xiazai2.m

x=2*sin(4*pi*t)+5*cos(8*pi*t) 对其进行快速傅立叶变换 加入高斯噪声 再进行频谱分析

t = 0:1/100:10-1/100;
x = sin(2*pi*15*t) + sin(2*pi*40*t);
y = fft(x); 
m = abs(y);
p = unwrap(angle(y));
f = (0:length(y)-1)'*100/length(y);
subplot(2,1,1), plot(f,m), 
ylabel('Abs. Magnitude'), grid on
subplot(2,1,2), plot(f,p*180/pi)
ylabel('Phase [Degrees]'), grid on
xlabel('Frequency [Hertz]')