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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"
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Snooping Through Walls with Microwaves

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  • by polysylabic psudonym ( 820466 ) on Wednesday October 26, 2005 @06:34AM (#13879259) Journal
    How many criminals protect against laser audio surveillance, where a laser beam is bounced off a window or other rigid surface, and the sound from the room vibrates the surface, wobbling the beam, the wobble being translated into audio by the snooper.

    The laser can be defeated by double glazing (I think), devices to vibrate windows and laser detectors (to tell you if you're being listened to).

    A microwave device can be defeated by the good old tinfoil hat - by which I mean wallpapering in foil or otherwise turning the room into a faraday cage.
  • by DrSkwid ( 118965 ) on Wednesday October 26, 2005 @06:38AM (#13879265) Homepage Journal
    Some associates were spied on by the telephone.

    Just because the receiver was on the cradle didn't mean that the microphone wasn't active.

    The cops played stuff back in interviews/court that was off topic but was the occupants bitching about each other to try and divide and conquer them.

    This was in Leeds, UK.

    I can't remember many more details or find a link. I didn't know them at the time and only heard about it later as a warning.

  • by cheekyboy ( 598084 ) on Wednesday October 26, 2005 @06:41AM (#13879275) Homepage Journal
    If the crims are making 100's of millions, spending 0.01% of counter measures is INSURANCE

    hence, the drug lords of south america spend tonnes of tonnes of cash on goodies.

    The best crims are never found out hence, their success and covertness.

    a) buy gold
    b) hide in 50% legit 5% return businesses
    c) learn sign language
    d) study tonnes of tonnes of history of cold ware espianage
    e) never ever talk , paint a false picture to everyone including your wife/kids
    f) cover tracks and never park anywhere, unless you own the govt, or they owe you billions.

  • This isnt new (Score:3, Interesting)

    by ( 632313 ) * on Wednesday October 26, 2005 @06:46AM (#13879290)
    This tech has been around for a very long time, just not in the public sector.

    If you look at any high security building(NSA, etc) they will have multi layers on the outside and inside of the buildings.

    Not only is it physical security, but sound and wireless security.
  • by Ancient_Hacker ( 751168 ) on Wednesday October 26, 2005 @07:30AM (#13879410)
    Uh, not quite. For many reasons.
    • There were no "lasers" in 1960. At least not the very stable continuous-wave lasers that you need for this, and especially not in the USSR.
    • Think-- do lasers go through glass? Do lasers bounce off glass? Might other wavelengths of electromagnetic radiation act similarly?
    • Microwaves bounce off most anything, if you pick the right angle. Conveniently, most buildings have the windows recessed a bit, and any concave corner makes an EXCELLENT "corner reflector", which has the amazing property of bouncing any incident beam right back to the sender.
    Not only did they bounce microwaves off glass-- they had the hutzpah to give the US ambassador a honorary plaque, which he hung on his office wall. Unbeknownst to us, there was a little diaphragm inside the plaque, just the right wavelength to reflect K-band microwavesm, which vibrated very nicely to every word spoken in his office. Look it up.
  • by Richard_at_work ( 517087 ) <> on Wednesday October 26, 2005 @07:44AM (#13879448)
    MI5 developed this in the 1950s, and called it Special Facilities. All it required at the start was a modification to the phone - a single washer, and the phone could be used as a surveillence device. Later versions enabled activation using high frequency radio waves to activate the telephones microphone and required no modification to the phone itself.

    Survellience was also carried out against embassy cypher machines using unshielded telephone cables picking up eletromagnetic emissions from the cypher machines, in many cases enabling the reading of both the en clair message and the cypher material.

    None of this was admissable in a UK court. Phone tap evidence still isnt.
  • Re:Invest in AA (Score:3, Interesting)

    by MacGod ( 320762 ) on Wednesday October 26, 2005 @07:45AM (#13879451)
    On the plus side, it should automagically explode all the super-evil RFID tracking tags in your razors and potato chip bags and whatnot. It's nice to trade one form of surveillance for another, and this sure would be faster than putting each individual item in the microwave oven one at a time!
  • Re:Fluff piece (Score:5, Interesting)

    by Ancient_Hacker ( 751168 ) on Wednesday October 26, 2005 @07:50AM (#13879462)
    >"You cant modulate a 3mm wave to record 0.001 mm changes." You're partially correct. It would be difficult to detect the modulations, EXCEPT that if you're also the sender of the original signal, you can mix the incoming and outgoing signals and extract the phase difference. Subtraction is a VERY powerful signal-extraction method!

    There's an anecdote in the engineering field: where some poor sods at Racal-Dana had a phase detector at 50MHz that was so sensitive to vibration they had to stop their experiments whenever a plane took off from Orange County Airport (quite a few miles away). They eventually had to get special thick aluminum wall castings to enclose the phase detector to block the vibrations. And this was at just 50MHz. Phase detectors get more sensitive proportional to operating frequency, so a 5,000 MHz phase detector is *mighty* sensitive!

