小弟有个波形想做FFT分析但不懂原理请版上帮教学
不好意思在此请版上各位教学如何用FFT与小弟程序波形ed求得结果在此先谢谢
這是小弟程序
%%%%%%%%%%%%%%%%%START
clc
clear all
U = 1;
w = 2*pi*60;
t = 0:0.000005:0.05;
num = length(t);
sa=zeros(1,num);
ea = sqrt(2)*U*sin(w*t);
eb = sqrt(2)*U*sin(w*t-2*pi/3);
ec = sqrt(2)*U*sin(w*t-4*pi/3);
for i = 1:num
if asin(ea(i)/sqrt(2)/U) >= pi/6 && asin(ea(i)/sqrt(2)/U) <= 5*pi/6
sa(i) = 1;
elseif asin(ea(i)/sqrt(2)/U) <= -pi/6 && asin(ea(i)/sqrt(2)/U) >= -5*pi/6
sa(i) = -1;
else
sa(i) = 0;
end
end
for i = 1:num
if asin(eb(i)/sqrt(2)/U) >= pi/6 && asin(eb(i)/sqrt(2)/U) <= 5*pi/6
sb(i) = 1;
elseif asin(eb(i)/sqrt(2)/U) <= -pi/6 && asin(eb(i)/sqrt(2)/U) >= -5*pi/6
sb(i) = -1;
else
sb(i) = 0;
end
end
for i = 1:num
if asin(ec(i)/sqrt(2)/U) >= pi/6 & asin(ec(i)/sqrt(2)/U) <= 5*pi/6
sc(i) = 1;
elseif asin(ec(i)/sqrt(2)/U) <= -pi/6 & asin(ec(i)/sqrt(2)/U) >= -5*pi/6
sc(i) = -1;
else
sc(i) = 0;
end
end
ed = sa.*ea+sb.*eb+sc.*ec;
plot(t,ed,'r')
grid on
hold off
%%%%%%%%%%%%%%%%%END
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