Back to the main page.
Bug 3169 - spectrogram power does not match with signal amplitude
| Status |
NEW |
| Reported |
2016-07-28 17:58:00 +0200 |
| Modified |
2016-07-28 17:58:58 +0200 |
| Product: |
FieldTrip |
| Component: |
specest |
| Version: |
unspecified |
| Hardware: |
PC |
| Operating System: |
Windows |
| Importance: |
P5 normal |
| Assigned to: |
Roemer van der Meij |
| URL: |
|
| Tags: |
|
| Depends on: |
|
| Blocks: |
|
| See also: |
|
Danial Arabali - 2016-07-28 17:58:58 +0200
Created attachment 806
simulate sinusoid and plot the spectrograms with hanning and multitapring methods
Hello,
I was trying to figure out the unit of the power in spectrograms. So I made a sinusoid with a certain amplitude and frequency and then plotted the spectrogram with two methods: hanning and multitapering. I expected that power should be close to the squared amplitude of signal but with neither methods I got this!
So, I suppose there is some kind of normalization going on inside fieldtrip which I do not understand, therefore I can not proceed with other kind of analysis if I do not know what are the values I get from spectrograms.
I attached the script I used for producing sinusoid and plots.
By the way, there is another post in the following link which raised the similar issue but unfortunately there was no answer to it:
https://mailman.science.ru.nl/pipermail/fieldtrip/2015-October/009723.html
Thank you in advance for clarifying this issue.
Best, Danial