How detect if MP3 player is recording in your room? [OT]
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?
Re: How detect if MP3 player is recording in your room? [OT]
"Joey" <js@foldback.net> wrote in message
news:Xns9857E3C284F9E74C1H4@127.0.0.1...
> Suppose someone visited your office or home and tried to make a voice
> recording using a hidden recorder.
Tad paranoid here.
>
> 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.
Yep
>
> 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?
Close. There are devices that are around that do exactly what you want.
Security firms and such use them to verify a room is bug free, etc.
Re: How detect if MP3 player is recording in your room? [OT]
Joey <js@foldback.net> wrote
> 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.
In practice that was always a lot easier to say than to do.
> But how would you detect if someone was secretly recording
> with an MP3 player that recorded to flash memory?
In theory any electronic device will produce some
EM so at least in theory that can be detected.
In practice there is so much of that stuff in any
normal room anyway that its just not feasible.
> Is there some transmission which could be detected?
> Perhaps some low power ultra high frequency from chip refresh cycles?
Re: How detect if MP3 player is recording in your room? [OT]
On Mon, 09 Oct 2006 22:23:22 +0100, Joey <js@foldback.net>
wrote:
>Suppose someone visited your office or home and tried to make a voice
>recording using a hidden recorder.
>
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.
>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.
Doubtful, and not worth the bother when you could just scan
them or search them physically.
>
>But how would you detect if someone was secretly recording with an MP3
>player that recorded to flash memory?
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?
>Is there some transmission which could be detected?
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?
>Perhaps some low power ultra high frequency from chip refresh cycles?
.... 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.
Re: How detect if MP3 player is recording in your room? [OT]
Joey <js@foldback.net> wrote in news:Xns9857E3C284F9E74C1H4@127.0.0.1:
> 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?
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.
Re: How detect if MP3 player is recording in your room? [OT]
In comp.sys.ibm.pc.hardware.storage Joey <js@foldback.net> wrote:
> 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?
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.
Re: How detect if MP3 player is recording in your room? [OT]
On Tue, 10 Oct 2006 01:08:40 GMT, Slow Code <my.mail@no.spam> wrote:
>Maybe belch and fart a lot too.
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.
--
When you hear the toilet flush, and hear the words "uh oh", it's already
too late. - by anonymous Mother in Austin, TX
Spam block in place, no emil reply is expected at all.
Re: How detect if MP3 player is recording in your room? [OT]
Joey wrote:
> 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?
3 AM with the right equipment it would be findable , now are you serious
or just another one of "them"?
Re: How detect if MP3 player is recording in your room? [OT]
Joey wrote:
> 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?
not sure if you could find it with a metal detector, but probably
Re: How detect if MP3 player is recording in your room? [OT]
meow2222@care2.com writes:
> > Is there some transmission which could be detected?
> > Perhaps some low power ultra high frequency from chip refresh cycles?
>
> not sure if you could find it with a metal detector, but probably
You'd still have to worry about mind reading satellites.
Re: How detect if MP3 player is recording in your room? [OT]
Picking up any signal is out of question. However, if you are a
paranoid suspecting someone is out to get you by recording, try this
one:
When she gets in your room/office, sing some line of song, like,
"Hellooo, is it me you're looking for? I can see in your eyes..." etc.
Stop kind of suddenly, look at her in the eye, and say, "If someone
recorded that song wouldn't it play back real nice?" She'll know you'd
caught her at her game and would blush or tremble or something.
Joey wrote:
> 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?
Re: How detect if MP3 player is recording in your room? [OT]
"Joey" <js@foldback.net> wrote in message
news:Xns9857E3C284F9E74C1H4@127.0.0.1...
> 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?
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.
Re: How detect if MP3 player is recording in your room? [OT]
On 09 Oct 2006, kony <spam@spam.com> wrote:
> On Mon, 09 Oct 2006 22:23:22 +0100, Joey <js@foldback.net>
> wrote:
>
>>Suppose someone visited your office or home and tried to make a
>>voice recording using a hidden recorder.
>>
>
> 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.
I say things in my conversation which i do not want to be broadcast in
the public media.
>
>
>>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.
>
> Doubtful, and not worth the bother when you could just scan
> them or search them physically.
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!
>>
>>But how would you detect if someone was secretly recording with an
>>MP3 player that recorded to flash memory?
>
> 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?
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.
>
>>Is there some transmission which could be detected?
>
> 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?
The latter. I am talking practicalitites ere.
>>Perhaps some low power ultra high frequency from chip refresh
>>cycles?
>
> ... 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.
If necessary I could have my PC turned off and my phone put further
away. But is there any leakage from solid MP3 recorders?
>
> 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.
Re: How detect if MP3 player is recording in your room? [OT]
On 10 Oct 2006, Slow Code <my.mail@no.spam> wrote:
> Joey <js@foldback.net> wrote in
> news:Xns9857E3C284F9E74C1H4@127.0.0.1:
>
>> 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?
>
>
> 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.
>
> Maybe belch and fart a lot too.
