----- Original Message -----
Sent: Tuesday, June 21, 2005 9:12
AM
Subject: RE: [digitalradio] Re: HF
Digital network modes
Mike,
One
thing that absolutely perplexes me is that people think that emergency digital
traffic will swamp the HF bands if they are allowed to expand. The facts are
clear from the last decade or so that this does not happen. Right now, anyone
can run a semi-automatic system (with a human on one end of the link and a
machine on the other) anyplace in the cw/digital area as long as it is under
500 Hz bandwidth. Only the fully automatic, machine to machine autoforwarding
and protocols over 500 Hz need to stay in the (very) narrow subbands.
On
the other hand, you have others who opposes using the internet to link ham radio to e-mail
addressees. They want RF only networks like the Winlink "Classic"
system. Now that would increase the use of HF but you would also lose the
synergy of the melded RF/internet network.
Winlink 2000 goes to the extreme in trying to use the
internet for most of the communications, thereby weakening its emergency
capability so there you have another approach. Most Winlink 2000 for emergency
use is not on HF, it is via Telpacs on VHF/UHF. Part of this is due to the
need to use frequencies above HF because many of the newer members are
Technician class hams and have no HF capability.
If
we had a major blackout, hopefully we would do whatever we can. We will be
limited, but we can do some things that others can not do. During the recent
Tsunami, it was coincidental that a major satellite failed above that part of
the world causing a huge loss of communications to that remote area at the
most critical time possible. They had few other long distance
communication other than amateur radio HF.
Reliance on the internet for the bulk of the
messaging is the complete opposite of what at least some of us are focusing on
with amateur radio emergency digital communications. It is OK to use the
internet as a melded technology, but not as the main technology. It is when
that resource fails that we need to have something to handle a tiny fraction
of the "normal" traffic during the emergency. It doesn't have to be high
bandwidth but it does need to get through under difficult conditions. We
don't seem to be focusing on this.
I
would never want to put myself in the situation of using a ham radio
satellite as the main link. This is another of those highly centralized single
point failures. Yes, it is cool to have, and should be used if we did
have it, but always realizing that it may not be there when you most need
it so you need other alternative paths.
We
have lots of spectrum to make this happen. Way more than anyone else. We
are not making use of modest distance HF digital, especially during the
daytime on 160 and 80 meters. I have asked the Winlink folks about this
and they are not very interested.
From
what I have seen over the years, I think the real issue is that there is
very little interest by enough hams to do digital work of this type.
73,
Rick, KV9U
Hi Joel, yes I have been reading it and it does
concern me quite a bit. But, they pass the majority of their traffic
over the Internet and use the radio if only no connection is possible by way
of the Internet. For an example. They use HF for boats and
missionary's who want to send or receive e-mail but if you use Airmail and
send a message to another place that has Internet service then it will be
sent that way rather than over HF. The part that I am concerned with
is if they can use any section of the band rather than held to a limited
piece of it they will spread out over it. I also see it having a major
possible flaw in the whole design. What happens if you had a 5 or 6
state major blackout? The Internet will be useless and their system
relies heavily on it plus the equipment is too damn
expensive.
This is where TAPR could become a shinning
light if they team up with the satellite boys.. I believe a geo
stationary satellite system with multiple channel capability that could
carry voice/data/and streaming video on each channel could be a better
answer. This could then become the main link to State level
EOC's. This system would be much more efficient than Winlink 2000
could ever be in an emergency situation. They already have done some
work that could be applied to this system. Instead of using their
design for spread spectrum they should be looking at possibly 802.11g to
make this work. Another advantage would be smaller antennas with
higher gains and making portable stations for field use a lot
easier.
Mike
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