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How do you get your kid to put down the tablet? Easy. Nuke your whole town's internet connection. But it worked!
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How realistic is it to build a Faraday cage for a house or room, to keep out wireless signals?
I guess that adding it to an existing building is not a viable option, but what if you include it from the early planning stages for the building?
I know Faraday cages only from physics lessons as a student, and got the impression that to keep electromagnetic radiation out is a piece of cake. It seems to be far more difficult in practice!
The elevator in the office building at work has steel plates in all walls, ceiling and floor. The door is of steel. The signal meter on my phone is not at all affected; the phone worked flawlessly from within the elevator, even when down in the basement.
If it really was simple, you'd think that shading movie theaters and ordinary theaters, schools etc. would be standard practice - but my experience is that phones work fine in all such areas. So it seems like either shading can't be done very efficiently, or (maybe equally likely?): No one dare to deprive anyone of their god given right to use their phones absolutely everywhere, without any restriction whatsoever. (I guess that if the father had succeeded in permanently shade the little girl's room completely, all the time, it could have a negative effect on the father-daughter relationship.)
Can anyone tell? I am planning extensions to my house that includes a home movie room. I'd like to make sure that none of my guests will be able to disturb the movie watching e.g. by looking up details from Wikipedia or IMDb about the movie or actors or music while the movie is running  Is there any chance of succeeding in this? I am fond of cabled computer connections, so even though I will have a computer in the movie room, shading WiFi as well, it is great! (And it will keep my guests from asking for access rights to my WiFi network to look up info in Wikipedia / IMDb because the mobile signals have disappeared ...)
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There are four general requirements for a Faraday cage:
- The cage must be complete - no holes in the ceiling, floor, doors, or windows.
- The cage must be made of electrically-conductive material
- The distance between the cage's "bars" must be smaller than (some fraction of) the shortest wavelength that you wish to block
- The faraday cage should be grounded
If you wish to stop everything up to Wi-Fi 6E (6GHz band), you will need a separation between "bars" of no more than 3x108/6x109 = 5x10-2 meters.
A few layers of metal mosquito netting covering the floor, walls, ceiling, doors, and windows should create a decent Faraday cage for Wi-Fi and cell-phone signals.
Freedom is the freedom to say that two plus two make four. If that is granted, all else follows.
-- 6079 Smith W.
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OR you could just take the device away from the child.
I’ve given up trying to be calm. However, I am open to feeling slightly less agitated.
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I was referring to trønderen's idea of building a Farady cage around his TV room. I agree that for children the best solution is to take away their phones when they aren't supposed to be using them.*
(*) Assuming that the kids aren't bigger and stronger than you are...
Freedom is the freedom to say that two plus two make four. If that is granted, all else follows.
-- 6079 Smith W.
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The elevator "cage", steel plates all over, definitely satisfies the first three criteria. It may not have been perfectly grounded, but I would expect it to hang in a steel chain with metallic contact to the walls, and I would expect the chain to have metallic contact to parts of the motor that is grounded. My expectations may be wrong.
The criteria are fine and clearly stated. Yet the realization seems to be more difficult than one might expect from the clearness of the criteria.
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I think you'll find that there is more plastic in those elevator cages than you think. For example, anodized plastic can look very much like stainless steel, but is much cheaper.
Again, just my theory. 
Freedom is the freedom to say that two plus two make four. If that is granted, all else follows.
-- 6079 Smith W.
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Plastic doesn't go clunck! in the same was as steel. Plastic doesn't fee cold the same way that steel does. I know the feeling of steel as opposed to anodized plastic!
OK, I'll accept your belief that if your guidelines are followed, a Faraday cage works as my schoolbooks said they will. You think they will. I'll let you believe so.
So I will have to ask someone else why our elevator cage - and numerous other attempts of shielding a room / cage from electromagnetic radiation - fail in creating an efficient Faraday cage. Your principles are obviously fine - as if quoted from textbooks I read long ago. But they fail do explain why it doesn't work in practice, in lots of specific cases.
If you think it really is as simple as you seem to suggest, then you might make a fortune on offering your services to this French father, to theaters, movie theaters and concert halls.
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trønderen wrote: So I will have to ask someone else why our elevator cage - and numerous other attempts of shielding a room / cage from electromagnetic radiation - fail in creating an efficient Faraday cage. Your principles are obviously fine - as if quoted from textbooks I read long ago. But they fail do explain why it doesn't work in practice, in lots of specific cases.
I give up. Perhaps you can write to the manufacturers of the elevator, and ask them about the design of their elevator cages. All I know is that the physics are correct, and if the Faraday cage is properly designed - it will work.
Freedom is the freedom to say that two plus two make four. If that is granted, all else follows.
-- 6079 Smith W.
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Thing is, you simply repeat what the textbook says, with no indication of where, why, how the straightforward approach fails (beyond repeating the textbook).
If I try building a Faraday cage, and it doesn't work well, I guess you would quote the textbook again. An expert would go searching for well known pitfalls, and probably find some. I'd love to know of those pitfalls in advance.
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That is awesome, give that man a prize!
