Hi all,
I have a simple problem: I have a 32-channel EEG signal, and I would like to calculate the amount of alpha activity averaged over all channels, so that I have input signal of 32 channels, and output signal of one channel with the average of all 32 channels.
Similarly, what if I want to calculate the ratio of Beta vs. Alpha activity? How do I access different channels in a signal. I tried simple dsp by giving it signal with two channels, and had a calculation of a+b, expecting the sum of two channels as one channel signal, but I received again two channel signal.
kind regards
newbie question : how to combine channels within a signal
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- Posts: 112
- Joined: Sun Mar 14, 2010 12:58 pm
Re: newbie question : how to combine channels within a signa
Hi Asparagus!
If you want to combine different channels, for instance to do averaging, the best box to use is the spatial filter box, which creates a linear combination of channels:
http://openvibe.inria.fr/documentation/ ... ilter.html
I hope this helps,
Fabien
If you want to combine different channels, for instance to do averaging, the best box to use is the spatial filter box, which creates a linear combination of channels:
http://openvibe.inria.fr/documentation/ ... ilter.html
I hope this helps,
Fabien
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- Posts: 775
- Joined: Tue Dec 04, 2012 3:53 pm
- Location: INRIA Rennes, FRANCE
Re: newbie question : how to combine channels within a signa
Agree with Fabien. And about the way Simple DSP works: you can use formulas across streams (e.g. a+b is a pairwise sum of the matrix chunks of streams a and b), but it cannot be utilized to do math on a channel vs channel level. If you really need to do that, you can use two channel selectors to split the stream, then give the two streams to simple dsp as a and b.
Cheers,
Jussi
Cheers,
Jussi