Frequency Modulation Transmitter

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  • Topic: Radio, FM broadcasting, Frequency modulation
  • Pages : 2 (455 words )
  • Download(s) : 161
  • Published : April 8, 2013
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An FM transmitter can either be built into a device or be a portable appliance that plugs into the headphone jack or proprietary output port of a portable audio or video device, such as a portable media player, CD player, or satellite radio system. The sound is then broadcast through the transmitter, and plays through an FM broadcast band frequency. Purposes for an FM transmitter include playing music from a device through a car stereo, or any radio. The FM transmitter plugs into the audio output of audio devices and converts the audio output into an FM radio signal, which can then be picked up by appliances such as car or portable radios. Most devices on the market typically have a short range of up to 100 feet (30 metres) with any average radio (up to about 300 feet (100 metres) with a very good radio under perfect conditions) this range can also be enhanced if operated in fixed locations of good high elevation, such as a multi-story apartment or tall building and can broadcast on any FM frequency from 87.5 to 108.0 MHz in most of the world, (or 88.1 to 107.9 in the US and Canada). Some lower-cost transmitters are hard-wired to the 87.7–91.9 MHz band allocated to educational broadcasts in the United States, or a certain other smaller range of frequencies. FM transmitters are usually battery driven, but some use the cigarette lighter socket in cars (and sometimes outside of vehicular use), or draw their power from a mains powered wall socket or the device itself. They are typically used with portable audio devices such as MP3 players, as well as hi-fi systems, message systems, etc.. They are also used to broadcast other outputs (such as that from a computer sound card) throughout a home or other building.


The relatively low power output of FM transmitters sometimes makes it unsuitable for use in some large urban areas because of the number of other radio signals. This is compounded by the fact that strong FM signals can bleed over into...
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