Raspberry PI radio transmitter (no additional hardware)
an idea by dheidler
Create a kernel module, which provides a virtual alsa sink, which transmits the audio through the air. see https://github.com/bmwiedemann/PiBits/tree/master/PiFmDma (code uses less cpu power)
ALSA Pure Digital Power Amplifier
a project by duwe
Building on top of <a href="http://rdimitrov.twistedsanity.net/blog/show.php?entry=Microcontroller%20Class%20D%20Amplifier,%20Rev2">Rouslan Dimitrov's Microcontroller Class D Amplifier</a>, I developed the idea to feed the power amplifier with PCM data directly. Rouslan does some dithering and noise shaping, but I'm convinced that proper interpolation would sound better. The ATtiny is too slow to do even cubic interpolation so I'll move that into the host.