Most of your questions are answered here: http://pskmail.wikispaces.com/PSK_arq
73, Rein PA0R > -----Ursprüngliche Nachricht----- > Von: digitalradio@yahoogroups.com > Gesendet: 07.01.08 02:37:18 > An: [EMAIL PROTECTED] > Betreff: [digitalradio] NBEMS experience today > > > > > Several of us were around the 10137 frequency earlier today and tried > various combinations of modes, including NBEMS. We had at least KH6TY, > K3UK, VE5MU, KC7GNM, and WD4KPD. Some attempts at making transfers was > done. I sent Skip one of my standard messages which is the Gettysburgh > Address. It took about 6 minutes or so to send with its 1419 character > length.using the PSK63 speed. I unfortunately did not record this > exactly. Not really fast, but we had quite a few repeats due to > conditions being marginal. Again, this mode is intended more for VHF, > but it does work on HF, even with fairly modest signals. The main thing > is that the message was completely accurate at the receiving station, > something nearly impossible to do with most of the sound card modes. > > What we probably should have done is try the same message with FAE 400 > mode and compare the throughput under similar conditions. > > Eventually it sounds like NBEMS may have a chat mode, which I think > would be a good thing, but you can easily switch back and forth between > the flarq ARQ add-on and the basic VBdigi program. I wonder if it might > be possible to eventually add the FAE 400 mode? > > In fact, later on I was tuning around and VE5MU was down the band > calling on FAE 400 and I just sort of set my cursor on the waterfall and > I was connected. We had a lengthy chat and if you have used this mode, > you know that it is hard to keep up with the throughput with less than > 40 wpm keyboard speed:) And that is when conditions are not the best. > > I am wondering if it might be possible to have this mode eventually > available on VBdigi as it clearly is the superior ARQ HF sound card mode > at this time. You can use wide FAE for more speed, but it is no where > near as sensitive as the 400 Hz narrower mode. And for those of us who > really do not want to operate with moderate width modes (under 500 Hz), > the 400 Hz wide mode is ideal. The 10130 to 10140 sub bands under the > new Region 2 Band Plan recommends no more than 500 Hz bandwidth. > > Questions about NBEMS: > > 1. I think I asked something like this before, but bear with me. It > seems to be sending several blocks of data because you see the inserted > characters that must be a checksum and if the receiving station decodes > all correctly it knows that. Is this a CRC kind of check or something > similar? > > 2. Am I correct that it only requests the parts that it can not decode > properly? And it does this even though in between blocks are OK and so > don't need ARQ? So you can send maybe three or more "blocks" with the > check and if only one is bad it only resends that one? > > 3. If it needs to repeat one or more blocks, the transmitting station > does the repeat, but then continues to send new data as well? Probably > to fill a maximum number of bytes per transmission? > > 4. If you see someone sending the flarq beacon in VBdigit, and their > callsign, is that just a general call to anyone? Or is there some way to > differentiate who is to get the message? > > 5. And then when their callsign appears automatically in the flarq > program, does that mean they are trying to connect specifically to your > callsign, or is your flarq program just responding to any flarq beacon? > > 6. If it is a general call, how do we know when you receive a message or > who it is supposed to go to? > > 73, > > Rick, KV9U > > > > -- http://pa0r.blogspirit.com Announce your digital presence via our Interactive Sked Page at http://www.obriensweb.com/sked DRCC contest info : http://www.obriensweb.com/drcc.htm Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) <*> To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
