msk调制matlab

% msk2_fading.m

%

% Simulation program to realize MSK transmission system

% (under one path fading)

%

% Programmed by R.Sawai and H.Harada

%

%******************** Preparation part *************************************

sr=256000.0; % Symbol rate

ml=1; % ml:Number of modulation levels

br=sr.*ml; % Bit rate

nd = 100; % Number of symbols that simulates in each loop

ebn0=15; % Eb/N0

IPOINT=8; % Number of oversamples

%******************* Fading initialization ********************

% If you use fading function "sefade

attn=0.5*spow*sr/br*10.^(-ebn0/10);

attn=sqrt(attn); % sqrt: built in function

%********************** Fading channel **********************

% Generated data are fed into a fading simulator

[ifade,qfade]=sefade(ich2,qch2,itau,dlvl,th1,n0,itnd1,now1,length(ich2),tstp,fd,flat);

% Updata fading counter

itnd1 = itnd1+ itnd0;

%********************* Add White Gaussian Noise (AWGN) **********************

[ich3,qch3]= comb(ifade,qfade,attn);% add white gaussian noise

syncpoint = 1;

ich5=ich3(syncpoint:IPOINT:length(ich3));

qch5=qch3(syncpoint:IPOINT:length(qch3));

%**************************** MSK Demodulation *****************************

demoddata2(1,1)=-1;

for k=3:2:nd*ml+1

demoddata2(1,k)=ich5(1,k)*qch5(1,k-1)*cos(pi*(k))>0;

end

for n=2:2:nd*ml+1

demoddata2(1,n)=ich5(1,n-1)*qch5(1,n)*cos(pi*(n))>0;

end

[demodata]=demoddata2(1,2:nd*ml+1);

%************************** Bit Error Rate (BER) ****************************

noe2=sum(abs(data1-demodata)); % sum: built in function

nod2=length(data1); % length: built in function

noe=noe+noe2;

nod=nod+nod2;

fprintf('%d\%e\

',iii,noe2/nod2); % fprintf: built in function

end % for iii=1:nloop

%****************************** Data file ***********************************

ber = noe/nod;

fprintf('%d\%d\%d\%e\

',ebn0,noe,nod,noe/nod); % fprintf: built in function

fid = fopen('BERmsk2fad.dat','a');

fprintf(fid,'%d\%e\%f\%f\\

',ebn0,noe/nod,noe,nod); % fprintf: built in function

fclose(fid);

%******************** end of file ***************************