test0801threesin.m

信号处理实例

%---------------------------------------------------------------------------------------
% test0801threesin.m,  for  example 1.1.1
% three sinus signal and its spectrum
% 2006.12.15 LYB
%----------------------------------------------------------------------------------------
echo off
clear
n=1024;
w=pi/16; %f=1,fs=32
t=1:n;
w1=t*w;
   part=n/4;
   for k=1:part,
   %    signal(k)=exp(j*k*w);
        signal(k)=sin(k*w);
   end;
   for k=(part+1):2*part,
   %    signal(k)=exp(j*2*k*w);
        signal(k)=sin(2*k*w);

   end;
   for k=(2*part+1):3*part,
   %    signal(k)=exp(j*3*k*w);
        signal(k)=sin(3*k*w);
   end;
   for k=(3*part+1):4*part,
   %    signal(k)=exp(j*3*k*w);
        signal(k)=sin(4*k*w);
   end;
figure(1);
subplot(211);
plot(t,signal);
axis([0 n-1 -1.5 1.5])
ylabel('time signal x(n)');


signalspectrum=abs(fft(signal));
subplot(212);
plot(signalspectrum(1:n/2));
axis([0 n/2-1 0 150])
ylabel('DFT X(k)'); 
text(450,170,'test0801threesin')

%tfrstft(signal');grid on;