数字信号处理实验报告实验一.doc

数字信号处理实验报告实验一
2-1.
R=50;
m=0:R-1;
s=2*m.*(0.9.^m);
d=rand(R,1)-0.5;
x=s+d';
x1=0;
for n=1:R;
d=rand(R,1)-0.5;
x=s+d';
x1=x1+x;
end
x1=x1/R;
subplot(2,2,1),stem(m,s),xlabel('Time index n');ylabel('Amplitude');title('Original uncorrupted data')
subplot(2,2,2),stem(m,d),xlabel('Time index n');ylabel('Amplitude');title('Noise')
subplot(2,2,3),stem(m,x),xlabel('Time index n');ylabel('Amplitude');title('Noise corrupted sequense')
subplot(2,2,4),stem(m,x1),xlabel('Time index n');ylabel('Amplitude');title('Ensemble average')

2-2-1.
a=input('Type in real exponent =');
b=input('Type in imaginary exponent =');
c=a+b*i;
K=input('Type in the gain constant =');
N=input('Type in length of sequence =');
n=1:N;
x=K*exp(c*n);
stem(n,real(x));
xlabel('Time index n');ylabel('Amplitude');title('Real part');
disp('PRESS RETURN for imaginary part');
pause
stem(n,imag(x));
xlabel('Time index n');ylabel('Amplitude');title('Imaginary part');

Type in real exponent =-1/12
Type in imaginary exponent =pi/6
Type in the gain constant =1
Type in length of sequence =40

2-2-2.
a = input('Type in argument = ');
K = input('Type in the gain constant = ');
N = input ('Type in length of sequence = ');
n = 0:N;
x = K*a.^n;
stem(n,x);
xlabel('Time index n');ylabel('Amplitude');
title(['\alpha = ',num2str(a)]);

Type in argument = 1.2
Type in the gain constant = 0.2
Type in length of sequence = 30
Type in argument = 0.9
Type in the gain constant = 20
Type in length of sequence = 30

2-2-3
w = input('Type in argument = ');
N = input ('Type in length of sequence = ');
n = 0:N;
y = 1.5.*cos(w.*n);
stem(n,y);axis([0 40 -2 2]);
xlabel('Time index n');ylabel('Amplitude');
title(['wo = ',num2str(w/pi),'π']);

Type in argument = 0.1*pi
Type in length of sequence = 40

2-3-1
R=50;
d=rand(R,1)-0.5;
m=0:1:R-1;
s=2*m.*(0.9.^m);
x=s+d';
plot(m,d,'r-',m,s,'b--',m,x,'g:')
xlabel('Time index n');ylabel('Amplitude');
legend('d[n]','s[n]','x[n]'); pause
M=input('Number of input samples =');
b=ones(M,1)/M;
y=filter(b,1,x);
plot(m,s,'r-',m,y,'b--')
legend('s[n]','y[n]');
xlabel('Time index n');ylabel('Amplitude');title(['M= ',num2str(M)]);

Number of input samples =3

2-3-2
R=50;
d=rand(R,1)-0.4;
m=0:1:R-1;
s=2*m.*(0.9.^m);
x=s+d';
M=input('Number of input sample =');
d=rand(R,1)-0.4;
x=s+d';
x2=[zeros(1,(M-1)),x];
for i=1:R;
sum=0;
for g=1:M;
sum=sum+x2(i+g-1);
end
y(i)=sum./M;
end
plot(m,s,'r-',m,y,'b--');length(y)
legend('s[n]','y[n]');
xlabel('Time index n');ylabel('Amplitude');title(['M= ',num2str(M)]);

Number of input sample =3

2-4-1
N = input('Median Filter Length = ');
R = 50; a = rand(1,R)-0.4;
b = round(a);
m = 0:R-1;
s = 2*m.*(0.9.^m);
x = s + b;
y = medfilt1(x,N);
subplot(2,1,1)
stem(m,x);axis([0 50 -1 8]);
xlabel('n');ylabel('Amplitude');
title('Impulse Noise Corrupted Signal');
subplot(2,1,2)
stem(m,y);
xlabel('n');ylabel('Amplitude');
title('Output of Median Filter');

Median Filter Length = 3

2-4-2
R=50;
a=rand(1,R)-0.4;
b=round(a);
m=0:R-1;
s=2*m.*(0.9.^m);
x=s+b;
M=input('Number of input samples = ');
x2=[zeros(1,(M-1)/2),x,zeros(1,(M-1)/2)];
for i=1:R;
c=sort(x2(i:i+M-1));
if mod(M,2)==1; y(i)=c((M+1)/2);
else y(i)=(c(M/2)+c(M/2+1))/2;
end
end
subplot(2,1,1)
stem(m,x);axis([0 50 -1 8]);
xlabel('n');ylabel('Amplitude');
title('Tmpulse Noise Corrupted Signal');
subplot(2,1,2)
stem(m,y);
xlabel('n');ylabel('Amplitude');
title('Output of Median Filter');

Number of input samples =3

2-6
a = input('Type in the first sequence = ');
b = input('Type in the second sequence = ');
c = conv(a, b);
M = length(c)-1;
n = 0:1:M;
disp('output sequence =');disp(c)
stem(n,c)
xlabel('Time index n'); ylabel('Amplitude');

Type in the first sequence = [-2 0 1 -1 3]
Type in the second sequence = [1 2 0 -1]
output sequence =
-2 -4 1 3 1 5 1 -3

2-1

2-2-1

2-2-2

2-2-3

2-3-1

2-3-2

2-4-1

2-4-2

2-6