matlab滤波器代码要点

1、数字信号处理： 已知通带截止频率fp=5kHz，通带最大衰减ap=2dB,阻带截止频率fs=2kHz，阻 带最小衰减as=30dB,按照以上技术指标设计 巴特沃斯低通滤波器： wp=2*pi*5000;ws=2*pi*12000;Rp=2;As=30; N,wc=buttord(wp,ws,Rp,As,s); B,A=butter(N,wc,s); k=0:511;fk=0:14000/512:14000;wk=2*pi*fk; Hk=freqs(B,A,wk); subplot(2,2,1); plot(fk/1000,20*log10(abs(Hk);grid on xlabel( 频率(

2、 kHz);ylabel(幅度( dB) axis(0,14,-40,5) 切比雪夫 1 型低通滤波器： wp=2*pi*3000;ws=2*pi*12000;Rp=0.1;As=60; N1,wpl=cheb1ord(wp,ws,Rp,As,s); %cheb1ord, 里面的是 1，不是 L B1,A1=cheby1(N1,Rp,wpl,s); subplot(2,2,1); fk=0:12000/512:12000;wk=2*pi*fk; Hk=freqs(B1,A1,wk); plot(fk/1000,20*log10(abs(Hk);grid on xlabel( 频率( kHz);

3、ylabel(幅度( dB) axis(0,12,-70,5) 椭圆模拟低通滤波器： wp=2*pi*3000;ws=2*pi*12000;Rp=0.1;As=60; N,wpo=ellipord(wp,ws,Rp,As,s); B,A=ellip(N,Rp,As,wpo,s); subplot(2,2,1); fk=0:12000/512:12000;wk=2*pi*fk; Hk=freqs(B1,A1,wk); plot(fk/1000,20*log10(abs(Hk);grid on xlabel( 频率( kHz);ylabel(幅度( dB) axis(0,12,-70,5) 295

4、 二 4 WPH2*4oo0 八 WSH2*20oo0HPH0.5HSH45 八 LZWCllbusorcKWpwsdprsx pAHbuffelxzwc)八 Lhk-wkllfreqz(B- fkuwk、pi*40 八 P_of(fk20*oglo(abs(hk)八 axis(p3oxoooD x_abe_ (-酋4M(kHzmy_abe_ (-B岡(d by)込 rid on WPH2*325K5500八 WSH2*225K5500HPH 1HSH40 八 N 一 wcHe 三 pod(wpws IP Is)八 pAHe三p(Ndpswc= Lhk-wkllfreqz(B- fkuwk、p

5、i*40 八 P_of(fk20*oglo(abs(hk)八 axis(p3oxoooD x_abe_ (-酋4M(kHzmy_abe_ (-B岡(d by)込 rid on P195-15 频率(kHZ) wp=2*4/80;ws=2*20/80;rp=0.5;rs=45; N,wc=cheb1ord(wp,ws,rp,rs); B,A=cheby1(N,rp,wc); hk,wk=freqz(B,A); fk=wk/pi*40; plot(fk,20*log10(abs(hk); axis(0,30,-100,0) xlabel(频率(kHZ);ylabel( 幅度(db);grid on

6、 切比雪夫低通滤波器 频率(kHZ) wp=2*pi*3000;ws=2*pi*12000;rp=0.1;as=60; N1,wp1=cheb1ord(wp,ws,rp,as,s); B1,A1=cheby1(N1,rp,wp1,s); subplot(2,2,1); fk=0:12000/512:12000;wk=2*pi*fk; hk=freqs(B1,A1,wk); plot(fk/1000,20*log10(abs(hk);grid on xlabel(频率(kHZ);ylabel( 幅度(db); axis(0,12,-70,5) 双音频检测 audiofile=test.wav =

7、nlaudipfs-bifslrwawead(audiofi-e= bbHchebylpp103)八 ouflaudioHfi_(D(bbjnlaudio)八 sound(ouflaudipfskfs)八 Wavwme(ouflaudipf3bifs=esflour= xkl Hffwnlaudioull 2)八 xk2H3(ouflaudip512)八 subp-0f(21- fkuwk、pi*40 八 P_of(fk20*oglo(abs(hk)八 axis(p3oxooo2 x_abe三 s (kHZ)y_abe三B岡(dBy) 一B啓s民w-Bs吏宝ffi話藩器 一 B- WPH2*p

8、i*3000八 WSH2*pi*l 2000HPHP1Q5SH60 八 三 wp lHchebod(wpws IP bss_)八 LbkQilllchebwml mwpk运)八 subp-0f(223八 fkHpk200552=200pwkH2*pi4;?T hkHfeqs(blQ)wkx p-of(fk/_k00020*02 0(abs(hk)=gl1d on x_abe三 s (khzmy_abe三B岡(dby) axis(p270ulD 5ffikhz) WPH2*pi*3000八 WSH2*pi*l 2000HPHP1Q5SH60 八 2 一 Wp2llcheb2od(wpwsdpbs

9、s-)八 Lb262llcheby2(n2Lpwp2)八 subp-0f(223八 fkHpk200552=200pwkH2*pi4;?T h kufreqs(b2 62 一 wk)八 p-of(fk/_k00020*02 0(abs(hk)=gl1d on x_abe三 s (khzmy_abe三B岡(dby) axis(p270ulD 裁青一 WPH2*pi*3000八 WSH2*pi*l 2000HPHP1Q5SH60 八 三 wp lHchebod(wpws IP bss_)八 al blllchebwmmwpk-T-OT- subp-0f(223八 fkHpk200552=200pw

10、kH2*pi4;?T hkHfeqs(blQ)wkx p-of(fk/_k00020*02 0(abs(hk)=gl1d on x_abe三 s (khzmy_abe三B岡(dby) axis(p270ulD sf(khz) WPH2*pi*3000八 WSH2*pi*l 2000HPHP1Q5SH60 八 rn一 wpoHe三pod(wpWSJPbss_)八 rbbHe三P(PP60WPP-S) subp-0f(223八 fkHpk200552=200pwkH2*pi4;?T hkHfreqs(bawk)- p-of(fk/_k00020*02 0(abs(hk)=gl1d on x_abe三 s (khzmy_abe三B岡(dby) axis(p270ulD 菌(52) WPH2*P 二200p9000rwsH2*p 二400P70001HPA6SH20 八 Lnpweplle三pod(wpwsdpbss-)八 bs