[FieldTrip] Changed phase convention 'wavelet' ('wltconvol')

Roemer van der Meij r.vandermeij at donders.ru.nl
Wed Apr 20 20:16:25 CEST 2011


Hi everybody,

We have changed the meaning of phases of /raw/ Fourier-coefficients of 
method = 'wavelet' (previously 'wltconvol'), so that it is in alignment 
with method = 'mtmconvol'.
All output is now phase-shifted such that an angle of 0 of any 
Fourier-coefficient always means a peak of an oscillation in the data, 
and an angle of pi/-pi will always mean the trough of an oscillation 
(wavelet wise angle = 0 is implemented as cosine at peak, and sine in 
up-going flank) (also documented in the FAQ section here 
<http://fieldtrip.fcdonders.nl/faq/what_are_the_differences_between_the_old_and_the_new_implementation_of_wavelet_formerly_wltconvol_in_ft_freqanalyis>)

Processed phases, like those in a cross-spectral density array and it's 
children like coherence, PLVs etc., will /not /be different. You will 
only notice the difference if you choose cfg.output = 'fourier'.

The change will be latest version on our FTP-server tonight.

Best,
Roemer

-- 
Roemer van der Meij M.Sc.
PhD student
Donders Institute for Brain, Cognition and Behaviour
Centre for Cognition
Radboud University Nijmegen
P.O. Box 9104
6500 HE Nijmegen
The Netherlands
Tel: +31(0)24 3655932
E-mail: r.vandermeij at donders.ru.nl
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