How can I apply median filter with sliding window for the ECG signal?

How can I apply median filter with sliding window n=200 ms and n=600 ms in Matlab fo a signalat sample rate 360 Hz?

load 100m.mat

figure(1);

plot(val)

x=medfilt1(val,200);

figure(2);

plot(x)

y=medfilt1(val,600);

figure(3);

plot(y)

Answer 1

[Daniel M]

The second input of the function medfilt1 determines the window size.

%   Y = MEDFILT1(X,N) specifies the order, N, of the median filter.
%   For N odd, Y(k) is the median of X( k-(N-1)/2 : k+(N-1)/2 ).
%   For N even, Y(k) is the median of X( k-N/2 : k+N/2-1 ).

In your case, the order will be however many samples it takes to 200 ms at 360 Hz. E.g. 0.600*fs = 216. Otherwise, it will be length(t)-1.

load 100m.mat
fs = 360; % Hz
t200 = 0:1/fs:0.2; 
t600 = 0:1/fs:0.6;

figure(1);
plot(val)
x=medfilt1(val,length(t200)-1);
figure(2);
plot(x)
y=medfilt1(val,length(t600)-1);
figure(3);
plot(y)

[Dhiyaa Al-Shammari]

Thanks alot dear brother

I think also the result of the x will be an input to the second medfilt1 as follow instead of putting val ine second filter I have put the variable x. Is that right ?

x=medfilt1(val,length(t200)-1);

y=medfilt1(x,length(t600)-1);

[Daniel M]

x is already a median filtered version of val. If you want to filter it again, then use x as an input to medfilt1.