东华大学信息学院信号与系统课程设计

word文档可自由复制编辑信号与系统的试验实验一连续时间信号时域分析1、用MATLAB表示连续信号：，，（1）代码clear;close;symstA=3a=2u=A*exp(a*t)ezplot(u,[-1010])xlabel('t');title('u(t)=A*exp(a*t)');gridon结果A=3a=2u=3*exp(2*t)图像（2），代码clearallcloseallsymstA=2w=1/2*pia=1/6*pif=A*cos(w*t+a)ezplot(f,[-1010]);xlabel('t');title('f(t)=A*cos(w*t+a)');holdon结果A=2w=1.5708a=0.5236f=2*cos(pi/6+(pi*t)/2)图像(3)代码clearallcloseallsymstA=2w=1/2*pia=1/6*pif=A*sin(w*t+a)ezplot(f,[-1010]);xlabel('t');title('f(t)=A*sin(w*t+a)');gridon结果A=2w=1.5708a=0.5236f=2*sin(pi/6+(pi*t)/2)图像2、用MATLAB表示抽样信号(sinc(t))、矩形脉冲信号(rectpuls(t,width))及三角脉冲信号(tripuls(t,width,skew))。抽样信号(sinc(t))代码clearallcloseallsymstf=sinc(t)ezplot(f,[-1010]);xlabel('t');title('f(t)=sinc(t)');gridon结果f=sin(pi*t)/(pi*t)图像(2)矩形脉冲信号(rectpuls(t,width))代码closeallwidth=1t=-10:0.001:10;f=rectpuls(t,width)plot(t,f)xlabel('t');title('f(t)=rectpuls(t,width)');axis([-10,10,-2,2])gridon结果（3）三角脉冲信号(tripuls(t,width,skew))代码clearall;closeall;t=-5:0.01:5width=4skew=0.5f=tripuls(t,width,skew)plot(t,f)xlabel('t');title('f=tripuls(t,width,skew)');axis([-10,10,-2,2])gridon图像3、编写如图3的函数并用MATLAB绘出满足下面要求的图形。(0)f（t）代码clearall;closeall;t=0:0.01:12f=4*rectpuls(t-6,12)+3*tripuls(t-6,4,0)plot(t,f)xlabel('t');title('f');axis([0,14,0,10])图像（1）f(-t)代码clearall;closeall;t=-20:0.01:20f=4*rectpuls(-t-6,12)+3*tripuls(-t-6,4,0)plot(t,f)xlabel('t');title('f(-t)');axis([-14,4,0,10])gridon图像（2）f(t-2)代码clearall;closeall;t=-20:0.01:20f=4*rectpuls(t-8,12)+3*tripuls(t-8,4,0)plot(t,f)xlabel('t');title('f(t-2)');axis([0,16,0,10])gridon结果（3）f(1-2t)代码clearall;closeall;t=-20:0.01:20f=4*rectpuls(1-2*t-6,12)+3*tripuls(1-2*t-6,4,0)plot(t,f)xlabel('t');title('f(1-2t)');axis([-6,6,0,10])gridon结果（4）f(0.5t+1)代码clearall;closeall;t=-20:0.01:30f=4*rectpuls(0.5*t+1-6,12)+3*tripuls(0.5*t+1-6,4,0)plot(t,f)xlabel('t');title('f(0.5t+1)');axis([-10,30,0,10])gridon结果实验二离散时间信号时域分析1、用MATLAB表示离散信号：，。（1）代码clearall;closeall;k=-10:10;a=2;f=a.^k.*u(k)%其中u(k)为被调用函数stem(k,f,'filled')xlabel('k')title('f=a^k*u[k]')axis([-10,10,0,300])结果u=Columns1through1400000000001111Columns15through211111111f=Columns1through70000000Columns8through140001248Columns15through211632641282565121024图像（2）代码clearall;closeall;k=-10:10;A=2f=A.