maryszoo
Newbie level 2
matlab fir1
Hi -
I am using FIR1, and then plotting the filter response. The definition of FIR1 says the response should be -6db at Wn. However, I have plotted this many differnet ways, and the -6dB point is not at Wn. Here is the code, to show the problem. I would appreciate any help.
%
% Plot the FIR filter using FREQZ
%
FIR_NUM = fir1(8,0.1); % Numerator
% This is a filter. It should have 9 coefficients,
% and the Wn value = 0.1*(100kHz/2) = 5kHz
% By definition, the response should be -6dB at 5kHz or Wn = 0.1
% normalized.
FIR_DEN = [1 0 0 0 0 0 0 0 0]; % Denominator
%
freqz(FIR_NUM,FIR_DEN)
% PROBLEM: The -6dB point is around 0.22, not 0.1
Thank you - Mary
Hi -
I am using FIR1, and then plotting the filter response. The definition of FIR1 says the response should be -6db at Wn. However, I have plotted this many differnet ways, and the -6dB point is not at Wn. Here is the code, to show the problem. I would appreciate any help.
%
% Plot the FIR filter using FREQZ
%
FIR_NUM = fir1(8,0.1); % Numerator
% This is a filter. It should have 9 coefficients,
% and the Wn value = 0.1*(100kHz/2) = 5kHz
% By definition, the response should be -6dB at 5kHz or Wn = 0.1
% normalized.
FIR_DEN = [1 0 0 0 0 0 0 0 0]; % Denominator
%
freqz(FIR_NUM,FIR_DEN)
% PROBLEM: The -6dB point is around 0.22, not 0.1
Thank you - Mary