It would be nice if ggwave made a apk available or published on f-droid.
[1] https://github.com/kamalmostafa/minimodem [2] https://www.youtube.com/watch?v=DfSHclXjobY [3] http://www.blog.jay-greco.com/wp/?p=116
There are a couple of good open source options for software-based AFSK APRS modem/TNCs:
Dire Wolf: https://github.com/wb2osz/direwolf minimodem: https://github.com/kamalmostafa/minimodem
You'll still need a USB sound card though, which adds weight and cabling. I would love to see some open-source SBC hardware a la Beaglebone Black or RasPi that had a high-quality sound card built onto the board and wired through a Molex-type plug that was suitable to the bumps and bounces of flying.
[1] https://github.com/chrissnell/GoBalloon -- This was my first project in Go and while it works well, it now looks pretty ugly to me with a year and a half of Go experience under my belt.
[2] https://github.com/chrissnell/GoBalloon/blob/master/ax25/dec...