[sdiy] A new shade of pink (noise)

[Brian Willoughby]

Thanks for sharing this paper, Tom.

A quick scan shows the author describing fixed point numbers, so by that stage in the algorithm the signal is no longer just a single bit. I hope that detailed reading will show how the weighting creates a "pink" spectrum from multiple white spectra.

In the analog domain, it would be possible to mix multiple digital noise sources together with an analog mixer, and the result would no longer be a square wave.

Brian


On Nov 24, 2020, at 04:57, Tom Wiltshire <tom at electricdruid.net> wrote:
> There’s an interesting paper by Stefan Stenzel on Github, describing a new digital pink noise generation algorithm:
> 
> 
> https://github.com/Stenzel/newshadeofpink/blob/master/newshadeofpink.pdf
> 
> 
> Has anyone seen this? I’ve read it, but there’s one thing I don’t understand. In the paper, he talks about taking multiple 1-bit noise sources (as you would in the Voss0-McCartney algorithm) but instead of using a “zero order hold” (e.g. “stretching” each sample) to decrease the sample rate, he uses linear interpolation.
> This is the bit I don’t get - how do you linearly interpolate a 1-bit signal? There’s nothing in between!
> He mentions at one point that the digital signal is to be interpreted as -1 or +1, which would mean that there is a 0 between the two values, but I still don’t understand how that makes sense when it’s a digital signal and not a bit of signal processing maths formula.
> 
> Any clarifications appreciated. I’d like to understand this method better, but the paper is very brief, assumes quite a lot of background I don’t have, and doesn’t provide any worked examples for illustration.
> 
> Many thanks,
> Tom