At 03:28 PM 3/3/2008, Ann wrote:
> >Sounds familiar. If you have a good signal-to-noise ratio, you can get
> >subpixel accuracy by oversampling the irfft, or better but slower, by
> >using numerical optimization to refine the peak you found with argmax.
the S/N here is poor, and high data rates wo
Thank you for the input!
It sounds like Fourier methods will be fastest, by design, for sample
counts of hundreds to thousands.
I currently do steps like:
Im1 = get_stream_array_data()
Im2 = load_template_array_data(fh2)
##note: len(im1)==len(im2)
Ffft_im1=fftpack.rfft(Im1)
Ffft_im2=fftpack.rfft(
On 03/03/2008, Ray Schumacher <[EMAIL PROTECTED]> wrote:
> Xie's 2D algorithm reduced to 1D works nicely for computing the
> relative phase, but is it the fastest way? It might be, since some
> correlation algorithms use FFTs as well. What does _correlateND use, in
> scipy?
Which way will be
On Mon, Mar 3, 2008 at 2:45 PM, Ray Schumacher <[EMAIL PROTECTED]>
wrote:
> At 01:24 PM 3/3/2008, you wrote:
> > > If you use 'same' or 'full' you'll end of with different
> > >amounts of offset. I imagine that this is due to the way the data is
> padded.
> > >The offset should be deterministic ba
On 03/03/2008, Ray Schumacher <[EMAIL PROTECTED]> wrote:
>
> I'm trying to figure out what numpy.correlate does, and, what are people
> using to calculate the phase shift of 1D signals?
I use a hand-rolled Fourier-domain cross-correlation, but then, I'm
using a Fourier-domain representation of my
At 01:24 PM 3/3/2008, you wrote:
> > If you use 'same' or 'full' you'll end of with different
> >amounts of offset. I imagine that this is due to the way the data is padded.
> >The offset should be deterministic based on the mode and the size of the
> >data, so it should be straightforward to compe
On Mon, Mar 3, 2008 at 12:57 PM, Ray Schumacher <[EMAIL PROTECTED]>
wrote:
> I'm trying to figure out what numpy.correlate does, and, what are people
> using to calculate the phase shift of 1D signals?
>
> (I coded on routine that uses rfft, conjugate, ratio, irfft, and argmax
> based on a paper
I'm trying to figure out what numpy.correlate does, and, what are
people using to calculate the phase shift of 1D signals?
(I coded on routine that uses rfft, conjugate, ratio, irfft, and
argmax based on a paper by Hongjie Xie "An IDL/ENVI implementation
of the FFT Based Algorithm for Automat
