# Very basic question about fir1 command

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Pelin Kaya on 30 Jun 2022
Commented: Star Strider on 30 Jun 2022
I'm all new to Matlab and everything including, i was taking some classes to learn matlab and signal processing and there was this question that my teacher asked during an exam and i still havent figured it out . She basically gave us a signal ;
t=0:1/500:0.3
n=cos(2*pi*10*t) + sin(2*pi*50*t);
and asked us to design a FIR filter with 32-order and then plot the signal. There's no other explanation, i'm assuming i should use fir1 command but i'm not sure how. If you guys help me, that'd really help.

Star Strider on 30 Jun 2022
Probably something like this —
t=0:1/500:0.3;
n=cos(2*pi*10*t) + sin(2*pi*50*t);
Fs = 500;
Fn = Fs/2;
b = fir1(32, 25/Fn);
figure
freqz(b, 1, 2^16, Fs)
n_filt = filtfilt(b, 1, n);
figure
plot(t, n)
hold on
plot(t, n_filt)
hold off
grid
legend('Original Signal','Filtered Signal', 'Location','best')
Experiment with it!
.
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Star Strider on 30 Jun 2022
My pleasure!
.