[PD] A 6th order hilbert transformer?

Alexandre Torres Porres porres at gmail.com
Fri Jun 24 03:47:15 CEST 2016


I guess I have to find a way to implement it and test it.

By the way, I'm testing max's hilbert~ with olli's - find picture attached.

is this a good way to test it by the way? Seems Max's is more accurate



2016-06-23 22:40 GMT-03:00 Matt Barber <brbrofsvl at gmail.com>:

> 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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>>>
>>
>
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