Matlab DSP Difference equation and invert Biquad?

Discussion in 'Homework Help' started by Andyfreqz, Dec 19, 2010.

  1. Andyfreqz

    Thread Starter New Member

    Dec 19, 2010
    1
    0
    Hi, i have done an awfull lot of my assignment but am stuck on a few things, i have to randomly choose to poles and zeros on a zplane of a biquad iir filter. I was just wondering how the difference equation should be calculated manually? I have used [b,a] = zp2tf (z,p,1); to calculate the a and b coefficients for the difference equation and used freqz to plot the frequency response, i was just wondering how one would do this manually?

    Also the only other bit i am stuck on is how to invert the BiQuad? Do i just use the same m file and add inverted zeros and poles to it?

    Any help is appreciated thanks! If any more information is needed i can provide that also!
     
  2. guitarguy12387

    Active Member

    Apr 10, 2008
    359
    12
    Typically you do pole/zero design in the frequency domain. So you'd choose your poles and zeros and derive your transfer function from those locations. Then take the inverse z transform to find the difference equation.

    Is that what you are asking?

    I am not familiar with this. What do you mean 'invert' the biquad? What purpose would this serve?
     
  3. shteii01

    AAC Fanatic!

    Feb 19, 2010
    3,377
    494
    Here is example from my DSP class.
     
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