of electronics is one of the key reasons for the new BV lab in the Detroit area. “In meeting after meeting, I was finding locally there's sometimes a three- to four-month lead time to get your product into an EMC lab to validate it,” explained Jennifer Gasparian, director of automotive for Bureau Veritas Technology North America.

“Because we know OEMs don't change the launch date, that's way too long, especially when they're trying to work out things on the system and debug in order to meet their deadlines,” Gasparian noted, adding that they saw an opportunity locally in the Tier-1 testing chain, reducing pain points as OEMs bring new features to market. “Once they're done validating, if their product has RF in it, maybe they have Bluetooth, WiFi, and they need to go through a whole series of regulatory tests,” she said. “We can do that testing as well.”

“There's no money any manufacturer can put on reduced lead times, to be able to make their timing and get into a test lab quickly,” Gasparian said. “An engineer comes in and they're completely stressed out. We have customer rooms where they can wait while they're testing and be right there to get the results and do any tweaks if they need to. This is a requirement for these manufacturers to get this done for the OEM, and it's a critical one.”