Re: Want a smooth function from Arg[ ]
- To: mathgroup@smc.vnet.net
- Subject: [mg12519] Re: Want a smooth function from Arg[ ]
- From: Mario Parra <parra@busco.lanl.gov>
- Date: Sat, 23 May 1998 18:10:49 -0400
- Organization: Los Alamos National Laboratory
Sean Ross wrote:
> The method you gave works beautifully for continuous functions or for
> smooth, discrete data. If there is the possibility of noise in the
> input function, then the problem becomes harder. My own meeting of
> this problem occurs in Fourier propagation of light. The phase output
> of an fft is totally chopped up for the same reason the Arg chops it
> up. I have had some success in minimizing the numerical first and
> second derivatives, but it is far from a trivial problem, especially
in
> two dimensions. If you hear of a different approach than an
> after-the-fact hunting for discontinuities, please let me know.
Take a look the following papers:
Phase unwrapping of signals propagated under the ....
IEEE trans. on Acoustics, Speech and signal processing
Vol 36, No 5. May 1988.
Exact computation of the Unwrapped phase of a ....
IEEE trans. on Acoustics, Speech and signal processing
Vol 36, No 11. Nov 1988.
A direct relation between a signal time series .....
IEEE trans. on Acoustics, Speech and signal processing
Vol ASSP-30, No 5. Oct 1982.
Phase unwrapping of digital signals.
IEEE trans. on Acoustics, Speech and signal processing
Vol 37, No 11. Nov 89.
A new phase unwrapping algorithm.
IEEE trans. on Acoustics, Speech and signal processing
Vol ASSP-25, No 2. Apr 77.
These papers address the problems that phase unwrapping gives. I recall
some of them talk about noise.... Hope they are helpful.
-Mario