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 o

2、n xlabel(' 频率( 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

3、/1000,20*log10(abs(Hk);grid on xlabel(' 频率( kHz)');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/

4、1000,20*log10(abs(Hk);grid on xlabel(' 频率( kHz)');ylabel('幅度( dB)')axis(0,12,-70,5)295 二 4WPH2*4oo0 八 WSH2*20oo0HPH0.5HSH45 八LZWCllbusorcKWpwsdprsxpAHbuffelxzwc)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 onWPH2*325

5、K5500八 WSH2*225K5500HPH 1HSH40 八N 一 wcHe 三 pod(wpws IP Is)八 pAHe三p(Ndpswc= 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 onP195-15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);

6、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 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=f

7、reqs(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'=nlaudipfs-bifslrwawead(audiofi-e= bbHchebylpp103)八 ouflaudioHfi_(D(bbjnlaudio)八 sound(ouflaudipfskfs)八 Wavwme(ouflaudipf3bifs=esflour= xkl Hffw

8、nlaudioull 2)八 xk2H3(ouflaudip512)八 subp-0f(21<=?s(Dm(abs(xk5八 Subp-of(212)gem(abs(xk2)xWPH2*pi*4000八 WSH2*pi*l 000HPH0" 16SH40 八 rn一 wcHbuffod(wpws IP bsS-)八 Lbhbhllbufl:e(pwchigh-Zs) subp-0f(223八 fkHpk200552=200pwkH2*pi4;?T hkHfeqs(bh bh 一 wk)八 p-of(fk/_k00020*02 0(abs(hk)=gl1d on x_abe三 s

9、 (khzmy_abe三B岡(dby) axis(p270ulDWPH2*pi*5000八 WSH2*pi*12000HPH2QiSH30 八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(khz)');ylabel(' 幅度(db)

10、') axis(0,14,-40,5) 巴特沃斯模拟带通滤波器频率忖z)wp=2*pi*4000,7000;ws=2*pi*2000,9000;n ,wc=buttord(wp,ws,rp,as,'s'); bb,ab=butter( n,wc,'s');subplot(2,2,1); fk=0:12000/512:12000;wk=2*pi*fk; hk=freqs(bb,ab,wk);plot(fk/1000,20*log10(abs(hk);grid on xlabel(' 频率(khz)');ylabel(' 幅度(db)

11、') axis(0,12,-70,5) 巴特沃斯带阻滤波器频率(khz：wp=2*pi*2000,9000;ws=2*pi*4000,7000;rp=1;as=20;s,b-wclrbus:od(wpwsdpbss-)八 Lbsbbsbllbusesb 一 wpsfop-zs-)八 subp-0f(223八fkHpk200552=200pwkH2*pi4;?T hkHfeqs(bsbbsb 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»4関。田a曲驾虫ff

12、io藩器-n 80可走aw酋«40.5)WPH2*4oo0 八 WSH2*20oo0HPH0.5HSH45 八LZWCllbusorcKWpwsdprsxpAHbuffelxzwc)八Lhk-wkllfreqz(B>- 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*pi*3000八 WSH2*pi*l 2000HPHP1Q5SH60 八 三 wp lHchebod(wpws IP bss_)八 LbkQilll

13、chebwml mwpk运)八 subp-0f(223八fkHpk200552=200pwkH2*pi4;?T hkHfeqs(blQ)wkxp-of(fk/_k00020*02 0(abs(hk)=gl1d on x_abe三 s (khzmy_abe三B岡(dby) axis(p270ulD5ffi>khz)WPH2*pi*3000八 WSH2*pi*l 2000HPHP1Q5SH60 八 2 一 Wp2llcheb2od(wpwsdpbss-)八 Lb262llcheby2(n2Lpwp2)八 subp-0f(223八fkHpk200552=200pwkH2*pi4;?Th kuf

14、reqs(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=200pwkH2*pi4;?T hkHfeqs(blQ)wkxp-of(fk/_k00020*02 0(abs(hk)=gl1d on x_abe三 s (khzmy_abe三B岡(dby) axis(p270ulDsf«(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>(5