第七个.txt

计算机端口扫描端口程序应用和开发的作用,供参考.

第一题：
wp=0.2*pi;
ws=0.3*pi;
Rp=1;
Rs=10;
Fs=1;
Ts=1/Fs;
wp1=wp*Ts;
ws1=ws*Ts;
wp2=2*Fs*tan(wp1/2);
ws2=2*Fs*tan(ws1/2);
[N,Wn]=buttord(wp2,ws2,Rp,Rs,'s');
[Z,P,K]=buttap(N);
[Bap,Aap]=zp2tf(Z,P,K);
[b,a]=lp2lp(Bap,Aap,Wn);
[bz,az]=bilinear(b,a,Fs);
[H,W]=freqz(bz,az);
subplot(1,1,1);
plot(W/pi,abs(H));
grid
xlabel('频率')
ylabel('幅度')
第二题:
 
wp=0.2*pi*2;
ws=0.3*pi*2;
Rp=1;
Rs=25;
Fs=1;
Ts=1/Fs;
wp1=wp*Ts;
ws1=ws*Ts;
wp2=2*Fs*tan(wp1/2);
ws2=2*Fs*tan(ws1/2);
[N,Wn]=buttord(wp2,ws2,Rp,Rs,'s');
[Z,P,K]=buttap(N);
[Bap,Aap]=zp2tf(Z,P,K);
[b,a]=lp2lp(Bap,Aap,Wn);
[bz,az]=bilinear(b,a,Fs);
[H,W]=freqz(bz,az);
subplot(2,1,1);
plot(W/pi,abs(H));
grid
xlabel('频率')
ylabel('幅度')
subplot(2,1,2);
plot(W/pi,20*log10(abs(H)));
grid;
xlabel('频率')
ylabel('幅度(dB)')