"the debugger doesn't tell me anything because this code compiles just fine" - random QA comment
"Facebook is where you tell lies to your friends. Twitter is where you tell the truth to strangers." - chriselst
"I don't drink any more... then again, I don't drink any less." - Mike Mullikins uncle
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I've been considering a similar civil disobedience action, more at the "prank" level:
I live at the outer coverage edge of the Frankfurt, Germany, radio clock DCF77 signal. If weather/atmospheric conditions are unfavorable, my 1st floor DCF77 clock may not be able to pick up the signal (once it was a day late before picking up the Daylight Savings Time change), while the 2nd floor clock usually synchronizes without problems. Yet, it shouldn't take much power to drown out the Frankfurt signal.
'77' in 'DCF77' refers to the frequency: 77.5 kHz. For a radio signal, that is very low. It is actually so low that you can generate it with any sound card handling 192 kHz sampling rate, and a lot of them do. A lot of modern stereo amps accept a 192 kHz PCM signal on the digital input, and can generate an analog signal up to 100 kHz on the speaker outputs. The encoding is rather primitive (Wikipedia: DCF77[^]) - I frequently jokingly refer to it as "Morse Mark II".
So if I make a small program for my PC, generating signals for all the DCF77 alarm clocks in the neighborhood that "It is six o'clock, time to get up!" a couple hours early ... My 50 W/channel amp, with an antenna connected to the speaker outlets would easily drown the Frankfurt DCF77 signal.
There is supposed to be a clock signal at 77.5 kHz. I think it would take the authorities a long time to discover that the signal is stronger than it "should be", and carrying an incorrect time value. Probably, the DCF77 alarm clock owners would blame their clocks, not the radio signal. I haven't dared to realize it, an I probably never will. Nevertheless, playing with the idea is sort of fun
(In other parts of the world, there are similar but not identical clock radio services, some at even lower frequencies. The data format may be different. If you pick up this idea to realize it in your district, let us hear about it!)
This idea is somewhat inspired by a couple of "community FM radio stations" long time ago, when Norway had a state monopoly on radio broadcasts. Usually, there were no broadcasts between midnight and 6 a.m. So some pirate radios picked up the state channel, retransmitting it locally on a different frequency, usually with a much higher signal level. So lots of listeners tuned their receivers to that frequency, giving the pirate radio a lot of listeners for their midnight-to-6am transmissions. At daytime, the authorities never paid any attention to the state radio being available at a frequency where it wasn't supposed to be.
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I know nothing about your countries telecom enforcement agencies; but suspect they'd have as negative a reaction as the French did in the linked story or the US FCC has in various other cases of unauthorized broadcasting I've read about over the years.
Did you ever see history portrayed as an old man with a wise brow and pulseless heart, weighing all things in the balance of reason?
Is not rather the genius of history like an eternal, imploring maiden, full of fire, with a burning heart and flaming soul, humanly warm and humanly beautiful?
--Zachris Topelius
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Well ... They wouldn't exactly embrace me for my inventiveness! There are reasons why I never tried out this in practice.
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Survey of Rust programmers indicates they enjoy using the language but writing production-ready code is sometimes a struggle. Insert almost any other programming language in that headline and it works
OK, maybe not perl
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IDEs are about typing shortcuts, and there are a limited number of things that they can show us and people who aren’t going to see the docs outside of the IDE are unlikely to look through all the options that a cramped dropdown offers them. All right, but apart from providing a common toolset, syntax checking, debugging, auto-completion, and resource management, what have IDEs ever done for us?
This rant brought to you by the 80s
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Kent Sharkey wrote: All right, but apart from providing a common toolset, syntax checking, debugging, auto-completion, and resource management, what have IDEs ever done for us?
Brought peace.
GCS d--(d-) s-/++ a C++++ U+++ P- L+@ E-- W++ N+ o+ K- w+++ O? M-- V? PS+ PE- Y+ PGP t+ 5? X R+++ tv-- b+(+++) DI+++ D++ G e++ h--- r+++ y+++* Weapons extension: ma- k++ F+2 X
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"Hi, I am an idiot. Here's an article explaining why."
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Kent Sharkey wrote: All right, but apart from providing a common toolset, syntax checking, debugging, auto-completion, and resource management, what have IDEs ever done for us?
DRAM Industry Veterans: "They put my kids through college"
Did you ever see history portrayed as an old man with a wise brow and pulseless heart, weighing all things in the balance of reason?
Is not rather the genius of history like an eternal, imploring maiden, full of fire, with a burning heart and flaming soul, humanly warm and humanly beautiful?
--Zachris Topelius
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SQL doesn’t have an open source ecosystem of software libraries to tackle certain common use cases, and that work across popular SQL systems. SELECT new vulnerabilities FROM shared_library
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The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has published a list of free cybersecurity services and tools to help organizations increase their security capabilities and better defend against cyberattacks. In case you've heard recently that there are security problems around
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As the article only mentions it and it was not so trivial to find (at least not for me...)
The list can be found in Free Cybersecurity Services and Tools | CISA[^]
Actually interesting. I knew some tools, had heard of others and didn't know about many.
M.D.V. 
If something has a solution... Why do we have to worry about?. If it has no solution... For what reason do we have to worry about?
Help me to understand what I'm saying, and I'll explain it better to you
Rating helpful answers is nice, but saying thanks can be even nicer.
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A new study shows that organizations continued to take an inordinately long time to fix vulnerabilities and fixed fewer known issues in their environments last year than in 2020. On the bright side: job security!
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