标签:ati its -- sig osi 正弦信号 tle blog nal
代码:
%% ------------------------------------------------------------------------ %% Output Info about this m-file fprintf(‘\n***********************************************************\n‘); fprintf(‘ <DSP using MATLAB> Exameple 9.4 \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); %% ------------------------------------------------------------------------ n = 0:256; k1 = 64; k2 = k1+32; m = 0:(k2-k1); %% ----------------------------------------------------------------- %% Plot %% ----------------------------------------------------------------- Hf1 = figure(‘units‘, ‘inches‘, ‘position‘, [1, 1, 8, 6], ... ‘paperunits‘, ‘inches‘, ‘paperposition‘, [0, 0, 6, 4], ... ‘NumberTitle‘, ‘off‘, ‘Name‘, ‘Exameple 9.4‘); set(gcf,‘Color‘,‘white‘); TF = 10; % (a) Original signal x = cos(pi*n); subplot(2, 2, 1); Ha = stem(m, x(m+k1+1), ‘g‘, ‘filled‘); axis([-1, 33, -1.1, 1.1]); grid on; set(Ha, ‘markersize‘, 2); xlabel(‘n‘); ylabel(‘Amplitude‘); title(‘Original Sequence x(n)‘, ‘fontsize‘, TF); set(gca, ‘xtick‘, [0, 16, 32]); set(gca, ‘ytick‘, [-1, 0, 1]); % (b) Interpolation by D = 2 I = 2; y = interp(x, I); subplot(2, 2, 2); Hb = stem(m, y(m+k1*I+1), ‘c‘, ‘filled‘); axis([-1, 33, -1.1, 1.1]); grid on; set(Hb, ‘markersize‘, 2); xlabel(‘n‘); ylabel(‘Amplitude‘); title(‘Interpolated by I = 2‘, ‘fontsize‘, TF); set(gca, ‘xtick‘, [0, 16, 32]); set(gca, ‘ytick‘, [-1, 0, 1]); % (c) Interpolation by I = 4 I = 4; y = interp(x, I); subplot(2, 2, 3); Hc = stem(m, y(m+k1*I+1), ‘r‘, ‘filled‘); axis([-1, 33, -1.1, 1.1]); grid on; set(Hc, ‘markersize‘, 2); xlabel(‘n‘); ylabel(‘Amplitude‘); title(‘Interpolated by I = 4‘, ‘fontsize‘, TF); set(gca, ‘xtick‘, [0, 16, 32]); set(gca, ‘ytick‘, [-1, 0, 1]); % (d) Interpolation by I = 8 I = 8; y = interp(x, I); subplot(2, 2, 4); Hd = stem(m, y(m+k1*I+1), ‘m‘, ‘filled‘); axis([-1, 33, -1.1, 1.1]); grid on; set(Hd, ‘markersize‘, 2); xlabel(‘n‘); ylabel(‘Amplitude‘); title(‘Interpolated by I = 8‘, ‘fontsize‘, TF); set(gca, ‘xtick‘, [0, 16, 32]); set(gca, ‘ytick‘, [-1, 0, 1]);
运行结果:
从图看,I的所有三个数值下的插值序列是合适的,在更高的采样率上展示了原始正弦信号x(n)。I=8的例子里,
插值序列从形状上看不像是精确的正弦信号。这可能是由于低通滤波器和理想低通滤波器有差距而造成的。
《DSP using MATLAB》示例 Example 9.4
标签:ati its -- sig osi 正弦信号 tle blog nal
原文地址:http://www.cnblogs.com/ky027wh-sx/p/6901452.html