DSP using MATLAB 随书示例Example2.8

x = [3, 11, 7, 0, -1, 4, 2]; nx = [-3:3];
h = [2, 3, 0, -5, 2, 1]; nh = [-1:4];

[y,ny] = conv_m(x,nx,h,nh)

结果：

　

　下面展示一些具体步骤：

%% ------------------------------------------------------------------------
%%            Output Info about this m-file
fprintf('\n***********************************************************\n');
fprintf('        <DSP using MATLAB> Exameple 2.8 \n\n');

time_stamp = datestr(now, 31);
[wkd1, wkd2] = weekday(today, 'long');
fprintf('      Now is %20s, and it is %7s  \n\n', time_stamp, wkd2);
%% ------------------------------------------------------------------------

% Input sequence
x = [3, 11, 7, 0, -1, 4, 2]; nx = [-3:3];
% Impulse Response sequence
h = [2, 3, 0, -5, 2, 1]; nh = [-1:4];

[y,ny] = conv_m(x,nx,h,nh)

figure('NumberTitle', 'off', 'Name', 'Exameple 2.8')
set(gcf,'Color','white'); 

% x(k) and h(k)
subplot(2, 2, 1); stem(nx, x); axis([-5, 5, -6, 12]); grid on;
hold on;
stem(nh+0.1, h, 'r:');
a = axis; text(a(2)+0.5, a(3), 'k'); text(-1.5, 11, 'Solid :x  Dashed :h');
title('x(k) & h(k)');
hold off; 

% x(k) and h(-k)
subplot(2, 2, 2); stem(nx, x);axis([-5, 5, -6, 12]); grid on;
hold on;
stem(-fliplr(nh)+0.1, fliplr(h), 'r:');
a = axis; text(a(2)+0.5, a(3), 'k'); text(-0.5, -1, 'n=0');
text(-1.5, 11, 'Solid :x  Dashed :h');
title('x(k) and h(-k)');
hold off; 

% x(k) and h(-1-k)
subplot(2, 2, 3); stem(nx, x);axis([-5, 5, -6, 12]); grid on;
hold on;
stem(-fliplr(nh)+0.1-1, fliplr(h), 'r:');
a = axis; text(a(2)+0.5, a(3), 'k'); text(-1-0.5, -1, 'n=-1');
text(-1.5, 11, 'Solid :x  Dashed :h');
title('x(k) and h(-1-k)');
hold off; 

% x(k) and h(2-k)
subplot(2, 2, 4); stem(nx, x);axis([-5, 5, -6, 12]); grid on;
hold on;
stem(-fliplr(nh)+0.1+2, fliplr(h), 'r:');
a = axis; text(a(2)+0.5, a(3), 'k'); text(2-0.5, -1, 'n=2');
text(-1.5, 11, 'Solid :x  Dashed :h');
title('x(k) and h(2-k)');
hold off;

　　运行结果：

左上角是x(k)和h(k)；右上角是x(k)和h(-k)，对h(k)进行了反转；左下角是x(k)和h(-1-k)，对h(k)进行了反转后再向左移一位；

右下角是x(k)和h(2-k)，对h(k)进行了反转后再向右移两位；