# Electronics and Communication Engineering - Signals and Systems - Discussion

Discussion Forum : Signals and Systems - Section 1 (Q.No. 4)
4.
Consider Pole zero diagram as shown, If two Poles are moved in opposite direction towards ω = p/2 and -p/2, the filter will be
change to high pass filter
change to Band Pass filter
remains same
change to LPF
Explanation:

But still we will get the same response, zero are at same position.

Discussion:
13 comments Page 1 of 2.

Neal said:   3 years ago
Not getting a clear solution. Anyone explain.

Fatima noor said:   4 years ago
Zeros are same but poles are changed. Then How we get the same response?

Geetha said:   5 years ago
I didn't understand, Please anyone, explain me.

Lavanya said:   5 years ago
I am not getting this, can anyone explain me in clear?

Rachana said:   5 years ago
Thank you all for providing best explanation.

K.ramesh said:   6 years ago
What is the LPF?

Kishore said:   6 years ago
In denominator how did z^2 came, poles should come in denominator and zeroes should come in the numerator. Explain me clearly.

Ghanshyam said:   7 years ago
How does it take to pole at the origin?

Bibo said:   8 years ago
For digital domain, in low frequency w = 0 hence z = exp(j0) = 1.
High-frequency w = pi, z = -1 now put z = 1 and -1 and find response, you will get zero every time.

Hence, both are Band Pass filter.

Neha said:   8 years ago
If you consider x(z) = (z-1)(z+1)/z2.

Then if z = ejw = cosw + jsinw.

Then x(ejw) = (e2jw - 1)/e2jw.

Now magnitude is X(w) = ((Cos 2w-1)2 + (sin 2w)2) 1/2.

As magnitude = (Real 2+image 2) 1/2.

So the plot is given for its magnitude similarly when you change the poles there won't be change in magnitude, hence filter remains the same.

Hope you will understand this.