Hello.
Thank you for the update.
First of all, I noticed a few points to be fixed.
For
Spectral analysis box, its outputs are amplitude, phase, real part, and imagery part of FFT.
Your data dimension is changed from [1 x time] -> [Frequency bins x 1]
Therefore, its first output is amplitude per frequency bin up to 250Hz/2 = 125Hz.
So, you should select frequency bands using the
Frequency Band Selector box after the
spectral analysis box, and you need
Spectrum Average box afterward. Then, it will produce one value.
Actually, you can divide branches into different bands after the spectral analysis box. You can filter the data with broadband to reduce motion artifacts and EMG, such as [1 40] Hz.
Here is my suggestion:
csv fille reader -> temporal filter -> channel selector -> spatial filter box (channel average) -> time-based epoching -> windowing -> spectral analysis -> frequency band selector (1: theta, 2: alpha, 3: beta branch) -> spectral average -> simple dsp -> epoch average -> csv writer.
Also, you need to be careful to apply CAR when there are only eight channels, as it can be affected by a few noisy channels.
I don't understand some questions below:
1. Output: a CSV file with that index, to which I'll be able to add event id for specific time periods
=> Usually, it is natural to record event markers during recording with continuous data, as it has time points.
The output of the scenario cannot have an exact time period because after FFT there is no time information, but it represents amplitude per frequency bin during the epoch extracted from time-based epoching box, then you averaged epochs through the epoch average box.
2. My output CSV file returns error messages (sampling rate cannot be 0, error have been thrown during streamed matrix, plus others). What am I doing wrong?
=> Because it is not signal, but spectrum. You need to change the input and out of somes boxes into a spectrum (yellow points). Based on your scenario, it will create a CSV with Time, End Time, frequency 0 to 125. With frequency band selector and spectrum average, it will have Time, End Time, and one column.
Maybe you can look at the neurofeedback scenario if you are interested in band power in addition to FFT amplitude.
http://openvibe.inria.fr/neurofeedback/
Best regards,
