FM frequency jammers

[TriggerHappy]

Do consumer level devices exist (hopefully for sale, at a reasonable price) which are capable of jamming a selected FM radio frequency within an area of say 10-15 meters in diameter?

Imagine an FM radio behind a locked door 5 meters away from you, feeding ceiling speakers that you could not turn off (either the speakers or the radio). Imagine that you were so sick of it you just had to find any possible way to shut it off (no, just turning it off is not an option, unfortunately).

Does a device exist that would allow me to do this?

I've only been able to find this online:

http://www.kenneke.com/plans.html#

But these are only plans to build one, and my knowledge of electronics is, well, nonexistant (and the source for these plans is not exactly trustworthy).

Believe me my search has been very extensive, i post this as my last resort :(

If anyone can give any advice/help at all it will be greatly appreciated.

[Selby]

As far as my knowledge goes, to jam a radio frequency, you have to broadcast at that frequency. The problem comes in that you need to have a license to broadcast in certain frequencies. Radio stations have bought blocks of a frequency that they use, and you would technically be intruding on their frequency (something the FCC doesn't approve of).

A strong electromagnetic pulse on the other hand would definitely do the trick... but I don't really advise that either.

Selby

[Rhydderch Hael]

Microwave an entire box of Ding Dongs (with the foil wrappers still on them), leaving the door open. Should do the trick, but I hope you were never planning on having children. ;)

Electronic warfare aside, just call the cops and make a noise complaint.

[wundergore]

A noise complaint to the local law enforcement is probably the safest, surest method.

W>

[Guest]

It isnt legal(for the use you intend), but it is pretty east to build a jammer. I didnt look at the plans you listed though.

[Jeunemaitre]

Imagine an FM radio behind a locked door 5 meters away from you, feeding ceiling speakers that you could not turn off (either the speakers or the radio).  Imagine that you were so sick of it you just had to find any possible way to shut it off (no, just turning it off is not an option, unfortunately).

You don't by any chance live in Syracuse, NY do you? I remember living on campus, and just off campus, not far from the transmitter for Jazz 88 (WAER) on top of one of the dorms. I think for a while the local CBS (either that or NBC, IIRC) affiliate had filed suit against them for impinging on their broadcast facility in the university hill area. It was miserable, you turn on the TV and you get not just the TV sound but the smooth sounds of Jazz 88. The signal carried enough power that if you left your stereo on the CD setting without turning it off, you could still get the radio station loud and clear through the speakers. On some days, you would get it in the background all the way around the FM dial... :angry:

This was the one time in my life when I believed that if you stood right, you could use your dental work to tune it in and turn your mouth into a speaker... :o

My god, what wouldn't I have given for a way to make the stupid thing stop...

[TriggerHappy]

Sorry, I should've provided more details.

This is a place of employment, where i spend 5 out of 8 hours completely alone, having to listen to this radio station (98.1). For fairly complicated reasons that are not under my employer's control, they can't turn that radio off at any point in the day (they simply don't have the ability, they just run the place). They themselves would love to shut the thing off while they're there.

We're at a point where we'd give anything to be able to jam this FM frequency (which never changes ... *shudder*). And we only need a jamming radius of about 10 meters to cover the place of work. If i understand how jammers work (which i honestly don't).

Personally, i've been combatting this infernal radio by getting closed style noise isolating headphones and listening to music while i work. The three pairs of headphones i've tried out all do the job admirably, but i can't remain in the headphones for 5 hours straight :(

My only consolation is that i won't be on this job starting this summer, when i'll be done with school and will (hopefully) find a *real* one in my field.

[TaiDaishar]

Are there no legal actions you can take?

I thought radio stations need to be very far away from every populated area...

[TriggerHappy]

No no, this is not a radio station, this is a store, and the music is for customers who come in during the day, except some idiot decided that they did not really need to turn off the radio during the night shift. No matter that there are people actually working at that time and no customers!

The radio is controlled from the "main office" and cannot be turned off at the site (simply cause we don't have access to the room :( ).

