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I need to find difference equation and frequency response

Asked by Noel on 15 Nov 2011

Given H(z)=(-3+z^z-1)/(1+2z^-1+3z^-2)

a) Find the difference equation

b) Plot the frequency response

1 Comment

Naz on 15 Nov 2011

Right. And what's your question?

Noel

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2 Answers

Answer by Walter Roberson on 15 Nov 2011

Please see this previous discussion

However, it appears to me that your equation probably cannot be analyzed through these techniques, as it is not in the form of a ratio of polynomials. The z^z term is going to lead you to a lot of problems.

0 Comments

Walter Roberson
Answer by Naz on 15 Nov 2011

Difference equation (I assume that z^z-1 should be z^-1):

3y[n-2]+2y[n-1]+y[n]=-3x[n]+z[n-1]

Frequency response:

B=[-3 1];
A=[1 2 3];
[H,W] = freqz(B,A);
plot(W,H);

2 Comments

Naz on 15 Nov 2011

The frequency is normalized to pi

Walter Roberson on 15 Nov 2011

My speculation was that the z^z-1 should be z^2 - 1 but that doesn't make sense with the leading -3 . So I still don't know what was intended.

Naz

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