Comparing the curves of the graphs
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Comparing the curves
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/902155/image.png)
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/902160/image.png)
>> NFFT = 2^nextpow2(L); % Next power of 2 from length of y
Y = fft(y,NFFT)/L;
f = Fs/2*linspace(0,1,NFFT/2+1);
% Plot single-sided amplitude spectrum.
plot(f,2*abs(Y(1:NFFT/2+1)))
title('Single-Sided Amplitude Spectrum of y(t)')
xlabel('Frequency (Hz)')
ylabel('|Y(f)|')
>> Fs = 1000; % Sampling frequency
T = 1/Fs; % Sample time
L = 1000; % Length of signal
t = (0:L-1)*T; % Time vector
% Sum of a 50 Hz sinusoid and a 120 Hz sinusoid
x = 0.7*sin(2*pi*50*t) + sin(2*pi*120*t);
y = x + 2*randn(size(t)); % Sinusoids plus noise
plot(Fs*t(1:50),y(1:50))
title('Signal Corrupted with Zero-Mean Random Noise')
xlabel('time (milliseconds)')
>>
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Answers (1)
Image Analyst
on 21 Feb 2022
The spectrum (left plot) shows a spike at 50 and 120 Hz. I'd never know that there is monotone noise at those exact frequencies just by looking at the time domain plot on the right. So I'd say the frequency domain plot is most informative in this particular case.
4 Comments
Image Analyst
on 27 Feb 2022
I don't know why you did that instead of what I suggested. Anyway, attach your y in a .mat file with the paperclip icon.
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