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.


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.

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.


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.




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 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.