A personal FM transmitter is a low-power FM

radio transmitter In electronics and telecommunications, a radio transmitter or just transmitter is an electronic device which produces radio waves with an antenna. The transmitter itself generates a radio frequency alternating current, which is applied to the ...

that broadcasts a signal from a portable audio device (such as an MP3 player) to a standard FM radio. Most of these transmitters plug into the device's

headphone jack A phone connector, also known as phone jack, audio jack, headphone jack or jack plug, is a family of electrical connectors typically used for analog audio signals. A plug, the male connector, is inserted into the jack, the female connect ...

and then broadcast the signal over an FM broadcast band frequency, so that it can be picked up by any nearby radio. This allows portable audio devices to make use of the louder or better sound quality of a home

audio system Sound recording and reproduction is the electrical, mechanical, electronic, or digital inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects. The two main classes of sound recording te ...

car stereo 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), ...

without requiring a wired connection. They are often used in cars but may also be in fixed locations such as broadcasting from a computer

sound card A sound card (also known as an audio card) is an internal expansion card that provides input and output of audio signals to and from a computer under the control of computer programs. The term ''sound card'' is also applied to external audio ...

throughout a building. Being low-powered, most transmitters typically have a short range of 100–300 feet (30–100 metres), depending on the quality of the receiver, obstructions and elevation. Typically they broadcast on any FM

frequency Frequency is the number of occurrences of a repeating event per unit of time. It is also occasionally referred to as ''temporal frequency'' for clarity, and is distinct from ''angular frequency''. Frequency is measured in hertz (Hz) which is eq ...

from 87.5 to 108.0

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 ...

in most of the world, 76.0 - 95.0 MHz for Japan, 65.0 - 74.2 MHz for Russia, and 88.1 to 107.9 MHz in the US and Canada.

Uses

Personal FM transmitters are commonly used as a workaround for playing portable audio devices on car radios that don't have an Auxiliary "AUX" input

jack Jack may refer to: Places * Jack, Alabama, US, an unincorporated community * Jack, Missouri, US, an unincorporated community * Jack County, Texas, a county in Texas, USA People and fictional characters * Jack (given name), a male given name, ...

or Bluetooth audio connectivity. They are also used to broadcast a stationary audio source, like a computer or a television, around a home. They can also be used for low-power broadcasting and

pirate radio Pirate radio or a pirate radio station is a radio station that broadcasts without a valid license. In some cases, radio stations are considered legal where the signal is transmitted, but illegal where the signals are received—especially ...

but only to a very limited audience in near proximity. They can also be used as a "talking sign" in

real estate Real estate is property consisting of land and the buildings on it, along with its natural resources such as crops, minerals or water; immovable property of this nature; an interest vested in this (also) an item of real property, (more general ...

sales or similar. Devices can be operated by connecting to the audio source or to a proprietary port of a specific device it is made for. In addition, certain devices such as hands-free car kits, navigation tools such as the

TomTom TomTom N.V. is a Dutch multinational developer and creator of location technology and consumer electronics. Founded in 1991 and headquartered in Amsterdam, TomTom released its first generation of satellite navigation devices to market in 2004. ...

GO, mobile phones like some

Nokia Nseries The Nokia Nseries was a high-end lineup of feature phones, smartphones, and tablets marketed by Nokia Corporation from 2005 to 2011. The Nseries devices commonly supported multiple high-speed wireless technologies at the time, such as 3G, or Wi ...

models, and MP3 players may have FM transmitters built-in, however this has become uncommon.

Legality

The legality and maximum permitted power levels or field strengths of these devices varies by country. In 2006 these devices became legal in most countries in the

European Union The European Union (EU) is a supranational political and economic union of member states that are located primarily in Europe. The union has a total area of and an estimated total population of about 447million. The EU has often been de ...

. In the UK Statutory Instrument IR2030/26/2 2011/0401/UK (from December 2011) permits unlicensed use of devices that can be shown to radiate less than 50 nanowatts (-43dBm), on a 0.2 MHz raster in the range 87.5–108 MHz. Industry Canada permits transmitters that have an output lower than 100 µV/m at (approximately 1 microwatt output). In 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 territori ...

, Part 15 of the

U.S. 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 jurisdictio ...

rules specifies that no license is needed if range of the transmitter does not exceed 200 feet (61 meters). In Japan, no license is needed for devices with a signal strength of less than 500 µV/m at 3 meters.

References

{{Reflist

External links

''Frequently Asked Questions on Low-Power FM Broadcasting from Industry Canada''

Micro-Broadcasting: ''Getting The Most Out Of Part 15 Radio'' originally published by ''Monitoring Times'', Sept. 2011

''Understanding the FCC Regulations for Low-Power, Non-Licensed Transmitters'' at the FCC. (USA)
IPod accessories Consumer electronics Digital audio players Wireless transmitters Radio hobbies Repurposing

Uses

Legality

See also

References

External links