mag_res.m

用dsp解压mp3程序的算法

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%
% mag_res.m - Magnitude response of first-order IIR filter
%
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alpha = 0.25; N = 64;
b = [alpha];              % coefficient vector of numerator
a = [1 -(1-alpha)];       % coefficient vector of denominator
H = freqz(b, a, N);       % frequency response of filter
magX=20*log10(abs(H));    % compute magnitude response in dB
plot(magX); axis([1 N/2 -inf inf]);
title('Magnitude response');
xlabel('Frequency index'), ylabel('Magnitude, dB');