Tucked away in the electromagnetic laboratory building is a room that looks like something out of science fiction. And it has the name to match: the anechoic chamber, decked out in futuristic black and white tile, is the main room used to test the effects of electromagnetic waves on Mazda vehicles.
We talked to Norishima Amimoto and Nobuyuki Shimada of Mazda’s Vehicle Development Division about their work.
“We examine impact of radio waves on our vehicles, as well as the strength of radio waves emitted from our vehicles,” says Amimoto, who has more than 30 years of experience studying electromagnetic waves. “TV, radio, mobile phones… We are surrounded by radio waves without even knowing. That’s why it is imperative to use a facility that can shut off all radio waves. It allows us to replicate certain conditions in testing and enables accurate examination of electromagnetic impact.”
Why examine radio waves?
Out of sight, out of mind, right? Not so with radio waves. Although they’re invisible, these electromagnetic waves from radio, television, cell phones and even other cars have a bigger effect on cars than you might imagine.
When cell phones first became a common commodity, they caused interference with car radios, usually just as white noise whenever the phone received a call while the car was running. The noise is a direct result of the electric current created when radio waves from the cell phone interact with the car radio’s metal parts.
So while car radios are affected by electromagnetic waves, it’s just noise—nothing too serious or harmful. But what about more critical devices that could be impacted by these waves?
“Just like a computer is run by electronic systems, our vehicles, engines and many safety features are all controlled by electronic devices,” Amimoto says. “You could even say that cars today are just ‘moving computers.’ Electronic devices are involved in almost all functions of an automobile.”
From the injection system that supplies fuel to the engine to safety features such as the anti-lock braking system, many of a car’s vital functions are controlled by electronic systems, cables and wires.
That’s why the anechoic chamber is so important. It allows vehicle technicians to test the effects of electromagnetic waves on every part of the car, ensuring that each electronic device is immune to interference. In the chamber, specialized antennas are set up to shoot radio waves of varying strength at running vehicles to verify whether each of the car’s functions operate as they should.
“During the verification test, we place a vehicle on the equipment called chassis dynamometer, and shoot radio waves from many different kinds of antennas to see if the vehicle is affected,” Amimoto says. “Some radio waves are quite strong, so the tests are carried out without humans present. Robots operate the throttle pedal, brake pedal, and push switches instead.”
Noise within and without
External sources such as TVs and mobile phones are not the only thing to create radio waves. Cars themselves are also a large source of this noise.
The electromagnetic noise a car produces is called “emission,” and while developing a vehicle, technicians at Mazda test for both its immunity—how it resists incoming radio waves—and its emission in the anechoic chamber. Together, this is called EMC, or electromagnetic capability.
“The engine spark plug uses high voltage circuits, and strong electromagnetic waves are constantly generated from around the engine due to that,” says Shimada, who works on developing powertrain reliability. “Left as-is, the electromagnetic waves would have some impact on the vehicle’s own electronic devices for sure, and also influence other cars, TVs in households, and even phones and other items. Strict regulations are in place today to restrict such noise generated by electromagnetic waves from automobiles. In a nutshell, we need to take countermeasures against not only the noise caused by external source, but also from inside.”
The technician’s job isn’t done once testing is complete. If any of the tests fail, it’s time to go back, identify the root cause and come up with a countermeasure.
“Radio waves are invisible, and make it enormously difficult to identify the root cause,” says Shimada, regarding his painstaking work.
He establishes certain hypothesis based on the data collected in the test, and repeats verification tests again and again to narrow down the root cause. The job requires patience and persistence. But his hard work is rewarded with the satisfaction of a job well done when he finally unravels the source of the problem and solves it.
These verification tests are carried out during the concept phase of a vehicle’s design, to avoid any potential problems once the car is ready for mass production. As our environment gets crowded with complicated radio waves, the roles and responsibilities on those who work on EMC are expected to become even more vital in future.