exmp2_8.m

用dsp解压mp3程序的算法

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% exmp2_8.m -  Compute and plot magnitude spectrum
%              of signal in data file sn.dat
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

load -ascii sn.dat;      % load sinewave from file
N = length(sn);          % length of data file
Xk = fft(sn);            % compute DFT coefficients
absXk=20*log10(abs(Xk)); % magnitude spectrum in dB
phaXk = angle(Xk);       % compute phase spectrum
plot(absXk);             % plot magnitude spectrum
axis([0 N/2 -inf inf])   % from 0 to N/2 (pi)
title('Magnitude spectrum of sinewave');
xlabel('Frequency index k');
ylabel('Magnitude in dB');