Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: mriver8 on 14/10/2014 00:51:32
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That is also ultrasound proof cheaply? With acoustic ultrasound absorbing foam, and mylar blankets? How could a second floor room be grounded? I am unaware of exactly how the grounding works or when it is neccessary.
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http://acoustics.co.uk/products/acoustic-absorbers-syntactic-foams/anechoic-absorbers/aptflex-f48/
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http://acoustics.co.uk/products/acoustic-absorbers-syntactic-foams/anechoic-absorbers/aptflex-f48/
The function of that foam is to absorb reflections from an ultrasound source in the room , like acoustic foam (https://www.google.com/search?site=imghp&tbm=isch&source=hp&biw=1280&bih=671&q=acoustic+foam&oq=acoustic+foam) in a recording studio , (incorrectly referred to as soundproofing), which reduce reverberation (http://en.wikipedia.org/wiki/Reverberation).
If the alleged source of ultrasound is outside the room , then the brick-wall separating you from them would be far more effective at blocking ultrasound than rubber foam.
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That is also ultrasound proof cheaply? With acoustic ultrasound absorbing foam, and mylar blankets? How could a second floor room be grounded? I am unaware of exactly how the grounding works or when it is neccessary.
Why mylar? It's not conductive in general, is it? You'd have to coat it with a conductive material. You could simply use aluminum. Even aluminum foil would work. Also, a Faraday cage doesn't have to be sheets of conductive material. It could simply be an array of wires such as chicken coop fencing. That would work wonderfully.
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That is also ultrasound proof cheaply? With acoustic ultrasound absorbing foam, and mylar blankets? How could a second floor room be grounded? I am unaware of exactly how the grounding works or when it is neccessary.
Why mylar? It's not conductive in general, is it? You'd have to coat it with a conductive material. You could simply use aluminum. Even aluminum foil would work. Also, a Faraday cage doesn't have to be sheets of conductive material. It could simply be an array of wires such as chicken coop fencing. That would work wonderfully.
Does it have to be grounded?
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http://acoustics.co.uk/products/acoustic-absorbers-syntactic-foams/anechoic-absorbers/aptflex-f48/
The function of that foam is to absorb reflections from an ultrasound source in the room , like acoustic foam (https://www.google.com/search?site=imghp&tbm=isch&source=hp&biw=1280&bih=671&q=acoustic+foam&oq=acoustic+foam) in a recording studio , (incorrectly referred to as soundproofing), which reduce reverberation (http://en.wikipedia.org/wiki/Reverberation).
If the alleged source of ultrasound is outside the room , then the brick-wall separating you from them would be far more effective at blocking ultrasound than rubber foam.
There is no brick wall, and the closed cells in the foam are what gives it it's properties, and not the material's impedance.
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I'd use Styrofoam or Celcon sheeting - in fact the stuff that's used for insulation in cavity walls and floors. Some brands come with a conductive surface too, so you can shield out those nasty Martian mind probes and dangerous mobile phone signals. The problem is the neutrino imaging system used by the agency whose name I cannot mention - neutrinos penetrate everything, including the lead that you use to stop x-rays. And once you start buying stuff to shield the room, they will know where you are likely to be. So the neat trick is to be somewhere else.
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Why mylar? It's not conductive in general, is it? You'd have to coat it with a conductive material.
There is aluminized mylar film ... http://en.wikipedia.org/wiki/Metallised_film
However for alleged "targeted individuals" subject to "electronic harassment (https://www.youtube.com/results?search_query=electronic+harassment)" who hear voices in their head, no barrier can stop them as they are not exogenous ...
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You do not really need to ground a Faraday cage to make it effective - the metal surface will reflect electromagnetic radiation.
You need to be careful about holes in the Faraday cage - a significant amount of radiation can get in (or out) if a hole is more than about 10% of the radiation wavelength. This also sets a limit on the use of bars on a cage. But copper wire mesh leaves very small holes.
What is not so obvious is that it is the length of the hole that matters, not its area. So a 1 mm wide x 2m seam between two conductive sheets will radiate very well at wavelengths 4m and shorter; some radiation with wavelengths as long as 20m will escape. To prevent this, there is commercially available conductive tape (with conductive glue!) that can be used to join together conductive sheets.
Especially tricky is doors - every time you close the door, it must make good electrical contact all the way around. You can get strips of metal fingers that make electrical contact every time you close the door.
But the best news is that the human skull is very effective at keeping radiation out, and keeping in nerve impulses - to get through this very effective barrier requires a lot of equipment, in very close proximity. It's not subtle.
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I have a few MRI suites with no measurable EM, electrostatic or magnetostatic field inside, and adequate soft wall material to attenuate any ultrasound. Happy to rent them out at £700 per hour, fully airconditioned and we pride ourselves on the quality of the coffee and sandwiches.
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The purpose of grounding a Faraday cage is to improve safety in case of an electrical short circuit to AC mains voltage.
A copper fly-wire mesh across a window will allow some natural light into your electronic dungeon.