In article , Justin
Ulysses Morse wrote:

He's not saying that dither can't be applied
in the digital domain. He's saying it needs to be applied prior to the
quantization (or re-quantization) that's being dithered.

In an ADC, this could occur in the analog domain, or in the case of an
oversampling converter, it could be done digitally before the signal is
quantized to 16 or however many bits.

In the case of truncating 24 bit data into 16 bits, he's saying you
have to add the dither BEFORE you lop off those bottom 8 bits. The
dither and the LSBs have to be summed before truncation.


Yes. If you do it after, the distortion is there, and possibly
(probably) aliasing from it, and there's no way to get rid of it once
it's there. However the designer wants to do it for the aplication at
hand (digital or analog), it needs to be done before the quantization or
requantization.


In article , Chris Hornbeck
wrote:
Hi Ulysses,
Thanks for your comments. I really don't know how to resolve this.
What you say makes perfect sense, but Watkinson says otherwise.
Maybe someone else could help out?.....


I think this has already been reolveed in other posts in the thread, so
I'll just add a small Watkinson quote:

"The introduction of dither PRIOR to a conventional quantizer inevitibly
causes a slight reduction in the signal-to-noise ratio attainable, but
this reduction is a small price to pay for the elimination of
non-linearities."

So obviously Watkinson does say it must happen before quantization. Your
Watkinson quote was talking about something a little different.

--
Jay Frigoletto
Mastersuite
Los Angeles
promastering.com