# C3_W1 channel noise

this video
Can some please explain to me this part: power noise thing. I cannot understand the math (or physics) of the relation between noise and message as related to chi distribution. I cannot even frame my problem! So confused.
I wonder why instructor cannot find easier example

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Hello @Hassan_Mohamed6,

Any real-world signal can be contaminated with noise. The lecture uses â€śmessageâ€ť because it carries noise and people process the noise in terms of power. Getting at the â€śpower of noiseâ€ť is the reason why the lecture spends the first 1:20. In other words, the lecture was just trying to find a practical use of Z^2 so that you know indeed such term is of interest. This is it, and this is all about whatever relation you can find with noise and message in this lecture, and nothing more, period.

After Z^2 is introduced, the lecture goes straight into discussing Chi-square distribution. You donâ€™t need layman concepts like message / power / noise to discuss Chi-Square, you can discuss Chi-square like what I have suggested in this reply to you.

Ok? So, donâ€™t dig too deep into message / noise / power stuff. It takes another long lecture focusing of these topics to understand them, not just in a 3:20 lecture for Chi-square distribution.

Cheers,
Raymond

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