Ecg Extraction Code

Contents

n ZERO CROSSING REMOVAL

n DETECT R_PEAK

n Calculate R in the actual Signal

n After R Peak Tracking ... DETCET OTHERS

n ONSET

n P Peak

n Q Detection

n S Detection

n T Peak

n END OF T

% Load original 1D signal.

clc;

clear all;

close all;

ELEVATED=[];

[fname path]=uigetfile('*.mat');

fname=strcat(path,fname);

load(fname );

z=zeros(100,1);

A=val(1,:);

v1=val(1,:)-val(1,1);

A=v1;

A=A';

zc=A(1);

A=[z;A;z];

% Plot Actual Signal s = A(1:1:400);

s = A;

ls = length(s);

figure(1)

plot(s);

title('Original Signal'),grid on

% Perform decomposition at level 8 of s using db4

[c,l]=wavedec(s,8,'db4');

ca1=appcoef(c,l,'db4',1);








%Plot the coefficient

figure(2)

plot(c),title('decomposed signal'),grid on

figure(3)

subplot(4,2,1)

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plot(ca1),title('1st level approximation'),grid on

subplot(4,2,2)

plot(ca2),title('2nd level approximation'),grid on

subplot(4,2,3)

plot(ca3),title('3rd level approximation'),grid on

subplot(4,2,4)

plot(ca4),title('4th level approximation'),grid on

subplot(4,2,5)


subplot(4,2,6)


subplot(4,2,7)


subplot(4,2,8)


% Extract detail coefficients at levels

% 1, 2 and 3, from wavelet decomposition

% structure [c,l].

[cd1,cd2,cd3,cd4,cd5,cd6,cd7,cd8] = detcoef(c,l,[1 2 3 4 5 6 7 8]);

figure(4)

subplot(4,2,1)

plot(cd1),title('detail coeff: level 1 cd1'),grid on

subplot(4,2,2)


subplot(4,2,3)


subplot(4,2,4)


subplot(4,2,5)


subplot(4,2,6)


subplot(4,2,7)


subplot(4,2,8)




ZERO CROSSING REMOVAL

base_corrected=ca2;

y=base_corrected-zc;

figure(5)

plot(y),grid on

title('Noise Free signal')


DETECT R_PEAK

y1=y;

m1=max(y1)-max(y1)*.60;

P=find(y1>=m1);

% it will give two two points ... remove one point each

P1=P;

P2=[];

last=P1(1);

P2=[P2 last];

for(i=2:1:length(P1))

if(P1(i)>(last+10))

last=P1(i);

P2=[P2 last];

end

end

Rt=y1(P2);

figure(6)

plot(y1),grid on,hold on

plot(P2,Rt,'*');

title('Rpos in downsampled signal');


C� � � � � � te R � n t� e � � t� � � S� � n� �

P3=P2*4;

Rpos=[];

for( i=1:1:length(P3))

range= [P3(i)-20:P3(i)+20];

m=max(A(range));

l=find(A(range)==m);

pos=range(l);

Rpos=[Rpos pos];

end

Ramp=A(Rpos);

figure(7)

plot(A),grid on,hold on

plot(Rpos,Ramp,'*');

title('Detected R peak in actual Signal');

R_peaks = length(Rpos)

%disp([num2str(R_peaks) ' peaks'])

R_peaks =

13


A� ter R Pe� � Tr� � � � n� � � � DETCET OT� ERS

ONSET

X=Rpos;

y1=A;

for(i=1:1:1)

for(j=1:1:length(X))

a=X(j)-100:X(j)-50;

m=max(y1(a));

b=find(y1(a)==m);

b=b(1);

b=a(b);

fnd=0;

for k=b-20:+1:b

if((y1(k)<=0) && (y1(k-1)>0))

qon1=k;

fnd=1;

break

end

end

if(fnd==0)

Qrange=b-20:+1:b;

qon1=find(y1(Qrange)==max(y1(Qrange)));

qon1=Qrange(qon1);

end


P Pe� �

� Dete� t� on

RON(i,j)=qon1(1);

fnd;

for k=b:+1:b+20

if((y1(k)<=0) && (y1(k-1)>0))

qon1=k;

fnd=1;

break

end

end

if(fnd==0)

Qrange=b:+1:b+20;


qon1=Qrange(qon1);

end

ROF(i,j)=qon1(1);

a=Rpos(i,j)-100:Rpos(i,j)-10;

m=max(y1(a));

b=find(y1(a)==m);

b=b(1);

b=a(b);

