波动信号的包络线MATLAB程序生成
<font color="#000000">此程序源自MATLAB CENTRAL。% Find upper and lower envelopes of a given signal
% The idea is from Envelope1.1 by Lei Wang, but here it works well when the signal contains
% successive equal samples and also includes first and last samples of the signal in the envelopes.
% inputs:
% sig: vector of input signal
% method: method of interpolation (defined as in interp1)
% outputs:
% upperenv: upper envelope of the input signal
% lowerenv: lower envelope of the input signal
function = envelope(sig, method)
if nargin == 1
method = 'linear';
end
upperind = find(diff(sign(diff(sig))) < 0) + 1;
lowerind = find(diff(sign(diff(sig))) > 0) + 1;
f = 1;
l = length(sig);
try
upperind = ;
lowerind = ;
catch
upperind = ;
lowerind = ;
end
xi = f : l;
upperenv = interp1(upperind, sig(upperind), xi, method, 'extrap');
lowerenv = interp1(lowerind, sig(lowerind), xi, method, 'extrap');
-----
用法如
sig=;
envelope(sig,'linear')
ans =
Columns 1 through 12
1.0000 2.0000 2.5000 3.0000 3.5000 4.0000 4.5000 5.0000 5.5000 6.0000 6.5000 7.0000
Columns 13 through 20
7.5000 8.0000 8.5000 9.0000 9.5000 10.0000 10.5000 11.0000
= envelope(sig, 'linear');
plot(sig);
hold on;
plot(upperenv); </font>
转自：http://blog.sina.com.cn/s/blog_49c02a8c0100yt0y.html
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