From: nobody@shell.portal.com
Date: Mon, 26 Sep 94 20:33:42 PDT
To: cypherpunks@toad.com
Subject: Spurious Emissions
Message-ID: <199409270333.UAA12451@jobe.shell.portal.com>
MIME-Version: 1.0
Content-Type: text/plain


Spurious Emissions Problem:

Get yourself a sheet of log/lin graph paper. Orient the paper so that the
log axis is horizontal, and the linear is vertical. 
On the very bottom major axis of the lin, mark it as -157.  The next major
axis up would be -147.  Next up from that is -137, and so on, to -117.
Label this axis as dbmV/m RMS.
On the very left of the log axis, mark it as 100.  Next major log line is
1K.  Next one is 10K, then 100K, 1M, 10M, 100M, 1G, 10G.  Label this as Hz.
Starting at the junction of 100/-148, draw a nice, straight line to 2K/-148.
Continue the line to 10K/-152, then 100M/-124, then 1G/-120, then to 10G/-120.
If a body was to test for emissions at a distance of 1 meter, and kept their
emission levels below that line, they might consider themselves Real Resistant.
Discussions with a Person Who Knows (but wishes to remain anonymous,
curiously) have indicated that a body might like to have a room like this:
steel outsides (like, say, one of those steel pre-fab sheds), and make sure
that steel was grounded *real good* (like at each vertical support, and for
each wall's outside material).  To make sure there weren't any gaps, a
person might want to use fastening screws every 2 or 3 inches, or better
still, weld all the junctions. Then they could put insulation (regular
thermal type) inside, and hold it in place with steel (or better still,
aluminum, since it literally blocks magnetic fields as opposed to absorbing
them like steel does) flyscreen, making sure to overlap the screen a good 6
inches at the junctions, covering all inside surfaces (including any
windows), and "sewing" the overlapped screen bits with metal wire
(preferably the same metal as the screen). Getting in and out screws up any
Effects and Properties, but those can be dealt with by having a good 6 inch
solid metal overlap on the door, so that it made good mechanical and
electrical contact with the wall when the door was closed - there are
companies that are more than happy to sell those little metal fingers that
you see on RF gear to help with this.  Power should be run through standard
solid metal conduit, underground, from the power source (electrically
isolated, like a transformer) and only appear aboveground inside the room.
It should also be *heavily* filtered. A room like this wouldn't be formally
certifiable in any official capacity, but would sure screw up anyone trying
to monitor emissions, forcing them to either get in real close (and risk
discovery), or give up as being too much trouble.
But of course, all this is Pure Supposition and Theory.
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