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Jeff Liebermann Jeff Liebermann is offline
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Default U.S. Embassy Spying - MSNBC Nov 15, 2017 (R Maddow)

On Sat, 18 Nov 2017 06:21:17 -0800 (PST),
wrote:

Yeah, that was really clever. However, I'm told that RF reflections
off of anything moving and metallic in the room made listening
difficult. At 330MHz, the transmit antenna beamwidth would have
covered the entire room and possibly much of the building. Later
models worked at microwave frequencies, which offered a narrower
beamwidth.


That is a good question: can ground-penetrating-emitted waves be
bent or corrupted easier than waves within a laser beam?


How easier RF is refracted (bent) or reflected varies with frequency,
material, density, magnetic field, etc. In other words, just about
everything you can put between the transmitter and receiver. For GPR,
the frequency is important as different frequencies penetrate
different materials in varying degrees. This chart sorta helps:
http://www.geophysical.com/antennas.htm
If you wanted to go through concrete, I would guess(tm) that 400 Mhz
would be about right. I don't have any experience with GPR, so I
don't know if this is correct.

However, we're not going through anything. The laser is being
reflected off of the surface, probably through a Low-E reduced heat
loss coating, and back to a receiver. The ideal surface would be a
mirror. The worst surface would be an RF transparent glass or plastic
window.

The exact opposite is true for the microphone RF cavity and antenna
contrivance. The RF has to penetrate the building or window, reflect
off the side of the cavity, go back through the building or window,
and somehow end up at the receiver. In this case, the ideal building
material would be totally transparent to RF. That's not going to
happen, so the best they could do was use lower frequencies, such as
300 Mhz, which sorta goes through building materials. However, the
frequency was probably selected because the cavity inside the seal had
to be big to pickup voice, and the optimum physical size that would
fit worked out to about 300 MHz.

Anywho, with a hard-wire connection (on the other hand) like with
high-speed internet, isn't interference more easily detected (and
less possible to apply)?


Why would I want to detect interference?

Here, electrodes would have to be applied to the window or some
other part of both the transmitting and receiving locations.


I suspect the embassy staff might have noticed the electrodes and
wires. Stealth means a listening device cannot be easily detected.

Electrodes (I guess) like the ones doctors use to attach to the
skull to determine brain signals, like if they wanted to merely
create the sensation of smoking, drinking, doing drugs, etc..)
without it actually being done.


You just walked off the deep end. I have no idea what you're
suggesting or asking. Please bug someone else.

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Jeff Liebermann

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