Re: Phase Noise and 1/f noise Generation

Started by Andor September 22, 2008
On 22 Sep., 18:22, robert bristow-johnson <r...@audioimagination.com>
wrote:
> On Sep 22, 12:21&#2013266080;pm, robert bristow-johnson > > > > > > <r...@audioimagination.com> wrote: > > On Sep 22, 9:32&#2013266080;am, Ikaro <ikarosi...@hotmail.com>
wrote:
> > > > > 1) Where should I set frequency offset and phase noise value in
the code?
> > > > Because I found that the above filter code doesn't contain that > > > > information. > > > > There should not be any frequency offset. The noise spectra should > > > cover all the sampled spectrum (0-fs/2). > > > or, as much of that spectrum as possible/practical/necessary.
&#2013266080;you can
> > filter white noise into pink with a 3-pole, 3-zero filter over 10 > > octaves from 0.0009*Nyquist to 0.9*Nyquist within +/- 0.3 dB error. > > > > The noise phase value is random, uniformly distributed betwee -pi/2 > > > and pi/2. > > > You should filter the white noise signal using the FILTFILT so that > > > the IIR filter so that the filtered signal will have zero phase
delay.
> > > not true at all. &#2013266080;since the phase of the white noise
signal going in
> > is totally random, whatever phase that the filter adds to it does not > > matter. > > > r b-j > > forgot to add: &#2013266080;this
pagehttp://www.firstpr.com.au/dsp/pink-noise/is
> a good one to look at.
Additionally, here is a nice bibliography on the subject: http://www.nslij-genetics.org/wli/1fnoise/
On 22 Sep., 18:22, robert bristow-johnson <r...@audioimagination.com>
wrote:
> On Sep 22, 12:21&#2013266080;pm, robert bristow-johnson > > > > > > <r...@audioimagination.com> wrote: > > On Sep 22, 9:32&#2013266080;am, Ikaro <ikarosi...@hotmail.com>
wrote:
> > > > > 1) Where should I set frequency offset and phase noise value in
the code?
> > > > Because I found that the above filter code doesn't contain that > > > > information. > > > > There should not be any frequency offset. The noise spectra should > > > cover all the sampled spectrum (0-fs/2). > > > or, as much of that spectrum as possible/practical/necessary.
&#2013266080;you can
> > filter white noise into pink with a 3-pole, 3-zero filter over 10 > > octaves from 0.0009*Nyquist to 0.9*Nyquist within +/- 0.3 dB error. > > > > The noise phase value is random, uniformly distributed betwee -pi/2 > > > and pi/2. > > > You should filter the white noise signal using the FILTFILT so that > > > the IIR filter so that the filtered signal will have zero phase
delay.
> > > not true at all. &#2013266080;since the phase of the white noise
signal going in
> > is totally random, whatever phase that the filter adds to it does not > > matter. > > > r b-j > > forgot to add: &#2013266080;this
pagehttp://www.firstpr.com.au/dsp/pink-noise/is
> a good one to look at.
Additionally, here is a nice bibliography on the subject: http://www.nslij-genetics.org/wli/1fnoise/