[PD] A 6th order hilbert transformer?

[Matt Barber]

csound's hilbert transform is also 6th-order. Code here:

https://github.com/csound/csound/blob/2ec0073f4bb55253018689a19dd88a432ea6da46/Opcodes/ugsc.c

On Thu, Jun 23, 2016 at 9:16 AM, katja <katjavetter at gmail.com> wrote:

> Attached is a zip with test patch for [olli~] and [hilbert~] so you
> can compare and also check with different sample rates. It seems that
> Olli's coefficients are optimized to work well from 20 Hz up at 44K1
> sample rate, and Pd's built-in from 80 Hz up. They both work at other
> samples rates too, but with different range.
>
> Since the coefficients for x[n-2] and y[n-2] are non-zero in the
> biquads, the maximum phase shift  is as large as in any 2nd order
> section, therefore I think the four sections together are 8 order
> equivalent indeed.
>
> By the way, the abstraction in my first response wasn't completely
> vanilla-compatible, this is fixed in current attachment (for anyone
> else interested).
>
> Katja
>
> On Thu, Jun 23, 2016 at 6:24 AM, Alexandre Torres Porres
> <porres at gmail.com> wrote:
> > Awesome, I can code it based on that :) but which order is it?
> >
> > I see it has 4 biquads, but it doesnt look like an 8th order because some
> > coefficients are zeroed out, so I'm confused.
> >
> > Another question, does it work at any sample rate? This question is also
> > aimed to pd's hilbert~ abstraction by the way.
> >
> > cheers
> >
> > 2016-06-22 17:27 GMT-03:00 katja <katjavetter at gmail.com>:
> >>
> >> Hi, Olli Niemitalou has coefficients published for a higher order
> >> 'hilbert transformer' on http://yehar.com/blog/, attached is [olli~]
> >> abstraction based on it.
> >>
> >> Katja
> >>
> >> On Wed, Jun 22, 2016 at 4:37 AM, Alexandre Torres Porres
> >> <porres at gmail.com> wrote:
> >> > Howdy, I'm working on a frequency shifter object (via single sideband
> >> > modulation / complex modulation).
> >> >
> >> > In Max they have a so called "6th order hilbert transformer with a
> >> > minimum
> >> > of error". In Pd, the hilbert~ abstraction is 4th order. I'm copying
> the
> >> > pd
> >> > abstraction for now, but I was hoping to use such a higher order
> filter
> >> > and
> >> > also use- but I can't find a source for such a formula. Any help
> finding
> >> > it?
> >> >
> >> > thanks
> >> >
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>
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