function Hd = lowpass_butterworth3
%LOWPASS_BUTTERWORTH 返回离散时间滤波器对象。

% MATLAB Code
% Generated by MATLAB(R) 9.9 and Signal Processing Toolbox 8.5.
% Generated on: 07-May-2021 21:25:33

% Butterworth Lowpass filter designed using FDESIGN.LOWPASS.

% All frequency values are in Hz.
Fs = 1000;  % Sampling Frequency

Fpass = 100;          % Passband Frequency
Fstop = 200;         % Stopband Frequency
Apass = 1;           % Passband Ripple (dB)
Astop = 80;          % Stopband Attenuation (dB)
match = 'stopband';  % Band to match exactly

% Construct an FDESIGN object and call its BUTTER method.
h  = fdesign.lowpass(Fpass, Fstop, Apass, Astop, Fs);
Hd = design(h, 'butter', 'MatchExactly', match);

% [EOF]
