From: gary@ke4zv.uucp (Gary Coffman)
Newsgroups: rec.radio.amateur.packet,rec.radio.amateur.misc
Subject: Re: New packeteer frustration
Date: 17 Aug 92 12:50:34 GMT
Reply-To: gary@ke4zv.UUCP (Gary Coffman)
Organization: Gannett Technologies Group

In article <1992Aug15.165855.19445@cs.yale.edu> ewing-martin@CS.YALE.EDU (Martin Ewing) writes:
>After many years of sitting by the packet sidelines, I've set up a KAM
>and started decoding the burps.  As someone who uses the Internet
>daily, this has been an eye-opening experience for me.
>
>As someone recently noted ham packet, as currently practiced, is an
>adventure in low-performance communications (but cost-effective).  Yeah,
>with incredible patience and luck, I've managed to connect from Phila-
>delphia to Maine.  I've seen umpteen users competing for a single
>1200 baud port to a PC.  And I note that 10s of kHz of precious HF
>spectrum are taken up by very unfriendly robots chatting at **300 baud**.
>(They won't give you the time of day, and the throughput is abysmal.)
>Now I see there's a big brouhaha about the ARRL not defending these
>terribly inefficient mail operations to the maximum of its ability.
>
>The contrast with the Internet is incredible.  I can easily transfer
>a megabyte per minute across the country, and I am somewhat annoyed
>I can't do better.  I can send dozens of e-mail messages around the
>world and often get replies in minutes.  But you all know that.
>
>My question here is where does one go for information about digital
>ham networking plans - especially the (very logical) use of Internet
>links for long haul?  It's not in QST, I think. :-)
>
>Until I get better adjusted to VHF packet, you'll probably find me
>on 20 m AMTOR.  There's a friendly medium!  Not much good for downloading
>software, however.

Well 300 baud does seem slow to someone who uses the government's
multi-million dollar internet. However, 300 baud was hot stuff on
telephone lines 15 years ago. And unfortunately it's as fast as the
FCC will allow on HF right now. There's no *technical* stopper preventing
faster operation. It wouldn't use 200 Hz shift FSK however. If you want
to talk about slow, the 45.5 baud AMTOR is slow, and can't even handle
a full character set. It's persistent in the face of errors however, as
is packet.

Today, the only practical use of HF is for robotic forwarding of Email.
The performance is too low for any other use. The robot has greater
patience than humans and will continue to try until the error free
transmission is successful. This is "good enough" for the volume of
mail currently in the system. It's not "good enough" for the various
other proposed uses of packet.

There are techniques on the horizon that would dramatically improve
HF thruput. Clover and Piccolo use multiple carriers to transmit
bits in parallel. That speeds thruput while keeping individual symbol
times long enough to prevent fading and noise bursts from corrupting
them. Spread spectrum is another technique that promises high thruput
in the face of noise and interference. 

Direct FSK symbol encoding is second only to AFSK in being spectrally
inefficient and error prone on a HF channel. PSK methods available
today can push 9600 baud over good HF channels. But the rules prevent
it.

The VHF/UHF systems *can* be much faster. We use 56 kilobaud links
in our network. But as KA9Q and I have been discussing, multiple
hops run into problems of long delay times. The AX25 protocol is
not well suited to dealing with this without a supervisory transport
protocol and considerable RAM buffering in the various switches.

IMHO, outside the local area, packet is useful only as a forwarding
medium controlled by automatic equipment with the patience to deal
with the large delays present in the system. The kind of speed and
interactivity associated with the internet requires high speed landlines
and intelligent routing and buffering. All of that costs a lot of money,
and amateurs haven't shown an interest in setting up multi-million
dollar dedicated linking systems of comparable performance.

Combination systems that use the internet for long haul transport
exist, but they really contravene the spirit of amateur networking.
Riding as they do on leased lines owned by government and industry,
they don't form an *alternative* communications network capable of
helping out in an emergency when the landlines are down. If using
government leased lines is the only way we can do high performance
networking as radio amateurs, then I think we shouldn't bother
trying to do high performance networks. The government has already
shown that they can build and support landline based high performance
networks. If we go that route, then we're the same as a DXer trying
to claim credit for a contact he made via AT&T.

Gary KE4ZV
Newsgroups: rec.radio.amateur.packet