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Window Design of Digital Filters

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Hi. I am calling the fir1 function to design an FIR filter. One argument of fir1 is the type of window that is to be used, e.g., hann, hamming, etc. However, the type of window depends on the stopband attentuation that one requires. So, I have an if ... else ... end conditional prior to callng fir1. it looks like
if deltadB_max <= 21
FixedWindow = 'rectwin';
else
FixedWindow = 'bartlett';
end
Now, when I invoke fir1, how can pass the variable FixedWindow into the arguments of fir1? Thank you.

Accepted Answer

Star Strider
Star Strider on 14 Apr 2020
Both the rectwin and bartlett functions have a single length argument. That simplifies this considerably.
if deltadB_max <= 21
FixedWindow = @(L) rectwin(L);
else
FixedWindow = @(L) bartlett(L);
end
L = 35;
b = fir1(34,0.48,FixedWindow(L)); % Test Design
freqz(b,1)
That ran without error and gave the appropriate result when I ran it (R2020a) with different values for ‘deltadB_max’.
For windows that require more parameters or different parameters, this would need to be changed appropriately. I leave that to you.
.
  2 Comments
Star Strider
Star Strider on 14 Apr 2020
As always, my pleasure!

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