Motorcycle Communication Box

Doing the Snowy Ride the past few years by myself, this past year I took my brother and my father along. Since communication by hand signals and yelling isn't much fun I invested some time investigating two-way radio communication between
bikes, and boy there are some expensive little boxes out there!

So, I decided I didn't want to spend 3 x $900+ AUD for our three bikes to communicate. So instead I bought three relatively cheap but very good 3W UHF CB radios which accepted headset input and build this little board for each.

** This was an early development board which was slightly larger than the final version and also had an error with the layout for one of the control pots... oops!

This board allows the rider to mix his iPhone/iPod/MP3/GPS into his helmet headset along with the two-way radio audio. When a signal is received via the two-way the input audio signal is "ducked" to a low level to allow the conversation to be heard. After a few short moments of no two-way signals the music resumes to the previous level. It works quite well, but does need a little refinement.

The first thing I'd like to do is implement some form of noise-cancellation in the microphone going to the radio. My brother uses an open-faced helmet and his voice can be sometimes hard to understand. However my microphone in my full-faced helmet is very clear.

The second thing and less important is fixing up the volume controls with some form of digital control. Knobs are a pain in tank-bags and can easily get changed when the luggage moves around.

Lastly, I need to implement a choke for the power input as considerable buzz occurs occasionally on my brothers bike. It probably has more to do with his electrics than my board, but it should cope with noise better.

I've recently purchased a dsPIC30 development board to hopefully utilise Microchips Noise-suppression library to try and eliminate the noise from the microphones. So far the library works well but the licensing is ridiculous for a non-commercial product. The dsPIC will also allow me to have full digital controls of the ducking and timing so no more analog noise paths etc etc.