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
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@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
Pd-list@lists.iem.at mailing list UNSUBSCRIBE and account-management -> https://lists.puredata.info/listinfo/pd-list
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@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@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
Pd-list@lists.iem.at mailing list UNSUBSCRIBE and account-management -> https://lists.puredata.info/listinfo/pd-list
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@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@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@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
Pd-list@lists.iem.at mailing list UNSUBSCRIBE and account-management -> https://lists.puredata.info/listinfo/pd-list
csound's hilbert transform is also 6th-order. Code here:
https://github.com/csound/csound/blob/2ec0073f4bb55253018689a19dd88a432ea6da...
On Thu, Jun 23, 2016 at 9:16 AM, katja katjavetter@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@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@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@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
Pd-list@lists.iem.at mailing list UNSUBSCRIBE and account-management -> https://lists.puredata.info/listinfo/pd-list
Pd-list@lists.iem.at mailing list UNSUBSCRIBE and account-management -> https://lists.puredata.info/listinfo/pd-list
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@gmail.com:
csound's hilbert transform is also 6th-order. Code here:
https://github.com/csound/csound/blob/2ec0073f4bb55253018689a19dd88a432ea6da...
On Thu, Jun 23, 2016 at 9:16 AM, katja katjavetter@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@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@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@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
Pd-list@lists.iem.at mailing list UNSUBSCRIBE and account-management -> https://lists.puredata.info/listinfo/pd-list
Pd-list@lists.iem.at mailing list UNSUBSCRIBE and account-management -> https://lists.puredata.info/listinfo/pd-list
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@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@gmail.com:
csound's hilbert transform is also 6th-order. Code here:
https://github.com/csound/csound/blob/2ec0073f4bb55253018689a19dd88a432ea6da...
On Thu, Jun 23, 2016 at 9:16 AM, katja katjavetter@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@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@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@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
Pd-list@lists.iem.at mailing list UNSUBSCRIBE and account-management -> https://lists.puredata.info/listinfo/pd-list
Pd-list@lists.iem.at mailing list UNSUBSCRIBE and account-management -> https://lists.puredata.info/listinfo/pd-list
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@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@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@gmail.com:
csound's hilbert transform is also 6th-order. Code here:
https://github.com/csound/csound/blob/2ec0073f4bb55253018689a19dd88a432ea6da...
On Thu, Jun 23, 2016 at 9:16 AM, katja katjavetter@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@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@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@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 > > _______________________________________________ > Pd-list@lists.iem.at mailing list > UNSUBSCRIBE and account-management -> > https://lists.puredata.info/listinfo/pd-list >
Pd-list@lists.iem.at mailing list UNSUBSCRIBE and account-management -> https://lists.puredata.info/listinfo/pd-list
The phase shift test from my previous mail expresses quadrature transformer output as normalized instantaneous frequencies (cycles). Depending on frequency (within the working range), deviation can be up to 1/100 of a cycle both for [olli~] and Pd's [hilbert~]. Of those two, [hilbert~] may even be most accurate, but [olli~]'s working range extends two octaves lower.
The question is what accuracy and range you need per application, and how audible deviations are in practice. Would be nice to have a catalog of quadrature transformers (in Pd abstraction) for testing and prototyping, including Csound's.
Katja
On Fri, Jun 24, 2016 at 3:47 AM, Alexandre Torres Porres porres@gmail.com wrote:
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@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@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@gmail.com:
csound's hilbert transform is also 6th-order. Code here:
https://github.com/csound/csound/blob/2ec0073f4bb55253018689a19dd88a432ea6da...
On Thu, Jun 23, 2016 at 9:16 AM, katja katjavetter@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@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@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@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 > > > > _______________________________________________ > > Pd-list@lists.iem.at mailing list > > UNSUBSCRIBE and account-management -> > > https://lists.puredata.info/listinfo/pd-list > >
Pd-list@lists.iem.at mailing list UNSUBSCRIBE and account-management -> https://lists.puredata.info/listinfo/pd-list
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Alexandre Torres Porres -
katja -
Matt Barber