滤波器设计库
此示例说明如何使用 Signal Processing Toolbox® 产品中的 designfilt 函数设计各种 FIR 和 IIR 数字滤波器。
该库旨在帮助您识别感兴趣的滤波器响应，查看代码，并在您自己的工程中使用它。它包含 designfilt 提供的每个可用滤波器响应的示例。但请注意，这些只是为每种响应类型设计滤波器的几种可能方式。有关设定集的详尽列表，请参阅 Signal Processing Toolbox 文档。
除非另有说明，否则在此示例中，所有频率均以赫兹为单位，所有波纹和衰减值均以分贝为单位。
低通 FIR 滤波器
等波纹设计
Fpass = 100; Fstop = 150; Apass = 1; Astop = 65; Fs = 1e3; d1 = designfilt("lowpassfir", ... PassbandFrequency=Fpass, ... StopbandFrequency=Fstop, ... PassbandRipple=Apass, ... StopbandAttenuation=Astop, ... DesignMethod="equiripple", ... SampleRate=Fs); filterAnalyzer(d1)
低通 IIR 滤波器
最平坦设计
Fpass = 100; Fstop = 150; Apass = 0.5; Astop = 65; Fs = 1e3; d2 = designfilt("lowpassiir", ... PassbandFrequency=Fpass, ... StopbandFrequency=Fstop, ... PassbandRipple=Apass, ... StopbandAttenuation=Astop, ... DesignMethod="butter", ... SampleRate=Fs); filterAnalyzer(d2)
通带和阻带中的波纹
N = 8; Fpass = 100; Apass = 0.5; Astop = 65; Fs = 1e3; d3 = designfilt("lowpassiir", ... FilterOrder=N, ... PassbandFrequency=Fpass, ... PassbandRipple=Apass, ... StopbandAttenuation=Astop, ... SampleRate=Fs); filterAnalyzer(d3)
高通 FIR 滤波器
等波纹设计
Fstop = 350; Fpass = 400; Astop = 65; Apass = 0.5; Fs = 1e3; d4 = designfilt("highpassfir", ... StopbandFrequency=Fstop, ... PassbandFrequency=Fpass, ... StopbandAttenuation=Astop, ... PassbandRipple=Apass, ... DesignMethod="equiripple", ... SampleRate=Fs); filterAnalyzer(d4)
高通 IIR 滤波器
最平坦设计
Fstop = 350; Fpass = 400; Astop = 65; Apass = 0.5; Fs = 1e3; d5 = designfilt("highpassiir", ... StopbandFrequency=Fstop ,... PassbandFrequency=Fpass, ... StopbandAttenuation=Astop, ... PassbandRipple=Apass, ... DesignMethod="butter", ... SampleRate=Fs); filterAnalyzer(d5)
通带和阻带中的波纹
N = 8; Fpass = 400; Astop = 65; Apass = 0.5; Fs = 1e3; d6 = designfilt("highpassiir", ... FilterOrder=N, ... PassbandFrequency=Fpass, ... StopbandAttenuation=Astop, ... PassbandRipple=Apass, ... SampleRate=Fs); filterAnalyzer(d6)
带通 FIR 滤波器
等波纹设计
Fstop1 = 150; Fpass1 = 200; Fpass2 = 300; Fstop2 = 350; Astop1 = 65; Apass = 0.5; Astop2 = 65; Fs = 1e3; d7 = designfilt("bandpassfir", ... StopbandFrequency1=Fstop1, ... PassbandFrequency1=Fpass1, ... PassbandFrequency2=Fpass2, ... StopbandFrequency2=Fstop2, ... StopbandAttenuation1=Astop1, ... PassbandRipple=Apass, ... StopbandAttenuation2=Astop2, ... DesignMethod="equiripple", ... SampleRate=Fs); filterAnalyzer(d7)
不对称频带衰减
N = 50; Fstop1 = 150; Fpass1 = 200; Fpass2 = 300; Fstop2 = 350; Wstop1 = 3; Wstop2 = 100; Fs = 1e3; d8 = designfilt("bandpassfir", ... FilterOrder=N, ... StopbandFrequency1=Fstop1, ... PassbandFrequency1=Fpass1, ... PassbandFrequency2=Fpass2, ... StopbandFrequency2=Fstop2, ... StopbandWeight1=Wstop1,StopbandWeight2=Wstop2, ... DesignMethod="equiripple",SampleRate=Fs); filterAnalyzer(d8)
带通 IIR 滤波器
最平坦设计
Fstop1 = 150; Fpass1 = 200; Fpass2 = 300; Fstop2 = 350; Astop1 = 65; Apass = 0.5; Astop2 = 65; Fs = 1e3; d9 = designfilt("bandpassiir", ... StopbandFrequency1=Fstop1, ... PassbandFrequency1=Fpass1, ... PassbandFrequency2=Fpass2, ... StopbandFrequency2=Fstop2, ... StopbandAttenuation1=Astop1, ... PassbandRipple=Apass, ... StopbandAttenuation2=Astop2, ... DesignMethod="butter", ... SampleRate=Fs); filterAnalyzer(d9)
通带和阻带中的波纹
N = 8; Fpass1 = 200; Fpass2 = 300; Astop1 = 65; Apass = 0.5; Astop2 = 65; Fs = 1e3; d10 = designfilt("bandpassiir", ... FilterOrder=N, ... PassbandFrequency1=Fpass1, ... PassbandFrequency2=Fpass2, ... StopbandAttenuation1=Astop1, ... PassbandRipple=Apass, ... StopbandAttenuation2=Astop2, ... SampleRate=Fs); filterAnalyzer(d10)
带阻 FIR 滤波器
等波纹设计
