"kony" wrote in message
...
On Sun, 15 Oct 2006 02:08:05 -0500, "Ken Maltby"
wrote:



1) A specific, exact scenario.

2) A method for discriminating recording MP3 players from
everything else, in the exact scenario. Not some vague
concept of detecting semiconductors, a mere HF signal or
anything else that is not unique to a multitude of different
MP3 players.

3) A device that can reliably use that method in that
scenario.

#2 is the linchpin, #3 may indeed be possible after #2 is
resolved to #1. So it is with any purpose built device.

All this proves is that you have not read or understood
my earlier posts. I described the way actual devices
operate to detect any device that is detecting audio.

You made a suggestion that was not resolvable to a
difference in operation of an MP3 player. With a constant
current and constant bitrate output, you'd essentially be
suggesting that from a distance you can discriminate which
bits are flowing on the bus to the memory, in what is likely
a shielded case. I find this highly unlikely.


I was suggesting no such thing. I find your idea that an
ungrounded MP3 recorder has any significant shielding,
very unlikely. The recorder to be a threat and to respond
to sound must let sound waves through, even if it is a
contact microphone/sensor/transducer, and they require
significant amplification in their operation.

It is not necessary to know "which bits are flowing on
the bus to the memory", the detection takes place before
that is even an issue.

If you are going to pretend you understand how the
device I described operates, try to approach it from
a different angle than; finding a way it couldn't work,
then deciding that is what I must be describing.


It
shouldn't be hard to realize that any device that is
responding to a pattern of sound is a threat.

Sure, but even ignoring the issue of whether it's feasible
to have test sound patterns at all, we don't have any
evidence a digitally recording MP3 player will have a
detectable response in particular scenarios, if in any at
all.

So now you doubt that it's possible to generate a
controlled pattern of sound? (You wouldn't be
responsible for Rap "Music", would you?)

I'm no giving you "evidence". But I must have missed
your "evidence" that the device I described doesn't
work. Evidence is something besides your opinion,
or your interpretation of High School Physics and needs
to be based in proven limitations.

Try the following:
http://www.testequipmentdepot.com/ra...ipment/rf1.htm
it's the cheapest way to even start to examine this issue with
an attempt to establish some "evidence", you should be able to
detect some response from a recording device. This is nothing
like the device I was describing, but if you can see a result with
this, even you would have to admit that much more sophisticated
devices can do what I've described.


For a
recorder, of any kind, to record the audio in a room
it must detect it, and amplify the detected signal.

The recorder does not necessarily need amplification prior
to digitization, it is commonly a single chip solution that
would not have to output to headphones either in this use.

Almost all audio detectors/sensors require amplification,
and those that don't, carry a significant bias current that
gets modulated, more than enough to be detectable with
modern equipment.


These processes can be detected, if this processing
matches the on and off timing of a known pattern
of sound, (which you control) you can isolate the
device. (Your "2" above.)

"IF" the process existed, and "IF" the detection device was
suitable sensitive, and "IF" the scenario allowed proximity,
then perhaps it's possible. None of these three IFs can be
assumed yet.


Isn't it fortunate that no one needs your agreement that it's
possible, to make and use such devices.


I hope you aren't going to say that while this type
of detector can detect that there is a device
responding to the sound in the room, and help you
locate it; this hasn't identified the device as an MP3
recorder.

Not at all, I'm going to say the device won't detect the MP3
player recording at all in most scenarios, that it might
detect "something" electronic is in the room but that's all,
it won't ID it as an MP3 player nor that it is responding to
sound in the room. "Maybe" if you had it right up against
the recorder, but do you expect that scenario?


I say that such devices can detect any device that is
responding to a supplied audio signal pattern. Any
device that is detecting the audio pattern. They can
detect anything electronic, that generates electrical
noise or signal when it detects acoustical energy.

There is a great deal more some of these devices
can do in the hands of a skilled operator/analyst.

It looks like we have established that you are going
to just deny the possibility. You can believe what
you wish, it has no impact on reality what so ever.


I would think even you realize that it is
of no importance what the device is, that is responding
to the audio pattern, it would need to be considered
a live threat.

You're drifting down a tangent that has not yet been
reached. I never argued that a detected response to an
audio pattern wasn't suspicious enough to draw a conclusion
about the operation of a device.

It still doesn't get us where we need to be, to detect a
recording MP3 player reliably and discriminate it from other
non-recording electronic devices. This is not the same as a
tape recorder.

You have been provided a description of how these devices
can do just that, your only answer seems to be that you don't
believe a device could work as I described. You provide no
explanation (much less evidence) of why it couldn't work.

You seem intent on saying "No they can't work." I know
that they most certainly do work. What point is there in
further argument, on that basis?

Luck;
Ken