[PD] phase locked loop

[Charles Z Henry]

On Mon, Mar 27, 2023 at 3:33 AM Claude Heiland-Allen <claude at mathr.co.uk> wrote:

> The [hilbert~] abstraction that comes with Pd has two all-pass biquad
> filters that give outputs approximately 90 degrees out of phase from
> each other, so calling its two outputs x and y, phase can be
> approximated with atan2(y, x) and amplitude with sqrt(x^2 + y^2).
> I don't know whether it works as-is for bass frequencies though - maybe
> needs a [deephilbert~] version?

I'm starting in on looking at that with ELSE's [biplot] abstraction.
So far, just copying/pasting things, like coeff from hilbert~ biquads
(2 in series for the left outlet, 2 in series for the right).  I'll
need to modify for adding/subtracting the phase results from each
other and to reduce the range to see the lowest freq in detail
https://github.com/czhenry/czbs/blob/master/analyze_hilbert.pd