[FieldTrip] MOrler wavelet nonconstant Q

Fanny fanny.lachat at gmail.com
Mon Dec 3 13:24:40 CET 2012

Dear  Fieldtrip users,

I am reading this paper :
1- Schneider, T.R., et al., Enhanced EEG gamma-band activity reflects
multisensory semantic matching in visual-toauditory
object priming, NeuroImage (2008),

I am interesting in the methodology : using a *nonconstant Q wavelet*.
However I am a little confused :

*Time-frequency analysis was performed for
each channel by convolving the data with a complex Morlet
wavelet w(t, f0) having a Gaussian shape in time (σt) and in
frequency (σf) around the center frequency ( f0). Nonconstant
wavelets with Q increasing from f0/σf =8.5 to 13 for frequencies
from 30 to 100 Hz (step size 2 Hz) were used.

-  I don't understand what is *f*0 and  σ*f*
and thus , how can I find the right Q with my data ..
I am trying to find the right Q for my analysis and it seems that a *nonconsant
Q* is what I need. ( 4-80HZ, step size 1Hz, form 1.2 sec to 1.3sec , time
step 0.002)

finally, Does anyone else used  also the nonconstant Q method ?

Thank you in advance.
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