How to make envelope of signal that connects its peaks?

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Salah Alfiky
Salah Alfiky 2023-2-23
评论： Salah Alfiky 2023-2-23
Ran in:
I want to make exactly this picture above
I used this code
clc
vmax=1;
f=50;
w=2*pi*f;
R=0.0019462;
L=3*10^-3;
Z=sqrt((R)^2+(w*L)^2);
t=[0:0.01*pi:3*pi];
alpha=0; %The parameter controls the instant on the voltage wave when short circuit occurs.
vs=sqrt(2)*vmax*sind(w*t+alpha);
%oThe short circuit is assumed to take place at t = 0
theta=rad2deg(atan(w*L/R));
is=((sqrt(2)*vmax)/Z)*sind(w*t+alpha-theta); %symmetrical sc component
it=((sqrt(2)*vmax)/Z)*sind(theta-alpha)*exp((-R/L)*t); %DC offset current2
time_constant=L/R
time_constant = 1.5415
vanish_time=5*time_constant
vanish_time = 7.7073
imm=2*max(is) %if the decay is to be neglected
imm = 3.0008
%{
This has the maximum possible value for = 0, i.e. short circuit occurring
when the voltage wave is going through zero.
%}
i=is+it;
plot(t,is,t,it,t,i)
hold on
grid on
yticks(-3:1:3)
xlim([0 vanish_time])
yline(imm)
hold off

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采纳的回答

Image Analyst
Image Analyst 2023-2-23
Did you try envelope (requires the Signal Processing Toolbox)?
  3 个评论
显示 1更早的评论
Askic V
Askic V 2023-2-23
Ran in:
THis small code should show you the trick:
t = 0:0.1:10;
y = exp(-0.1*t).*sin(10*t);
[yup,ylo] = envelope(y);
plot(t,y)
hold on
plot(t,yup,t,ylo)
Salah Alfiky
Salah Alfiky 2023-2-23
Ran in:
thank you it worked bu I added 'peak' to the attributes of the envelope function to make it look smooth
clc
vmax=1;
f=50;
w=2*pi*f;
R=0.0019462;
L=3*10^-3;
Z=sqrt((R)^2+(w*L)^2);
t=[0:0.01*pi:3*pi];
alpha=0; %The parameter controls the instant on the voltage wave when short circuit occurs.
vs=sqrt(2)*vmax*sind(w*t+alpha);
%oThe short circuit is assumed to take place at t = 0
theta=rad2deg(atan(w*L/R));
is=((sqrt(2)*vmax)/Z)*sind(w*t+alpha-theta); %symmetrical sc component
it=((sqrt(2)*vmax)/Z)*sind(theta-alpha)*exp((-R/L)*t); %DC offset current2
time_constant=L/R
time_constant = 1.5415
vanish_time=5*time_constant
vanish_time = 7.7073
imm=2*max(is) %if the decay is to be neglected
imm = 3.0008
%{
This has the maximum possible value for = 0, i.e. short circuit occurring
when the voltage wave is going through zero.
%}
i=is+it;
[yup, ydown]=envelope(i,30,'peak');
plot(t,i)
hold on
plot(t,is,"LineStyle","--")
plot(t,it,"LineStyle","--")
grid on
yticks(-3:1:3)
xlim([0 vanish_time])
yline(imm)
ylabel("Short Circuit Current (A) / Voltage (V)")
xlabel("time (s)")
plot(t,vs)
plot(t,yup,"LineStyle","--")
plot(t,ydown,"LineStyle","--")
legend("Total SC Current","is","it","Vs")
hold off

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