心电信号进行stockwell变换matlab

以下是进行心电信号的Stockwell变换的MATLAB代码示例：

%导入心电数据
data = load('ecg_data.mat');
ecg = data.ecg_data;

%计算Stockwell变换
[s, f, t] = st(ecg);

%绘制Stockwell图
imagesc(t, f, abs(s).^2);
set(gca,'YDir','normal');
xlabel('时间（秒）');
ylabel('频率（Hz）');
title('心电信号的Stockwell变换');

%定义Stockwell变换函数
function [s, f, t] = st(x)
%计算频谱宽度
T = length(x);
dt = 1;
pad = 1;
J = ceil(log2(T*dt/pad));
Q = 2^J;
Q2 = Q/2;
L = Q2+1;
%计算Stockwell变换
t = [0:T-1]*dt;
f = [0:L-1]/L/dt;
ff = fft(x,Q);
W = ones(L,1)*ff;
for j=1:J
p = pi*([1:Q2]-1)/Q2;
W(2:Q2,j+1) = W(2:Q2,j).*exp(-i*p').*(ones(Q2-1,1)*sqrt(1-2.^(1-2*j)));
W(Q2+2:Q,j+1) = W(Q2+2:Q,j).*exp(i*p').*(ones(Q2-1,1)*sqrt(1-2.^(1-2*j)));
W(1,j+1) = sqrt(Q)*sum(x.*gausswin(Q)')/sqrt(sum(gausswin(Q)));
W(Q2+1,j+1) = sqrt(Q)*sum(x.*hamming(Q)')/sqrt(sum(hamming(Q)));
W(:,j+1) = fft(W(:,j+1),Q);
end
s = zeros(L,T);
for j=1:J
s = s+W(1:L,j)*ones(1,T).*conj(W(1:T,j));
end
s = s/L;
end