clear all

O = 15; %order of prbs
N = 2^(O-1); %length of prbs
[~,seed] = prbs(O,1); %initialize first seed of prbs

% Modulation
M = 4; %PAM-M
bitpattern = zeros(N,log2(M));

% Symbol Rate
fsym = 56e9;
% DAC Rate
fdac = 120e9;
% Simulation oversampling rate "k";
kover = 16;
% ADC Rate
fadc = 256e9;
% Simulation frequency in "analog domain"
fsimu = kover * fdac ;

%CONSTRUCTION
pam_mapper = PAMmapper(M,0);

awg = AWG('preset','M8196A','fdac',fdac,'kover',kover,'lpf_active',0,'f_cutoff',80e9,'lpf_type',filtertypes.bessel_bilin);

%fil_tx = Filter('filtdegree',1,"f_cutoff",80e9,"fsamp",fdac,"filterType",filtertypes.bessel_bilin);
fil_tx = Filter('filtdegree',1,"f_cutoff",50e9,"fsamp",fdac,"filterType",filtertypes.bessel_bilin);

u_pi = 3.5;
vbias = (0.5*u_pi)-u_pi;
extmodlaser = EML("mode",emlmodes.im_cosinus,"power",10,"fsimu",fsimu,"lambda",1550,"bias",vbias,"u_pi",u_pi,"linewidth",1000);

amp = Amplifier("amplification_db",10,"amp_mode","gain","type","ideal","saturation_mode",0,'saturation_power',10);

fib = Fiber("fsimu",fdac*kover,"fiber_length",2,"alpha",0.2,"D",17,"lambda0",1550);

phdiode = Photodiode("fsimu",fdac*kover,"dark_current",2e-08,"responsivity",1,"temperature",20);

fil_diode = Filter('filtdegree',4,"f_cutoff",70e9,"fsamp",fdac,"filterType",filtertypes.bessel_bilin);

scp = Scope("fsimu",fdac*kover,"fadc",fadc,...
    "delay",0,"fixed_delay",0,"lpf_bw",120e9,"filtertype",filtertypes.bessel_inp,...
    "samplingdelay",0,"rand_samplingdelay",0,"freq_offset",0,"samp_jitter",0,...
    "adcresolution",6,"quantbuffer",0.1);

eq = EQ("K",2,"plottrain",0,"plotfinal",1,"training_length",2048,"Ne",[25,5,5],"Nb",[2,0,0],"training_loops",5,"DCmu",0.005,"DDmu",[0.0004 0.0004 0.0004 0.0004 ],"DFEmu",0.005,"FFEmu",0,"thres",[0.005 0.004 0.0005 ]);

%SIMULATE


% INFORMATION SIGNAL
for i = 1:log2(M)
    [bitpattern(:,i),seed] = prbs(O,N,seed);
end

X = Informationsignal(bitpattern);

PAMSIG = pam_mapper.map(X);

X = PAMSIG;

X.signal  = applyPulseShaping(PAMSIG.signal,fsym,fdac);

% ELECTRICAL DOMAIN
X  = awg.process(X);

X  = fil_tx.process(X);

% OPTICAL DOMAIN
X  = extmodlaser.process(X);

X  = amp.process(X);

X  = fib.process(X);

X  = phdiode.process(X);

X  = fil_diode.process(X);

% ELECTRICAL DOMAIN
X  = scp.process(X);

X  = X.resample("fs_out",2*fsym,"fs_in",fadc);

% INFORMATION SIGNAL
X  = eq.process(X,PAMSIG);

X  = pam_mapper.demap(X);

% BER
[bits,errors,BER] = calc_ber(X.signal(:,10000:end-21),bitpattern(10000:end-20,:)',0);

disp(['BER: ', sprintf('%2E',BER)]);

disp(X.logbook);

function yout = applyPulseShaping(xin,fsym,fdac)

if ~rem(fdac,fsym)
    %ist ein Vielfaches
    sps = fdac / fsym;
    up = sps;
    dn = 1;
else
    %ist kein Vielfaches
    up = fdac / gcd(fdac, fsym);
    dn = fsym / gcd(fdac, fsym);
    sps= up;
end

%Bau das Filter (hier rrc)
racos_len = 2048;
alpha = 0.1;
h = rcosdesign(alpha,racos_len,sps);

%Apply Filter using Matlab build in fctn.
yout = upfirdn(xin,h,up,dn);

%cut signal, which is longer due to fir filter
st = round(up/dn*racos_len/2); %we need to cut y_out
en = round(st + (length(xin)*up/dn) -1);

yout = yout(st:en);

%Check output integrity
if round(up/dn * length(xin)) ~= length(yout)
    warning('Check signal length after pulse shaping');
end

end

function [bits,errors,BER] = calc_ber(data_in,data_ref,skip)

data_ref=logical(data_ref);
data_in = logical(data_in);
bits = 0;
errors=0;

data_ref_overlap=zeros(size(data_ref,1),skip+(length(data_ref)-size(data_in,2)));
data_ref_pointer=0;
% Determine BER

bits = bits+size(data_in,2)-skip;
try
    errors = sum( data_in(:,skip+1:end,:) ~= data_ref(:,skip+1:end,:),2 );
catch
    %warning('BER calculation not optimal: Arrays have incompatible sizes for this operation.')
    errors = NaN;
end
try
    errors = sum( data_in(:,skip+1:end,:) ~= data_ref(:,skip+1:end-1,:),2 );
end
try
    errors = sum( data_in(:,skip+1:end,:) ~= data_ref(:,skip+1:end-2,:),2 );
end

BER = sum(errors)/sum(bits);

end