Compliance Mark Definitions

Digital equipment sold in the United States that contain clocks with the speed of 9kHz and above must be tested for compliance to the Federal Communications Commission (FCC) specifications. Additionally, devices transmitting information over the airwaves or cable must be tested for FCC approval.

When digital equipment is in operations, radio frequency (RF) signals will be transmitted from these devices: these are called RF emissions. These emissions can be either intentional or unintentional in nature. Additionally, these radiators of electromagnetic interference may affect the operation of other equipment located in proximity to the emitting device. Intentional emitters (i.e. wireless applications, radios, cellular telephones, etc.) are tested to determine that they emit in the correct frequency assigned by the FCC and transmit with the correct amplitude allowed by the FCC. Unintentional emitters (i.e. computers, TV's, telephones, etc.) are tested to determine that the RF emissions from the devices do not interfere with the operations of other devices in the home or the office.

The FCC determines the proper testing criteria for the digital equipment using the 'environment of use' characteristic. If the device is to be used in the professional arena or in public places a less stringent emissions criteria is levied on the device. If the device is for home use, the emissions are tightly controlled.