*sin(k)stem(k,f,'filled')xlabel('k');title('f=Asin[k]');axis([-10,10,-4,4])gridon;结果A=2f=Columns1through81.0880-0.8242-1.9787-1.31400.55881.91781.5136-0.2822Columns9through16-1.8186-1.682901.68291.81860.2822-1.5136-1.9178Columns17through21-0.55881.31401.97870.8242-1.0880图像2、已知离散序列波形如图4所示，试用MATLAB绘出满足下列要求的序列波形。(1)f[k-2]u[k](2)f[-k](3)f[-k+2](4)f[k-2]u[k-2]图4（0）f=f[k]代码clearall;closeall;k=-10:10;f=0*x(k+6)+x(k+5)+3*x(k+4)+6*x(k+3)+10*x(k+2)+15*x(k+1)+14*x(k)+12*x(k-1)+9*x(k-2)+5*x(k-3)+0*x(k-4)+0*x(k-5)stem(k,f)xlabel('k');title('f[k]');axis([-10,10,0,16])gridon结果x=Columns1through1400000000000000Columns15through210100000f=Columns1through14000001361015141295Columns15through210000000图像f1=f[k-2]u[k]代码clearall;closeall;k=-10:10;f1=(0*x(k-2+6)+x(k-2+5)+3*x(k-2+4)+6*x(k-2+3)+10*x(k-2+2)+15*x(k-2+1)+14*x(k-2)+12*x(k-2-1)+9*x(k-2-2)+5*x(k-2-3)+0*x(k-2-4)+0*x(k-2-5)).*u(k)stem(k,f1)xlabel('k1');title('f[k-2]u[k]');axis([-10,10,0,16])gridon结果x=Columns1through1400000000000000Columns15through210001000u=Columns1through1400000000001111Columns15through211111111f1=Columns1through14000000000010151412Columns15through219500000图像（2）f2=f[-k]代码clearall;closeall;k=-10:10;f2=0*x(-k+6)+x(-k+5)+3*x(-k+4)+6*x(-k+3)+10*x(-k+2)+15*x(-k+1)+14*x(-k)+12*x(-k-1)+9*x(-k-2)+5*x(-k-3)+0*x(-k-4)+0*x(-k-5)stem(k,f2)xlabel('k');title('f2=f[-k]');axis([-10,10,0,16])gridon结果x=Columns1through1400000100000000Columns15through210000000f2=Columns1through14000000059121415106Columns15through213100000图像（3）f3=f[-k+2]代码clearall;closeall;k=-10:10;f3=0*x(-k+2+6)+x(-k+2+5)+3*x(-k+2+4)+6*x(-k+2+3)+10*x(-k+2+2)+15*x(-k+2+1)+14*x(-k+2)+12*x(-k+2-1)+9*x(-k+2-2)+5*x(-k+2-3)+0*x(-k+2-4)+0*x(-k+2-5)stem(k,f3)xlabel('k');title('f3=f[-k+2]');axis([-10,10,0,16])gridon结果x=Columns1through1400000001000000Columns15through210000000f3=Columns1through1400000000059121415Columns15through2110631000图像(4)f4=f[k-2]u[k-2]代码clearall;closeall;k=-10:10;f4=(0*x(k-2+6)+x(k-2+5)+3*x(k-2+4)+6*x(k-2+3)+10*x(k-2+2)+15*x(k-2+1)+14*x(k-2)+12*x(k-2-1)+9*x(k-2-2)+5*x(k-2-3)+0*x(k-2-4)+0*x(k-2-5)).*u(k-2)stem(k,f4)xlabel('k');title('f4=f[k-2]u[k-2]');axis([-10,10,0,16])gridon结果x=Columns1through1400000000000000Columns15through210001000u=Columns1through1400000000000011Columns15through211111111f4=Columns1through140000000000001412Columns15through219500000图像3、若，计算。clearall;closeall；x=[1,1,1,1,0,0]f=conv(x,x)n=0:10stem(n,f,'filled')xlabel('n');title('f=x[n]*x[n]');axis([0,10,0,10])gridon结果x=111100f=12343210000n=012345678910图像——————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————实验内容1.