Identifying filter type based on magnitutde reponse

This question is one on magnitude respone.

Question:

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Answer:

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You can refer to the answer to see the different values you get when you sub in omega,anyway,the rough sketch of the magnitude response from 0 to pi that I got looks like this:

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Looking at the magnitude response it looks like a band stop filter to me,but the answer provided said that it was a low pass filter? Is the answer wrong maybe?Or am I doing something wrong?

Thanks for the help!

Chebychev LPF, the reason why the magnitude go's back up because its inherent to the chebychev type, butterworths don't have this.

kind regards

For a band stop filter the right side of the response gain after 2*pi/3 would be as large as the left side. The response at pi is much less then the response at 0 (assuming we are looking at a log or dB plot). This means the response is a low pass filter (with ripple in the stop band).

ooh.No wonder the answers said it was a lowpass filter! Thanks alot. =)

Hi,

Sometimes you have to look at more of the response too. If you look at only part of a response it may look like a bandstop but if you look at more of it you'll see that the hills go up and down several times (looks like a hair comb) but the general tendency is to decrease with frequency so overall it's still a low pass filter.
I havent checked this actual response myself (yet) but from what others are saying that's most likely what threw you off.