I was able to find some interesting data on poor channel performance of the 110A modem from one company:
http://www.etools.de/software/telekommunikation/komponenten/milstd188110a.htm Depending upon the BER you can tolerate, it appears that the 2400 bps speed can only handle around +10 to +14 S/N dB. The slower bps rates can work to around zero S/N. Te 150 bps shows something around -1 to -4. Another interesting specification is the the multipath tolerance. They claim 6 msec at 2400 bps, 8 ms from 150 to 1200 bps, and 12 mec at 75 baud. That seems to have good ability to cope with ISI. Now these are the bps rates. Isn't the baud rate the same 2400 baud, all the time for this modem, contrary to what Bonnie claims? 73, Rick, KV9U expeditionradio wrote: > --- In digitalradio@yahoogroups.com, kv9u <[EMAIL PROTECTED]> wrote: > >> If the 110A works this well at 2400 baud, what would happen with slower >> speeds? From what I understand, it does require a good signal to get >> through, perhaps comparable to the WinDRM software at maybe +10 S/N dB >> or maybe a bit below that? >> >> 73, >> >> Rick, KV9U >> > > Hi Rick, > > Your understanding is not correct. The lower baud rates of the 188-110 > PSK system work in *negative SNR*. > That is much farther down into the noise than DRM. > > May I suggest you download RFSM2400 and receive some of the signals on > the air. This might give you a better feel for it. > > Bonnie KQ6XA > > .
