Hi @PauloKanda,
You can create and add whatever annotations you like to the raw data, they don’t have to always designate bad signal regions. Take a look at this tutorial.
Only annotations whose description begin with 'bad' or 'BAD' are treated as signal segments to ignore in later analysis steps, so for example:
- when creating epochs, epochs overlapping with these segments will be automatically dropped (this behavior is controlled via
reject_by_annotationargument, see this tutorial) - when computing fft on raw data, signal segments with bad annotations are ignored
What I want is to select, 20 or 30 epochs of 2 secs or 4 secs and apply FFT on them to get spectral analysis of all bands
If you want to epoch your continuous data - then I would first add bad annotations (these signal segments will not be epoched), then epoch the data (follow this tutorial) and then perform the FFT. You can then average predfined frequency ranges (some advice on how this can be done can be found here and here).