# Region of Covolution

Discussion in 'Homework Help' started by Anthony Quah, Apr 1, 2008.

1. ### Anthony Quah Thread Starter Active Member

Dec 1, 2007
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Guy,

i failed to image how the ROC graph will look like...any help?

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Nov 9, 2007
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3. ### Mark44 Well-Known Member

Nov 26, 2007
626
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Anthony,
What are you trying to do? Do you understand what's going on in the scanned image you sent?
The title of the thread if Region of Covolution (actually the word is convolution), but I suspect that ROC in the image you sent stands for region of convergence.

There's not enough information in what you sent for me to follow the argument. In part a, I think they're taking the Z transform of x[n] to get X(z), but then they say to use H(z) = Y(z)/X(z) to find H(z). Nowhere is there a definition of Y(z) in what you sent. At the end of part a, they say that H(z) causal (I don't know what that means) implies that ROC |z| > 1. I take it that this means that the function H(z) converges for complex values lying outside a circle of radius 1 centered at the origin of the complex plane.

Anthony, you're tackling some very weighty concepts that require a solid knowledge of calculus. I suspect that you don't have much background in calculus, based on a question you asked in another thread about the integration symbol. If my suspicions are correct, you're going to have a difficult time understanding the material you're studying until you get a better understanding of integration, one of the two main concepts of calculus.
Mark

4. ### Anthony Quah Thread Starter Active Member

Dec 1, 2007
80
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yeah..but unfortunately my lecturer dont understand student lack of knowledge..

5. ### Mark44 Well-Known Member

Nov 26, 2007
626
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On the other hand, an instructor is obligated to cover a certain set of topics in the class, and must be able to assume that students have the requisite knowledge for the class.

Are there prerequisites for the class you're taking? If so, have you taken those classes? If you haven't, it isn't reasonable for you to expect your instructor to bring you up to where you need to be.

I'm not trying to discourage you in your studies, but you need to be realistic about the level of difficulty of the course you're in and what it will take to be successful.
Mark

6. ### Dave Retired Moderator

Nov 17, 2003
6,960
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I assume you or your parents are paying for your studies - if so you have an expectation of the quality of service the lecturer is expected to provide, and if you feel he is not providing you with sufficient support then you should register your complaint to the college/university department.

Just because a lecturer has a status within an institution does not mean they don't have obligations to the students that pay for tuition.

Dave