[Discuss-gnuradio] Re: D-Star with gnuradio?

[Patrick Strasser]

schrieb Rafael Diniz on 2011-01-09 03:56:
> Hi Patrick,
> Thanks for the answer.
> I know about codec2, but how about what modulation to use?
> I read about the AOR ARD9000MK2[1] modem, that uses the:
> "G4GUO open protocol".
> Do you know if is possible to implement this OFDM based one?

Unfortunately I could not find any document that describes the G4GUO
protocol. Would be very interested too.

>From http://www.aorusa.com/ard9800.html I got:

Modulation method:      OFDM
Band width:     300 Hz - 2500 Hz, 36 carriers
Symbol Rate:    20 mS (50 baud)
Guard interval:         4mS
Tone steps:     62.5 Hz
Modulation method:      36 carriers: DQPSK (3.6K)
AFC:    +/- 125 Hz
Error correction:       Voice: Golay + Hamming
Video/Data: Covolution + Reed-Solomon
Header:         1 Sec. 3 tones + BPSK training pattern for synchronization
Digital voice:  AMBE2020 coder, decoder
Signal detection:       Automatic Digital detect, Automatic switching
between analog mode and digital mode
Video Compression:      AOR original adaptive JPEGFrom

Seems not too far off to implement in Gnu Radio/USRP.

Patrick