Hello,Eric- I agree on the interleave- As I said I was unsure about the 3/2s, and in the end we ended up at the same place. Until I crashed headlong into other differences in the codec...
On decoding with the USB3000- That is neat- given that device, all of mbelib could probably be replaced. Those run about $300?
On the subject of mbelib decoding dstar- give the people involved some more time, but significant progress is being made. From the recording I most recently heard, the decoding is quite reasonable, with some artifacts that I'm sure will be fixed in the coming days. Stay tuned.
And finally, I don't know if many people know, but there is a much improved implementation of imbe (both decoder as well as encoder!) available as part of the OP25 project. Supposedly the code is significantly more efficient than the code in mbelib. See imbe_vocoder in trunk
The version that includes P25 IMBE is slightly more. You could buy a digital scanner for the money, but it would not do DMR, Nxdn, etc,...
Rate Control Words are used to setup the chip, and tables in the documentation give the RCW values for various rates. The table also indicates if the settings are compatible with the 1000 (AMBE), 2000 (AMBE+), or 3000 (AMBE+2) chips. The rates that will interoperate with DSTAR and APCO/DMR are marked. The DV Dongle uses an AMBE 2000 series chip(AMBE+) and it can also do AMBE.
I noticed mbelib lists the AMBE codec as 2250 bps speech rate, but the DVSI documentation lists APCO Half Rate/DMR as 2450 bps speech rate.
There are configurations without the FEC and Bit Interleaving. I had to use the 4400 bps total rate IMBE setting for Provoice and do FEC/Interleaving in code. I may do the same as an experiment with DStar, compare the 2400 AMBE+ 2400 AMBE+2, and 2450 AMBE+2.