I was watching the data arriving today on my DIY kit when I suddenly remembered that I have done this before.
Does anyone remember the good ole days of AMSAT and the PacSats? We used to runs a software tool called PB and another called PG. Between them they would ingest everything that was being transmitted from the PacSats using the FTL0 protocol.
I went looking for it and found it here ftp://ftp.amsat.org/amsat/software/Linux/
The thing that is making me think is that the PacSats were polar orbiting just as the CubeSats will be. We got 3 or so passes a day from them and at 9600bd using the G3RUH/GMSK modem we would still have to wait days for a complete file to come down. But, it was 9600bd rather than 2400bd.
Amsat modems and protocols are in the public domain. Perhaps we can get learn some tricks?