Car interference testing. Researcher placing sensors used in electromagnetic compatibility (EMC) testing inside a car. EMC testing checks whether the onboard electronics of a vehicle will operate correctly when exposed to electromagnetic (EM) signals from outside sources. Sources include TV and radio transmitters, radio communications equipment and mobile phone masts. To simulate their effects, vehicles are exposed to a wide range of EM waves in shielded rooms. The sensors measure the EM levels inside the car. Photographed at a facility owned by UTAC, the French industrial testing and standards body.