# Convolution

Discussion in 'Homework Help' started by ihaveaquestion, Oct 25, 2009.

1. ### ihaveaquestion Thread Starter Active Member

May 1, 2009
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Hi guys,

I'm in need of some help understanding convolution.

I understand the process of flipping one signal, shifting it, multiplying the two signals and integrating... but I'm not too good at applying this process yet.

I'm trying to understand this example given in the book.

http://img25.imageshack.us/img25/7140/img0002vv.jpg
http://img195.imageshack.us/img195/1317/img0003dl.jpg

I see what they did to flip the first signal in 15.11b, but the rest is sort of a blur to me.

1) Does it matter how far you shift it like in 15.11b? Why did they decide to shift it halfway across the vertical axis like that?

2) When they shift it for 1 < t < 2 in 15.12b, I don't understand how inside the integral they get (2)(1)... I'm guessing the (2) is from the height of the shaded rectangle, but I don't know about the (1). I do see how they got the boundaries between 1 and t though, since that's the how much of the horizontal axis is shaded.

That's some questions for starters...

Last edited: Oct 26, 2009