南理工数字信号处理matlab题库文档格式.docx
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南理工数字信号处理matlab题库文档格式.docx
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DigitalFilterImplementation.
%[GdA,w]=grpdelay(num,den,512);
%figure
(2);
%plot(w/pi,GdH+GdA);
%xlabel('
ylabel('
%title('
GroupDelayEqualizedFilter'
2设计巴特沃兹模拟低通滤波器,其滤波器的阶数和3-dB截止频率由键盘输入,程序能根据输入的参数,绘制滤波器的增益响应。
%Program2
%ProgramtoDesignButterworthAnalogLowpassFilter
%Typeinthefilterorderandpassbandedgefrequency设计边缘频率
N=input('
Typeinfilterorder='
Wn=input('
3-dBcutoffangularfrequency='
%Determinethetransferfunction
[num,den]=butter(N,Wn,'
s'
%计算滤波器的分子和分母
%
Computeandplotthefrequencyresponse
[h,w]=freqz(num,den);
plot(w/pi,20*log10(abs(h)));
Magnitude,dB'
Themagnituderespponseofthesystem'
)
axis([03-805])
3%%%%%%%%%%
%Tousetheresidue
num=[1,-0.2,0.5,0,0];
den=[1,3.2,1.5,-0.8,1.4];
[r,p,k]=residue(num,den)
4%Program4
%Cheby1analoghighpassfilterdesign
Wp=0.75;
Ws=0.35;
Rs=43;
Rp=0.5;
[N,Wn]=cheb1ord(Wp,Ws,Rp,Rs,'
%Determinethecoefficientsofthetransferfunction
[num,den]=cheby1(N,Rp,Wn,'
high'
'
%Computeandplotthefrequencyresponse
omega=[0:
1:
30*pi];
%w=0:
0.01:
pi;
h=freqs(num,den,omega);
%plot(w/pi,20*log10(abs(h)))
plot(omega/(2*pi),20*log10(abs(h)));
Magnitude,dB'
IIRChebyshev1HighpassFilter/digital'
5.
%Programto绘制30点序列的实部与虚部
n=0:
29;
x=0.2*exp((0.4+0.5*j).*n);
subplot(1,2,1)
stem(n,real(x))
Therealpart'
n'
magnitude'
subplot(1,2,2)
stem(n,imag(x))
Theimaginepart'
6.
%ProgramtoDesignType1ChebyshevanalogLowpassFilter
%Readinthefilterorder,passbandedgefrequency
%andpassbandrippleindB
Order='
Wc=input('
typeinthe3dBcutofffrequency='
Rp=input('
Typeinthepeakripplevalueinpassband:
'
[num,den]=cheby1(N,Rp,Wc,'
[h,w]=freqs(num,den);
Frequency,Hz'
magnitude,dB'
IIRChebyshev1LowpassFilter/analog'
gridon
7.
%DeterminationoftheFactoredForm
%ofaRationalz-Transform
%熟悉命令[num,den]=residuez(r,p,k);
[r,p,k]=residuez(num,den)
clearall
r=[10.61.8];
p=[-3.22.42.4];
k=0.2;
[num,den]=residuez(r,p,k);
disp('
Numeratorpolynomialcoefficients'
disp(num)
Denominatorpolynomialcoefficients'
disp(den)
8,
设计IIR数字带通滤波器
%ProgramtoDesigniirdigitalbandpassFilter
Wp=[0.40.6];
%WpandWs都是向量组,带通的性质
Ws=[0.30.7];
Rp=0.6;
Rs=35;
[N,Wn]=buttord(Wp,Ws,Rp,Rs);
[b,a]=butter(N,Wn);
%巴特卧兹滤波器的分子和分母
[h,w]=freqz(b,a,256);
%求出在频域的画图点,256,即要花的点数
gain=20*log10(abs(h));
plot(w/pi,gain);
IIRButterworthBandpassFilter'
9%drawtherequestedsequence
clear
23;
x=2*0.9.^n;
stem(n,x)
x[n]'
10%
%ProgramtoDesignEllipticanalogLowpassFilter
%椭圆模拟低通滤波器设计
%Readinthefilterorder,passbandedgefrequency,
%passbandrippleindBandminimumstopband
%attenuationindB
typeinthe3dBcutofffrequency='
typeinthepeakripplevalueofpassbandindB='
Rs=input('
typeintheMinimumstopbandattenuationindB='
[num,den]=ellip(N,Rp,Rs,Wn,'
%Determinethecoefficientsofthetransferfunction
plot(w/2*pi,20*log10(abs(h)));
Gain,dB'
title(‘iirelliplowpassfilter’)
girdon
%%%%%
num=[1,-0.2,0.5];
y=impz(num,den,30);
%inverse–transform
n=1:
30;
stem(n,y);
%%%%%%%%%%%
N=5;
Rp=0.8;
Rs=35;
Wn=0.35;
%去掉了pi的输入
[num,den]=ellip(N,Rp,Rs,Wn);
0.3;
[GdH,w]=grpdelay(num,den,512);
%gd=grpdelay(num,den,w,2);
群时延的另外一个公式
figure
(1),plot(w/pi,GdH);
grid
ThegrpdelayofIIREllipLowpassFilter'
g=grpdelay(num,den,F,2);
[num,den]=iirgrpdelay(10,F,[00.3],Gd);
He=dfilt.df2(num,den);
He1=dfilt.df2(num,den);
%下面是另外一种方法
gridon
13%Programtodrawsignalandsignalwithnoise
N=40;
N-1;
s=3*(n.*(0.8.^n));
d=1.2.*rand(1,N)-0.6;
x=s+d;
figure
(1)
stem(n,s)
timeindexn'
amplitude'
originalsignals[n]'
figure
(2)
stem(n,d)
noised[n]'
figure(3)
signalwithnoisex[n]'
%generatemovingaveragefilter
b=ones(4,1)/4;
%windowlengthis4
y=filter(b,1,x);
%letsignalgothroughthefilter
figure(4)
stem(n,y)
signalthroughfiltery[n]'
figure(5)
plot(n,d,'
g:
'
n,s,'
b'
n,x,'
c--'
n,y,'
r-.'