分别用函数lsim和卷积积分两种方法求如图8所示系统的零状态响应。其中L=1，R=2，，。图8方法一lsim方法求解零状态响应系统函数方程为Li’(t)+Ri(t)=e(t)带入L=1R=2得i’(t)+2i(t)=e(t)代码clearall;closeall;ts=0;te=10;dt=0.001;t=ts:dt:te;e=exp(-t).*u(t)a=[12];b=[1];y=lsim(b,a,e,t);plot(t,y);xlabel('Time(sec)')ylabel('y(t)')axis([010,00.3])gridon;结果方法二卷积积分法求零状态响应系统的冲激响应为h(t)=exp(-2t)u(t)则系统的零状态响应为y(t)=h(t)*e(t)代码clearall;closeall;symsxt;e=exp(-x);h=exp(-2.*(t-x));y=int(e.*h,x,0,t);ezplot(y,[0,10]);xlabel('Time(sec)');ylabel('y(t)');title('exp(-t)*exp(-2t)');gridon;结果2.求上述系统的冲激响应与阶跃响应。系统的冲激响应代码clearall;closeall;t=0:0.01:10;a=[12];b=[1];impulse(b,a,10);xlabel('Time(sec)');ylabel('h(t)')axis([0,10,-0.2,1]);gridon;结果系统阶跃响应代码clearall;closeall;t=0:0.01:10;a=[12];b=[1];step(b,a,10);xlabel('Time(sec)');ylabel('i(t)')axis([0,10,-0.2,1]);gridon;结果实验四离散时间系统时域分析1、假设某系统的单位函数响应，系统激励信号，求系统的零状态响应，并画图表示。解：y[k]=h[k]*x[k]代码clearall;closeall;x=[1,1,1,1]k=[0,1,2,3];h=(0.8).^k.*u(k)y=conv(h,x)k=[0,1,2,3,4,5,6];stem(k,y,'filled');xlabel('k');ylabel('y[k]')title('y=x[k]*h[k]');axis([0,8,0,4]);gridon;结果x=1111h=1.00000.80000.64000.5120y=1.00001.80002.44002.95201.95201.15200.5120图像2、采用P61recur.M计算系统响应：画出时的系统响应。四、实验内容1、求如图10所示周期矩形脉冲信号的Fourier级数表达式，画出频谱图，并用前N次谐波合成的信号近似。解：实验原理：——————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————(0)f(t)的原函数图像代码clearall;closeall;symstn;T=2*pi;%设T为2*PIN=9;%设N为f=heaviside(t)-2*heaviside(t-T/2)+heaviside(t-T);ezplot(f,[0,2*pi]);title('原函数');xlabel('t');ylabel('f(t)')gridon;图像(1)f(t)的频谱图代码clearall;closeall;symstn;T=2*pi;%设T为2*PIN=9;%设N为f=heaviside(t)-2*heaviside(t-T/2)+heaviside(t-T);%原函数h=exp(-j*n*2*pi/T*t);%用指数傅里叶级数表示，角频率2*pi/TC1=int(f.*h,t,0,T);C2=1/T*C1;forn1=-N:-1C(n1+10)=subs(C2,n,n1);endforn1=1:NC(n1+10)=subs(C2,n,n1);endC(10)=0;subplot(2,1,1);k=-N:N;stem(k,abs(C));%作出幅度谱title('Cn的频谱')ylabel('|Cn|');xlabel('w');gridon;subplot(2,1,2);stem(k,angle(C));%作出相位谱title('Cn的相位谱')ylabel('φn');xlabel('w');gridon;图像（2）前N次谐波合成的信号近似代码clearall;closeall;symsnt;T=2*pi;N=9;f=heaviside(t)-2*heaviside(t-T/2)+heaviside(t-T);%原函数h=exp(-j*n*2*pi/T*t);%用指数傅里叶级数表示，角频率2*pi/TC1=int(f.