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Re: Speech sensors?




On Fri, 26 Dec 1997 09:31:58 -0600 brian whatcott <inet@intellisys.net>
writes:
Margaret,
I have seen internet discussion of the method.
There is some doubt in my mind as to whether success depends on
a perpendicular view of a single-glazed glass pane, or if
audio can also be extracted from oblique laser views of windows.

What is certainly well-established is an Eastern Bloc substitution
at the height of the cold-war for a US wall emblem mounted on the
wall of a secure room.
This provided a passive microwave cavity with a flexible diaphragm
and a little monopole antenna.
When illuminated by an external microwave beam, a return signal
was modulated by any sound available in the room.
This illustrates the general principle.

Brian

At 22:36 12/26/97 +1100, you wrote:
Does anyone out there more knowledgable than me (and that's not hard)

know if the following
technique is for real or is an urban myth: that industrial-espionage
type
sensors exit which can reconstruct an internal conversation from the
remotely-sensed vibrations of a room window?
If it is genuine, how is it done in practice?
Cheers and Christmas Greetings to all
Margaret Mazzolini



brian whatcott <inet@intellisys.net>
Altus OK

Brothers and Sisters, a friend who occupied a fairly high-level
administrative job at U. of Houston claimed that the speaker-phone
transducers in the office phones were active regardless of whether the
the phone was in use or not and that every word spoken in the office
wherein the speaker phone was placed was recorded digitally and scanned
for key words like "pot", "freedom", "explosion", "nose", "candy",
"snort", "gun", "politician", etc. True or false - I know not.

Happy new year / The Dilettante