View Full Version : Choi-Williams responses

Dr. Axel Knicker
09-14-1998, 10:40 PM
Hello all!

Before I left for a longer stay in Australia I distributed the following
message and received several extremely usefull replies which I have
added after the original message.
Thanks to all who responded

Dr. Axel Knicker

Original message:

Hello in biomch-l Land!
> In order to determine electrical activation parameters from dynamic
> contractions I wanted to utilise FFT procedures. As I learned from
> literature studies this is not the appropriate way as the signal of the
> EMG is not stationary. The procedure of choice is supposed to be the so
> called Choi-Williams algorithm. Who of you can give me some more details
> on that topic and the Choi-Williams in particular. Where can I find the
> algotrithm and background information about the conditions it can be
> applied to. What exactly does the Choi-Williams do with my signals. In
> how far is it different to FFT?
> Take your time to reply. All of them will be posted as usual, but it
> will take a while as I will not be in the office in August.


A good choice may be to start with Chapter 57 of The Biomedical
Engineering Handbook (Bronzino, ed.). It is quite overwhelming, both
the book, which is 7.5 cm thick, and the paper, in
number of formulae. You should not shy of some mathematics anyway, if
you will
go into time frequency distributions.
Good luck,
At Hof
Department of Medical Physiology
University of Groningen
Bloemsingel 10 |----/\/\/\/----| |\