Meaning
Electromagnetic compatibility requirements enforced by the Federal Communications Commission for unintentional radiators govern the allowable limits of high-frequency emissions from digital devices. Compliance with FCC Part 15b ensures that computing platforms and integrated circuits do not cause harmful interference to authorized radio services. The standard divides products into Class A for industrial environments and Class B for residential environments.
Manufacturers must obtain verification or certification through an accredited test laboratory before distributing their products in the United States.
Testing Procedure
Radiated and conducted emissions are measured inside specialized anechoic chambers and shielding rooms to evaluate compliance. The device under test is configured to run at maximum processing load while antennas sweep across a wide frequency spectrum to capture stray signals. Power cables are monitored for conducted noise that could travel back into the electrical grid.
Design Mitigation
Engineers incorporate ferrite beads, shielding cans, and ground planes into their circuit board layouts to suppress unwanted emissions. Decoupling capacitors are placed close to high-speed digital processors to absorb voltage ripples that can radiate through the board.
Compliance Certification
Passing the required laboratory testing allows the manufacturer to issue a declaration of conformity and apply the FCC logo to the product label. This documentation forms a necessary part of the technical construction file required for market access.
