Code of Federal Regulations
In the law of the United States, the ''Code of Federal Regulations'' (''CFR'') is the codification of the general and permanent regulations promulgated by the executive departments and agencies of the federal government of the United States. ...
, '
Title 47, Part 15(47 CFR 15) is an oft-quoted part of
Federal Communications Commission
The Federal Communications Commission (FCC) is an independent agency of the United States federal government that regulates communications by radio, television, wire, satellite, and cable across the United States. The FCC maintains jurisdiction ...
(FCC)
rule
Rule or ruling may refer to:
Education
* Royal University of Law and Economics (RULE), a university in Cambodia
Human activity
* The exercise of political or personal control by someone with authority or power
* Business rule, a rule perta ...
s and
regulation
Regulation is the management of complex systems according to a set of rules and trends. In systems theory, these types of rules exist in various fields of biology and society, but the term has slightly different meanings according to context. For ...
s regarding
unlicensed transmission
Transmission may refer to:
Medicine, science and technology
* Power transmission
** Electric power transmission
** Propulsion transmission, technology allowing controlled application of power
*** Automatic transmission
*** Manual transmission
*** ...
s. It is a part of
Title 47 of the Code of Federal Regulations The Code of Federal Regulations, Telecommunications, containing the U.S. federal regulations for telecommunications can be found under 'Title 47'' of the United States Code of Federal Regulations.
Commonly referenced parts
*Part 15—concerning unl ...
(CFR), and regulates everything from
spurious emission
In radio communication, a spurious emission is any component of a radiated radio frequency signal the complete suppression of which would not impair the integrity of the modulation type or the information being transmitted. A radiated signal out ...
s to unlicensed
low-power broadcasting
Low-power broadcasting is broadcasting by a broadcast station at a low transmitter power output to a smaller service area than "full power" stations within the same region. It is often distinguished from "micropower broadcasting" (more commonly " ...
. Nearly every electronics device sold inside the
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
radiates unintentional emissions, and must be reviewed to comply with Part 15 before it can be advertised or sold in the US market.
Subparts
A - General
Subpart A includes 21 sections from 15.1 to 15.38.
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.
the definitions are defined by the definition given.
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.
prohibits intentional
damped wave
Damping is an influence within or upon an oscillatory system that has the effect of reducing or preventing its oscillation. In physical systems, damping is produced by processes that dissipate the energy stored in the oscillation. Examples inc ...
transmissions such as
spark-gap transmitter
A spark-gap transmitter is an obsolete type of radio transmitter which generates radio waves by means of an electric spark."Radio Transmitters, Early" in Spark-gap transmitters were the first type of radio transmitter, and were the main type use ...
s which were common before the 1920s but occupy a needlessly wide range of frequencies.
prohibits operating a device under Part 15 for the purpose of
eavesdropping
Eavesdropping is the act of secretly or stealthily listening to the private conversation or communications of others without their consent in order to gather information.
Etymology
The verb ''eavesdrop'' is a back-formation from the noun ''eaves ...
, except when under lawful authority of law enforcement or when all parties in a conversation consent.
B - Unintentional radiators
Subpart B deals with
unintentional radiators—devices for which the purpose is not to produce radio waves, but which do anyway, such as
computer
A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as C ...
s. There are 16 sections between 15.101 and 15.123.
C - Intentional radiators
Subpart C deals with devices that are specifically designed to produce coherent radio waves, such as small
transmitter
In electronics and telecommunications, a radio transmitter or just transmitter is an electronic device which produces radio waves with an antenna (radio), antenna. The transmitter itself generates a radio frequency alternating current, which i ...
s. Specific to
broadcasting
Broadcasting is the distribution (business), distribution of sound, audio or video content to a dispersed audience via any electronic medium (communication), mass communications medium, but typically one using the electromagnetic spectrum (radio ...