Fpass1 = 100; Fstop1 = 150; Fstop2 = 350; Fpass2 = 400; Apass1 = 0.5; Astop = 65; Apass2 = 0.5; Fs = 1e3; d11 = designfilt("bandstopfir", ... PassbandFrequency1=Fpass1, ... StopbandFrequency1=Fstop1, ... StopbandFrequency2=Fstop2, ... PassbandFrequency2=Fpass2, ... PassbandRipple1=Apass1, ... StopbandAttenuation=Astop, ... PassbandRipple2=Apass2, ... DesignMethod="equiripple", ... SampleRate=Fs); filterAnalyzer(d11)
不对称通带波纹
N = 30; Fpass1 = 100; Fstop1 = 150; Fstop2 = 350; Fpass2 = 400; Wpass1 = 1; Wpass2 = 10; Fs = 1e3; d12 = designfilt("bandstopfir", ... FilterOrder=N, ... PassbandFrequency1=Fpass1, ... StopbandFrequency1=Fstop1, ... StopbandFrequency2=Fstop2, ... PassbandFrequency2=Fpass2, ... PassbandWeight1=Wpass1, ... PassbandWeight2=Wpass2, ... DesignMethod="equiripple", ... SampleRate=Fs); filterAnalyzer(d12)
带阻 IIR 滤波器
最平坦设计
Fpass1 = 100; Fstop1 = 150; Fstop2 = 350; Fpass2 = 400; Apass1 = 0.5; Astop = 65; Apass2 = 0.5; Fs = 1e3; d13 = designfilt("bandstopiir", ... PassbandFrequency1=Fpass1, ... StopbandFrequency1=Fstop1, ... StopbandFrequency2=Fstop2, ... PassbandFrequency2=Fpass2, ... PassbandRipple1=Apass1, ... StopbandAttenuation=Astop, ... PassbandRipple2=Apass2, ... DesignMethod="butter", ... SampleRate=Fs); filterAnalyzer(d13)
通带和阻带中的波纹
N = 8; Fpass1 = 125; Fpass2 = 375; Apass = 0.5; Astop = 65; Fs = 1e3; d14 = designfilt("bandstopiir", ... FilterOrder=N, ... PassbandFrequency1=Fpass1, ... PassbandFrequency2=Fpass2, ... PassbandRipple=Apass, ... StopbandAttenuation=Astop, ... SampleRate=Fs); filterAnalyzer(d14)
任意幅值 FIR 滤波器
单频带任意幅值设计
N = 300; % Frequencies are in normalized units F1 = 0:0.01:0.18; F2 = [0.2 0.38 0.4 0.55 0.562 0.585 0.6 0.78]; F3 = 0.79:0.01:1; FreqVect = [F1 F2 F3]; % vector of frequencies % Define desired response using linear units A1 = 0.5+sin(2*pi*7.5*F1)/4; % Sinusoidal section A2 = [0.5 2.3 1 1 -0.2 -0.2 1 1]; % Piece-wise linear section A3 = 0.2+18*(1-F3).^2; % Quadratic section AmpVect = [A1 A2 A3]; d15 = designfilt("arbmagfir",... FilterOrder=N, ... Amplitudes=AmpVect, ... Frequencies=FreqVect,... DesignMethod="freqsamp"); filterAnalyzer(d15,MagnitudeMode="zerophase")
多频带低通设计，阻带具有阶梯式衰减电平
N = 150; B = 2; % Number of bands % Frequencies are in normalized units F1 = [0 0.25]; % Passband F2 = [0.3 0.4 0.401 0.5 0.501 0.6 0.601 0.7 0.701 0.8 0.801 0.9 0.901 1]; % Stopband A1 = ones(size(F1)); % Desired amplitudes for band 1 in linear units A2 = zeros(size(F2)); % Desired amplitudes for band 2 in linear units % Vector of weights W = 10.^([0 0 5 5 10 10 15 15 20 20 25 25 30 30 35 35]/20); W1 = W(1:2); % Weights for band 1 W2 = W(3:end); % Weights for band 2 d16 = designfilt("arbmagfir", ... FilterOrder=N, ... NumBands=B, ... BandFrequencies1=F1, ... BandAmplitudes1=A1, ... BandFrequencies2=F2, ... BandAmplitudes2=A2, ... BandWeights1=W1, ... BandWeights2=W2); filterAnalyzer(d16)
FIR 微分滤波器
全频带设计
N = 41; Fs = 1e3; d17 = designfilt("differentiatorfir", ... FilterOrder=N, ... DesignMethod="equiripple", ... SampleRate=Fs); filterAnalyzer(d17,MagnitudeMode="zerophase",OverlayAnalysis="phase")
部分频带设计
N = 40; Fpass = 100; Fstop = 150; Fs = 1e3; d18 = designfilt("differentiatorfir", ... FilterOrder=N, ... PassbandFrequency=Fpass, ... StopbandFrequency=Fstop, ... DesignMethod="equiripple", ... SampleRate=Fs); filterAnalyzer(d18,MagnitudeMode="zerophase",OverlayAnalysis="phase")
希尔伯特 FIR 滤波器
等波纹设计
N = 40; Tw = 50; Fs = 1e3; d19 = designfilt("hilbertfir", ... FilterOrder=N, ... TransitionWidth=Tw, ... DesignMethod="equiripple", ... SampleRate=Fs); filterAnalyzer(d19,MagnitudeMode="zerophase",OverlayAnalysis="phase")
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