I spent some time looking at the D-Star spec, which is supposedly
“open”. Unfortunately, the published DOC (yes, singular) out there
are far from complete. Fortunately, Moe, Pieter and Robin did some
work analyzing D-Star and posted their results…
Doing D-Star with the USRP looks easily done and most stuff is there
such as GMSK, inter-leaving, Trellis, etc. I think that what is
missing is a scrambling and of course a framer.
While I’m not sure that D-Star has much advantage over other protocols
available in amateur radio, it seems to be taking off. Networks are
being built. D-Star can transport data, such as short-messages and
most importantly Ethernet frames. AMBE could be replaced by Speex.