[xhat1,nd1] = cceps(x1); 
 [xhat2,nd2] = cceps(x2); 
 [xhat3,nd3] = cceps(x3); 
 [xhat4,nd4] = cceps(x4);  
 [xhat,nd] = cceps(w);   %求倒譜 
  
 y1=xhat1-xhat; 
 y2=xhat2-xhat; 
 y3=xhat3-xhat; 
 y4=xhat4-xhat; %計算材料倒譜 
  
 z1=fft(y1); 
 z2=fft(y2); 
 z3=fft(y3); 
 z4=fft(y4); 
  
 s1=exp(z1);  %取指數運算 
 s2=exp(z2); 
 s3=exp(z3); 
 s4=exp(z4); 
  
 f1=ifft(s1); 
 f2=ifft(s2); 
 f3=ifft(s3); 
 f4=ifft(s4); 
  
 r1=abs(f1);  
 r2=abs(f2);  
 r3=abs(f3);  
 r4=abs(f4); 
  
 y1=1:240; 
 y1=y1' 
 r1=real(f1); 















 t=0:1999; 
>> t=(0:1999)'; 
>> figure,plot(t,re); 
>> title('Signal in time domain') 
xlabel('time(nanoesecond)') 
>> Fre=fft(re,2048); 
>> Pre=Fre.*conj(Fre)/2048; 
>> f=1000*(0:1023)/2048; 
>> figure,plot(f,Pre(1:1024)); 
>> title('Signal in frequency domain') 
xlabel('frequency(MB)')%求采樣點為2000個的時域信號功率譜
















Tar1=tar1.*20+re; 
>> figure,plot(t,Tar1); 
>> title('Signal in time domain') 
xlabel('time(nanoesecond)') 
>> FTar1=fft(Tar1,2048); 
>> PTar1=FTar1.*conj(FTar1)/2048; 
>> figure,plot(f,PTar1(1:1024)); 
>> title('Signal in frequency domain') 
xlabel('frequency(MB)')%求采樣點為2000個的時域信號功率譜