The signal will most likely drop off in a non linear and non circular
pattern.
>From 100 feet your should not be picking up those computers, at least that
has been my experience. Of course there could be open cases, poor
shileding, unterminated wires, and other reasons for the radiation including
network cables running close to the antennas.
I'm only running 4 computers, but I can not hear them beyong 10 to 15 feet.
The cat5e wired network cable runs with the coax cables and within 10 feet
of the the tower base on it's way to the shop.
When I was in college (SVSU undergrad and CMU graduate) I could use my HTs
right in the computer rooms although there were places in there where they
would not work. After college I worked in with the computers at a large
chemical corporation. I had no problems even in the main computer room. In
my office I had my HT setting on top of my monitor. I did not hear
anything on the HF bands more than a couple of feet from the computers and
the whole place was a maze of network cables.
> Folks,
>
> I am helping a local university bring up an HF station equipped with
> Winlink Modems and softare to use as a medium for teaching computer
> networking and security. The station antenna is set up in the main
> student and classroom computing center, on the roof, within 100 ft of
> maybe
> 150-200 networked computers. Surprise Surprise, S-9 white noise hash on
> most bands.
To me that is a surprise as I'd not expect to hear them that far from the
computers.
> My question is, We need to have the Transmitter and winlink setup located
> at
> a classroom teaching position, along side the HF station, but it may be
> possible to move the antenna some distance away from the building. Is it
You need a portable HF rig to do some sniffing. You probably have a problem
with one or more pieces of equipment if you are hearing the computers from a
100 feet even if there are a 100 to 200 of them.
> likely that a movement of the antenna from directly over the computing
> rooms, to, say 150 ft horizontally away will reduce the current noise
> sufficiently to be usable? How rapidly does the signal intensity
> decrease,
> as I move the antenna away from the building?
All bets are off when you have network cables running hither and yon as well
as the possiblility of computers with the panels off, loose and unterminated
wires, poor or non existent grounds....You may even find the antenna grounds
are tied into the same lines as the computers which may be many feet from
ground.
*Normally* the signal falls off with the inverse square of the distance, but
in this kind of environment the best bet is to do some "sniffing" to find
the source of radiation.
Good Luck,
Roger Halstead (K8RI and ARRL 40 year Life Member)
N833R - World's oldest Debonair CD-2
www.rogerhalstead.com
>
> Thanks,
>
> Pat Barthelow aa6eg@hotmail.com
>
>
> _______________________________________________
>
> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
> Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with
> any questions and ask for Sherman, W2FLA.
>
> _______________________________________________
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>
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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