All attempts at negotiation to turn it off were unsuccessful, because some techs somewhere think it's too much of a bother to remember to turn the radio off at 11pm and back on at 7 am. Legal action would result in my employers' and then my own termination.

This is one of those really, really idiotic situations.

[Dozer]

Climb a ladder, find the speaker wire, and take it out - then put it back in in the morning. :D

[--Pete]

Hi,

It is easy enough to jam a frequency, simply broadcast a signal on that frequency. If your signal is stronger at the antenna than the signal you are trying to jam, your signal gets through and the other gets swamped.

Problem is, you will still get a signal through. So, unless you broadcast the music you want to hear, you'll probably end up just listening to noise, static as it were. Probably not what you had in mind. To build something that will broadcast the music you want will lead to two problems. First, it becomes a much more complex piece of gear. Second, to carry a detectable signal, you'll need to pump out enough power that you'll probably make some enemies at the FCC (or their equivalent).

--Pete

[kandrathe]

That was my thought, only I'd follow the speaker wires back to the area source and install a simple toggle switch in some easy access location like the stock room. If anyone finds it, make believe it was always there.

[NiteFox]

[TriggerHappy]

It is easy enough to jam a frequency, simply broadcast a signal on that frequency. If your signal is stronger at the antenna than the signal you are trying to jam, your signal gets through and the other gets swamped.

How much would such a system cost (and are they actually available to consumers)? I mean the kind that will broadcast on that frequency and override the existing signal with a stronger one. Yes, we're willing to listen to white noise instead of that station, we are that sick of it. We'd get sick of any station when it plays for 8 hours 5 days a week for me and 16 hours for my bosses.

How much more would a system that can broadcast our own sound cost? We could eliminate the white noise from jamming by broadcasting music of our own but doing so at no volume.

Even though i can split the cost with my bosses, i fear it might be out of our reach. We're desperate, but not enough to spend $1,000 on the problem. Well i am, but can't afford to spend that kind of money on what can realistically be tolerated (if it doesn't drive me insane) for the next 6 months.


One of the first things we tried was to unplug the speakers themselves, but they are soldered in. Can't install a switch to turn them off either, since a company inspector visits the site once a month checking everything from A to Z. Can't pretend a switch was already there cause the tech knows it wasn't. Even though there mostly likely would be no repercussions if the tech found the switch, it'll just be removed.

*sigh*

I fear there are simply no alternatives but to bear the situation :(

[--Pete]

Hi,

Since there probably isn't much of a market for jammers for commercial radio frequencies, I doubt if anyone makes a unit commercially. If you're not looking to modulate the signal in any way, the transmitter is very simple and shouldn't take more than a few bucks of components from your friendly rat shack.

Sorry.

--Pete

[--Pete]

Hi,

Reminds me of my indoctrination into the Boeing engineering philosophy.

Me: "If all you have is a hammer, everything looks like a nail."

Jud: "If your hammer's big enough, everything *is* a nail."

--Pete

[TaiDaishar]

Me: "If all you have is a hammer, everything looks like a nail."

Jud: "If your hammer's big enough, everything *is* a nail."

--Pete

Simply brilliant! :lol:

[TriggerHappy]

Looks like i will try that. Will get those plans i found online first, see if i can make one myself or with alittle help. If not, i'll try to get one made in custom electronics places.

Thanks for the ideas all.


P.S.

That "hammer" solution is so very tempting ...

[Taem]

Before CD players in cars became the norm, I had a portable CD player which plugged into the cigaratte lighter and had a small antenna which broadcasted on whatever signal I wanted, but only had a 5' radius if I remember correctly. If you can get one of these simple signal broadcasters, just set it next to your reciever/stereo unit and whola - problem solved without spending a lot of money on a jammer. :P

[Saxywoo]

Hey there....

Sounds to me like a simple pair of wire cutters and a good idea of where the wires go would definately solve the problem. As for a jamming device, I know a guy that secretly declared war on a radio station (for reasons I won't disclose, and he's essentially jammed one of the stations broadcast towers that feeds 1/4 of a moderately sized city. The best thing - he built it himself. I'll talk to him a little later and see how he did it.

-SaxyCorp
It's not guns that kill people, it's just that sound they make.