MATLAB: Hi, how can I divide this signal into 3 segments? The first segment I want to be the signal before the major peak, the second segment would be the major peak and the last segment would be the signal after the peak.

signalsignal processingsignal segmentation

The first segment I want to be the signal before the major peak, the second segment would be the major peak and the third segment would be the signal after the major peak. You can find the signal attached.

Best Answer

One approach:

The Code —

D = load('signals (1).mat');
Signal = D.Signal;                                                                                      % Get ‘Signal’
N = length(Signal);
t = linspace(0, 1, N) * N;                                                                              % Create Time Vector
[pk,loc] = findpeaks(Signal, 'MinPeakHeight',1);                                                        % Determine Indices Of Various Components
[trofs,trlocs] = findpeaks(-Signal);
ltidx = find(trlocs < loc, 1, 'last');
gtidx = find(trlocs > loc, 1, 'first');
Out{1} = {Signal(1:trlocs(ltidx)); Signal(trlocs(ltidx)+1:trlocs(gtidx)-1); Signal(trlocs(gtidx):end)}; % ‘Signal’ Cell Array
Out{2} = {t(1:trlocs(ltidx)); t(trlocs(ltidx)+1:trlocs(gtidx)-1); t(trlocs(gtidx):N)};                  % ‘t’ Cell Array
figure
plot(Out{2}{1}, Out{1}{1}, 'r')
hold on
plot(Out{2}{2}, Out{1}{2}, 'g')
plot(Out{2}{3}, Out{1}{3}, 'b')
hold off
grid

The Plot —

Related Solutions

MATLAB: How to plot the spectrum of two segments from this signal

Try this:

D = load('signals (1).mat');
Signal = D.Signal;                                                                                      % Get ‘Signal’
N = length(Signal);
t = linspace(0, 1, N) * N;                                                                              % Create Time Vector
[pk,loc] = findpeaks(Signal, 'MinPeakHeight',1);                                                        % Determine Indices Of Various Components
[trofs,trlocs] = findpeaks(-Signal);
ltidx = find(trlocs < loc, 1, 'last');
gtidx = find(trlocs > loc, 1, 'first');
Out{1} = {Signal(1:trlocs(ltidx)); Signal(trlocs(ltidx)+1:trlocs(gtidx)-1); Signal(trlocs(gtidx):end)}; % ‘Signal’ Cell Array
Out{2} = {t(1:trlocs(ltidx)); t(trlocs(ltidx)+1:trlocs(gtidx)-1); t(trlocs(gtidx):N)};                  % ‘t’ Cell Array
figure
plot(Out{2}{1}, Out{1}{1}, 'r')
hold on
plot(Out{2}{2}, Out{1}{2}, 'g')
plot(Out{2}{3}, Out{1}{3}, 'b')
hold off
grid
xlim([min(t) max(t)])
figure
subplot(2, 2, 1);
plot(Out{2}{1}, Out{1}{1}, 'r')
grid
subplot(2, 2, 2);
plot(Out{2}{2}, Out{1}{2}, 'g')
grid
subplot(2, 2, 3);
plot(Out{2}{3}, Out{1}{3}, 'b')
grid
FFTN = 2^14;
% Fv = linspace(0, 1, fix(FFTN/2)+1);
for k1 = 1:numel(Out{1})
    Ts = mean(diff(Out{2}{k1}));
    Fs = 1/Ts;
    Fn = Fs/2;
    FTSeg{k1} = fft(Out{1}{k1},FFTN);
    Fv{k1} = linspace(0, 1, fix(numel(FTSeg{k1})/2)+1)*Fn;
    Iv{k1} = 1:numel(Fv{k1});
end
ttlcs = {'Signal Before Peak', 'Peak', 'Signal After Peak'};
figure
for k1 = 1:numel(Out{1})
    subplot(numel(Out{1}), 1, k1)
    plot(Fv{k1}, abs(FTSeg{k1}(Iv{k1})*2))
    xlim([0  0.02])
    title(ttlcs(k1))
end

The Plot —

How can I plot the spectrum of two segments from this signal - 2018 12 30.png

MATLAB: How to smooth a signal while preserving peaks in MATLAB (R2013a)

In order to smoothe noisy data while preserving the peaks, you can use the function MSSGOLAY, which smoothes a signal with peaks using least-squares polynomial or MSLOWESS, which smoothes a signal with peaks using nonparametric method.

More information on either of these algorithms can be found in the Documentation:

>> doc mssgolay
>> doc mslowess

Best Answer

Related Solutions

MATLAB: How to plot the spectrum of two segments from this signal

MATLAB: How to smooth a signal while preserving peaks in MATLAB (R2013a)

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