Error with freqz plot

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Stefan
Stefan on 8 Aug 2014
Commented: BHASKER GURRAM on 28 Mar 2021
Hello, I am trying to see the frequency plot of the filter but it is showing error as
The Numerator and denominator of the transfr frunstion must be stored in vectors at this line freqz(sos1,1001);
Fs = 100;
Fn = Fs/2;
% Design First Filter:
Ws1 = [0.2 0.35]/Fn;
n1 = 2; % Filter ORder
R = 20; % Stopband Attenuation
[b1, a1] = cheby2(n1,R,Ws1,'stop'); % Create Filter
[sos1,g1] = tf2sos(b1,a1); % SOS Implementation
figure(5)
freqz(sos1,1001) % Plot Normalised Response
Can anyone explain why is the error showing up. thanks.
  2 Comments
Star Strider
Star Strider on 8 Aug 2014
No idea. I just ran that code again (I tested it before I posted it) and it ran without errors (R2014a).
BHASKER GURRAM
BHASKER GURRAM on 28 Mar 2021
i am also facing same problem

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Answers (1)

Honglei Chen
Honglei Chen on 8 Aug 2014
If I remember correctly you have an older version of MATLAB which does not support this syntax. You could try the following instead
freqz(b1,a1,1001)
For a 2nd order filter, they should be pretty much the same.
HTH

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