  • by data64 ( 300466 ) on Wednesday October 26, 2005 @08:05AM (#13879523)
    but wouldn't the simple precaution of turning up the radio/TV defeat this ? Humans can pickout certain noise and filter out everything else quite easily. How does tinfoil and other "vibrating surfaces" fare in this regards ?
  • by maxwell demon ( 590494 ) on Wednesday October 26, 2005 @08:05AM (#13879527) Journal
    Tinfoil is an excellent reflector. Therefore I'm sure tinfoil hats will actually help the snooper by creating much better signals.
  • by Technician ( 215283 ) on Wednesday October 26, 2005 @09:38AM (#13880053)
    Not only did they bounce microwaves off glass-- they had the hutzpah to give the US ambassador a honorary plaque, which he hung on his office wall. Unbeknownst to us, there was a little diaphragm inside the plaque, just the right wavelength to reflect K-band microwavesm, which vibrated very nicely to every word spoken in his office. Look it up.

    I looked it up. 330 MHZ is not K-Band microwaves. It's UHF. HF is from 3-30Mhz VHF is from 30-300...

    The bugged seal had a resonant quarterwave antenna tuned to 330 MHZ. This used 1946 technology, not K band microwaves. K band is near 20 GHZ. There wasn't much in the 1 GHZ and up band then. Vacuum tubes just didn't work that high.
  • Re:Invest in AA (Score:2, Interesting)

    by goosman ( 145634 ) * on Wednesday October 26, 2005 @10:09AM (#13880221)
    On the contrary lead is excellent at sound proofing. Studios are sometimes built with lead sheathing in the walls. 1/64th sheets are common. Google "lead soundproofing" and you'll get a bunch of info.
  • by goombah99 ( 560566 ) on Wednesday October 26, 2005 @10:57AM (#13880538)
    The first sign the Fed's are listening to you is when they give you a nice small bust of lenin for your mantle peice. That's exactly what the British did to the russian ambassador back in the post world-war two era. They gave him a a gift of a small statue and inside it they had mounted a corner cube which is a passive device that enhances the retro-reflection of microwaves beamed at it. (read about it is Peter Wright's (banned in UK) book Spycatcher--wright [] was the science officer for MI5 and inventor of the technique [])

    The second sign is when you feel toasty warm and the chair feels cold. In the 70's and 80's the carter and reagan administrations were perpetually complaining that the level of microwave energy measured inside the US embassy exceeded the OSHA limits for exposure. Eventually the US built a new embassy with enhanced shielding. UNfortunately the Soviet's put listening devices into the bricks. The embassy had to be knocked down and rebuilt. Of course, peter wright [] did exactly the same thing to the Soviet embassy in canada. Each night he snuck into the construction site and pulled wires up the inside of the walls to his microphones in specially made window sills. The soviet's learned about it from a mole in MI5 and had to build a second interior wall so that no rooms were near the windows.

    Doppler microwave spying is quite old. As is laser vibrometry on windows.
  • by zardo ( 829127 ) on Wednesday October 26, 2005 @12:00PM (#13881381)
    It used to be that the old dot matrix printers used to require heavy shielding, because the solenoids inside the printer head would generate a certain radio "sound" for each letter. A van could sit outside an embassy, focus in on the location of a printer, and reproduce a duplicate.

    The United States used this against the soviets for quite a while.

  • Used Here (Score:4, Interesting)

    by waldoj ( 8229 ) <waldo&jaquith,org> on Wednesday October 26, 2005 @02:25PM (#13882844) Homepage Journal
    Here in Charlottesville, home of the National Ground Intelligence Center (you might know them for a little kerfuffle involving their providing bad intelligence about nuclear weapons to some president...something about a war?), they've long had a thick wire mesh covering all of their windows. A former employee told me, when I was a kid, that it was designed to reflect microwaves for this very reason.

    -Waldo Jaquith
  • by qwertykid ( 59308 ) on Wednesday October 26, 2005 @05:16PM (#13884239)
    I'm actually making devices to do this as part of an undergraduate research project. The devices I'm making are passive with frequency response up to the 100 GHz range. The best part these is that they don't require any DC bias and as such aren't subject to 1/f noise like schottky diodes. Right now we're looking at applications for security (really advanced metal/explosives detector) and aviation (water vapor is transparent in that frequency range).
  • by Ungrounded Lightning ( 62228 ) on Wednesday October 26, 2005 @05:52PM (#13884531) Journal
    This stuff has been happening since the fifties. Nothing new here.

    The russians did that to the US, too. With a nice giant carving of the Great Seal - with a device behind a small hole beneath the beak.

    Consisted of a cavity resonator about the size of a stack of 10 or so dimes, with a tuning post up the middle, a diaphragm for one end (to detune it according to air pressure) and a wire antenna maybe a foot long coupled into the cavity. Excite it with a microwave signal near but not dead-on the resonance and the reflection is amplitude modulated by the sound from the room.

    Better yet: Put a diode in a movable surface. Excite it and it returns harmonics (easy to sort out from other reflections because they're on a different frequency), phase-modulated by doppler shift from the object's motion (like its variant FM, PM is very noise-resistant).

    Russian laborers constructed an embassy where the walls were FULL of thousands of diodes - embedded in the construction material. US had to abandon the building and build one of their own. News items suggested the diodes were to make it hard to sniff for bugs. But IMHO they were the bugs themselves, using the harmonic-generation/doppler/PM trick.

    Like the posting in the root article, this makes every surface a bug. You have to get diodes into them, but the return is cleaner and stronger than echoes from a passive reflector.

To write good code is a worthy challenge, and a source of civilized delight. -- stolen and paraphrased from William Safire