3 Dec
2011
3 Dec
'11
12:57 a.m.
Brent Hilpert wrote:
In the analogy with the FSK modem in your other
message
then: simply put, whether the demodulated signal is time-quantised
depends on the properties of the modulating signal.
I still find that I can't agree with your definition of quantization as
applied to signals. In particular, you seem to think that quantization
is a characteristic of the content of the signal, while I consider it a
characteristic of the representation of the signal.
Here are a few questions as part one of a thought experiment:
I go to a concert hall and listen to music performed on a (mechanical)
piano. Is the sound in the concert hall quantized?
I take my Olympus LS11 PCM audio recorder with me to the concert hall,
and with the LS11 sticking out of my shirt pocket, record the concert
from my seat, using stereo 96 kHz 24-bit sampling with
the built-in
microphones.
Is the PCM recording in the flash memory of the LS11 quantized?
When I get home, I play back the recording through a DAC, reconstruction
filter, amplifier, and speaker, and listen sitting in my easy chair. As
I listen to the playback, is the signal from the output of the speaker
(sound waves) quantized?
Is the signal impinging on my ears (sound waves) quantized?
Note that the sound waves at my ear are not identical to those at the
speaker, and that it would be relatively difficult to exactly
reconstruct those at the speaker from those at my ear. If you were to
say that the sound waves at the speaker are quantized, does the
distortion introduced by the "channel" the signal passes through,
between the speaker and my ear, make any difference to your opinion as
to whether the signal at my ear is quantized?
I have further questions for part two of the thought experiment, after
we've considered part one.
Eric