15.221(an
15.219 deal with the AM band;
15.239deals with the FM band
15.247covers most
Wi-Fi
Wi-Fi () is a family of wireless network protocols, based on the IEEE 802.11 family of standards, which are commonly used for local area networking of devices and Internet access, allowing nearby digital devices to exchange data by radio wave ...
frequencies that aren't
U-NII
The Unlicensed National Information Infrastructure (U-NII) radio band, as defined by the United States Federal Communications Commission, is part of the radio frequency spectrum used by WLAN devices and by many wireless ISPs.
As of March 2021, U-N ...
.
D - Unlicensed PCS devices
Sections 15.301 to 15.323 deal with unlicensed
PCS devices from 1.91 to 1.93
GHz
The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one he ...
.
Cordless telephones using DECT 6.0 standards use this unlicensed PCS band.
E - Unlicensed NII devices
15.401 to 15.407 deal with unlicensed
National Information Infrastructure The National Information Infrastructure (NII) was the product of the High Performance Computing Act of 1991. It was a telecommunications policy buzzword, which was popularized during the Clinton Administration under the leadership of Vice-President ...
(U-NII) devices
F - Ultra-wideband operation
15.501 to 15.525 deal with
ultra-wideband
Ultra-wideband (UWB, ultra wideband, ultra-wide band and ultraband) is a radio technology that can use a very low energy level for short-range, high-bandwidth communications over a large portion of the radio spectrum. UWB has traditional applicati ...
(UWB) devices, including
ground-penetrating radar
Ground-penetrating radar (GPR) is a geophysical method that uses radar pulses to image the subsurface. It is a non-intrusive method of surveying the sub-surface to investigate underground utilities such as concrete, asphalt, metals, pipes, cables o ...
.
G - Access Broadband over Power Line
15.601 to 15.615 deal with
broadband over power lines
Broadband over power lines (BPL) is a method of power-line communication (PLC) that allows relatively high-speed digital data transmission over the public electric power distribution wiring. BPL uses higher frequencies, a wider frequency range and ...
(BPL) devices operating in the 1.705–80 MHz band over
medium
Medium may refer to:
Science and technology
Aviation
*Medium bomber, a class of war plane
*Tecma Medium, a French hang glider design
Communication
* Media (communication), tools used to store and deliver information or data
* Medium of ...
- or
low-
voltage
Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to m ...
lines
Line most often refers to:
* Line (geometry), object with zero thickness and curvature that stretches to infinity
* Telephone line, a single-user circuit on a telephone communication system
Line, lines, The Line, or LINE may also refer to:
Arts ...
.
H - Television Band Devices
15.701 to 15.717 deal with (TVBDs),
TV-band device {{Short description, Radio frequency device
TV band devices or TVBDs are unlicensed radio frequency devices operating in the vacant channels or white spaces between US television channels in the range of 54 to 698 MHz. The rules defining these ...
s that operate on an available
television channel
A television channel is a terrestrial frequency or virtual number over which a television station or television network is distributed. For example, in North America, "channel 2" refers to the terrestrial or cable band of 54 to 60 MHz, with ...
in the
broadcast 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.
Subjects
Unintentional radiators
Unintentional radiators are designated in two major classes:
*Class A Device marketed for use in business/industrial/commercial environments.
*Class B Device marketed for use in a residential environment, notwithstanding use in industrial or commercial environments
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 include
personal computer
A personal computer (PC) is a multi-purpose microcomputer whose size, capabilities, and price make it feasible for individual use. Personal computers are intended to be operated directly by an end user, rather than by a computer expert or tec ...
s and
peripheral device
A peripheral or peripheral device is an auxiliary device used to put information into and get information out of a computer. The term ''peripheral device'' refers to all hardware components that are attached to a computer and are controlled by the ...
s, and
electrical ballast
An electrical ballast is a device placed in series with a load to limit the amount of electric current, current in an electrical network, electrical circuit.
A familiar and widely used example is the inductive ballast used in fluorescent lamp ...
s for
fluorescent light
A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, which produces short-wave ultraviolet lig ...
s.
Unlicensed broadcasting
On the standard
AM broadcast band
AM broadcasting is radio broadcasting using amplitude modulation (AM) transmissions. It was the first method developed for making audio radio transmissions, and is still used worldwide, primarily for medium wave (also known as "AM band") transm ...
