[PD] A 6th order hilbert transformer?

[Matt Barber]

Not sure. I've used csound's a lot in ambisonic decoding and it's always
worked well.

On Thu, Jun 23, 2016 at 6:06 PM, Alexandre Torres Porres <porres at gmail.com>
wrote:

> olli's seems easier for me to code, and better than csound's huh?
>
> thanks
>
> 2016-06-23 11:27 GMT-03:00 Matt Barber <brbrofsvl at gmail.com>:
>
>> 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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