Leading The Way In Vehicle EMC Testing
Elite is the leading independent automotive EMC testing lab in North America, providing testing and consulting services to car, truck, SUV and off-road vehicle manufacturers, alike. Our capabilities include environmental stress and EMC testing for automotive equipment and components, as well as whole vehicles in our large, extensively-equipped indoor RF test chambers.
Overview of Automotive EMC Standards: CISPR & ISO
Not surprisingly, the automotive industry has numerous electromagnetic compatibility (EMC) requirements it must adhere to. Two of them, the CISPR and ISO standards (organizations that develop and maintain standards for use at the international level), require electronic systems not to emit excessive electromagnetic interference (EMI) or noise, in addition to being immune to emissions from other systems. Here's a closer look at each:
CISPR 25 & 12
CISPR 25 is a standard that provides limits to help evaluate the level of radiated emissions from a vehicles and their components (i.e., a radio). The primary purpose of a CISPR 25 test is to ensure the component in question will not interfere with other systems in the vehicle.
Regarding the actual test, CISPR 25 requires the electromagnetic noise level in the testing room to be at least 6dB lower than the lowest levels being measured. For examples, in some cases CISPR 25 calls for levels as low as 18 dB (µV/m), so an ambient level of less than 12 dB (µV/m) is needed. (As a reference, this is the field strength for a typical AM radio station, one kilometer from the antenna.)
Today, the only way to achieve such a testing environment is by using a special chamber designed to isolate the test from external, unintended interference. What's more, since the chamber is usually of finite size, the testing environment must also be protected from reflected signals within the room itself. Therefore, the walls of the test chamber must be lined with a material that will not reflect electromagnetic (EM) waves.
Another testing standard is the ISO 11452-4 Bulk Current Injection (BCI) suite of tests that are used to verify if a component is adversely affected by narrow-band electromagnetic fields. Testing is done by inducing disturbance signals directly into the wiring harnesses with a current probe.