[GreenKeys] UPPER and LOWER case

[Jeffrey D Angus]

On 9/5/2015 1:19 AM, drlegendre . wrote:
> WTH is "tempest" magnetic shielding? Being that you can't actually
> /shield/ magnetic fields, the concept is even more dubious. 
Tempest was the anal-retentive paranoid design engineering about keeping
others from "listening in" by listening to the magnetic or electronic pulses
from machinery. When you're dealing with the spook agencies, you have a
lot of money to play with, and the paranoia to justify it with.

And yes, actually you can shield magnetic fields using mu-metal.
<https://en.wikipedia.org/wiki/Mu-metal>
Most oscilloscopes have mu-metal shielding around the CRT to prevent
stray magnetic fields (like the power transformer) from distorting the 
trace.
And commercially...
<http://www.magnetic-shield.com/custom-mumetal-zero-gauss-chambers.html?gclid=CjwKEAjwgqWvBRC2kajZjqeOn0oSJADqBi-ldi-xsnLy-MwT7fjrTXMQeb06dl6zXgGmQPpyJIq8LBoCcG_w_wcB>

-- 
Jeff-1.0
wa6fwi
http://www.foxsmercantile.com