dsbpsk_ok.m

采用dpsk方式调制的直扩信号

clear

s=2;%  num. of sin_period per chip
fs=32;  %  sampling rate of sin function 
%%%%%%%%  fs/s  :sampling num. per period of c
r=1;   %  
%__________________________________________ generate PN code
sm=4;
pn=genpncode(sm);
pn(length(pn)+1)=-1;
%_______________________________org_data____________________________________
orglen=10;
org=randsrc(orglen,1);
%_______________________________spreading______________________________
ds=kron(org,pn');
%_______________________________  rc  _________________________________
data_rc=rcosflt(ds,1,fs);
figure;freqz(data_rc);title('data_srrc');
%________________________________BPSK __________________________________
%________________________________ see comment in notebook   5.9
bpsk=1;
if bpsk==1
    T=1;
    ts=s*T/fs;
    tt=ts:ts:length(data_rc)*ts;
    c=cos(2*pi*tt+0.5);
    figure;freqz(c);title('c');
    data_bpsk=data_rc.*c';
    figure;freqz(data_bpsk);title('data_bpsk');
end

%____________________________________ AWGN_____________________________
SNR=100;
data_awgn=awgn(data_bpsk,SNR);
figure;freqz(data_awgn);title('data_awgn');
%_____________________________________ de-bpsk ________________________
data_dem=data_awgn.*c';
figure;freqz(data_dem);title('data_dem')
%load f;
%data_dem=filter(f,1,data_dem);
%figure; freqz(data_dem);