how to make an envelope of a signal?
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He,
I have some trouble with making an envelope of a noisy signal with Matlab. Is there some function to do this?
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Image Analyst
am 12 Mär. 2012
Try morphological dilation and erosion - they're the local max and min. Use imdilate and imerode if you have the image processing toolbox.
numberOfSamples = 200;
t = linspace(0, 4*pi, numberOfSamples);
decay = exp(-t);
y = 10 .* sin(t) .* exp(-t) + rand(1, numberOfSamples);
plot(t, y, 'r-');
grid on;
% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);
upperEnvelope = imdilate(y, true(1, 9));
lowerEnvelope = imerode(y, true(1, 9));
hold on;
plot(t, upperEnvelope, 'b-', 'LineWidth', 2);
plot(t, lowerEnvelope, 'b-', 'LineWidth', 2);
Or try this File Exchange submission: http://www.mathworks.com/matlabcentral/fileexchange/27662-evolve-top-and-bottom-envelopes-for-time-signals-i-e
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Andrei Bobrov
am 12 Mär. 2012
Use rand, randn, etc.
eg
x = linspace(0,2*pi,300);
sx = sin(x);
out = sx + .2*(2*rand(size(x)) - 1);
plot(x,sx,'b.',x,out,'r*'); grid on
2 Kommentare
sunil kalyankar
am 26 Mär. 2018
i have data in time domain envelope analysis pls help me in writing matlab code pls pls
Image Analyst
am 26 Mär. 2018
There are now boundary() and envelope() functions in MATLAB. Try them.
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