Hello Sholto and all, The minimum S/N is -11.5 dB (-13 dB with many repetitions). ARQ FAE is an asynchronous system (synchronous systems as Pactor are not possible under Windows, as it is impossible to control the timing of each sample (but it was possible under DOS)). So to lose temporary connection is possible and in ARQ FAE the connection is recovered due to an asymetry (in time to wait) between Master and Slave (it is supposed that PC are sufficiently fast not to introduce big CPU additive delays). Consequently some few collisions are normal and don't normally prevent the re-connection.
However, in real QSB conditions, below a S/N of -10 dB, if the link is lost, it is almost impossible to recover connection (it is left one minute for attempts). In that case, the best is disconnect and try it afterwards. To help for re-connection and solve this problem, I'm thinking to force the ALE400 or ALE RS ID transmission after 2 or 3 attempts. This RS ID will permit to recover exact time and frequency at a S/N (-16 dB to -18 db) much lower that the minimum S/N in ARQ FAE. Perhaps in the future... 73 Patrick ----- Original Message ----- From: "Sholto Fisher" <sho...@probikekit.com> To: <digitalradio@yahoogroups.com> Sent: Saturday, August 29, 2009 8:11 PM Subject: Re: [digitalradio] Weak Signal ALE-400 > Trip, > > I've been using ALE400 for quite a while and never really had too many > problems with collisions in the past. Only recently since I am /QRP only > have I noticed the problem. I would take this to mean that it really > only manifests when signals are very weak. > > The problem with slot-times or even timers in general is that Windows is > not a particularly good time keeper and some system tasks will rob the > cpu of cycles at critical moments. This is one of the reasons why Pactor > ARQ wouldn't be successful on a sound card/Windows PC. > > There's a fine balance between using time delays and maintaining overall > throughput but I think the solution will probably need to be in the form > of entering a waiting/listening state after a certain number of "no > acknowledgments". > > It will be interesting to read Patrick's comments on this. > > 73 Sholto > K7TMG > > > KT4WO wrote: >> >> >> ***********" Sync issues: >> >> The mode can lose sync now and then when signals collide. We haven't >> figured out a way around that other than dropping the link and >> reconnecting. >> >> Sholto and I thought that clearing the outgoing text would allow the >> mode to sit idle long enough to reestablish synchronization, but it >> seems the clear button does not actually clear what's in the outgoing >> buffer. We'll have to ask Patrick about that. "*********** ****** >> >> >> I have brought this up to Patrick a few times....I asked for a >> "slottime" or some random timer... >> I think this would solve the problem. This is a MAJOR ISSUE with ALE400. >> Until this is fixed...ALE400 will never become "mainstream" >> I have been fighting this issuse sense ALE400 came out. >> So far...he has not worked on that..maybe you will have better luck >> getting >> him to address this.??!!??! !?? >> Maybe now that someone other than me and Dave "sees" this is a problem, >> Patrick >> will fix it??? >> >> >> Trip - KT4WO >> Mostly on 80-30meters >> kt4w...@gmail. com <mailto:kt4w...@gmail.com> >> >> >> > > > ------------------------------------ > > Announce your digital presence via our Interactive Sked Pages at > http://www.obriensweb.com/sked > > Recommended digital mode software: Winwarbler, FLDIGI, DM780, or Multipsk > Logging Software: DXKeeper or Ham Radio Deluxe. > > > > Yahoo! Groups Links > > > >
