Area of a signal

Hi, need to find area of an emg signal

With this code:

for c=2:2

A=strcat('S1_',num2str(c));

B=strcat(A,'.emt');

D=importdata(B,'\t',12);

[F, C]=size(D.data);

x=filter(Filtro_emg,D.data);

centro=(F-mod(F,2))/2;

x=x((centro-4000)+133:(centro-4000)+483,:);

RMS = Rms_emg (x,100)*1000;

S=smoothdata(RMS);

figure

for b=3:3

plot(S(:,b));title('Tibial anterior');grid;xlabel('Tiempo mseg');ylabel('uV');

AreaGM1=sum(S(:,b));

end

end

I have a result of 42756.251 uV (I supose it's impossible in a time of 350 miliseconds-line 8). If x is time in miliseconds, how could I add it in my code?

Thank you so much

[AndresVar]

What are the units of S?, if S is in uV, then actually your area is 42756.251 uV*ms?

if x is in miliseconds and dx = 1 ms then i suppose your sample rate is uniform 1kHz

area = sum(dS*dt)=sum(dS)*dt~sum(S)*1ms

[Julio Martín]

Hi Thanks, don’t know what you mean with d or dt, none of my variables has that name Thanks

Answer 1

[KSSV]

Read about trapz.

[Julio Martín]

Thanks