At 6:09 PM -0800 1/8/2001, David Honig wrote:
>At 07:51 PM 1/8/01 -0500, Arnold G. Reinhold wrote:
>...
> By shielding the fixtures, they effectively
>>place the lights outside of the enclosure.
>
>Yes. But 1. you'd still want a filter the power mains
>inside your physically secured zone 2. The site had a
>generator... and presumably a guarded perimeter (think
>1/R^2) so emissions were probably less important than
>listening sensitivity...
I suspect they would not rely on the guarded perimeter for TEMPEST,
at least not back then. The 1/R^2 attenuation applies to reception
as well. One would put distance between the antennae and the
buildings housing the computers and other sources of noise.
>
>I'll bet the wiring to
> >those fixtures is within carefully grounded conduit.
>
>Building codes often require this, anyway, though probably
>not grounded to the extent of someone concerned with emissions.
I doubt they require conduit in rural NC. And my guess is you'll see
welded straps bridging each joint.
>Again, it makes much more sense (cost, number of items to check
>periodically) to put isolation centrally.
The kind of filtering you need for TEMPEST is pretty fancy (and
expensive no doubt). I have heard numbers like 100+ db. The filters
have to be located at boundary of the shielded enclosure. I don't
believe you can do it centrally.
The more I think about it, the less convinced I am that this was a
intercept receiving site. If it were, why was it abandoned? Surely
NSA does not have less need for that sort of thing in the post-cold
war era? And why put one in North Carolina?
It may have been a site for operational control of NSA satellites.
The large antennae and secluded location would make jamming more
difficult. The dual systems and self-contained power would insure
high availability and the shielding and fibre optics might also be
directed to EMP protection. The 1995 abandonment might have been due
to a realization that NSA could safely share satellite control
facilities with other DOD satellite owners, once the
money-is-no-object era ended.
>
>>It would be fun to take a tour!
>
>It looks like those RF astronomers would be willing, if you
>shut your cell phone off while visiting :-), though likely
>miffed that you're more interested in the facility than in the
>astronomy...
>
>---------
>
>Another possibility is that they were so freaked by the static sensitivity
>of early MOS devices that they grounded the carpets...
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