clear
% Abtastfrequenz Halbband 44Mhz
% Eingangsfrequenz 11Mhz
% target freq 310kHz
nn = 31*10^5*11 ; % Fensterbreite
ff=linspace(0,44e6,nn);
%32Bit DDS
ph=uint64(0);
aaa=zeros(1,nn);% Volle DDS
msb=zeros(1,nn);% MSB
for(k=1:nn)
  if(rem(k,100000)==0) disp(nn-k); end;
  if(rem(k,4)==0)
      ph=ph+uint64(round(2^32*31/1100));
      ph=bitand(ph,uint64(2^32-1));
  end;    
  msb(k)=2*(bitand(ph,uint64(2^31))>0)-1;   
  
  hh=double(ph);
  hh=fix(hh/2^20); % zeitdiskret, 12Bit
  hh=cos(2*pi*hh/2^12);
  hh=fix(hh*2^15); %16 Bit Amplitude
  aaa(k)= hh;
end
spmsb=fft(msb);
spmsb=spmsb/(max(abs(spmsb)));
spaaa=fft(aaa);
spaaa=spaaa/(max(abs(spaaa)));
bis=max(find(ff<11e6));
plot(ff(1:bis),20*log10(abs(spmsb(1:bis))),'b.-',....
     ff(1:bis),20*log10(abs(spaaa(1:bis))),'r.-');
title('DDS 32Bit 11MHz->310kHz blau MSB only, rot 2048er Tabelle, 16Bit')
ylabel('[dB]')
xlabel('f [Hz]')

grid



return