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MP3 Transmitters Now Legal In the UK
SilentOneNCW writes "From December 8th, it will be once more legal to own and operate an MP3 Transmitter in the UK, primarily used to convey music between an MP3 player such as Apple's iPod to your home or car stereo. The device was originally banned because their transmissions can override and interfere with legal radio stations, which is prohibited by the Wireless Telegraphy Act of 1949. Strong consumer demand for the devices and pressure from Liberal Democrats were among the primary motivators for the amendment."
That's the point; they broadcast on a frequency that can be picked up by your car radio. But the power is so low that it's unlikely to travel far outside your car.
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No, most all of them can be tuned to any frequency in the FM band. The ones like the Belkin TuneCast and the iTrip are within the legal power limits. Units made by companies like Ramsey (do a search for Ramsey FM10) are theoretically legal, as long as you don't use a transmitting antenna with too much gain. So, if you really wanted to, you could get one of these, add the proper (or improper) antenna, and easily exceed the allowed power output for an unlicensed transmitter. Not that I'm recommending this, you understand. I'm just saying that it can be done.
It's a power-level issue. The FCC allows unlicensed transmitters under Part 15; the maximum allowed varies with frequency. You can see the limits on this page. For example, above 960 MHz, unlicensed devices can transmit a field strength of up to 500 microvolts/meter, measured at three meters from the radiating device. (Those units seem a little odd to me, but that's what the table lists.)
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Actually, the BBC has a story on it. That's where I read about it. http://news.bbc.co.uk/2/hi/uk_news/politics/617782 0.stm
At first I thought this was something for transmitting MP3 files around, but it's just a low-power FM audio transmitter to transmit to nearby FM radios. Those things have been around for decades, all the way back to 8-track players and drive-in movie theaters. All the TVs at my gym have one, transmitting on different frequencies.
If you're in a major metropolitan area where all the FM broadcast slots are in use, you may not have much success with one of these things.