Authored by: Ashley Yip, Engineering Co-op Student
In our daily lives we depend on countless wireless electronic devices, from morning alarms on our cellphones, to listening to music using wireless earbuds, to joining a virtual meeting on a laptop. You may be surprised to find that all the devices you use undergo rigorous testing to ensure that they meet EMC compliance standards. The EMC compliance standards certify that the devices function properly and are safe to use. Most electronic devices emit a form of electromagnetic radiation called radio frequency (RF) energy. RF energy is a type of electromagnetic wave, which means it consists of an alternating electric and magnetic field. Many applications employ the use of RF energy, for example in communication devices such as transmitters, radios and Bluetooth devices. RF energy is a necessary component in various medical technologies such as magnetic resonance imaging (MRI) and radiofrequency ablation (RFA). However, in some cases unwanted RF energy is generated such as in computer chips and electric motors. With so many devices utilizing RF energy, we need to perform electromagnetic compatibility (EMC) testing to establish the RF energy performance and safety of electronic devices.
During EMC testing, the two main types of tests are immunity tests and emissions tests. Immunity tests observe the functionality of the electronic device when subjected to external signals generated from other surrounding devices. Two types of immunity testing include continuous and transient tests. Continuous testing is used to simulate a RF environment similar to real life and are applied over a longer period of time, whereas transient tests consist of short bursts of energy. Immunity testing consists of generating an electromagnetic field at different frequencies using signal generators, antennas, and amplifiers. The device is exposed to the fields and the device’s performance is measured.
Emissions tests measure the amount of electromagnetic energy the device is producing when it is operating. The emitted energy can disturb or interfere with other devices in the environment, impairing their functionality. This interaction is termed electromagnetic interference (EMI) and would ideally be avoided. As there are increasing amounts of electronic devices being produced and used in our daily lives, EMC testing only becomes more relevant.
Common wireless devices such as cellphones, laptops, and headsets emit RF energy. If unaccounted for in the design, external RF energy may interfere with the performance of another device. For example, studies have shown that wireless devices may interfere with some electronic medical devices such as a cardiac pacemaker implanted into a patient, when in close proximity. The effects of this could be fatal for the patient if the function of the pacemaker is negatively impacted and pulses are delivered irregularly or even stopped from being delivered. Thus, standards are established to ensure the safety of the wireless device for both the user as well as protecting the performance of other devices in the environment.
Standards for compliance pertaining to wireless devices include CISPR 22 and FCC 15 sub-part b. These standards attempt to standardize EMC performance in wireless devices by outlining immunity and emissions requirements as well as the test methods and equipment. EMC compliance testing and strict standards ensure that our wireless devices are safe, effective, and work consistently. As our world becomes increasingly interconnected and electronic devices become global, applying these standards will allow us to work together towards a more innovative and safe future.