A general purpose radio frequency transmitter for Raspberry Pi which doesn't require any other hardware unless filter to avoid intererence. It can handle frequencies from 5 KHz up to 1500 MHz. Plug a wire into GPIO pin 4 (hardware pin 7) and it'll broadcast just about whatever you tell it to. Has an installation script. It's recommended that you use a bandpass filter to minimize noise on the air. Works with just about every RasPi (except the B). Has a text based menu to control it. Defaults to 434 MHz (international free ISM band). You can even broadcast spectrogram pictures! Can even do POCSAG to activate pagers!
An archive of pirate radio broadcasts from the late 1990's at archive.org. You can download them for free or listen to them online. The quality of some of the recordings is kind of poor (it is pirate radio, after all) but occasionally you'll come across a gem in the rough.
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