南理工数字信号处理matlab题库.docx

DSP题库详解?1已知3阶椭圆IIR数字低通滤波器的性能指标为：通带截止频率0.4π，通带波纹为0.6dB，最小阻带衰减为32dB。设计一个6阶全通滤波器对其通带的群延时进行均衡。绘制低通滤波器和级联滤波器的群延时。%Progranm 1% Group-delay equalization of an IIR filter.%[n,d] = ellip(3,0.6,32,0.4);[GdH,w] = grpdelay(n,d,512);plot(w/pi,GdH); gridxlabel(\omega/\pi); ylabel(Group delay, samples);title(Original Filter);?F = 0:0.001:0.4;g = grpdelay(n,d,F,2);?? % Equalize the passbandGd = max(g)-g;% Design the allpass delay equalizer[num,den,tau] = iirgrpdelay(6, F, [0 0.4], Gd);?????????????????? %设计六阶的全通滤波器[b,a]=iirgrpdelay(6,F,[0 0.4],Gd);He1=dfilt.df2(b,a);He=dfilt.df2(n,d);He_all=dfilt.cascade(He,He1);grpdelay(He_all)??????????????????????????????????????????? %DFILT:Digital Filter Implementation.%[GdA,w] = grpdelay(num,den,512);%figure(2);%plot(w/pi,GdH+GdA); grid%xlabel(\omega/\pi);ylabel(Group delay, samples);%title(Group Delay Equalized Filter);?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。% Program 2% Program to Design Butterworth Analog Lowpass Filter% Type in the filter order and passband edge frequency设计边缘频率N = input(Type in filter order = );Wn = input(3-dB cutoff angular frequency = );% Determine the transfer function[num,den] = butter(N,Wn,s);? %计算滤波器的分子和分母% Compute and plot the frequency response[h,w]=freqz(num,den);plot (w/pi,20*log10(abs(h)));xlabel(\omega/\pi); ylabel(Magnitude, dB);title(The magnitude respponse of the system)axis([0 3 -80 5])?3%%%%%%%%%%% To use the residuenum=[1,-0.2,0.5,0,0];den=[1,3.2,1.5,-0.8,1.4];[r,p,k]=residue(num,den)?4% Program 4% Cheby1 analog highpass filter design%Wp=0.75;Ws=0.35;Rs=43;Rp=0.5;[N,Wn]=cheb1ord(Wp,Ws,Rp,Rs,s);% Determine the coefficients of the transfer function[num,den]=cheby1(N,Rp,Wn,high,s);% Compute and plot the frequency responseomega=[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)));xlabel(\omega/\pi);ylabel(Magnitude,dB);title(IIR Chebyshev1 Highpass Filter/dig