I'm pretty darn happy with the performance of Olivia without the added complexity of ARQ and the one on one aspect of the ARQ protocals.
I'm not sure about pskmail arq chat mode, but some of the other ARQ protocals I've played with look like a mess when you're a station on the outside looking in... that's something I really never liked about any of the ARQ/handshaking modes. It's like you're turning your little channel into a private line. FLDIGI has the WRAP checksum feature which allows an unlimited number of receiving stations to confirm 100% from a single uninterrupted transmission. And stations that don't have WRAP get to see the message too. -Dave, KB3FXI --- In digitalradio@yahoogroups.com, Rein Couperus <r...@...> wrote: > > What I don't understand is why NOBODY uses the pskmail arq chat mode, which > adds > an ARQ layer to modes like PSK250R, THOR22 or MFSK32. > > Why accept 5% error when you can have it 100% error free? Are you afraid your > typing errors get to the other end undamaged? > > Rein PA0R > > > > MFSK16 always seems to come up near or at the top of the simulated tests > > but I can't duplicate that in the real world. > > > > My experience is that Olivia 8/500 does as well if not better and gives > > MUCH greater latitude in tuning while still providing 100% copy under > > moderate to poor conditions. Olivia 16/500 is much slower but goes way > > into the noise where I've had terrible results with MFSK16 under the same > > conditions. And if 8/250 Olivia (slower yet) doesn't do it, I just turn > > off the HF rig. > > > > BTW, my experience is almost all on 80m with NVIS antennae. > > > > -Dave, KB3FXI > > > > > > --- In digitalradio@yahoogroups.com, Wes Cosand <wes.cosand@> wrote: > > > > > > I have finished a series of simulations looking at the performance of > > > several modes that seemed appropriate for extended keyboard to > > > keyboard rag chew QSOs. I was looking at modes that offered a > > > throughput of about 40 wpm so they could keep up with a reasonable > > > typist with a bandwidth of no more than 500 hz. > > > > > > I used PathSim to measure accuracy of text transmission under white > > > noise and CCIR 520-2 "Poor" simulated propagation conditions. I > > > measured text accuracy over at least seven minutes of text for each > > > data point. > > > > > > The graph can be found at > > > http://mysite.verizon.net/wz7i/modeimages/Digital%20Modes%20Poor%20Condx.png > > > The methodology, including software packaged used, is outlined at > > > http://mysite.verizon.net/wz7i/digitalmodes.html > > > > > > Summarizing, I arrived at the following SNR (db) for a character error > > > rate of 5%: > > > > > > AWGN "Poor" > > > DonimnoEX8 -15.3 -3.1 > > > MFSK16 -14.7 -8.5 > > > PSK31 -13.2 -0.8 > > > Contestia500/16 -14.0 -9.2 > > > RTTY -9.1 +3.7 > > > > > > I probably need to look at Olivia 500/4 > > > > > > These data confirm my prejudice about the excellent performance of > > > MFSK16. With the extended low tones implemented in several packages, > > > the mode is not difficult to tune. > > > > > > A couple things surprised me. I would have expected DominoEX to do > > > better under poor propagation. Another surprise is the difference in > > > performance between different software implementations of a given > > > mode. A software program may have excellent decoding performance with > > > one mode and then have performance with another that is not > > > competitive. The above numerical data would vary a good deal if > > > different decoding software were used. So if you find operating with > > > a given mode frustrating, don't discard it without trying another > > > program. > > > > > > I hope that with RSID some of these excellent modes will find greater use. > > > > > > The web site may well have errors so if you find something surprising, > > > please let me know so I can check things. I don't want to mislead > > > anyone. > > > > > > Wes, WZ7I > > > www.wz7i.com > > > > > > > > > > > > > ------------------------------------ > > > > Try Hamspots, PSKreporter, and K3UK Sked Page > > http://www.obriensweb.com/skedpskr4.html > > Yahoo! Groups Links > > > > > > > > > > -- > http://pa0r.blogspirit.com >
