S4285

WA2ZKD

The 4285 extension was never completed but given that 4285 is virtually dead,  maybe not a real issue. The professional community has abandoned that waveform as it does not have a good sync scheme. It has been replaced by the newer stuff in MIL-STD-110C and D

jks

True. Very difficult to find open source demodulator code for any of those modems though. We were fortunate to have code donated for s4285. But it needs serious performance improvements before it will work on the Beagle (i.e. it's currently too slow to keep up with realtime).

The other problem is that most of the traffic sent using these modems is encrypted. Although the French Navy runs a worldwide s4285 network that is open. I was always more interested in finally understanding what those strange "chug-chug-chug" sounds on HF were all about.

More info for anyone interested:

http://www.udxf.nl/Some-Notes-on-STANAG4285.pdf

http://i56578-swl.blogspot.co.nz/2014/05/8ary-psk.html

http://hflink.com/standards/HF_modems_explained_stanag.pdf

http://www.n2ckh.com/MARS_ALE_FORUM/s4285.PDF

WA2ZKD

MELP Digital Voice is also sent via those 110 modems at rates from 600-2400 bps