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Code of Federal Regulations,Title 47, Part 15 (47 CFR 15) is an oft-quoted part ofFederal Communications Commission (FCC)rules andregulations regardingunlicensedtransmissions. It is a part ofTitle 47 of the Code of Federal Regulations (CFR), and regulates everything fromspurious emissions to unlicensedlow-power broadcasting. Nearly every electronics device sold inside theUnited States radiates unintentional emissions, and must be reviewed to comply with Part 15 before it can be advertised or sold in the US market.
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Subpart A includes 21 sections from 15.1 to 15.38.
47 CFR15.1 states that any radiator (that which emits radio energy), whether or not intentional, must be licensed unless it meets 47 CFR 15 or is otherwise exempted by the FCC.
47 CFR15.3 the definitions are defined by the definition given.
47 CFR15.5 contains a general provision that devices may not cause interference and must accept any interference received. You are cautioned that any changes or modifications to devices not expressly approved by the party responsible for compliance may void your authority to operate devices.
47 CFR15.5 prohibits intentionaldamped wave transmissions such asspark-gap transmitters which were common before the 1920s but occupy a needlessly wide range of frequencies.
47 CFR15.9 prohibits operating a device under Part 15 for the purpose ofeavesdropping, except when under lawful authority of law enforcement or when all parties in a conversation consent.
Subpart B deals withunintentional radiators—devices for which the purpose is not to produce radio waves, but which do anyway, such ascomputers. There are 16 sections between 15.101 and 15.123.
Subpart C deals with devices that are specifically designed to produce coherent radio waves, such as smalltransmitters. Specific tobroadcasting,15.221 (and15.219) deal with the AM band; &15.239 deals with the FM band.15.247 covers mostWi-Fi frequencies that aren'tU-NII.
Sections 15.301 to 15.323 deal with unlicensedPCS devices from 1.91 to 1.93GHz.
Cordless telephones using DECT 6.0 standards use this unlicensed PCS band.
15.401 to 15.407 deal with unlicensedNational Information Infrastructure (U-NII) devices
15.501 to 15.525 deal withultra-wideband (UWB) devices, includingground-penetrating radar.
15.601 to 15.615 deal withbroadband over power lines (BPL) devices operating in the 1.705–80 MHz band overmedium- orlow-voltagelines.
15.701 to 15.717 deal with (TVBDs),TV-band devices that operate on an availabletelevision channel in thebroadcast television band. An available channel is a 6 megahertz television channel that is not being used by an authorized service in a given geographical location, and thus may be used by unlicensed devices under the provisions of this rule part.
Unintentional radiators are designated in two major classes:[1]
The emission limits for Class B devices are about 10 dB more restrictive than those for Class A devices since they are more likely to be located closer to radio and television receivers.
These devices includepersonal computers andperipheral devices, andelectrical ballasts forfluorescent lights.
On the standardAM broadcast band, under 15.219, transmission power is limited by 100 milliwatts of DC input power to the final RF stage (with restrictions on size, height of, and type of antenna), or alternatively, under 15.221, if the AM transmission originates on thecampus of an educational institution, the transmission can theoretically be any power so long as it does not exceed the field strength limits stated in 15.209 at the perimeter of the campus, 24,000/fkHzμV/m.
Unlicensed broadcasts on theFM broadcast band (88 to 108 MHz) are limited to afield strength of 250 microvolts per meter (~48 dBμ) measured at a distance of 3 meters. This corresponds to a maximum effective radiated power of 0.01 microwatts.[2] Emissions must be kept within the 88.0 to 108.0 MHz band under 15.239 rules.
Unlicensed broadcasts on theTV broadcast bands are prohibited, except for certain medical telemetry devices, wireless microphones, and other low power auxiliary stations. 87.5 to 88.0MHz is considered part of theVHF TVlow band. For TV, 15.241 and 15.242 deal withhigh VHF (channels 7 to 13), 15.242 also deals withUHF (band IV andband V).
Frequently encountered types of "Part 15" transmitters include:
Electronic equipment fromcomputers to intentionaltransmitters can produce unwanted radio signals and are subject to FCC regulation. For digital devices including computers and peripherals, FCC Class B is the more stringent standard, applying to equipment marketed for use in the home, even if it could be used elsewhere. Home users are likely to be annoyed byinterference to TV and radio reception. Class A is a looser standard for equipment intended only forbusiness, industrial and commercial settings.
Transmitters also must adhere to aspectral mask, to preventadjacent-channel interference,intermediate frequency interference, andintermodulation.
