systemtestask.m

可以实现DDC各个模块的功能

x=randint(15,1)
Fc=70000;
Fd=128;
Fs=65536;
[y,t]= dmod(x,Fc,Fd,Fs,'ASK',4);
len=length(y);

pause   % Press any key to see plots after sampling
subplot(2,1,1);
plot(y) 
xlabel('points');
title('sampling time domain signal');
subplot(2,1,2);
fft_y=fft(y,4096);
am_y1=abs(fft_y); 
f = Fs*(0:2048)/4096;
plot(f,am_y1(1:2049))
title('sampling frequency domain signal');
xlabel('Frequency');

len=length(y);
std_val=0.2;
n=std_val*randn(len,1);
y=y+n;
z=y;

pause %see plot after adding nosie
subplot(2,1,1);
plot(z)
xlabel('points');
title('adding noise time domain signal');
subplot(2,1,2);
fft_z=fft(z,4096);
am_z=abs(fft_z);
f = Fs*(0:2048)/4096;
plot(f,am_z(1:2049))
title('adding noise frequency domain signal');
xlabel('Frequency');

int_z=zeros(len,1);
for i=1:len
    int_z(i)=int16(y(i)*32768);
end; 
%plot(int_z)
nco_freq=Fc-Fs;
ad_freq=Fs;
len=length(y);
nco=zeros(len,1);
nco_out=zeros(len,1);
for i=1:len
    nco(i)=cos(nco_freq*2*pi*i/ad_freq);
    nco_out(i)=nco(i)*int_z(i);
end;

pause %see plot after mixing
subplot(2,1,1);
plot(nco_out)
xlabel('points');
title('mixing time domain signal');
subplot(2,1,2);
fft_nco=fft(nco_out,4096);
am_nco=abs(fft_nco);
f = Fs*(0:2048)/4096;
plot(f,am_nco(1:2049))
title('mixing frequency domain signal');
xlabel('Frequency');

m1=16;
D1=8;
cic_mid1=zeros(len,1);
cic_out1=zeros(len/D1,1);
cic_mid2=zeros(len/D1*D1,1);
cic_mid3=zeros(len/D1*D1*D1,1);
cic_mid4=zeros(len/D1*D1*D1*D1,1);
cic_mid5=zeros(len/D1*D1*D1*D1*D1,1);

for i=m1:len
    for j=1:m1
        cic_mid1(i)=cic_mid1(i)+nco_out(i-j+1);
        cic_mid2(i)=cic_mid2(i)+cic_mid1(i-j+1);
        cic_mid3(i)=cic_mid3(i)+cic_mid2(i-j+1);
        cic_mid4(i)=cic_mid4(i)+cic_mid3(i-j+1);
        cic_mid5(i)=cic_mid5(i)+cic_mid4(i-j+1);
        
        
    end;    
end;
%for i=m1:len/D1
 %   for j=1:m1
  %      cic_mid2(i)=cic_mid2(i)+cic_mid1(i-j+1);
        %  end;    
        %end;
%subplot(312);
%plot(cic_mid)
for i=1:len/D1
    cic_out1(i)=cic_mid5(i*D1-D1/2);  
end;

pause %see plot after CIC
subplot(2,1,1);
plot(cic_out1)
xlabel('points');
title('CIC time domain signal');
subplot(2,1,2);
fft_cic1=fft(cic_out1,4096);
am_cic1=abs(fft_cic1);
f = (Fs/D1)*(0:2048)/4096;
plot(f,am_cic1(1:2049))
title('CIC frequency domain signal');
xlabel('Frequency');





%subplot(313);
%plot(cic_out)
hb0=[-0.031303406,0.00000,0.281280518,0.499954224,0.281280518,0.00000,0.281280518];
hb1=[0.005929947,0.000000,-0.049036026,0.0000000,0.29309082,0.499969482,0.29309082,0.0000000,-0.049036026,0.000000,0.005929947];
hb2=[-0.0130558,0.0000000,0.012379646,0.0000000,-0.06055069,0.0000000,0.299453735,0.499954224,0.299453735,0.0000000,-0.06055069,0.0000000,0.012379646,0.0000000,-0.0130558];
before_half=conv(hb0,cic_out1);
half_out=zeros(length(before_half)/2,1);
for i=1:length(before_half)/2
    half_out(i)=before_half(2*i-1);
end;

pause %see plot after  HB
subplot(2,1,1);
plot(half_out)
xlabel('points');
title('HB time domain signal');
subplot(2,1,2);
fft_half=fft(half_out,4096);
am_half=abs(fft_half);
f = Fs/(2*D1)*(0:2048)/4096;
plot(f,am_half(1:2049))
title('HB frequency domain signal');
xlabel('Frequency');


D2=2;
Wn=0.75;
coef=fir1(256,Wn);
fvtool(coef,1);
before_filter=conv(half_out,coef);
len=length(half_out/D2)
fir_out=zeros(floor(len/D2),1);
for i=1:len/D2
    
   fir_out(i)=before_filter(floor(256/2+0.5)+i*D2-floor(D2/2));
end;


pause %see plot after FIR
subplot(2,1,1);
%x1=0:1:15;
plot(fir_out)
xlabel('points');
title('FIR time domain signal');
subplot(2,1,2);
fft_fir=fft(fir_out,4096);
am_fir=abs(fft_fir);
f = Fs/(2*D2*D1)*(0:2048)/4096;
plot(f,am_fir(1:2049))
title('FIR frequency domain signal');
xlabel('Frequency');