, 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 the
campus
A campus is traditionally the land on which a college or university and related institutional buildings are situated. Usually a college campus includes libraries, lecture halls, residence halls, student centers or dining halls, and park-like se ...
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/''f''
kHz μV/m.
Unlicensed broadcasts on the
FM broadcast band
The FM broadcast band is a range of radio frequencies used for FM broadcasting by radio stations. The range of frequencies used differs between different parts of the world. In Europe and Africa (defined as International Telecommunication Union (I ...
(88 to 108 MHz) are limited to a
field strength In physics, field strength means the ''magnitude'' of a vector-valued field (e.g., in volts per meter, V/m, for an electric field ''E'').
For example, an electromagnetic field results in both electric field strength and magnetic field strength.
As ...
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. Emissions must be kept within the 88.0 to 108.0 MHz band under 15.239 rules.
Unlicensed broadcasts on the
TV broadcast bands are prohibited, except for certain
medical
Medicine is the science and practice of caring for a patient, managing the diagnosis, prognosis, prevention, treatment, palliation of their injury or disease, and promoting their health. Medicine encompasses a variety of health care practic ...
telemetry
Telemetry is the in situ data collection, collection of measurements or other data at remote points and their automatic data transmission, transmission to receiving equipment (telecommunication) for monitoring. The word is derived from the Gr ...
devices and other low power auxiliary stations. 87.5 to 88.0
MHz
The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one he ...
is considered part of the
VHF TV
low band. For TV, 15.241 and 15.242 deal with
high VHF (channels 7 to 13), 15.242 also deals with
UHF (
band IV Band IV is the name of a radio frequency range within the ultra high frequency part of the electromagnetic spectrum.
Sources differ on the exact frequency range of the band. For example, the ''Swiss Federal Office of Communications'', the ''Broadca ...
and
band V
Band V (meaning ''Band 5'') is the name of a radio frequency range within the ultra high frequency part of the electromagnetic spectrum. It is not to be confused with the '' V band'' in the extremely high frequency part of the spectrum.
Sources d ...
).
Common uses of Part 15 transmitters
Frequently encountered types of "Part 15" transmitters include:
*
802.11
IEEE 802.11 is part of the IEEE 802 set of local area network (LAN) technical standards, and specifies the set of media access control (MAC) and physical layer (PHY) protocols for implementing wireless local area network (WLAN) computer com ...
wireless LAN
A wireless LAN (WLAN) is a wireless computer network
A wireless network is a computer network that uses wireless data connections between network nodes.
Wireless networking is a method by which homes, telecommunications networks and bus ...
s: (e.g.
WiFi
Wi-Fi () is a family of wireless network protocols, based on the IEEE 802.11 family of standards, which are commonly used for local area networking of devices and Internet access, allowing nearby digital devices to exchange data by radio waves ...
): 2.4 GHz, 5 GHz (
U-NII
The Unlicensed National Information Infrastructure (U-NII) radio band, as defined by the United States Federal Communications Commission, is part of the radio frequency spectrum used by WLAN devices and by many wireless ISPs.
As of March 2021, U-N ...
)
*
802.15 PANs (e.g.
Bluetooth
Bluetooth is a short-range wireless technology standard that is used for exchanging data between fixed and mobile devices over short distances and building personal area networks (PANs). In the most widely used mode, transmission power is limi ...
,
ZigBee
Zigbee is an IEEE 802.15.4-based specification for a suite of high-level communication protocols used to create personal area networks with small, low-power digital radios, such as for home automation, medical device data collection, and othe ...
): 2.4 GHz
*
Cordless phone
A cordless telephone or portable telephone has a portable telephone handset that connects by radio to a base station connected to the public telephone network. The operational range is limited, usually to the same building or within some short ...
s: 900 MHz; 1.9 (U-PCS), 2.4, 5 GHz (U-NII)
*
Microbroadcasting
Microbroadcasting is the process of broadcasting a message to a relatively small audience. This is not to be confused with low-power broadcasting.