>
> SC
The situation I describe is where the MP3 plater/recorder is carried
by the person.
Re: How detect if MP3 player is recording in your room? [OT]
On 10 Oct 2006, atec77 <""atec77 \"@ hotmail.com"> wrote:
> Joey wrote:
>> 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?
>
>
> 3 AM with the right equipment it would be findable , now are you
> serious or just another one of "them"?
Nope, I am not one of "them". This is very much for real.
Re: How detect if MP3 player is recording in your room? [OT]
> "Joey" <js@foldback.net> wrote in message
>
>> 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?
On 10 Oct 2006, Ken Maltby <kmaltby@sbcglobal.net> wrote:
>
> 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.
>
> Luck;
> Ken
Generate a pattern of sound part of which is inaudible?
Re: How detect if MP3 player is recording in your room? [OT]
Joey <js@foldback.net> wrote in message
news:Xns9857E3C284F9E74C1H4@127.0.0.1...
> Suppose someone visited your office or home and tried to make a voice
> recording using a hidden recorder.
>
Your only real option is to hold your meetings in the middle of field, and
for everyone to be naked.
Aside from that, unless you work for MI5 or have alot of money then the
above would be far easier. If it was that important you wouldn't be asking
the question here.
Re: How detect if MP3 player is recording in your room? [OT]
Joey <no@no-email.com> wrote
> kony <spam@spam.com> wrote
>> Joey <js@foldback.net> wrote
>>> Suppose someone visited your office or home and
>>> tried to make a voice recording using a hidden recorder.
>> 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.
> I say things in my conversation which i do not
> want to be broadcast in the public media.
Then you have a problem for which there
is no solution given the other detail below.
>>> 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.
>> Doubtful, and not worth the bother when you
>> could just scan them or search them physically.
> 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!
Then you have a problem.
>>> But how would you detect if someone was secretly recording
>>> with an MP3 player that recorded to flash memory?
>> 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?
> 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.
Sure, but it just isnt practical.
>>> Is there some transmission which could be detected?
>> 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?
> The latter. I am talking practicalitites ere.
The short story is that it isnt practical to do what you want to do.
>>> Perhaps some low power ultra high frequency from chip refresh cycles?
>> ... 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.
> If necessary I could have my PC turned off and my phone put further away.
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.
> But is there any leakage from solid MP3 recorders?
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.
>> 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.
Re: How detect if MP3 player is recording in your room? [OT]
On Tue, 10 Oct 2006 15:51:51 +0100, Joey <no@no-email.com>
wrote:
>If necessary I could have my PC turned off and my phone put further
>away. But is there any leakage from solid MP3 recorders?
>
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.
Re: How detect if MP3 player is recording in your room? [OT]
Joey <no@no-email.com> wrote in news:Xns9858A161645B271F3M4@127.0.0.1:
> 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!
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.
Re: How detect if MP3 player is recording in your room? [OT]
Joey wrote:
> On 10 Oct 2006, atec77 <""atec77 \"@ hotmail.com"> wrote:
>
>> Joey wrote:
>>> 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?
>>
>> 3 AM with the right equipment it would be findable , now are you
>> serious or just another one of "them"?
>
>
> Nope, I am not one of "them". This is very much for real.
>
> What is "3 AM".
Your kidding ?
do you read analogue clocks ?
Re: How detect if MP3 player is recording in your room? [OT]
On Tue, 10 Oct 2006 15:51:51 +0100, Joey <no@no-email.com>
wrote:
>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!
Then the only practical alternative remaining is to have
them consent to and go through a metal detector, and of
course it has to be actively manned to discriminate a
potential recorder from some other device, object, etc.
If you find what might be an MP player, you won't be able to
determine if it's recording, rather than playing, or if
recording off the radio. Unless MP3 players become
illegal devices, or at least clearly posted as banned on
private premises, you can't justify a search or seizure
either (depending on laws in your locale). If private
property, the other party may still refuse a search and
seizure attempt.
Even scanning for such a device's radiated energy at
entrance to an area, that wouldn't prevent them from turning
on the device later. Unless you have the expectation that
you can seize such equipment, you should follow the same
guidelines you should have otherwise- not saying anything of
importance in the presence of someone who can't be trusted
not to repeat, reproduce, etc., in any way.
Ultimately going to such extra lengths will tend to make
people suspect you have something to hide and put your
activities under more scrutiny.
Re: How detect if MP3 player is recording in your room? [OT]
On Tue, 10 Oct 2006 15:54:06 +0100, Joey <no@no-email.com> wrote:
>What is "3 AM".
On digital clock, it would read 3:00 and the PM indicator would be
off.
On analoug clock, the big hand would be pointing at 12 and small hand
at 3 and outside should be still dark (no sun)
--
When you hear the toilet flush, and hear the words "uh oh", it's already
too late. - by anonymous Mother in Austin, TX
Spam block in place, no emil reply is expected at all.
