[sdiy] Vector-based ADC/DAC?

[ASSI]

On Freitag, 12. November 2004 01:33, Jay wrote:
> It would be basically consist of using a high speed ADC to convert
> audio vector curves, sort of an EPS file for sound recordings. Then
> using what I can best describe as a "digitally voltage-controlled
> high speed variable slope analog envelope generator" as a sort of
> DAC.

I'm pretty certain that something akin to this has been implemented, 
just not under that name. Subsampling Sigma-Delta DACs could be using 
such techniques internally for instance. 

> Excuse me if my idiocy in this field is showing, but wouldn't 
> that then eliminate all quantization that is inherent in digital
> recordings?

You can't get rid of quantization that way, it just shows up in 
different places. If you just use linear slopes, you have to change 
that slope at some point. A scheme like that (if I understood you 
correctly) would be extremely prone to sampling jitter and accumulated 
error, so you'd have to reset from time to time.

> Is this even possible in real time?
> Is it possible as a DIY project? 

If you drop the high-speed requirement, it should be possible to do a 
proof-of-concept. Of course you'd use completely different techniques 
for the analog part than if you were doing a monolithic integration, 
but the digital part is not much of a problem. There have been a number 
of hybrid DAC/ADC implementations using FPGA and some analog circuits, 
mostly of Sigma-Delta type because you can trade off analog and digital 
complexity over a wide range for those.


Achim.
-- 
+<[Q+ Matrix-12 WAVE#46 Neuron microQkb Andromeda XTk sonic heaven]>+

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