ЦОС(лаба2_1)

N=8;

n=0:1:7;

t=1/8000;

x=2*sin(2*pi*3000*n*t)+sin(2*pi*2000*n*t+5*pi/6)/3;

figure(1)

plot(x),grid on

y=fft(x)

figure(2)

stem(real(y)),grid on

figure(3)

stem(imag(y)),grid on

Xm=abs(y)

figure(4)

stem(Xm),grid on

Xmm=abs(y)/N

figure(5)

stem(Xmm),grid on

N=18;

n=0:1:17;

t=1/81000;

x=sin(2*pi*9000*n*t);

y=fft(x);

xp=fftshift(y);

f=-N/2:1:(N/2-1);

a=abs(xp)/9;

figure(1)

stem(f,a),grid on

x2=sin(2*pi*22222*n*t);

y2=fft(x2);

xp2=fftshift(y2);

a2=abs(xp2)/9;

figure(2)

stem(f,a2),grid on

N=20;

T=1;

fs=100;

t=-1:1/fs:1-1/fs;

nh=(1:N)*2-1;

y=cos(2*pi*nh'*t/T);

Am=2/pi./nh;

Am(2:2:end)=-Am(2:2:end);

s1=y.*repmat(Am',1,length(t));

s2=cumsum(s1);

for k=1:N

subplot(4,5,k)

plot(t,s2(k,:))

end