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 timesI 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
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