Re: How detect if MP3 player is recording in your room? [OT]
On 10 Oct 2006, Impmon <impmon@digi.mon> wrote:
> On Tue, 10 Oct 2006 15:54:06 +0100, Joey <no@no-email.com> wrote:
>
>>What is "3 AM".
>
> On digital clock, it would read 3:00 and the PM indicator would be
> off.
>
> On analoug clock, the big hand would be pointing at 12 and small hand
> at 3 and outside should be still dark (no sun)
What are you doing? Water divining with the twig split 90 degrees? Or
searching for MP3 recorder output with the birch twig?
Re: How detect if MP3 player is recording in your room? [OT]
On 10 Oct 2006, Aly <alison@logicsaysNOSPAM.com> wrote:
>
> Joey <js@foldback.net> wrote in message
> news:Xns9857E3C284F9E74C1H4@127.0.0.1...
>> Suppose someone visited your office or home and tried to make a
>> voice recording using a hidden recorder.
>>
>
> Your only real option is to hold your meetings in the middle of
> field, and for everyone to be naked.
>
> Aside from that, unless you work for MI5 or have alot of money then
> the above would be far easier. If it was that important you
> wouldn't be asking the question here.g
Is that right?
Hear this radio programme (under 30 mins).
Use whichever protocol works best for you, both are the same.
Re: How detect if MP3 player is recording in your room? [OT]
On 10 Oct 2006, kony <spam@spam.com> wrote:
> On Tue, 10 Oct 2006 15:51:51 +0100, Joey <no@no-email.com>
> wrote:
>
>
>>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!
>
>
> Then the only practical alternative remaining is to have
> them consent to and go through a metal detector, and of
> course it has to be actively manned to discriminate a
> potential recorder from some other device, object, etc.
>
> If you find what might be an MP player, you won't be able to
> determine if it's recording, rather than playing, or if
> recording off the radio. Unless MP3 players become
> illegal devices, or at least clearly posted as banned on
> private premises, you can't justify a search or seizure
> either (depending on laws in your locale). If private
> property, the other party may still refuse a search and
> seizure attempt.
>
> Even scanning for such a device's radiated energy at
> entrance to an area, that wouldn't prevent them from turning
> on the device later. Unless you have the expectation that
> you can seize such equipment, you should follow the same
> guidelines you should have otherwise- not saying anything of
> importance in the presence of someone who can't be trusted
> not to repeat, reproduce, etc., in any way.
>
> Ultimately going to such extra lengths will tend to make
> people suspect you have something to hide and put your
> activities under more scrutiny.
Thanks Kony. So the MP3 recorder is essentially undetectable during its
operation. OK. Thanks.
Maybe that explains why I can't find any follow-on products for tape
recorder detection while many of the the older devices are no longer
available.
Re: How detect if MP3 player is recording in your room? [OT]
Joey <no@no-email.com> wrote in news:Xns9858A18B4798171F3M4@127.0.0.1:
> On 10 Oct 2006, Slow Code <my.mail@no.spam> wrote:
>
>> Joey <js@foldback.net> wrote in
>> news:Xns9857E3C284F9E74C1H4@127.0.0.1:
>>
>>> 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?
>>
>>
>> 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 a stereo for your office and play it real loud all the
>> time.
>>
>> Maybe belch and fart a lot too.
>>
>> SC
>
> The situation I describe is where the MP3 plater/recorder is carried
> by the person.
Well in that case, the farting and belching should work to keep them away
and presto, no recordings, but you'll have to live with the stinky smell.
Re: How detect if MP3 player is recording in your room? [OT]
Slow Code wrote:
> Joey <no@no-email.com> wrote in news:Xns9858A18B4798171F3M4@127.0.0.1:
>
> > On 10 Oct 2006, Slow Code <my.mail@no.spam> wrote:
>
> Well in that case, the farting and belching should work to keep them away
> and presto, no recordings, but you'll have to live with the stinky smell.
Re: How detect if MP3 player is recording in your room? [OT]
"Joey" <no@no-email.com> wrote in message
news:Xns9858A22E6A2F571F3M4@127.0.0.1...
>> "Joey" <js@foldback.net> wrote in message
>>
>>> 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?
>
> On 10 Oct 2006, Ken Maltby <kmaltby@sbcglobal.net> wrote:
>>
>> 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.
>>
>> Luck;
>> Ken
>
>
> Generate a pattern of sound part of which is inaudible?
>
Acoustic energy then, what the microphone/audio detection
picks up. (It will cover more frequencies that humans can
hear.)
The pattern is on at a particular time then off, it varies in
certain ways that will enable further analysis of any:
> IF and RF?
Intermediate Frequencies (IF) or Radio Frequencies (RF)
given off by a device reacting to the pattern of sound.
If there is any IF or RF detected that corresponds/matches
the on off times of the pattern of sound, you know there is
a device responding to the sound in the room.
A more sophisticated analysis of the detected response
to the pattern, can provide a great deal of information
about the device detected. That would be beyond the
scope of your question, and your security clearance, as
well.
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How detect if MP3 player is recording in your room? [OT] 
Linear Mode
