audio recorder jammer

[karmax]

hello ,
    I want to make audio recorder jammer so that i can jam all recorders (digital and analog both) specially mobile integrated microphone.Can some one help me regarding this jammer.please tell me the theory behind this jammer .

[corrado33]

Couldn't you just have something that broadcasts some kind of low frequency wave that messes with microphones?  Something that we can't hear, but microphones will be messed up by?  I'd experiment, and see what happens.

[Soeren]

Hi,

Small microphones won't be sensible at sub-audible frequencies. Most of them are limited to less than the audible range.

Only way to jam some of them (not all, as this cannot be done) is to pulse a signal with extremely fast rise times, as this will interfere with some recorders.
A well designed recorder will be immune though and I don't think there's a way to scramble pro recorders like my Zoom H4.

Best way to outlive that paranoia is a full body search (although it won't catch all either).

What is the purpose?

[Cristi_Neagu]

How about broadcasting white noise via radio? I mean... not modulated, just generated and sent via an antenna. A simple sine wave would do, i think, but it won't be as effective as white noise, or pink noise for that matter. The radio sound would get picked up by the internal wiring of the recorder. It's just like standing with a cell phone close to a TV or a stereo, and you hear those digital noises.

The only thing is that the lower the frequency, the bigger the antenna gets... It's been a while since i brushed up on my RF knowledge...

[Soeren]

Hi,

How about broadcasting white noise via radio? I mean... not modulated, just generated and sent via an antenna. A simple sine wave would do, i think, but it won't be as effective as white noise, or pink noise for that matter.

Whether white noise (or any other color noise, even if they're less efficient) or sine waves it is all modulation.
The unmodulated carrier is just the base frequency (in theory a pure sine, but total silence in a receiver).

It's just like standing with a cell phone close to a TV or a stereo, and you hear those digital noises.

Not at all. The reason the cell phone blasts through is that it sends in bursts which is as I described - extremely fast risetimes and hence an incredible amount of harmonics.

A sine would never be able to do this, as it is just one frequency (like the LASER is theoretically just one single frequency), while a (perfect) square is a composite of numerous sine waves of different frequency.

[Cristi_Neagu]

Well... How about standard 50Hz induced noise? Let me give you an example: when i play my guitar (electric), depending on my orientation relative to my computer, i hear a 50Hz noise in my speakers. There are no connections between my computer and my sound amplification. The strings on my guitar act just like an AM antenna.

Also, as far as i know, in AM broadcasting, you use a low frequency wave (a voice, let's say), which is modulated with a high frequency sine wave (in the MHz or kHz regions). I was talking about sending just an unmodulated carrier, but not in the MHz region, but somwhere around 1000Hz. There should be no modulation involved. Just like with the 50Hz mains noise, it would get induced in the wiring of a recorder, which would act like an antenna.

Anyways, there could be problems with this: the antenna might be too large, low frequency broadcasts require more power, and if the recorder has proper shielding or grounding, it won't work.

[karmax]

I am making it so that no one can record my private talks.Please share some circuits if someone now so that we can try to realize that circuits..

Hi,

Small microphones won't be sensible at sub-audible frequencies. Most of them are limited to less than the audible range.

Only way to jam some of them (not all, as this cannot be done) is to pulse a signal with extremely fast rise times, as this will interfere with some recorders.
A well designed recorder will be immune though and I don't think there's a way to scramble pro recorders like my Zoom H4.

Best way to outlive that paranoia is a full body search (although it won't catch all either).

What is the purpose?

[TrickyNekro]

DO you even know how many ways are to get your private talks...

A position pointing microphone with some good DSP filtering afterwards can even give you a studio recording quality...

And the matter fact is that... usually... for breaking into a system... people are the most sensitive factor... Not even need to
spy on someone...

Dude what do you have there, drug cartels? Business dirty works? Weapons? If you have some of those you wouldn't be
asking us for sure...

And nobody is really concert about your private life unless you are homosexual and your mother is worried or something... 
Any kind of sudden loud noise in a repetitive manner will do as said...
But it would be even better if you start some kinda of codex with your friends while you talk...

Anyone who wants to find something... really, after some time finds it.... ;-)

[corrado33]

What are you really trying to accomplish?  You said in another thread that this was for a university project, now it's so people can't "spy" on your private conversations?  If someone REALLY wants to know what you have to say, you have (almost) no way of stopping them (besides talking/writing in code all of the time, and even then, simple codes usually aren't that hard to break when you have supercomputers).  If you're worried about the government spying on you, then good luck.  They have better technology than you could ever dream of making. 

If this is a legitimate project, then we'd be happy to help or discuss the theory behind the idea, but when it comes to building it, unless we ACTUALLY know what you're doing, I doubt anyone will be willing to help you.  Besides, isn't jamming (whether radio/cell phone) illegal? (Maybe in the US only?)  I doubt it'd be legal to do it, because it could REALLY mess up communications for people you aren't trying to affect.

[Soeren]

Hi,

I am making it so that no one can record my private talks.

