Producing the sinc roll off of a DAC

Discussion in 'Homework Help' started by jayo57, Jul 3, 2013.

  1. jayo57

    Thread Starter New Member

    Apr 21, 2013
    4
    0
    Hi,

    I'm trying to produce the sinc roll off a DAC (it's non flat frequency response) as shown in the below image. I've managed to plot it theoretically using scilab but now i need to prove it, by producing it using a for loop, but I'm not quite sure how to do this. Any help with this would be much appreciated.

    [​IMG]

    Scilab code for Theoretical plot;

    Code ( (Unknown Language)):
    1.  
    2. Fcar=100;
    3. Roll = [sin(%pi/Fcar)/(%pi/Fcar),sin(10*%pi/Fcar)/(10*%pi/Fcar),sin(20*%pi/Fcar)/(20*%pi/Fcar),sin(30*%pi/Fcar)/(30*%pi/Fcar),sin(40*%pi/Fcar)/(40*%pi/Fcar),sin(50*%pi/Fcar)/(50*%pi/Fcar),sin(60*%pi/Fcar)/(60*%pi/Fcar),sin(70*%pi/Fcar)/(70*%pi/Fcar),sin(80*%pi/Fcar)/(80*%pi/Fcar),sin(90*%pi/Fcar)/(90*%pi/Fcar),sin(100*%pi/Fcar)/(100*%pi/Fcar)]; etc.......
    4.  
    5. plot(Roll);
    6. xlabel('Time index n'); ylabel('Amplitude');
    7. title('Sinc Roll Off');
    8.  
    9. rect=[1 -0.3 55 1.1];
    10. zoom_rect(rect)
    11.  
    I have also managed to plot it using the following code;

    Code ( (Unknown Language)):
    1.  
    2. stacksize('max')
    3. FS=192000;
    4. fout=1920;
    5. t=0:1:FS;
    6. sig=sinc(2*%pi*t*fout/FS);
    7. //playsnd(sig,FS)
    8. plot2d(sig)
    9. //plot(sig)
    10. rect=[0 -0.4 2000 1.3];
    11. zoom_rect(rect)
    12.  
    Thanks in advance.
     
    Last edited by a moderator: Jul 4, 2013
  2. WBahn

    Moderator

    Mar 31, 2012
    17,743
    4,790
    You may not be sure how to do it, but I am quite unsure what you are even trying to do. Could you explain what you are trying to accomplish a bit more clearly.
     
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