that many of us used, starting in the 1980's, migrated from Amtor to
Pactor and Clover II with the Winlink system. Amtor, even though an ARQ
mode, had errors sent when conditions were deteriorating. This would
send incorrect data into a BBS system and make things very difficult to
proceed.
Eventually, due to what was believed to be much slower operation with
Clover II, they abandoned that mode after a number of years of use. It
seems that this may have been unfortunately due to some software glitch
that made it appear to work much slower than Pactor, but the decision
was made and Pactor was made "the" mode for HF. By 1995, Pactor 2 came
on the scene so Pactor modes became much faster than any other amateur
ARQ mode.
By the time things transitioned from Winlink (amateur radio networking)
to the current Winlink 2000 (hybrid which is primarily an internet based
system that has HF and VHF connectivity to amateur radio), Pactor 3 was
the next step up in speed, although with a much larger footprint.
Winlink 2000 is not really what I would call designed for emergency use.
It is more applicable for casual ham to non-ham communications that are
not critical. However, it can have utility in some cases, particularly
if you need to send e-mail to non-ham contacts and you have large
amounts of data and even attachments. Even then, much of the routing
would be via VHF/UHF and not HF unless you had a severe widespread
disaster or were remote from a Telpac connection. Since very few hams
have this capability and most will never buy a $1000 modem for the rare
case when it might be needed.
The ARRL Board of Directors have not selected any particular system as
the ARRL system, but at this time Winlink 2000 is the only thing
available and has become the default system. The BOD has directed the
ARRL to develop enhancements to the system and interoperability. JNOS2
has been greatly enhanced and can do some of the Winlink 2000
connectivity as well as the normal JNOS type of connections, so there
are some alternatives. The Winlink 2000 system of multiple servers is
complicated, but it makes the system more user friendly and takes care
of e-mail addresses no matter where you connect into the system. Another
alternative system is the PSKmail system developed in Europe however
this system only operates using the Linux OS so is not likely to be very
popular here in the U.S. for now. The ideal would be to move to more
interoperability so the weaknesses of the systems can be compensated for
by multiple ways to route traffic.
My understanding is that the long term goals of Winlink 2000, would also
include the ability to provide HF forwarding when everything else fails.
While this is unlikely, it is something that some of us feel has to be
in place to have a truly viable emergency communications system.
The Winlink 2000 programmer did extensive development several years ago
and culminated in the initial SCAMP mode. For some reason he did not
understand that the RDFT protocol that was formerly used by SSTVers,
needed around a 10 db S/N ratio to work. Somehow, it was thought that
this mode could work down to near 0 db S/N, but clearly this was not
possible. Also, it uses a very high baud rate of 122 and this can be
problematic for many HF conditions.
SCAMP did have two major new findings:
First, the proof of concept that channel busy detect software could be
developed and would work with any type of modulation including a dead
carrier. Up until then, there were those who said this was not possible.
But it really does work well.
Second, that it is absolutely possible to develop a powerful ARQ mode
that can use pipelined processing so that you can be receiving the
incoming data at the same time that you are processing the last packet
behind the scenes. This is highly significant in my view and hopefully
the amateur digital community will progress someday toward having
programmers who have the ability (and of course interest) to create an
ARQ HF mode for sound cards. So far there just has not been the interest
or the time to do this by the handful who have this ability but we can
hope.
The time line for further development has been delayed tremendously
considering that SCAMP development ended just about one year ago. The
beta software had timers that rendered the software unusable after last
summer. The Winlink 2000 system is owned by only a few hams and they
have tight control of the software so it is nothing like collaborations
you see with Source Forge or open source which is more in the spirit of
amateur radio. But Rick, KN6KB, has indicated that he will eventually
place the SCAMP mode, or at least parts of it in the GPL. After all,
some of the components are from Linux and the GPL although Winlink 2000
does not support Linux at this time.
The bottom line is that amateur radio desperately needs a true ARQ error
free sound card mode that is adaptable to the varying condition of HF
and other than one ham programmer at one time attempting the ARQ MT-63,
there doesn't seem to be much interest. Most of the programmers are more
interested in developing keyboard modes and they have done a very good
job considering all the choices we now have.
Would love to hear of any on-going programming for HF ARQ sound card
modes so if anyone does this or knows anything about it, please let us
know.
73,
Rick, KV9U
Andrew O'Brien wrote:
>I'm not debating PACTOR operations or the utility of the mode, just
>wondering why "they" chose PACTOR as the mode for emergency
>communications on HF via WL2K/Airmail ? I'll include the ARRL in the
>"they" since they have endorsed the concept.
>
>The ideas behind WL2K seems to be extremely well thought out (in the
>most part) but it seems to me that one part of the history of hams in
>emergency communications ....is the simplicity of the process and
>availability. ( e.g. most hams can get on the air in a hurry, have
>alternative power sources, and there are plenty of us). The law of
>averages would indicate that of the thousands of hams, a few hundred
>would surely get on the air in a real emergency situation.
>
>If I am correct, WL2K HF system is dependent on PACTOR. PACTOR is a
>proprietary system that is extremely expensive , not something
>available easily to all hams. Reliable hardware for PACTOR II and III
>is more expensive than a new HF rig these days.
>
>Would it not have been "better" to choose a system that is not
>proprietary and thus more likely to be included in the many public
>domain/free software applications? Since sound cards are used as a
>modem these days, and almost everyone has a sound card, would it not
>have been better (or more practical ) to develop something that works
>with the WL2K/AIRMAIL concept that all have can access?
>
>I am aware that VHF and packet radio may be fairly well developed as
>an alternative to PACTOR/HF reliance. However, I have seen the
>vulnerability of VHF systems in rural areas and really feel that an HF
>system, not dependent on expensive , minority owned, systems ...is
>needed. Yes, I KNOW, we can all do CW when we have to but I am
>talking about an organized system (like W2LK) but one that encompasses
>as many hams as possible.
>
>
>--
>Andy K3UK
>Fredonia, New York.
>Skype Me : callto://andyobrien73
>Also available via Echolink
>
>
Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org
Other areas of interest:
The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/
DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion)
SPONSORED LINKS
| Ham radio | Craft hobby | Hobby and craft supply |
YAHOO! GROUPS LINKS
- Visit your group "digitalradio" on the web.
- To unsubscribe from this group, send an email to:
[EMAIL PROTECTED]
- Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
