example8_2.m

用dsp解压mp3程序的算法

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%Example8_2.m - Program for example 8-2
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

clear all; close all;
n = 0:1:63, T = 1/128; Fs = 128; N = 64;
x = sin(2*pi*20*n*T) + sin(2*pi*41*n*T)+2;
Xc = 20*log10(abs(fft(x,N)));

subplot(211), plot(n*Fs/N,Xc);title('spectrum plot'); xlabel('frequency in Hz'); ylabel('Amplitude in dB');
axis([0 128 0 70]);

nshift = (-32:1:31)*Fs/N;
subplot(212), plot(nshift,fftshift(Xc));title('shifted spectrum plot');xlabel('frequency in Hz'); ylabel('Amplitude in dB');
axis([-64 64 0 70]);