滤波器

Lowpass-filter signals

Matlab提供函数lowpass

y = lowpass(x,wpass)

y = lowpass(x,fpass,fs)

y = lowpass(xt,fpass)

y = lowpass( ,Name,Value)

[y,d] = lowpass()

lowpass()

直接设计低通滤波器的参数
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N   = 100;        % FIR filter order
Fp  = 20e3;       % 20 kHz passband-edge frequency
Fs  = 96e3;       % 96 kHz sampling frequency
Rp  = 0.00057565; % Corresponds to 0.01 dB peak-to-peak ripple
Rst = 1e-4;       % Corresponds to 80 dB stopband attenuation

eqnum = firceqrip(N,Fp/(Fs/2),[Rp Rst],'passedge'); % eqnum = vec of coeffs
fvtool(eqnum,'Fs',Fs,'Color','White') % Visualize filter

N 表示transition region 的sharp程度，数字越大，越sharp；

Fp：通带截止频率

Fs：信号采样频率

Rp: 通带波纹ripple

Rst: 阻带衰减