can't fing notching filter

hi everyone! for some reason i don't have a notching filter in "filter designer". could someone say if maybe i don't have a needed version or some additional app? thank you in advance!

Answer 1

[Star Strider]

First, the bandstop function is likely an effective substitute.

Second, both FIR and IIR notch filters are straightforward to design in MATLAB.

A design for a FIR notch filter for 60 Hz mains interference is —

Fs = 250;                                                               % Use Correct Sampling Frequency (Must Be Greater Than 250 Hz)
fcomb = [55 59 61 64]-10;
mags = [1 0 1];
dev = [[0.5 0.1 0.5]];
[n,Wn,beta,ftype] = kaiserord(fcomb,mags,dev,Fs);
hh = fir1(n,Wn,ftype,kaiser(n+1,beta),'noscale');

figure
freqz(hh, 1, 2^20, Fs)
set(subplot(2,1,1), 'XLim', [0 100])                                    % Zoom X-Axis
set(subplot(2,1,2), 'XLim', [0 100])                                    % Zoom X-Axis

Fn = Fs/2;
N = 2^14;
t = linspace(0, 100, N);
s = randn(size(t));
s_filt = filtfilt(hh, 1, s);
FTs = fft([s(:) s_filt(:)])/N;
Fv = linspace(0, 1, N/2+1)*Fn;
Iv = 1:numel(Fv);

figure
subplot(2,2,1)
plot(t, s)
grid
xlabel('t')
title('Original (Time Domain')
subplot(2,2,2)
plot(t, s_filt)
grid
xlabel('t')
title('Filtered (Time Domain')
subplot(2,2,3)
plot(Fv, abs(FTs(Iv,1))*2)
grid
xlabel('f')
title('Original (Frequency Domain)')
xlim([0 Fn])
subplot(2,2,4)
plot(Fv, abs(FTs(Iv,2))*2)
grid
xlabel('f')
title('Filtered (Frequency Domain)')
xlim([0 Fn])

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