[PD] A 6th order hilbert transformer?

Alexandre Torres Porres porres at gmail.com
Fri Jun 24 00:06:54 CEST 2016


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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