General > General Technical Chat
Microwave weapons?
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David Hess:
Considering how easy it would have been for the US to have a technical person make measurements and track down any ultrasonic, RF, or microwave attack, I am dubious about the whole thing.  There should be a whole lot more evidence.

djacobow:

--- Quote from: coppercone2 on September 01, 2018, 07:30:52 pm ---I tried to frey myself but I could never figure it out (up to 20W at microwave with a horn)

--- End quote ---

One must be careful not to fry oneself while Freying oneself. :-)
djacobow:

--- Quote from: David Hess on September 01, 2018, 10:59:10 pm ---Considering how easy it would have been for the US to have a technical person make measurements and track down any ultrasonic, RF, or microwave attack, I am dubious about the whole thing.  There should be a whole lot more evidence.

--- End quote ---

Though I find it hard to believe that an embassy would not have some kind of "signals/Tempest" person on staff who would be All. Over. This., it is getting harder to be surprised by incompetence in the US gov't. Also, the attack could be intermittent, and directed away from where any fixed sensors or antennas are known to be. For example, if the guys in "the van" know when the RF guy gets in in the morning, or goes out to get coffee, etc, or if the embassy staff are being attacked while at home or out and about, it could be reasonably easy to avoid detection. The obvious countermeasure for this would be for the staffers to wear some kind of RF/ultrasonic-detecting device on their person, like a radiation film badge.

All that said, you're probably right.
chris_leyson:
Frey's 1st paper linked in the New York Times article, quotes the average power density for the "threshold of hearing" in eight subjects at two frequencies, 400uW/cm2 at 1.31GHz and 2mW/cm2 at 2.982GHz. Just to put things into perspective the IRPA limit for a microwave oven is 1mW/cm2 measured at 2.5cm I think, I can't remember the exact figures. Anyway 1mW/cm2 is 10W/m2 is not really that high in terms of power density, it won't cause tissue heating so it's not going to literally going to "fry your brain".
From a microwave point of view I think it's plausable.

@djacobow Thanks for the posting the NYT article. It makes a pleasent change to see a well researched article. I wasn't aware of the "Frey effect" on the auditory sytem but after reading Allen H Frey's paper I think it's more likely to be microwave evesdropping and the modulation scheme used produces audible intermod products. I'm surprised that Uncle Sam didn't make any effort in detecting the so called weapons.
coppercone2:
How do you do it? Like what modulation scheme? AM does not seem to work. I can try it right now with up to 10W from 0.5-18Ghz.

I did non-up-against-my-head experiments with microwave AM modulated by music from a MP3 player before just messing around, I never heard nothing. Tried like depache mode iirc. I honestly thought the frey effect was bullshit.

you wuold figure there would be frey headphones or something if it was real. They have bone conduction.
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