legend('
noise'
s[n]'
y[n]'
)
%在图上加方框对其标注
14%%%%%%
N=10;
x=ones(1,10);
[h,w]=freqz(x,1,16);
subplot(2,1,1)
plot(w,abs(h))
\omega/'
amplituderesponse'
subplot(2,1,2)
plot(w,angle(h))
phase(rad)'
phaseresponse'
%notice:
hereomegahasn’tbeen归一化
15%
%已知系统的系统函数为:
%用MATLAB的filter函数求h[n]的前20个样本
N=20;
x=zeros(1,N);
x
(1)=1;
%x=[1,zeros(1,19)]
h=filter(num,den,x);
y=impz(num,den,N);
%用filter和z反变换impz对比
stem([0:
N-1],h)
h[n]'
N-1],y)
16%
%利用Hermann公式估计FIR低通滤波器的阶数。
该滤波器的性能指标为:
通带截止频率为1500Hz,阻带截至频率为1800Hz,通带纹波为=0.015,阻带纹波为=0.021,抽样频率为5000Hz
fedge=[15001800];
%unitHz
mval=[10];
%desiredmagnitudevaluesineachband
dev=[0.0150.021];
%通带和阻带波纹
Ft=5000;
N=remezord(fedge,mval,dev,Ft)
%第二种方法
%clearall
%formatlong
%a1=0.005309;
a2=0.07114;
a3=-0.4761;
a4=0.00266;
a5=0.5941;
a6=0.4278;
%b1=11.01217;
b2=0.51244;
%f=[1500,1800];
%w=2*pi*f/5000;
%wp=w
(1);
ws=w
(2);
%delta_p=0.015;
delta_s=0.021;
%delta=[0.015,0.021];
%ifdelta_p>
=delta_s
m=1;
n=2;
%D=(a1*(log10(delta(m)))^2+a2*log10(delta(m))+a3)*log10(delta(n))-(a4*(log10(delta(m)))^2+a%5*log10(delta(m))+a6);
F=b1+b2*(log10(delta(m))-log10(delta(n)));
%else
m=2;
n=1;
%end
%N=ceil((D-F*((ws-wp)/2/pi)^2)/((ws-wp)/2/pi))
(anotherversionof13,14,15,16)
13%编写四点滑动平均滤波器。
原始未受干扰的序列为:
,加性噪声信为随机序列,幅度0.6,受干扰的序列为:
\*MERGEFORMAT,分别绘制长度为40的原始序列,噪声序列和受干扰序列,以及滑动平均滤波器的输出。
R=40;
d=1.2*rand(1,R)-0.6;
R-1;
x=3*n.*(0.8).^n;
s=x+d;
bla'
r'
n,s);
d[n]'
m=4;
%input('
pleaseinputthenumberofpointsyouwantfilt='
m=(0:
m-1)/m;
y=filter(m,1,x);
figure
plot(n,s,n,y,'
g'
14%绘制长度为10点的矩形序列的16点离散傅里叶变换样本的幅度和相位
a=input('
pleaseinputthemagnitudeoftheN-pointsequence='
N=input('
pleaseinputthelenthofsequence='
M=input('
pleaseinputthelenthoftheDFTsequence='
u=a*ones(1,N);
h=fft(u,M);
m=0:
M-1;
subplot(2,1,1);
stem(m,abs(h)),title('
subplot(2,1,2);
stem(m,angle(h)),title('
phase'
pleaseinputthelenthofthewantedsequence='
n=ones(1,N);
请按降幂输入分子系数='
b=input('
请按降幂输入分母系数='
y=filter(a,b,n)
fedge=input('
Typeinthebandedges='
mval=input('
Desiredmagnitudevaluesineachband='
dev=input('
Allowabledeviationineachband='
FT=input('
Typeinthesamplingfrequency='
[N,fpts,mag,wt]=remezord(fedge,mval,d
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