[FieldTrip] Fwd: Wavelet-transform based SAM beamforming

giskeopheim giskeopheim at nru.dk
Tue Jan 17 15:59:48 CET 2017


Dear fieldtrip experts, 

I hope it is okay to ask a more general "pipeline" question, instead of
one specifically related to some issue with code, since I do not know
anyone who has experience with it. 

Is there currently any way to perform wavelet-based SAM beamforming with
fieldtrip?  I'm thinking something like 'cfg.wavelet' = 'yes' during
preprocessing.., or, by all means, a way to convert output from
transform functions to desired structs to use in both averaging and
analysis functions?  

Transforming with ft_specest_wavelet to get the convolution in the time
domain, gives a 'chan X freqoi X timeoi complex double', which of course
is not the struct neccessary for performing the beamforming. Using the
ft_freqanalysis with cfg.method = 'wavelet' does not give time domain
output neccessary for SAM method, since it does a multiplication with
the frequencies.  

I am working on a project where I want to build something crudely
comparable to the algorithms used in the MEG Processor software up until
its accumulated spectrograms (assuming you are familiar), but am facing
the obvious problems mentioned above. I am of course open to the
possibility of me misunderstanding of something essential, but I send
this email in hope of getting some input even if that's the case..  

Best regards,
Giske (graduate student)
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