*h,t,0,T);C2=1/T*C1;forn1=-N:-1C(n1+10)=subs(C2,n,n1);endforn1=1:NC(n1+10)=subs(C2,n,n1);endC(10)=0;f1=0;form=-N:Nf1=f1+1/2*C(m+10)*exp(j*m*t);%前N次谐波合成的信号近似endezplot(f1,[0,2.01*pi]);title('前N次谐波合成的信号近似图像');xlabel('t');ylabel('f1（t）')gridon;图像试用fourier()函数求下列信号的傅里叶变换,并画出实验原理—————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————(1)代码clearall;closeall;symstFf=t*exp(-3*t)*heaviside(t)F=fourier(f)ezplot(abs(F));title('F(jw)=1/(3+jw)^2')xlabel('Time(sec)');ylabel('|F(jw)|');gridon;结果>>ex_5_2_1f=t*exp(-3*t)*heaviside(t)F=1/(w*i+3)^2图像(2)代码clearall;closeall;symstFf=2*heaviside(t)-1F=fourier(f)ezplot(abs(F));title('F(jw)=-(2*j)/w')xlabel('Time(sec)');ylabel('|F(jw)|');gridon;结果>>ex_5_2_2f=2*heaviside(t)-1F=-(2*i)/w图像3、调制信号为一取样信号，利用MATLAB分析幅度调制(AM)产生的信号频谱，比较信号调制前后的频谱并解调已调信号。设载波信号的频率为100Hz。代码clearall;closeall;symstwx=sin(20*pi*t)/(20*pi*t)subplot(4,2,1)ezplot(x,[-0.20.2])axis([-0.2,0.2,-0.5,1.0]);title('Ô­º¯Êý');xlabel('t');ylabel('x(t)');gridon;Fx=fourier(x)subplot(4,2,2);ezplot(Fx,[-50*pi,50*pi]);axis([-50*pi,50*pi,-0.05,0.15]);title('Ô­ÐźÅƵÆ×');xlabel('w');ylabel('Fx(w)')gridon;m=cos(200*pi*t)subplot(4,2,3)ezplot(m,[-0.05,0.05])axis([-0.05,0.05,-1.1,1.1]);title('Ôز¨º¯Êý')xlabel('t')ylabel('m(t)')Fm=fourier(m)subplot(4,2,4)ezplot(Fm,[-210*pi,210*pi])axis([-210*pi,210*pi,-1,1])title('Ôز¨ÐźÅƵÆ×');xlabel('w');ylabel('Fm(w)');gridon;y=x*msubplot(4,2,5);ezplot(y,[-0.20.2])axis([-0.2,0.2,-0.5,1.0]);title('µ÷ÖƺóÐźÅ');xlabel('t');ylabel('y(t)');gridon;Fy=fourier(y);subplot(4,2,6);ezplot(Fy,[-300*pi,300*pi]);axis([-300*pi,300*pi,-0.1,0.1]);title('µ÷ÖƺóÐźÅƵÆ×');xlabel('w');ylabel('Fy(w)');gridon;x1=y*mFx1=fourier(x1)H=-heaviside(w-20*pi)+heaviside(w+20*pi);Fx2=Fx1*Hx2=2*ifourier(Fx2)subplot(4,2,7)ezplot(x2,[-0.2,0.2])axis([-0.2,0.2,-0.5,1.0])title('½âµ÷ºóÐźÅ');xlabel('t');ylabel('x2(t)');gridon;subplot(4,2,8)ezplot(Fx2,[-50*pi,50*pi])axis([-050*pi,50*pi,-0.05,0.1])title('½âµ÷ºóÐźÅƵÆ×');xlabel('w')ylabel('Fx2(w)');结果四、实验内容1、如图11所示系统：图10(1)对不同的RC值，用freqs函数画出系统的幅频曲线。(2)信号包含了一个低频分量和一个高频分量，确定适当的RC值，滤除信号中的高频分量并画出信号和在s范围内的波形。提示：为最大值的处对应的频率为通带截止频率，首先求取并找到和RC关系，然后根据题意选定即可确定RC值。解：原理分析：—————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————（1）代码clearall;closeall;b=[01];forc=-5:2RC=10^c;a=[RC1];freqs(b,a);axis(10^(-5),10^(2),0.1,1);holdon;end结果（2）代码clearall;closeall;t=0:0.001:0.2;f=cos(100*t)+cos(2000*t);subplot(2,1,1);plot(t,f);%画出原信号的图像title('原函数');xlabel('t');ylabel('f（t）');gridon;y1=cos(100*t)/(1+j*100*10^(-2))+cos(2000*t)/(1+j*2000*10^(-2));%将高频信号去除subplot(2,1,2);plot(t,y1);%画出去除之后的图像title('滤除高频信号后函数');xlabel('t');ylabel('y（t）');gridon;图像2、信号任选，分析以下几种情况下信号的频谱和波形变化：系统满足线性不失真条件时；系统只满足恒定幅值条件时；系统只满足相位条件时；（4）系统两个条件均不满足时。