From: zlau@arrl.org (Zack Lau)
Newsgroups: rec.radio.amateur.packet
Subject: Re: Link between BBS via Amateur Radio
Date: 31 Aug 92 14:53:26 EDT
Organization: American Radio Relay League

In rec.radio.amateur.packet, ifjrs@acad3.alaska.edu (John Stannard) writes:
>In article <1992Aug26.220803.14284@aio.jsc.nasa.gov>, mancus@norm.jsc.nasa.gov (Keith Mancus) writes:
>> In article <17gsrjINN9pn@network.ucsd.edu>, brian@ucsd.edu (Brian Kantor) writes:
>>> beaurega@ireq.hydro.qc.ca (Denis Beauregard) writes:
>>> >I would like to know if it is already done or not, to use
>>> >Ham radio to link stations in a BBS network.
>> 
>>   Nonsense.  You are making assumptions about using 1200 baud VHF links.
>> We can achieve much higher bandwidths using good compression strategies
>> and by moving up into the microwave region.  My reading so far indicates
>> that 30-40 mile microwave links running 10 Mbit/sec should be possible
>> without outrageous investments.
>
>	Oh Right!  Let's see...between me and Fairbanks, that would mean
>only about 12 to 16 new sites and their associated equipment...what was
>	that about "hams don't have barrels of money to burn"?
>How much would you estimate the cost of ONE complete microwave station,
>incl. hardware, software and/or node/tcp-ip setup?  I've already spent
>thousands already just setting up HF/VHF equipment at this QTH for packet
>use as a bbs/forwarding station--not to mention what I'm putting into
>trying to get 9600 baud use (rigs/modems/tncs) going.

The RF hardware is actually quite cheap.   New 10 GHz gunn diode
transceivers run about $40 new.  Used units sell from $5 to $20.
True, the varactor tuned ones for really high bandwidth/high speed
systems will run you $70, the difference in cost is probably insignifcant
compared to going from digital hardware that handles 9600 pbs to one
that handles 25 megabits per second.  The N6GN hardware is limited by
the slow poke digital stuff.  But, I haven't been paying close attention
to what the digital folks are doing, so maybe I should be working on 
an optimized varactor setup that will handle 50 to 100 Mbps.  Its just
that I haven't seen a digital box to plug this into...

>
>Well, let's see...I forgot I've got two major mountain ranges to cross,
>one with a 20,400 mountain to cross...yes, we've used knife-edge on 2m
>to get across before...but microwave?  Better add 10 or so more sites,
>just to make sure...

Yes, knife edge stuff also works on microwaves.  However, rain is a real
problem in the 10 GHz cumulatives.  It was so bad in August that many
people stayed home.  I was able to work one station operating from home
using 150 ft of feedline (talk about lossy transmission lines!), but
most of the people who didn't go out were off the air.  Fortunately, three of
my friends braved the lousy weather and gave me easy 70 to 133 km contacts
though the rain.  I must admit that you would probably have to use 4 foot
dishes to get booming signals we got (probably at least 60 dB out of
the noise on one 100 km path)  (2 MHz vs 3 kHz).  But, with digital hardware,
do you really need such great signal to noise ratios?  

Without trees in the way (wonder if they are such a problem in Alaska),
signals are always better on 10 GHz than they are on 2 meters (probably
because we run just a few watts--and not high power amplifiers on 2M).
Of course, this assumes I have the 2 foot dish aimed correctly on one
end with the feedhorn approximately pointed on the other.

Zack Lau  KH6CP/1

Internet: zlau@arrl.org           Busy building 10 GHz SSB/CW gear     
			          Operating Interests: 10 GHz CW/SSB/FM
US Mail: c/o ARRL Lab				       80/40/20 CW
	225 Main Street		  Station capability: QRP, 1.8 MHz to 10 GHz
	Newington CT  06111	               modes: CW/SSB/FM/packet
						      amtor/baudot
Phone (if you really have to): 203-666-1541

>>   The existing packet network is very poor, but that's just because
>> it's dated.  Technology very quickly becomes obsolete these days, and
>> we hams don't have barrels of money to burn.
>>   Ultimately, the packet network needs to put its backbones up in the
>> microwave region and run Internet speeds.
>> 
>> -- 
>>  Keith Mancus    <mancus@sweetpea.jsc.nasa.gov>                         |
>>                  N5WVR                                                  |
>>   "If I owned Texas and I owned Hell, I'd rent out Texas and live       |
>>   in Hell." -General Sheridan                                           |
>-- 
>--
>
>John Stannard
>ifjrs@acad3.alaska.edu		BITNET:  IFJRS@ALASKA
>KL7JL@KL7JL.AK.USA.NA		kl7jl.ampr.org  [44.22.0.1]
>
>"God is the Answer!"   "Oh?? ... er, ... What was the Question?"
>
>--
>
Newsgroups: rec.radio.amateur.packet