On Sun, 15 Oct 2006 09:32:39 -0500, "Ken Maltby"
wrote:


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.

Define significant. Many have grounded copper foil in them.
It's not as though this is a high powered device to begin
with, though, and would commonly have to be detected at a
distance.

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.

No, you are thinking of older devices. There needs be no
amplification prior to the digitization chip which can run
at constant current, very low voltage and no easily
detectable response to room noise from a distance.

We might consider it mere coincidence that it is recording
something, because the means to that end are different than
in a recording device with a different (end) medium and
analog amplification.




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.

You mean "IF" it could, it would.



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.

I'm not going to pretend anything, I'm suggesting you are
not describing an MP3 player in recording mode.

All the rest of your supportive argument hinges on being
able to detect a signal that may not exist at all, or in
cases where it does, are not sufficient strenth to measure
at any distance. Remember it is not enough to find one
particular MP3 player, nor a dissimilar device like a tape
recorder, that can be detected- it has to be effective
against the entire class of devices, or at the very least
the common ones available on the market.