Hell, just set up a spark jammer, or some other _very_ electrically-noisy
device. Or build an active Farrady cage around the room, with a "noise"
signal piped into it. While these measures will not totally mask the
emissions of your equipment, they will provide sufficient interference to
make remote monitoring a chancy proposition, at best. There is, of course,
the consideration that these measures may (and almost cretainly will)
cause a certain amount of interference in your own systems. It's a matter
of balancing security versus convenience.

BTW, I'm an ex-Air Force Telecommunications Systems Control Supervisor and
Telecommunications/Cryptographic Equipment Technician.