Microbroadcasting, in radio terms, is the use of low-power transmitters (often Title 47 CFR Part 15 ...
, often by hobbyists,
drive-in theater
A drive-in theater or drive-in cinema is a form of movie theater, cinema structure consisting of a large outdoor movie screen, a projection booth, a concession stand, and a large parking area for automobiles. Within this enclosed area, customers ...
s, or on
college
A college (Latin: ''collegium'') is an educational institution or a constituent part of one. A college may be a degree-awarding tertiary educational institution, a part of a collegiate or federal university, an institution offering ...
or
high school
A secondary school describes an institution that provides secondary education and also usually includes the building where this takes place. Some secondary schools provide both '' lower secondary education'' (ages 11 to 14) and ''upper seconda ...
campuses.
*
Small FM radio transmitters designed to hook to the audio output of an
iPod
The iPod is a discontinued series of portable media players and multi-purpose mobile devices designed and marketed by Apple Inc. The first version was released on October 23, 2001, about months after the Macintosh version of iTunes ...
or other portable audio device and broadcast the audio so that it can be heard through a
car audio
Vehicle audio is equipment installed in a car or other vehicle to provide in-car entertainment and information for the vehicle occupants. Until the 1950s it consisted of a simple AM radio. Additions since then have included FM radio (1952), 8 ...
system that is not equipped with an audio input.
* Very low power transmitters, often referred to as ''"talking roadsign"'', ''"talking houses"'' or ''"talking billboards",'' which will air a repeating loop of highway construction, traffic, promotional or advertising information. These transmitters typically operate on empty channels on the AM broadcast band. A sign placed near the transmitter is used to entice passersby (nearly always in automobiles) to tune in. The talking house gets its name from the fact that such transmitters are installed at houses that are on sale, thus enabling a passerby to learn features of the interior of the house without touring the building.
* Some
wireless microphone
A wireless microphone, or cordless microphone, is a microphone without a physical cable connecting it directly to the sound recording or amplifying equipment with which it is associated. Also known as a radio microphone, it has a small, battery- ...
s and
headsets
Headset may refer to:
* Headset (audio), audio headphone(s), particularly with an attached microphone
* Head Set (band), an American alternative rock band
* Headset (bicycle part), a bicycle part that connects the fork to the frame
* Head-mounte ...
that broadcast to a receiver which amplifies the audio. Wireless microphones allow the user to move about freely, unlike a conventional microphone and are thus popular with musicians. Some professional wireless microphones and 'low power auxiliary' stations (including those labeled as "UHF") are licensed under Part 74, Subpart H of the FCC's rules. However, as of January 2010, many professional wireless microphones, and other Part 74 certified 'low power auxiliary' stations with a 50 mW output or less, can be operated in the "core TV band" (TV channels VHF 2-13 and UHF 14-51, except 37) frequencies without a license under a waiver of Part 15 rules. This waiver is expected to become permanent.
Units using the high UHF channels (700 MHz band) revoked from the
TV bandplan in June 2009 became illegal to operate in June 2010.
* Toys such as the popular late-1970s
Mr. Microphone and its imitators, which would broadcast the user's voice to a nearby
radio receiver
In radio communications, a radio receiver, also known as a receiver, a wireless, or simply a radio, is an electronic device that receives radio waves and converts the information carried by them to a usable form. It is used with an antenna. Th ...
. Variations on this type of transmitter were advertised for sale in radio
magazine
A magazine is a periodical publication, generally published on a regular schedule (often weekly or monthly), containing a variety of content. They are generally financed by advertising, purchase price, prepaid subscriptions, or by a combinatio ...
s as far back as the 1920s.
*
Walkie talkie
A walkie-talkie, more formally known as a handheld transceiver (HT), is a hand-held, portable, two-way radio transceiver. Its development during the Second World War has been variously credited to Donald Hings, radio engineer Alfred J. Gross, ...
s intended for children's use, baby monitors, and some older
cordless phone
A cordless telephone or portable telephone has a portable telephone handset that connects by radio to a base station connected to the public telephone network. The operational range is limited, usually to the same building or within some short ...
s operate on frequencies in the 49 MHz band or at the upper end of the AM broadcast band.
