Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

Sampo, it is not the poles and zeros that alternate on the real line but the poles of the two all-pass filter paths. The 90 deg phase difference band is almost from 0 to Nyquist. In my filter pair they are from 0.001 pi to 0.999 pi. On z-plane those corner frequencies are at (0.95, 0.003) and

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

> how do you quadrature modulate without Hilbert filters? > Perhaps I'm using the wrong term - the operation in question is just the multiplication of a signal by e^jwn. Or, equivalently, multiplying the real part by cos(wn) and the imaginary part by sin(wn) - a pair of "quadrature oscillators."

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

Original Message Subject: Re: [music-dsp] � 45� Hilbert transformer using pair of IIR APFs From: "Ethan Duni" <ethan.d...@gmail.com> Date: Thu, February 9, 2017 5:06 pm To: "A discussion list for music-re

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

On Tue, Feb 7, 2017 at 6:49 AM, Ethan Fenn wrote: > So I guess the general idea with these frequency shifters is something > like: > > pre-filter -> generate Hilbert pair -> multiply by e^iwt -> take the real > part > > Am I getting that right? > Exactly, this is a

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

Am 09.02.2017 um 14:15 schrieb Theo Verelst: The idea of estimating a single sine wave frequency, amplitude and phase with a short and easy as possible filter appeals to me though. Did you listen to the example I posted? Do you think it's useful? Or too many artefacts?

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

On 2017-02-07, Theo Verelst wrote: Like with many transforms, I can't help but practically think that it's hard to make a tradeoff between the meaning of the results, such as [...] Here there's an rather simple optimization criterion: a constant 45 degree phase offset, or perhaps a pair of

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

Thinking about it, I recall there was some from of transform used for frequency/time analysis for instance for radar problems (maybe books from before WWII, or more recent frequency/time analyzers) and without checking though it was in popular DSP speak something like the Hilbert transform, but

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

On 2017-02-06, robert bristow-johnson wrote: [...] and analytic signal      a(t)  =  x(t)  +  j y(t)            =  g(t) cos(w t)  +  j g(t) sin(w t)            =  g(t) e^(j w t) the analytic envelope is      |a(t)|  =  sqrt( x(t)^2  +  y(t)^2 )              =  g(t) so that works great for a

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

Yes, there are lots of interesting things that can be done with frequency shifting. Feedback suppression in a PA system by frequency shifting was suggested by Manfred Schroeder a long time ago. I have occasionally found it to be useful to broaden a mono signal by feeding it through a hilbert

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

A nice thing are the endless phase shifts, if you feed back a frequency shifter. It’s like a Shepard tone. If you have Logic Pro or MainStage, try the RingShifter, it can do such tricks. It has 2x6 Allpass filters for the constant phase shift and a quadrature oscillator with FM and a delay.

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

On 02/07/2017 07:49 AM, Ethan Fenn wrote: So I guess the general idea with these frequency shifters is something like: pre-filter -> generate Hilbert pair -> multiply by e^iwt -> take the real part Am I getting that right? Now that I think about it, another application might be in stereo

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

So I guess the general idea with these frequency shifters is something like: pre-filter -> generate Hilbert pair -> multiply by e^iwt -> take the real part Am I getting that right? Now that I think about it, another application might be in stereo imaging. Start with a mono signal, generate the

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

On Feb 6, 2017, at 11:19 PM, robert bristow-johnson wrote: > with a harmonic musical note this beat frequency would be the difference > between two harmonics, which could be any integer times the fundamental. > that's much faster than beating. an r.m.s. envelope would be the square root >

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

On 2/7/17 12:39 AM, Eric Brombaugh wrote: On Feb 6, 2017, at 8:24 PM, robert bristow-johnson wrote: On 02/05/2017 07:52 PM, robert bristow-johnson wrote: I'm curious what aspects of a music make the complex magnitude of the analytic signal inappropriate for estimating the envelope? In

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

On Feb 6, 2017, at 8:24 PM, robert bristow-johnson wrote: > > On 02/05/2017 07:52 PM, robert bristow-johnson wrote: > >> > >> > I'm curious what aspects of a music make the complex magnitude of the > >> analytic signal inappropriate for estimating the envelope? In > >> communications signal

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

If there are zeroes on the unit circle in the z-plane, I don't think it will be a very good all-pass filter... (Because some sinusoid frequencies would be blocked entirely) Neat topic so far! I'd love to see an illustration of this real-line "zebra stripe" design. Also wondering what sort of

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

� Original Message Subject: Re: [music-dsp] � 45� Hilbert transformer using pair of IIR APFs From: "Eric Brombaugh" <ebrombau...@cox.net> Date: Mon, February 6, 2017 11:37 am To: music-dsp@mu

