Suppose someone visited your office or home and tried to make a voice recording using a hidden recorder.
If they used a older-style dictation machine based on tape then you could detect the electromagnetic transmissions from the dictation machine when it was recording.
But how would you detect if someone was secretly recording with an MP3 player that recorded to flash memory?
Is there some transmission which could be detected? Perhaps some low power ultra high frequency from chip refresh cycles?
Ok, why do you care? Don't have sensitive conversations with anyone you can't trust, if you're going to be saying anything that shouldn't be recorded.
Doubtful, and not worth the bother when you could just scan them or search them physically.
Scan them or search them. What makes you think you should detect it? Don't they have a right to a recording of any conversation they're participating in?
Do you mean "wild hypothetical way that some future technology or extremely expensive equipment and controlled environment could detect", or do you mean, practically speaking?
... and you're discriminate this from everything else, all other HF noise, how? Get a baseline maybe, but noise is random unless a controlled environment.
You just need to have everyone strip down nude and then do body cavity searches, X-Rays, exploratory surgery, then never let them leave so it doesn't really matter if anything was recorded so long as the environment has sufficient RF shielding.
Joey wrote in news:Xns9857E3C284F9E74C1H4@127.0.0.1:
There probably is a little electro magnetic energy leaving the device, but what frequency would you try to find it on? Other electronic things such as computers, printers, etc in the office most likely emit far more RF noise than the MP3 device. It would be hard to find it. Eventually, the power would run down and the thing would stop recording. Someone would have to come by again and pick up the recorder. So your best bet is to be on the lookout for any suspicious recorder placement and pick up activity.
Or just buy as stereo for your office and play it real loud all the time.
Not really. You could maybe detect that it was turned on with an RF scanner. But if it is low power enough (most MP3 players are, since they are optimised for that) and well shielded, you would likely get nothing in today's RF polluted environment. In addition the attacker may just add some more shielding to be sure. I think you can basically forget about this, unless you can take the devices away from people.
Or a noisy computer placed close to where the suspected mp3 recorder would be. I have an ancient 286 whose 80MB hard drive sounds like it's about to take off and its fan is second only to vacuum cleaner on the noise level.
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What is done is to generate a pattern of sound, only part of which is audible, and then detect the low level IF and RF that any sound equipment emits. Then follow the signal detected to its source.
I say things in my conversation which i do not want to be broadcast in the public media.
You say, "search them physically"? I have to tell you that I don;'t work in the sort of environment where that kind of behaviour is considered acceptable!
They have the right to record themselves. I have the right not to have my words broadcast. Unfortunately obtaining redress can be expensive. So prevention is beter than cure.
The latter. I am talking practicalitites ere.
If necessary I could have my PC turned off and my phone put further away. But is there any leakage from solid MP3 recorders?
Then you have a problem for which there is no solution given the other detail below.
Then you have a problem.
Sure, but it just isnt practical.
The short story is that it isnt practical to do what you want to do.
Wouldnt be enough given the minimal leakage from a decently designed solid state MP3 recorder. In spades with one that has been designed to be undetectable.
Corse there is, but the level will be so low that you wont be able to find it with all the other stuff around that is radiating, even if you turn off everything in your house when a visitor shows up.
I'm sure there is a tiny bit, but it cannot be much from such a small device operating off very low voltage and the frequency is an unknown variable. it goes back to the idea about a controlled environment and very expensive equipment, that you'll probably have more background noise than what's coming from the recorder, to find it would entail what amounts to an active search.
Joey wrote in news:Xns9858A161645B271F3M4@127.0.0.1:
Would an all nude work environment be acceptable? It would make hiding such devices difficult so you wouldn't have to do anything untoward like searching people.
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