FCC Part 15 Modular Certification Rules Baseline Guidelines
FCC Part 15 modular rules allow pre-certified radios in host devices provided shielding, power regulation, labeling, and antenna limits match grant guidelines.
Subpart B
Meaning
Segment of the Federal Communications Commission rules governing unintentional radiators that generate radio frequency energy without a deliberate transmitter. Compliance with subpart b is mandatory for almost all digital electronics sold in the United States, including laptop computers and printers. These devices produce incidental signals during normal operation.
Device Category
Radiated and conducted energy must stay below specific levels to prevent interference with radio services. According to subpart b, the limits are divided into Class A for industrial environments and Class B for residential use. Class B requirements are more stringent because homes are more likely to have sensitive television or radio receivers nearby.
Testing Standard
Manufacturers typically follow the Supplier’s Declaration of Conformity process for these devices. Under subpart b, this involves testing the product at an accredited laboratory and keeping the results on file as proof of compliance. The device must carry a specific warning label about interference.
Labeling Duty
Every component of a larger assembly contributes to the final emission profile. If a single board fails to meet subpart b, it can cause the entire product to fail. High-speed data lines and oscillators are the most common sources of these emissions.
A power supply must also meet these limits to prevent noise from entering the public electrical grid. The physical layout of the circuit board often includes ground planes and decoupling capacitors to keep the noise within the legal boundaries.