linuxaudio.org

Frank Barknecht wrote:

quoted text
>

> Hey, that's actually the first time I read about 1-bit recording and

> at first I thought you were joking or had a typo. But you weren't and

> hadn't.

It works pretty well and is easy to implement in silicon.
Back in college, using a few square inches of printed circuit board, a

soldering iron and a handful of components, I made two little devices

whose only purpose in life was to:

1. Grab an analog input and transform it into a 1-bit digital signal

2. Grab the 1-bit digital signal and convert it back to analog
Not very useful in practice, but a fun project for a boring week-end

afternoon. The toys were so simple, they didn't even have a clock, the

transitions between 1 and 0 happened whenever the proper conditions were

met (there was a capacitor somewhere that was either charging or

discharging very quickly, with the average voltage trying to follow the

analog input, and it was sending to the digital output the information

of either "I'm charging" or "I'm discharging"). I guess the digital

"carrier" was somewhat self-stabilizing (somewhere in the MHz range I

guess).

Those of you familiar with electronics can probably figure out the rough

design of the scheme already.
The sound quality was pretty damn good too, which is somewhat odd given

the rudimentary technology.
With minimal effort, more complex converters can be made that can offer

much better quality. Mine was a hack.
>   Single-stage, 1-bit sigma-delta converters are in principle

quoted text
>   imperfectible. We prove this fact. The reason, simply stated, is that,

>   when properly dithered, they are in constant overload. Prevention of

>   overload allows only partial dithering to be performed. The

>   consequence is that distortion, limit cycles, instability, and noise

>   modulation can never be totally avoided.

Interesting.
--

Florin Andrei
http://florin.myip.org/