提示：利用fourier求取信号的傅立叶变换E(jω)，然后设计使之满足不同条件，计算R(jω)=E(jω)H(jω)并画频谱图。原理分析—————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————系统满足线性不失真条件时；代码：clearall;closeall;symstaFwf=t*exp(-3*t)*heaviside(t)%原函数subplot(2,3,1)ezplot(f);title('原函数')xlabel('t');ylabel('f(t)');gridon;F=fourier(f);%对原函数进行傅里叶变换subplot(2,3,2)ezplot(abs(F));%绘制变换后幅频图像title('幅度谱')xlabel('Time(sec)');ylabel('|F(jw)|');gridon;i=1;fora=-3:0.02:3R11=subs(F,w,a);C(i)=angle(R11);%用angle函数返回每个a对应的三角值，且值的取值范围在+-180范围内i=i+1;endb=-3:0.02:3;subplot(2,3,3);plot(b,C);%绘制变换后相频图title('相位图');xlabel('w')ylabel('φ')axis([-3,3,-1,1]);gridon;H1=4*exp(-j*w*1)Y1=H1*F;y1=ifourier(Y1);subplot(2,3,4);ezplot(y1);title('线性不失真传输条件下输出y1(t)');xlabel('t');ylabel('y1(t)');gridon;subplot(2,3,5);ezplot(abs(Y1));title('幅度谱');xlabel('w');ylabel('|Y1(jw)|');gridon;i=1;fora=-3:0.02:3R11=subs(Y1,w,a);C(i)=angle(R11);%用angle函数返回每个a对应的三角值，且值的取值范围在+-180范围内i=i+1;endb=-3:0.02:3;subplot(2,3,6);plot(b,C);%绘制变换后相频图title('相位图');xlabel('w')ylabel('φ')axis([-3,3,-1,1]);gridon;图像系统只满足恒定幅值条件时；代码clearall;closeall;symstaFwf=t*exp(-3*t)*heaviside(t)%原函数subplot(2,3,1)ezplot(f);title('原函数')xlabel('t');ylabel('f(t)');gridon；F=fourier(f);%对原函数进行傅里叶变换subplot(2,3,2)ezplot(abs(F));%绘制变换后幅频图像title('幅度谱')xlabel('Time(sec)');ylabel('|F(jw)|');gridon;i=1;fora=-3:0.02:3R11=subs(F,w,a);C(i)=angle(R11);%用angle函数返回每个a对应的三角值，且值的取值范围在+-180范围内i=i+1;endb=-3:0.02:3;subplot(2,3,3);plot(b,C);%绘制变换后相频图title('相位图');xlabel('w')ylabel('φ')axis([-3,3,-1,1]);gridon;H1=(1-j)/(1+j);Y1=H1*F;y1=ifourier(Y1);subplot(2,3,4);ezplot(y1);title('系统只满足恒定幅值条件时y2(t)');xlabel('t');ylabel('y1(t)');gridon;subplot(2,3,5);ezplot(abs(Y1));title('幅度谱');xlabel('w');ylabel('|Y1(jw)|');gridon;i=1;fora=-3:0.02:3R11=subs(Y1,w,a);C(i)=angle(R11);%用angle函数返回每个a对应的三角值，且值的取值范围在+-180范围内i=i+1;endb=-3:0.02:3;subplot(2,3,6);plot(b,C);%绘制变换后相频图title('相位图');xlabel('w')ylabel('φ')axis([-3,3,-1,1]);gridon;结果系统只满足相位条件时；代码clearall;closeall;symstaFwf=t*exp(-3*t)*heaviside(t)%原函数subplot(2,3,1)ezplot(f);title('原函数')xlabel('t');ylabel('f(t)');gridon;F=fourier(f);%对原函数进行傅里叶变换subplot(2,3,2)ezplot(abs(F));%绘制变换后幅频图像title('幅度谱')xlabel('Time(sec)');ylabel('|F(jw)|');gridon;i=1;fora=-3:0.02:3R11=subs(F,w,a);C(i)=angle(R11);%用angle函数返回每个a对应的三角值，且值的取值范围在+-180范围内i=i+1;