* Remote controls for various toys, garage door openers, etc. These transmitters usually operate in the 27, 72-76, or 315-433MHz ranges; data stream duty cycle has to be limited due to certain transmit power requirements. However, some remote control devices operate under Part 95 of the FCC rules, which permit higher transmit power on the 26/27 MHz and 72 MHz/75 MHz bands. Lower cost devices on these bands (particularly in the 27 MHz, 49 MHz, 310 MHz, 315 MHz and 433 MHz bands) are regulated under Part 15.
Spurious emissions
Electronic equipment from
computer
A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as C ...
s to intentional
transmitter
In electronics and telecommunications, a radio transmitter or just transmitter is an electronic device which produces radio waves with an antenna (radio), antenna. The transmitter itself generates a radio frequency alternating current, which i ...
s 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 by
interference
Interference is the act of interfering, invading, or poaching. Interference may also refer to:
Communications
* Interference (communication), anything which alters, modifies, or disrupts a message
* Adjacent-channel interference, caused by extr ...
to TV and radio reception. Class A is a looser standard for equipment intended only for
business
Business is the practice of making one's living or making money by producing or Trade, buying and selling Product (business), products (such as goods and Service (economics), services). It is also "any activity or enterprise entered into for pr ...
, industrial and commercial settings.
Transmitters also must adhere to a
spectral mask
{{unreferenced, date=February 2008
In telecommunications, a spectral mask, also known as a channel mask or transmission mask, is a mathematically-defined set of lines applied to the levels of radio (or optical) transmissions. The spectral mask ...
, to prevent
adjacent-channel interference
Adjacent-channel interference (ACI) is interference caused by extraneous power from a signal in an adjacent channel. ACI may be caused by inadequate filtering (such as incomplete filtering of unwanted modulation products in FM systems), improper t ...
,
intermediate frequency
In communications and electronic engineering, an intermediate frequency (IF) is a frequency to which a carrier wave is shifted as an intermediate step in transmission or reception. The intermediate frequency is created by mixing the carrier sign ...
interference, and
intermodulation
Intermodulation (IM) or intermodulation distortion (IMD) is the amplitude modulation of signals containing two or more different frequencies, caused by nonlinearities or time variance in a system. The intermodulation between frequency compo ...
.
See also
*
TEMPEST
Tempest is a synonym for a storm.
'' The Tempest'' is a play by William Shakespeare.
Tempest or The Tempest may also refer to:
Arts and entertainment Films
* ''The Tempest'' (1908 film), a British silent film
* ''The Tempest'' (1911 film), a ...
*
Microbroadcasting
Microbroadcasting is the process of broadcasting a message to a relatively small audience. This is not to be confused with low-power broadcasting.
Microbroadcasting, in radio terms, is the use of low-power transmitters (often Title 47 CFR Part 15 ...
*
RSS-210, the equivalent
Industry Canada
Innovation, Science and Economic Development Canada (ISED; french: Innovation, Sciences et Développement économique Canada; french: ISDE, label=none)''Innovation, Science and Economic Development Canada'' is the applied title under the Federal I ...
law specifying ultra-low-power license-exempt radio broadcasting devices.
References
External links
* U.S. government websites:
FCC rules are located in Title 47 of the Code of Federal Regulations (CFR)FCC Public Notice Dated July 24, 1991Covers some basic questions about Part 15 and what is considered a compliant transmission distance.
OET Bulletin 63 Dated October 1993 and Edited and Reprinted February 1996Covers some popular FAQ's about low-power non-licensed transmitters.
2015 edition 47 CFR §15"Understanding the FCC Regulations for computers and other digital devices"by the FCC
Part15.us– a popular discussion board for Part 15 broadcasting hobbyists
(from Archive.org April 2006)
{{DEFAULTSORT:Title 47 Cfr Part 15
United States communications regulation
Broadcast law
Electronics and the environment
Federal Communications Commission
Code of Federal Regulations
Low-power FM radio stations in the United States
Radio regulations