Jamming nearby cell phones

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doug-doug the mighty's picture
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Jamming nearby cell phones

As I will be teaching Physics in a local high school this fall, I was interested in learning more about jamming cell phones. I am not aware of my school having any technology to do so, nor is there any policy against doing so.

I am completely ignorant on what is involved in setting up a dampening field to do so, but I essentially want to disable student texting in my classroom during the classtime.

Discussions as to the legality or whatever are out of scope here - I just want to know how to do it and what is involved. Only then will I discuss tha matter with my principal and appropriate legal entities.


eeun's picture
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Joined: Dec 19 2003 - 17:34
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Came across [url=http://64.23

Came across This site, chock full of schematics, theoretical information, and the kitchen sink.
Note it's cached from Google, so some links aren't working.

Commercial jammers are available for purchase, so maybe you can propose the school buy one or more. I like the idea.

The closest we got to texting when I was in school was typing 5318008 into our calculators and showing it to the next desk over.

Jon's picture
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Joined: Dec 20 2003 - 10:38
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The #1 problem would be emerg

The #1 problem would be emergency contact. Your policies may prevent the kids from using a cell phone in class, but I think you'd have a hard time justifying jamming. It would also block students nearby who are legitimately using the phone, say, in the hall way, or of another teacher or administrator. It's not that I have any love of phones in the class room, but jamming seems a bit over reaching.

I'd suggest finding out the school policy as clearly as you can, then spell it out to the students. Zero tolerance may work well in the first few days of class, and be completely within school rules and laws. Jamming would come under the jurisdiction of the FCC, I'd guess, as it'd be blocking/causing interference of regulated channels.

pmjett's picture
Last seen: 2 years 10 months ago
Joined: Sep 4 2005 - 22:47
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A laudable goal

DDTM- I think it's a great idea. I also think it will cause you no end of headaches. The FCC is mighty particular about things, and jamming anything is, as one the DIY jammer links eeun posted says, completely illegal. In your situation, I understand completely. Nothing pleases me more than aggravating people who think they are getting something over on folks trying to do right.

Sticking to the question in the OP, I hadn't actually gone looking for RF jamming projects, but I just spent 30 mins looking over one in eeun's links, and it looks absolutely legit (technically). One had an effective radius of influence of 20 feet. That'd cover any of the classrooms I've been in, excluding lecture halls. With that localized of an area, seems like you wouldn't bother the folks in the hall, out side, etc. That would require some tweaking of the jammer to make sure.

Now, being married to someone in the education profession, and hearing first hand about how parents and students make being an administrator or teacher tough- I'd have to say that you might have pulled this off in black ops style. But, if anyone got wind of it, it'd be a PR nightmare. The whole scenario of trying to beat students at there own game by jamming their phones is just perfect for a local TV news story. Then the FCC and ACLU (strange bedfellows, no?) could find you, and put you under the jail as they say.

Maybe something like Jon suggests, where you have a zero tolerance policy. Seems like you'd need a little help from the gods of tech though. I haven't researched this, but it seems like you could build/borrow a field strength meter-like device that is looking for radiated RF in the cell bands. Then you could see if anyone was covertly using their phones, and confiscate them for the period. Just a thought.

I like simplicity of the first idea better though ;). Maybe if I'm ever a teacher, I'll just build the jammer and tell no one. Then everyone will just wonder why there is a hole in the coverage in my room only. Heh.


mmphosis's picture
Last seen: 1 day 15 hours ago
Joined: Aug 18 2005 - 16:26
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physics, eh?

Hmmm, perhaps you could have an "ongoing experiment" setup in the classroom to teach students about the physics of electromagnetism, specifically in the radio spectrum of cell phones.

iantm's picture
Last seen: 6 months 1 week ago
Joined: Apr 2 2005 - 14:01
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At my work (biomedical resear

At my work (biomedical research facility) there are machines that render my cellphone unusable (of course this may just be impeding the GSM network) when I am on the ground floor. (on the other floors - my phone works fine) The easiest way to get around the issue is by inadvertantly jamming with a piece of equipment.

I'm not sure which machines are rendering the GSM spectrum jammed though, (they're also $100k+ no doubt) and don't forget that once you impede GSM - CDMA may still work. As for AMPS and D-AMPS - not many providers still use those networks.

madmax_2069's picture
Last seen: 10 years 10 months ago
Joined: Sep 24 2005 - 07:28
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i think devices like these sh

i think devices like these should be put into place in like a movie theater, library, schools, and a few other establishment that will interfere with someone else,

i always hated being somewhere and having to hear someone's foul mouth when trying to enjoy a meal. or watching a movie and someone getting into a argument over a cell phone. or being in class with students are not paying any attention in class cause they are to busy sending text messages to someone.

there should be a appropriate place that these can be used and a place these are not allowed period or to be turned off.

if people dont have the common respect for other in these places then something should force them to abide by the rules. i want to buy one of these devices to i can block cell phone reception around me when i am in a place that one should not be used in.

i have respect for others, but only to the point of if they disrespect me i wont respect them. and disturbing someone when they are trying to enjoy themselves in places like these is a bit disrespectful to others around them.

the bad thing is in the USA they are illegal to own or operate you can get a fine up to $11K USD and prison time. so the only way to get one is to build it yourself.

here is one that will block most cell phone transmissions up to 30 feet.

cell phone jammer SH066P

Last seen: 6 years 3 months ago
Joined: Feb 20 2005 - 18:27
Posts: 18
Wave Bubble

Limor Fried has done a fantastic job with the Wave Bubble. It is an open source cell phone jammer project. She provides all of the board files and schematics, etc... http://www.ladyada.net/make/wavebubble/ She also provides much of the legal issues surrounding cell phone jamming.

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