實(shí)驗(yàn)三 信號與系統(tǒng)的頻域分析

信號與系統(tǒng)實(shí)驗(yàn)報(bào)告信號與系統(tǒng)實(shí)驗(yàn)報(bào)告4-4-PAGE4姓名：姓名：實(shí)驗(yàn)名稱：實(shí)驗(yàn)三連續(xù)系統(tǒng)的頻率響應(yīng)分析學(xué)號：實(shí)驗(yàn)時(shí)間：評語：一.實(shí)驗(yàn)?zāi)康纳钊肜斫庀到y(tǒng)頻率響應(yīng)的物理意義Matlab分析系統(tǒng)頻率響應(yīng)的方法理解系統(tǒng)對信號的作用關(guān)系二.實(shí)驗(yàn)內(nèi)容RC電路如圖：R+y(t)f(t) C-對不同RC值，freqs畫出系統(tǒng)的幅度響應(yīng)曲線H()。f(t)=cos(100t)+RCf(t)f(t)y(t)在0-0.2s范圍內(nèi)的波形。（3）50Hz的交流信號經(jīng)過全波整流后可表示為f(t)=10t)試取不同的RC值，計(jì)算并畫出f(t)通過系統(tǒng)的響應(yīng)y(t)。計(jì)算f(t)的直流分量。f(t)和f(t)見下圖：1 2f(tf(t)11011f2(t)t012（1）取t:0.05:2.5,計(jì)算信號f(t)=f(t)+f

(t)*cos(50t)的值，并畫出波形;1 2一可實(shí)現(xiàn)的系統(tǒng)的頻率響應(yīng)函數(shù)為H(j)

104(j)426.131(j)3341.42(j)22613.1(j)10000用freqs畫出H(j)的幅度響應(yīng)和相位響應(yīng)曲線。和f(t)*cos(50t)y(t)和y(t),并根據(jù)理論知識解1 2釋所得結(jié)果。三.仿真分析1 RCH(j)

1/RCj1/RC%(1)RC1=0.001;RC2=0.002;RC3=0.005;a1=1/RC1;a2=1/RC2;a3=1/RC3;A1=[1a1];A2=[1a2];A3=[1a3];B1=a1;B2=a2;B3=a3;w1=linspace(0,3000,200);w2=linspace(0,3000,400);w3=linspace(0,3000,500);H1=freqs(B1,A1,w1);H2=freqs(B2,A2,w2);

xlabel('\omega(title('RC=0.002')subplot(3,1,3);plot(w3,abs(H3));xlabel('\omega(rad/s)')title('RC=0.005')RC=0.00110.500 500 1000 1500 2000 2500 3000(rad/s)RC=0.002H3=freqs(B3,A3,w3);figure(1)subplot(3,1,1);plot(w1,abs(H1));

10.500 500 1000 1500 2000 2500 3000(rad/s)xlabel('\omega(rad/s)')title('RC=0.001')

10.5

RC=0.005subplot(3,1,2);plot(w2,abs(H2));%(2)t=0:0.0001:0.2;

00 500 1000 1500 2000 2500 3000(rad/s)f(t)=cos(100*t)+cos(3000*t)f=cos(100*t)+cos(3000*t);Hw1=a3/(j*100+a3);Hw2=a3/(j*3000+a3);y=abs(Hw1)*cos(100*t)...+abs(Hw2)*cos(3000*t);figure(2)subplot(2,1,1);plot(t,f);xlabel('t (s)')ylabel('f(t)')title('f(t)=cos(100*t)+cos(3000*t)')subplot(2,1,2);plot(t,y);xlabel('t (s)')ylabel('y(t)')

210-1-20 0.02 0.04 0.06 0.08 0.1t(s)10.50-0.5-10 0.02 0.04 0.06 0.08 0.1t(s)

0.12 0.14 0.16 0.18 0.20.12 0.14 0.16 0.18 0.2%(3)clearRC31=0.01;RC32=0.02;RC33=0.05;a31=1/RC31;a32=1/RC32;a33=1/RC33;A31=[1a31];A32=[1a32];A33=[1a33];B31=a31;B32=a32;B33=a33;sys=[tf(B31,A31);tf(B32,A32);tf(B33,A33)];t3=0:0.0005:0.25;f3=abs(10*sin(100*pi*t3));y3=lsim(sys,f3,t3);

figure(1)plot(t3,f3);xlabel('t title('f(t)=|10*sin(100*pi*t3)|')figure(2)plot(t3,y3);legend('RC=0.01時(shí)系統(tǒng)的輸出',...'RC=0.02時(shí)系統(tǒng)的輸出','RC=0.05時(shí)系統(tǒng)的輸出',4)f(t)=|10*sin(100*pi*t3)|10 7968576 45432100 0.05

t(s)

0.15 0.2 0.25

32100 0.05 0.1

RC=0.01時(shí)系統(tǒng)的輸出RC=0.02時(shí)系統(tǒng)的輸出RC=0.05時(shí)系統(tǒng)的輸出0.2 0.25直流分量的計(jì)算：fDC

(t)=

12%(1)2%(1)t=0:0.01:2.5;f1t=rectpuls(t-0.5,1);f2t=tripuls(t-1,2,0);ft=f1t+f2t.*cos(50*t);subplot(3,1,1);plot(t,f1t);axis([-0.52.6-0.51.2])ylabel('f1(t)');subplot(3,1,2);plot(t,f2t);axis([-0.52.6-0.51.2])ylabel('f2(t)')subplot(3,1,3);plot(t,ft);ylabel('f(t)')axis([-0.52.6-0.51.2])10.5f0-0.5-0.500.511.522.51f0.50-0.5-0.500.511.522.510.5f0-0.5-0.500.511.522.5

10

0.01sin(100t)dt0

206.37%(2)%(2)a=[126.131341.422613.110000];b=[1000];w=linspace(0,15,500);w1=w*pi;H=freqs(b,a,w1);figure(2)subplot(2,1,1);plot(w,abs(H));xlabel('\omega(\pirad/s)')ylabel('|H(j\omega)|')subplot(2,1,2);plot(w,angle(H));xlabel('\omega(\pirad/s)')ylabel('\phi(\omega)')0.20.15)0.1|0.050051015(rad/s)