

Snooping Through Walls with Microwaves 217
denis-The-menace writes "According to an article from newscientist, scientists have devised a system to use microwave energy for surveillance. If people are speaking inside the room, any flimsy surface, such as clothing, will be vibrating. This modulates the radio beam reflected from the surface. Although the radio reflection that passes back through the wall is extremely faint, the kind of electronic extraction and signal cleaning tricks used by NASA to decode signals in space can be used to extract speech. Although, I doubt it would work in this room"
Re:Invest in AA (Score:4, Informative)
Not new tech (Score:4, Informative)
Fluff piece (Score:5, Informative)
Even at 100GHz, the wavelength of microwaves is 3 mm. But sound waves inside a room would cause a surface to vibrate perhaps 0.001 mm. You cant modulate a 3mm wave to record 0.001 mm changes.
Very dangerous!!! (Score:4, Informative)
Re:In analogue phone days (Score:3, Informative)
Foil Room fallacy (Score:3, Informative)
To truly block signals, you'd need to build a actual Faraday "cage" built with the smallest possible 'holes' so the waves created inside (be it voice, the sound of you typing or even waves emitted by the blinking LED from your Ethernet card) will be cancelled out. This is the same technology that the intelligence agencies employ against counter intelligence. That with foil (which is properly grounded) will work.
Solid surfaces such as foil can actually act as large AMPLIFIERS if implemented incorrectly since the waves will
Note that your microwave is surrounded by a Faraday cage to protect you from the rays; not foil.
A quick Google to back up my post yielded this page [montalk.net] discussing similar topics.
Not quite microwave (Score:4, Informative)
Re:Invest in AA (Score:5, Informative)
Electronic signal cleaning technhiques (Score:3, Informative)
That being said it is easily defeated. For example - short wavelengths below 1cm start resonating with water vapor. That's why doppler radar has been such a boon to meteorology.
But there are ways to stop it. Metal impregnated and grounded cement walls that are, oh, 6 to 8 feet below grade level would be reasonably safe. Of course don't put any windows, just ventilation.
And if you're really that much of a target they'd bug the place before they resorted to using microwave to listen in. BTW, for a good fantasy view of using microwave to peek in I highly recommend watching "The Siege" with Denzel Washinton and Tony Shaloub.
OT: Einstein quotes... (Score:2, Informative)
Here [quotationspage.com] is one such site.
Re:Invest in AA (Score:3, Informative)
I say this as an Australian.
old hat (Score:2, Informative)
Perverting Technology (Score:2, Informative)
Microwave Impulse Radar / Ultra Wideband Radar (Score:3, Informative)
Here's a typical article about MIR [llnl.gov]. Last I read, there were legal battles about shoddy treatment of potential vendors by the LLNL. Slashdot readers would probably do well to track this technology!
A taste of this from http://www.eurekalert.org/features/doe/2004-09/dl
Old news (Score:4, Informative)
The only update in the article is now they use microwaves and common materials already in a room.
Details here;
http://www.spybusters.com/Great_Seal_Bug.html [spybusters.com]
This bug is was delivered in 1946 and discovered in 1952.
Tin Foil Hat Designs (Score:3, Informative)
Re:Fluff piece (Score:1, Informative)
That anecdote is most certainly false. First, the phase detector merely responds to the difference in phase between two signals. Any vibrations will have negligible effect on the phase difference.
Second, encasing the circuit in a heavy aluminum block will not have any effect on vibrations. They will still pass through the aluminum. In order to provide isolation, the circuit has to be mounted on vibration isolators, such as used for old-style turntables, or simple rubber tires.
Third, the vibration caused by an airplane taking off miles away is much less than ordinary street traffic, or even by people walking around in the building. Again, the vibration won't cause any change in the phase of the incoming signals, and placing the circuit in a aluminum block will have no effect on the output.
Fourth, the sensitivity of the phase detector is limited by ordinary thermal noise generated in the electronics. This means the circuit most certainly cannot have the sensitivity needed to detect the low level vibrations from an airplane miles away.
Fifth, I have been developing sensitive phase detectors since 1969, and have received a number of patents in phase detectors and related support circuitry. I can assure you that ordinary system noise makes it impossible to detect vibrations from airplanes taking off miles away.
So the anecdote is false. Don't believe everything you hear.
Mike Monett
Re:OLD NEWS:This has been in active use since the (Score:3, Informative)
Oh, yes. They also did one on that pattern that was disguised as an olive-on-a-toothpick, to put in a martini glass and carry around or leave sitting about at embassy parties.
And the diode trick also turns anything with a diode in it into a bug.