matlab上机完美版答案.doc

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。 %Q1_solution %ellip(N,Ap,Ast,Wp)//双线性法设计低通滤波器 %N---The order of the filter %Ap--ripple in the passband %Ast-a stopband Rs dB down from the peak value in the passband %Wp--the passband width [be,ae]=ellip(3,0.6,32,0.4); hellip=dfilt.df2(be,ae); f=0:0.001:0.4; g=grpdelay(hellip,f,2); g1=max(g)-g; [b,a,tau]=iirgrpdelay(6,f,[0 0.4],g1); hallpass=dfilt.df2(b,a);//级联 hoverall=cascade(hallpass,hellip); hFVT=fvtool([hellip,hoverall]); set(hFVT,Filter,[hellip,hoverall]); legend(hFVT,Lowpass Elliptic filter,Compensated filter);//添加图例的标注 clear; [num1,den1]=ellip(3,0.6,32,0.4); [GdH,w]=grpdelay(num1,den1,512); plot(w/pi,GdH); grid xlabel(\omega/\pi); ylabel(Group delay, samples); F=0:0.001:0.4; g=grpdelay(num1,den1,F,2); % Equalize the passband Gd=max(g)-g; % Design the allpass delay equalizer [num2,den2]=iirgrpdelay(6,F,[0,0.4],Gd); [GdA,w] = grpdelay(num2,den2,512); hold on; plot(w/pi,GdH+GdA,r); legend(Original Filter,Compensated filter); 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。 clear; N=input(Type in the order N = ); Wn=input(Type in the 3-dB cutoff frequency Wn = ); %模拟频率 [num,den]=butter(N,Wn,s); w=0:2*Wn; h=freqs(num,den,w); plot(w,20*log(abs(h))),grid; 3．已知系统的系统函数为： 用MATLAB进行部分分式展开，并写出展开后的表达式。 % Partial-Fraction Expansion of Rational z-Transform num = [0 0 1 -0.2 0.5]; den = [1 3.2 1.5 -0.8 1.4]; [r,p,k] = residuez(num,den); disp(Residues);disp(r) disp(Poles);disp(p) disp(Constants);disp(k) 设计切比雪夫I型IIR数字高通滤波器，其性能指标为：通带波纹，最小阻带衰减，通带和阻带边缘频率和绘制所设计的滤波器增益响应。 %a4 disp(prewapping is done,and T=2); Wp = tan(0.75*pi/2); Ws = tan(0.5*pi/2); Rp = 0.5; Rs = 43; [N,Wn] = cheb1ord(Ws,Wp,Rp,Rs,s); [b,a] = cheby1(N,Rp,Wn,s); [bt,at]=lp2hp(b,a,Wp); [num,den]=bilinear(bt,at,0.5); [h,omega] = freqz(num,den); plot (omega/pi,20*log10(abs(h)));grid; xlabel(\omega/\pi); ylabel(Gain); title(Type I Chebyshev Highpass Filter); clear;%预畸变 Rp=0.5; Rs=43; Wp=0.7