Over at Make, they’ve posted an interesting project showing you how to convert your $35 Raspberry Pi into a wide coverage FM transmitter.
This simple hack turns your Raspberry Pi into a powerful FM transmitter! It has enough range to cover your home, DIY drive-in movie, a high school ball game, or even a bike parade (depending on the stragglers).
The hack, called PiFM, uses hardware meant to generate spread spectrum clock signals and outputs them as RF energy on the Raspberry Pi’s GPIO (general purpose input/output) pins. The original creators report getting a range of 50m through heavy walls and multiple rooms.
Luckily, they include this helpful warning:
The Raspberry Pi’s broadcast frequency can range between 1Mhz and 250Mhz, which may interfere with government bands. We advise that you limit your transmissions to the standard FM band of 87.5MHz–108.0MHz (see Step 3) and always choose a frequency that’s not already in use, to avoid interference with licensed broadcasters.
Good advice, don’t you think? :-/