Ppos(i,j)=b;

Pamp(i,j)=m;

end

a=Rpos(i,j)-50:Rpos(i,j)-10;

m=min(y1(a));

b=find(y1(a)==m);

b=b(1);

b=a(b);

Qpos(i,j)=b;

Qamp(i,j)=m;

%%%%% ONSET

fnd=0;

for k=b-20:+1:b

if((y1(k)<=0) && (y1(k-1)>0))

qon1=k;

fnd=1;

break

end

end

if(fnd==0)

Qrange=b-20:+1:b;


qon1=Qrange(qon1);

end

QON(i,j)=qon1(1);

fnd;

for k=b:+1:b+20

if((y1(k)<=0) && (y1(k-1)>0))

qon1=k;


S Dete� t� on

T Pe� �

fnd=1;

break

end

end

if(fnd==0)

Qrange=b:+1:b+20;


qon1=Qrange(qon1);

end

QOF(i,j)=qon1(1);

a=Rpos(i,j)+5:Rpos(i,j)+50;

m=min(y1(a));

b=find(y1(a)==m);

b=b(1);

b=a(b);

Spos(i,j)=b;

Samp(i,j)=m;

%%%% onset off

fnd=0;

for k=b-5:+1:b

if((y1(k)<=0) && (y1(k-1)>0))

qon1=k;

fnd=1;

break

end

end

if(fnd==0)

Qrange=b-20:+1:b;


qon1=Qrange(qon1);

end

SON(i,j)=qon1(1);

fnd=0;

for k=b:+1:b+20

if((y1(k)<=0) && (y1(k-1)>0))

qon1=k;

fnd=1;

break

end

end

if(fnd==0)

Qrange=b:+1:b+20;


qon1=Qrange(qon1);

end

SOFF(i,j)=qon1(1);


m=max(y1(a));

b=find(y1(a)==m);

b=b(1);

b=a(b);


END O� T

Tpos(i,j)=b;

Tamp(i,j)=m;

%%%% onset off

fnd=0;

for k=b-20:+1:b

if((y1(k)<=0) && (y1(k-1)>0))

qon1=k;

fnd=1;

break

end

end

if(fnd==0)

Qrange=b-20:+1:b;


qon1=Qrange(qon1);

end

TON(j,i)=qon1(1);

fnd=0;

for k=b:+1:b+20

if((y1(k)<=0) && (y1(k-1)>0))

qon1=k;

fnd=1;

break

end

end

if(fnd==0)

Qrange=b:+1:b+20;


qon1=Qrange(qon1);

end

TOFF(j,i)=qon1(1);

if(Tamp(i,j)<Pamp(i,j))


m=min(y1(a));

b=find(y1(a)==m);

b=b(1);

b=a(b);

Tpos(i,j)=b;

Tamp(i,j)=m;

ELEVATED=[ELEVATED j];

end

end

figure;

k=1;

for(i=1:1:1)

%subplot(6,1,k);

plot(y1), hold on;

plot(Rpos(i,:),Ramp(i,:),'*'),hold on;

plot(Qpos(i,:),Qamp(i,:),'+'),hold on;

plot(Spos(i,:),Samp(i,:),'+'),hold on;

plot(Ppos(i,:),Pamp(i,:),'.'), hold on

plot(Tpos(i,:),Tamp(i,:),'^')


legend('Ramp','Qamp','Samp','Pamp','Tamp')

grid on;

k=k+1;

if(k>6)

k=1;

figure;

end

end

% Detected no of peaks


P_peaks = length(Ppos)

T_peaks = length(Tpos)

S_peaks = length(Spos)

Q_peaks = length(Qpos)

clc;

flag=0;

if(length(ELEVATED)>ceil(.8*length(Rpos)))

disp('T inverted (MI Detected) with T inverted Logic')

return;

else

flag=1;

end


P_peaks = length(Ppos)

T_peaks = length(Tpos)

S_peaks = length(Spos)

Q_peaks = length(Qpos)

R_peaks =

13

P_peaks =

13

T_peaks =

13

S_peaks =

13

Q_peaks =

13

R_peaks =

13


Published with MATLAB® 7.14

P_peaks =

13

T_peaks =

13

S_peaks =

13

Q_peaks =

13


Date post:	28-Apr-2015
Category:	Documents
Upload:	abdkabeer-akande
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Ecg Extraction Code

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