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What is the mean of EMG signal? And what's the purpose of removing it?

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https://docs.google.com/document/d/e/2PACX-1vRH3qfvMvmHBdHhg3sFQKTwo1-blg8luLXSQRhsIhEgwFj3QmWGStUhvslrVuVzP-aQ3T0YNs-lUsOz/pub

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    $\begingroup$ What's wrong with starting to read the wikipedia article about it? en.wikipedia.org/wiki/Electromyography Basically you measure the electrical activity of muscles. The nerves controling it using electrical patterns to achieve a certain activity of the muscle. In decoding that you are not interested in the exact signal but rather in the underlying code. So you want to determine the "1" and "0" state from the recorded signal. So basically you are measuring an analogue signal but want to determine a digital one. $\endgroup$ Mar 8, 2021 at 11:57
  • $\begingroup$ @Adam Heinrich: Sorry for asking, but what's your background? The mean (or average) is a very basic statistical concept typically covered in middle school. $\endgroup$
    – Hilmar
    Mar 8, 2021 at 13:03
  • $\begingroup$ I am a biomedical engineer :D $\endgroup$ Mar 8, 2021 at 13:21

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What is the mean of EMG signal?

Like with any other signal, the mean is simply the average of all samples. It's a very basic math concept and is also sometimes called "bias", "offset", "DC offset", "first moment", etc. Example: the mean of $[1,2,8,9]$ would be $5$

And what's the purpose of removing it?

Look at the graph. The left one is centered around 320 or so and the right is centered around 0. Your original signal consist of a huge constant value with some small wiggles on top of it. You are interested in the wiggles, not the constant value, so you simply subtract it out.

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