endb=-3:0.02:3;subplot(2,3,3);plot(b,C);%绘制变换后相频图title('相位图');xlabel('w')ylabel('φ')axis([-3,3,-1,1]);gridon;H1=w*exp(-j*w*1);Y1=H1*F;y1=ifourier(Y1);subplot(2,3,4);ezplot(y1);title('系统只满足相位条件时y3(t)');xlabel('t');ylabel('y1(t)');gridon;subplot(2,3,5);ezplot(abs(Y1));title('幅度谱');xlabel('w');ylabel('|Y1(jw)|');gridon;i=1;fora=-3:0.02:3R11=subs(Y1,w,a);C(i)=angle(R11);%用angle函数返回每个a对应的三角值，且值的取值范围在+-180范围内i=i+1;endb=-3:0.02:3;subplot(2,3,6);plot(b,C);%绘制变换后相频图title('相位图');xlabel('w')ylabel('φ')axis([-3,3,-1,1]);gridon;结果系统两个条件均不满足时。代码clearall;closeall;symstaFwf=t*exp(-3*t)*heaviside(t)%原函数subplot(2,3,1)ezplot(f);title('原函数')xlabel('t');ylabel('f(t)');gridon;F=fourier(f);%对原函数进行傅里叶变换subplot(2,3,2)ezplot(abs(F));%绘制变换后幅频图像title('幅度谱')xlabel('Time(sec)');ylabel('|F(jw)|');gridon;i=1;fora=-3:0.02:3R11=subs(F,w,a);C(i)=angle(R11);%用angle函数返回每个a对应的三角值，且值的取值范围在+-180范围内i=i+1;endb=-3:0.02:3;subplot(2,3,3);plot(b,C);%绘制变换后相频图title('相位图');xlabel('w')ylabel('φ')axis([-3,3,-1,1]);gridon;H1=w*(1-j)/(1+j);Y1=H1*F;y1=ifourier(Y1);subplot(2,3,4);ezplot(y1);title('系统两个条件均不满足时y4(t)');xlabel('t');ylabel('y1(t)');gridon;subplot(2,3,5);ezplot(abs(Y1));title('幅度谱');xlabel('w');ylabel('|Y1(jw)|');gridon;i=1;fora=-3:0.02:3R11=subs(Y1,w,a);C(i)=angle(R11);%用angle函数返回每个a对应的三角值，且值的取值范围在+-180范围内i=i+1;endb=-3:0.02:3;subplot(2,3,6);plot(b,C);%绘制变换后相频图title('相位图');xlabel('w')ylabel('φ')axis([-3,3,-1,1]);gridon;结果四、实验内容1.已知，以为采样频率，对进行采样得到，观察随着由小变大，频谱的变化，最后得出与两者频谱之间的关系。—————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————代码clearall;closeall;symstw;f=sin(2*t)/(2*t);subplot(3,2,1);ezplot(f,[-5,5]);title('ʱÓòÐźÅ');gridon;ff=fourier(f);subplot(3,2,2);ezplot(ff,[-5,5]);title('ƵÆ×ÐźÅ');gridon;fs=1;fc=0;forn=-6:6fc=fc+(pi/2)*fs*(-heaviside(w-2-n*2*pi*fs)+heaviside(w+2-n*2*pi*fs));endsubplot(3,2,4);ezplot(fc,[-40,40]);title('²ÉÑùÐźÅƵÆ×£¬²ÉÑùƵÂÊ1');gridon;fs=3;fc=0;forn=-3:3fc=fc+(pi/2)*fs*(-heaviside(w-2-n*2*pi*fs)+heaviside(w+2-n*2*pi*fs));endsubplot(3,2,5);ezplot(fc,[-40,40]);title('²ÉÑùÐźÅƵÆ×£¬²ÉÑùƵÂÊ3');gridon;fs=5;fc=0;forn=-3:3fc=fc+(pi/2)*fs*(-heaviside(w-2-n*2*pi*fs)+heaviside(w+2-n*2*pi*fs));endsubplot(3,2,6);ezplot(fc,[-40,40]);title('²ÉÑùÐźÅƵÆ×£¬²ÉÑùƵÂÊ5');gridon;fs=0.5;fc=0;forn=-3:3fc=fc+(pi/2)*fs*(-heaviside(w-2-n*2*pi*fs)+heaviside(w+2-n*2*pi*fs));endsubplot(3,2,3);ezplot(fc,[-40,40]);title('²ÉÑùÐźÅƵÆ×£¬²ÉÑùƵÂ