cp6_1.m

来自「离散控制系统设计的MATLAB 代码」· M 代码 · 共 62 行

%%%%%%%%%%% Comprehensive Problem 6.1 %%%%%%%%%%%
%   Discrete-Time Control Problems using        %
%       MATLAB and the Control System Toolbox   %
%   by J.H. Chow, D.K. Frederick, & N.W. Chbat  %
%         Brooks/Cole Publishing Company        %
%                September 2002                 %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%   ---- Drum beat sound track ----
%
% drum sound track recorded by Nick Chbat
% m file by Joe Chow

load local
fs = 16384    % sampling rate
% 
% extract the main part of the signal
% use 65536 point
N = 2^16;
%
kstart = 10000;
y = local(kstart:kstart+N-1);
t=[0:length(y)-1]'/fs;
figure, plot(t,y),grid
xlabel('Time (sec)')
ylabel('local')
title('Original drum beats')
sound(y,fs)
disp('Playing original drum beat sound track')
disp('*******>'), pause
disp('Frequency response of original signal')
yfft = fft(y);
% frequency scale
df = fs/N;
f = [0:df:fs-df];
figure, plot(f,abs(yfft)),grid
xlabel('Frequency (Hz)')
ylabel('Magnitude')
title('Magnitude of frequency response of original signal')
disp('*******>'), pause

% 1st order butterworth filter
H1 = tf([0.5792 0.5792],[1 0.1584],1/fs);
H1 = ss(H1);
H = H1*H1;
yf = lsim(H,y,t);
figure, plot(t,yf),grid
xlabel('Time (sec)')
ylabel('local')
title('Low-pass filtered drum beats')
sound(yf,fs)
disp('Playing filtered drum beat sound track')
disp('*******>'), pause
disp('Frequency response of filtered signal')
yffft = fft(yf);
% frequency scale
df = fs/N;
f = [0:df:fs-df];
figure, plot(f,abs(yffft)),grid
xlabel('Frequency (Hz)')
ylabel('Magnitude')
title('Magnitude of frequency response of the filtered signal')
%%%%%%%%%%