Mini transmitter

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Mini transmitters (also transmitters called) distribute any audio signal in the immediate vicinity of an FM - frequency . This z. B. the music of an MP3 player can be played on any radio without the need for a cable connection to the radio. This is e.g. B. advantageous if a car radio has no external audio inputs.

In the past few years, such mini-transmitters were initially found outside of Germany. a. in the USA, widespread. Operation is also permitted there. In Germany, the channels have been offered en masse in Internet auctions since around 2003 , although their operation was initially prohibited. Since the beginning of 2006, the Federal Network Agency has allowed the operation of devices with a CE mark and an effective transmission power of 50 nanowatts ERP .

Use is also permitted in other German-speaking countries - but only in Switzerland if the device can transmit on all VHF frequencies from 87.5 to 108 MHz; in Austria the sale and use has been allowed since December 2006. With the approved transmission power of 50 nanowatts, only a few meters can be bridged. However, devices are also available whose transmission power is in the range of a few milliwatts. In the open air, these can be heard up to 200 meters with a normal radio and can interfere with other radios at close range if an already occupied frequency is selected. There are users who solder a piece of wire as an antenna to the transmitting transistor and thus multiply the range.

The mini-transmitters usually cost between 10 and 50 euros and some are stereo-capable. Some can use PLL technology to select any frequency in the entire range from 87.5 to 108 MHz . Others only offer a few permanently set frequencies (these are not permitted in Switzerland). The unapproved devices also include devices that can transmit below the VHF limit of 87.5 MHz. These devices use frequencies in the 4 meter band , which are used in Germany for non-public BOS radio , among other things .

To operate such a mini transmitter, a frequency is required on which no radio program is broadcast.

Some smartphones (such as the Nokia N8 and Nokia 808 PureView ) or navigation systems have integrated FM transmitters with which music, but also, for example, the navigation announcement , can be transmitted to the car radio.

See also ultra short wave transmitter .

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