Fun fact, pirate radio stations were intially trasmitted from ships to avoid getting in trouble for running "illegal" radio stations.
My Inspiration was to embrace both the hack and nautical (pirate) theme of this hackathon. I am going for the hardware nautical theme. I wanted it to be completely portable so if I were on a ship, I would be able to use it without the need for any internet.
What it does
It turns a Raspberry Pi into a FM Transmitter, that can connect with a bluetooth audio device, essentially making a pirate radio. It can play local files as well.
How I built it
I used a raspberry pi, bluetooth adapter, raspbian linux, a couple of wires connected to the gpio, and blueAlsa as way to pipe audio it recieves. It relies heavily on (PiFmRDS)[https://github.com/ChristopheJacquet/PiFmRds].
Most of the work I did was actually creating scripts and setting up the proper parameters to allow the different libraries to talk to each other.
Challenges I ran into
I currently only have a chromebook and so getting that into developer mode and installing crouton and setting up a dev environment took as long as setting up the raspberry pi and configuring blueAlsa to detect bluetooth and pipe that to SOX. I also needed to find a old school fm reciever to be able to test it. I ran into some antenna trouble and finding a clean unused fm frequency that wouldn't get me in trouble with the FCC.
I also could not edit a nicer video for my project, because I am working from a chromebook, but I managed the main features of my setup.
Accomplishments that I'm proud of
I am proud of how it is completely standalone. With a startup script, it shows up as a bluetooth device and after finishing boot, the raspberry pi will keep working as long as the battery bank works. I calculated that the battery bank would allow it run for (~1000mA draw for the rpi + bluetooth, with a 26800mAh battery bank ) 24ish hours. Skipping tracks or changing the gain on the radio, while making audio clearer, would cut down on the battery life run time.
What I learned
I learned a lot about lower level linux operations in how it handles Audio. I also learned to appreciate how much can be done with so little.
What's next for PirateRadio
Currently HD Radio has been pushed for digital radio broadcasts, however the format is encrypted and a license is needed to run a "pirate" radio station. I would love to reverse engineer the broadcast format, the codec used is known but there is DRM attached unfortunately. Most radio stations still have a fallback, and the honda civic I used only has an analog radio.
Something else that has interested me is going all in on ICECast and running an internet radio station.