Oh, I was under the impression that you asked us to make it

As TrickyNero pointed out so gentle, it's really a bit self-centered to think that the rest of the world would be interested in recording what your lips pass.

Surround yourself whit huge amounts of white noise and talk close so somebodys ear... Or don't talk about what you won't risk others to hear/record.
Technology is not a replacement for common sense.

[karmax]

As i said earlier also that its for university project thats true as our university vice chancellor given this project to our team and why should i need audio recorder jammer ?There is no use for me ...I hope you will understand my concern and help me for the same.

Hi,

I am making it so that no one can record my private talks.

Oh, I was under the impression that you asked us to make it

As TrickyNero pointed out so gentle, it's really a bit self-centered to think that the rest of the world would be interested in recording what your lips pass.

Surround yourself whit huge amounts of white noise and talk close so somebodys ear... Or don't talk about what you won't risk others to hear/record.
Technology is not a replacement for common sense.

[Soeren]

Hi,

Well... How about standard 50Hz induced noise? Let me give you an example: when i play my guitar (electric), depending on my orientation relative to my computer, i hear a 50Hz noise in my speakers. There are no connections between my computer and my sound amplification. The strings on my guitar act just like an AM antenna.

I don't think it's the strings, but rather the open pickup coil(s) picking up H-fields ("magnetic fields" rather than E-fields). If you wanna know for sure, remove the strings and see if you are still able to get mains hum. The strings probably enlarges the pickup, not from antenna action, but since they're steel, they're sensitive to H-fields and they widen the area of pickup.
A steep notch filter in the input of your amp should help a lot.

Also, as far as i know, in AM broadcasting, you use a low frequency wave (a voice, let's say), which is modulated with a high frequency sine wave (in the MHz or kHz regions). I was talking about sending just an unmodulated carrier, but not in the MHz region, but somwhere around 1000Hz. There should be no modulation involved. Just like with the 50Hz mains noise, it would get induced in the wiring of a recorder, which would act like an antenna.

Some recorders (of the cheap variety) will be sensitive, as long as the transmitter uses an H-field, but one would need to make the transmitter very rigid, or it would transmit audible waves as well and that may not go well with the Cloak & Dagger perspective 

Anyways, there could be problems with this: the antenna might be too large, low frequency broadcasts require more power, and if the recorder has proper shielding or grounding, it won't work.

You wouldn't use an antenna in the regular sense, but a very high powered version of a inductive loop, like used for hearing aids. Transmitting white noise will work better, as it will render speech unintelligible.
The H-field approach has the added advantage of attacking subcircuits like the AGC and will go through most skimpy screens in cheap recorders.

It would probably influence humans in the field in a nasty way as well, but if you really care for your privacy, a brain tumor is a small sacrifice   

[Soeren]

Hi,

As i said earlier also that its for university project thats true as our university vice chancellor given this project to our team and why should i need audio recorder jammer ?There is no use for me ...I hope you will understand my concern and help me for the same.

I hope you'll understand our concerns.
If we provide you with the details, you don't really make it and I suppose that's the whole point of the drill.
Or do we get the graduation diplomas from your university? 

I wonder why this vice chancellor would want you to make potentially illegal stuff. Perhaps you should ask him/her that, as there are a world of possible circuits that cannot be misused, but will still be valid projects with potential to teach you something.

No reason for PMs requesting help either, you won't get better answers from that.

[TrickyNekro]

As TrickyNero pointed out so gentle, it's really a bit self-centered to think that the rest of the world would be interested in

Yeah true... Sorry... I just wanted to sound funny not insulting... my bad...

The problem is... well that's not a problem...
That you don't need technology to deform a codex...

The math behind deforming a codex and so on exist one or two centuries ago... I don't really remember...
There are some mathematical series that given a long long long polynomial,
they can replicate books, talks, pictures, songs and so on...
They may not make an exact replica, but surely they come very close....

Technology only gave us the processing power...


It's more logical to EMP the recording device than trying to jam it...
And EMP isn't that hard... to make after all... X-D

[Soeren]

Hi,

It's more logical to EMP the recording device than trying to jam it...
And EMP isn't that hard... to make after all... X-D

No, a small nuke will do that

Just be sure all your electronic devices (except thermionic valve devices) are off when pulsing, or you may need new ones.

[TrickyNekro]

I don't thing that you actually need a nuke...
Any plastic explosive with do...
You only need a big boom :-D

Unless planning on to paralyze half US.... hehehehehe


You don't wonder anymore why I'm just a fan of big kabooms??

"Don't play with matches.... hahhaha"

[Soeren]

Hi,

You don't wonder anymore why I'm just a fan of big kabooms??

"Don't play with matches.... hahhaha"

I'm just surprised that the caretakers allow matches in closed confines with padded walls   
And how to strike them with aq jacket that straight

Well, back on topic and seriousity:
I'm not sure plastic booms will knock out electronics with EMP, wasn't on the plan back when I was a (non-drafted) soldier.
But I really don't recommend experimenting with that, so let's leave it to a maybe/maybe not.