[FieldTrip] spectrum interpolation

philip Joadavi p.joadavi at gmail.com
Wed Aug 24 16:57:07 CEST 2022

Dear all,

I have a question (which might be very stupid) regarding the line noise
removal using spectrum interpolation using DFT method.

currently, I'm applying the notch filter on my data, but I noticed for some
of my subjects the 50Hz is not entirely removed.

I have 32-channel EEG data (with a sampling frequency of 2048) with many
trials that have different lengths (from 15 seconds to 5 min). If I
understood correctly the best method for removing the 50 Hz from this kind
of data is spectrum interpolation. Unfortunately, I'm having a hard time
making it to work.

here is what I have defined:
cfg.dftfilter       = 'yes';
cfg.dftreplace  = 'neighbour';
cfg.continuous = 'yes';
cfg.padding      =  (2^nextpow2(size(Data{1}.trial,2)))/Data{1}.fsample
cfg.padtype      =  'data'

so, my first trial has a length of 368200, which for the cfg.padding I
use 256.
here is where I'm stuck and apparently I'm doing something wrong, which
gives me this error:
=>* "Padding by data mirroring is not supported for spectrum interpolation"*
I also remove the option for continuous data, but it did not solve my

I would appreciate any help!

Thanks a lot!
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