MATLAB: How can i smooth this plot

datafiltersmooth

Regards, I have this curve that I show in the screen capture, but its tendency is very scattered I would like to know if there is the possibility of approaching it to a graph of the linear type by means of a filter

thank you very much

attached the data

Best Answer

You have broadband noise. There may be a signal at about 0.35 Hz.

The Fourier transform analysis:

D = xlsread('power.xls');
t = D(:,1);
p = D(:,2);
L = length(t);
Ts = mean(diff(t));                             % Sampling Interval (sec)
Fs = 1/Ts;                                      % Sampling Frequency (Hz)
Fn = Fs/2;                                      % Nyquist Frequency (Hz)
FT_p = fft(p - mean(p))/L;                      % Fourier Transform (Discrete)
Fv = linspace(0, 1, fix(length(t)/2)+1)*Fn;     % Frequency Vector
Iv = 1:length(Fv);                              % Index Vector
figure(1)
plot(Fv, abs(FT_p(Iv))*2)
grid

I will leave it for you to sort this.

Related Solutions

MATLAB: Convert time to frequency domain

To normalise it to a maximum value of 1, divide the Fourier transformed data by the maximum of the Fourier transformed data:

D = load('time_domain.txt');
t = D(:,1);
s = D(:,2);
L = numel(t);                                                   % Vector Length
Ts = mean(diff(t));                                             % Sampling Interval
Fs = 1/Ts;                                                      % Sampling Frequency
Fn = Fs/2;                                                      % Nyquist Frequency
FTs = fft(s)/L;                                                 % Fourier Transform
Fv = linspace(0, 1, fix(L/2)+1)*Fn;                             % Frequency Vector
Iv = 1:numel(Fv);                                               % Index Vector
FTs_plot = abs(FTs(Iv))/max(abs(FTs(Iv)));                      % Normalised Fourier Transform
figure
plot(Fv, FTs_plot)
grid
xlim([0 0.5])

MATLAB: What do I need to add to the code when using loglog to plot

Hi Taylor Grey,

the mistake is in the line when you call the loglog function.

loglog(Fv, 20*log10(abs(FT_af(Iv,2))*2)), xlabel('Frequency, Hz', ylabel('Amplitude, dB'));

you are using the function ylabel as an argument for xlabel, while instead you should separate those commands.

loglog(Fv, 20*log10(abs(FT_af(Iv,2))*2)); xlabel('Frequency, Hz'); ylabel('Amplitude, dB');

Given the fact that you also call xlabel and ylabel later in the script, i would suggest you to just keep the last xlabel and ylabel calls in the following way:


[audio_file, Fs] = audioread("Handgun.wav");
L = size(audio_file,1);
Ts = 1/Fs;                                                      % Sampling Interval
Fn = Fs/2;                                                      % Nyquist Frequency
FT_af = fft(audio_file)/L;                                      % Fourier Transform
Fv = linspace(0, 1, fix(L/2)+1)*Fn;                             % Frequency Vector
Iv = 1:numel(Fv);                                               % Index Vector
[PksL,LocsL] = findpeaks(20*log10(abs(FT_af(Iv,2))*2), 'MinPeakHeight',-90, 'MinPeakDistance',50);
[PksR,LocsR] = findpeaks(20*log10(abs(FT_af(Iv,2))*2), 'MinPeakHeight',-90, 'MinPeakDistance',50);
figure(1);
loglog(Fv, 20*log10(abs(FT_af(Iv,2))*2));
hold on
loglog(Fv(LocsR), PksR, '^r', 'MarkerFaceColor','r')
hold off
xlabel('Frequency (Hz)')
ylabel('Amplitude (dB)')
title('Handgun')

Best Answer

Related Solutions

MATLAB: Convert time to frequency domain

MATLAB: What do I need to add to the code when using loglog to plot

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