Time-frequency analysis suggests that the frequency of my data is very low,
(i.e. S2-S3 channel)
but the frequency of my raw data is very high.
What could be the cause of this discrepancy?
What could be the cause of this discrepancy?
If I interpret this correctly, your trace in the last figure shows 15 seconds of data. I estimated the strong rhythmic component to have approximately 100 cycles in that time, giving a strong component between 6 and 7 Hz, while your multitaper runs between 10 and 220 Hz. It might also help to change the scaling of your plots.
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Like @SBeumer said + you may want to standardize your time-frequency plots using zscoring or equivalent as described in the relevant tutorial section. This is to compensate for the 1/f decrease of signal power.
Thank you for your response. How should I set the parameters?
@LanLingXiaoXiaoSheng you can review this tutorial:
https://neuroimage.usc.edu/brainstorm/Tutorials/TimeFrequency#Normalized_time-frequency_maps