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

On 2017-02-06, Eric Brombaugh wrote: well, with a single sinusoid, there should be no intermodulation product so the analytic envelope should be exactly correct. but consider: [...] I might be way off base here, but... As Olli said, both the poles and the zeroes sorta "like to be" on the

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

On 02/05/2017 07:52 PM, robert bristow-johnson wrote: > I'm curious what aspects of a music make the complex magnitude of the analytic signal inappropriate for estimating the envelope? In communications signal processing we use this often, even for signals that are fairly wide-band with

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

Funny that no one mentioned this https://www.native-instruments.com/fileadmin/ni_media/downloads/pdf/VAFilterDesign_1.1.1.pdf Particularly, formula 7.43 Regards, Vadim -- Vadim Zavalishin Reaktor Application Architect Native Instruments GmbH +49-30-611035-0 www.native-instruments.com

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

Original Message Subject: Re: [music-dsp] � 45� Hilbert transformer using pair of IIR APFs From: "Eric Brombaugh" <ebrombau...@cox.net> Date: Sun, February 5, 2017 8:22 pm To: "A discussion list for music-re

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

On Feb 5, 2017, at 12:54 PM, robert bristow-johnson wrote: > using the analytic filter to get the instantaneous amplitude envelope (and, > also, instantaneous frequency by differentiating phase) is something that > works only with single sinusoids that are AM'd or FM'd. for music, i think i

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

Original Message Subject: Re: [music-dsp] � 45� Hilbert transformer using pair of IIR APFs From: "Ethan Fenn" <et...@polyspectral.com> Date: Sun, February 5, 2017 1:39 pm To: music-dsp@mu

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

nking about how to approach that. APFs so the gains stay 1 and we don't > care about the phase as long as the difference is 90°. still don't know > how i might set up an optimization problem. probably the best measure is > the negative frequency rejection with regard to the positive frequ

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

problem. probably the best measure is the negative frequency > rejection with regard to the positive frequency gain. > > r b-j > > > > ------------ Original Message > Subject: Re: [music-dsp] ± 45° Hilbert transformer using

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

typofix: "and their companion poles" -> "and their companion zeros" -olli On Sun, Feb 5, 2017 at 1:52 PM, Olli Niemitalo wrote: > 90 deg phase difference all-pass filter pairs... Lemme wave my hands a bit: > > It's been years, but I recall I first tried a structure with complex >

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

90 deg phase difference all-pass filter pairs... Lemme wave my hands a bit: It's been years, but I recall I first tried a structure with complex conjugate pairs of poles (and their companion poles to make the filters all-pass). Globally optimizing that using Differential Evolution, the poles

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

robert bristow-johnson wrote: cool, so it appears from your comments to be real poles. complex conjugate poles are not considered in the design. i wonder why that is? I’m not the author of the formula, I just implemented it and don’t understand how it produces these filters. I guess the

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

� cool, so it appears from your comments to be real poles. �complex conjugate poles are not considered in the design. �i wonder why that is? r b-j Original Message Subject: Re: [music-dsp] � 45� Hilbert transformer using pair of IIR

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

robert bristow-johnson wrote: so Olli, how do you get your coefficients? (if i may ask?) If I may reply, I wrote long time ago a C++ library implementing this kind of polyphase halfband filter, including a coefficient calculator involving elliptic stuff (way beyond my knowledge). Check the

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

-McClellan or Prony). maybe that's what > Olli is doing. > > > -- > > r b-j r...@audioimagination.com > > "Imagination is more important than knowledge." > > > > ------------ Original Message -------

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

-------------- Original Message -------- > > Subject: Re: [music-dsp] � 45� Hilbert transformer using pair of IIR APFs > > From: "Eric Brombaugh" <ebrombau...@cox.net> > > Date: Sat, February 4, 2017 8:55 pm > > To: musi

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

[music-dsp] � 45� Hilbert transformer using pair of IIR APFs From: "Eric Brombaugh" <ebrombau...@cox.net> Date: Sat, February 4, 2017 8:55 pm To: music-dsp@music.columbia.edu -- > The original Csound sou

Re: [music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

The original Csound source has a set of coefficients for this type of hilbert transform but they don't say how the coefficients were derived and the performance is fairly lackluster. The only reference I've come across for this was Olli Niemitalo's: http://yehar.com/blog/?p=368 He gives a

[music-dsp] ± 45° Hilbert transformer using pair of IIR APFs

� hey guys, what's the best online reference you can tell me for theory and practice of designing APF pairs with � 45� phase (+ a linear phase that represents causality delay)�to result in a Hilbert pair for audio processing. �i know how to do this for FIR and to use half-band symmetry, but