Re: Is the audio output of a CD player analog or digital?

Meindert Sprang wrote:
"Don Pearce" <spam@xxxxxxxx> wrote in message
news:4ae26503.236738843@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
The anti alias filter removes the quantization steps.

Of course it does not!!
Let's simplify the system William describes to a one bit system, sampling at
2 kHz. If you put a 1kHz sinewave in, you get a square wave in the digital
domain, which will be a sinewave again after the D/A conversion and
filtering, simply because the filter removes anything above 2kHz. So indeed,
you won't be able to measure any quantisation on the output, *as long as you
put this sine wave in*. Now, lower the input fequency to, say, 1Hz. Et
voila, on the output appears a square wave with rounded edges... Now you can
clearly observe that this system can only represent two stable levels.

The only thing an anti alias filter does is smooth the transitions between
quantization steps.

Meindert




This simply isn't true. All the quantization noise is out
of the passband of the signal.

--
Les Cargill
.

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