信号与系统Word文件下载.docx
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delta[n]'
m=-10:
0.1:
y=(m==0);
subplot(1,2,2);
plot(m,y,'
b'
Impulsefunction'
m'
delta(m)'
b.n=-10:
y=(n>
=0);
...
stepsequence'
u(n)'
y=(m>
r'
stepfunction'
u(m)'
2.产生并画出下列信号:
a.在[-2π,2π]的范围内,画出正弦信号sin(t);
b.利用sawtooth函数,在[-5π,5π]的范围内,画出周期三角波和锯齿波;
c.利用square函数,在[-5π,5π]的范围内,画出周期方波;
a.>
t=-2*pi:
pi/20:
2*pi;
plot(t,sin(t));
Sinewave'
t'
sin(t)'
b.>
t=-5*pi:
5*pi;
>
x=sawtooth(t,0.5);
subplot(2,1,1);
plot(t,x);
Triangularwave'
y=sawtooth(t);
subplot(2,1,2);
plot(t,y);
Sawtoothwave'
c.>
pi/100:
y=square(t);
axis([-5*pi,5*pi,-1.5,1.5]);
Squarewave'
y'
3.在[-4π,4π]的范围内,产生sinc函数曲线与diric函数曲线(阶数N=5)
sinc函数定义:
sinc(t)=sin(πt)/πt,diric函数的定义:
diric(t,,N)=sin(Nt/2)/Nsin(t/2)
t=-4*pi:
4*pi;
N=5;
subplot(2,1,1);
plot(t,sinc(t));
Sincfunction'
gridon;
sinc(t)'
subplot(2,1,2);
plot(t,diric(t,5));
Diricfunction'
diric(t)'
4.在n=[-10:
10]范围内产生离散信号:
当-3≤n≤3时,x[n]=2n;
取其余值时,均为0
n=[-10:
10];
x=2*n.*((n<
=3)&
(n>
=-3));
stem(n,x);
Adiscretesignal'
x[n]'
5.在n=[-10:
10]范围内画出以下信号:
a.X[n]=δ[n];
b.X[n]=δ[n+2];
c.X[n]=δ[n-4];
d.X[x]=2δ[n+2]-δ[n-4];
n=[-10:
subplot(2,2,1);
y=(n==-2);
subplot(2,2,2);
y=(n==4);
subplot(2,2,3);
y=2*(n==-2)-(n==4);
subplot(2,2,4);
6.产生复信号:
a.x[n]=e0≤n≤32
b.x[n]=e-10≤n≤10
并画出他们的实部和虚部及模值和相角
n=0:
32;
x=exp(j*(pi/8)*n);
subplot(2,2,1);
stem(n,real(x));
stem(n,imag(x));
subplot(2,2,3);
stem(n,abs(x));
stem(n,(180/pi)*angle(x));
x=exp((-0.1+j*0.3)*n);
subplot(2,2,4);
7.已知x[n]=u[n]-u[n-10],要求将它进行奇偶分量分解,分解为奇分量x[n]与偶分量x[n]
n=[0:
x=stepseq(0,0,10)-stepseq(10,0,10);
[xe,xo,m]=evenodd(x,n);
stem(n,x);
Stepsequence'
axis([-10,10,-1.2,1.2]);
stem(m,xe);
Evenpart'
xe[n]'
stem(m,xo);
Oddpart'
xo[n]'
Stepseq.m和evenodd.m的源程序如下:
stepseq.m
function[x,n]=stepseq(n0,n1,n2)
ifnargin~=3;
disp('
Usage:
Y=stepseq(n0,n1,n2)'
return;
elseif((n0<
n1)|(n0>
n2)|(n1>
n2))
error('
argumentsmustsatisfyn1<
n0<
n2'
)
end
n=[n1:
n2];
x=[(n-n0)>
=0];
evenodd.m
function[xe,xo,m]=evenodd(x,n)
ifany(imag(x)~=0)
xisnotarealsequence'
m=-fliplr(n);
m1=min([m,n]);
m2=max([m,n]);
m=m1:
m2;
nm=n
(1)-m
(1);
n1=1:
length(n);
x1=zeros(1,length(m));
x1(n1+nm)=x;
x=x1;
xe=0.5*(x+fliplr(x));
xo=0.5*(x-fliplr(x));
8.已知序列x[n]当n=0时,x[n]=2;
n=2时,x[n]=1;
n=3时,x[n]=-1;
n=4时,x[n]=3;
n为其余值时,x[n]=0
a.画出x[n]
b.画出y[n]=x[n-2]
c.画出y[n]=x[n+1]
d.画出y[n]=x[-n]
a.x=[zeros(1,10),2,0,1,-1,3,zeros(1,6)];
b.x=[zeros(1,12),2,0,1,-1,3,zeros(1,4)];
subplot(2,2,2);
c.x=[zeros(1,9),2,0,1,-1,3,zeros(1,7)];
d.x=[zeros(1,6),3,-1,1,0,2,zeros(1,10)];
9.在n=[0:
31]范围内画出下列信号:
a.x[n]=sin()cos()
b.x[n]=sin(n)
31;
x=sin(n*pi/4).*cos(n*pi/4);
plot(n,x);
y=sin(n);
plot(n,y);