O = 14; %order of prbs
N = 2^(O-1); %length of prbs
[~,seed] = prbs(O,1); %initialize first seed of prbs

% Modulation
M = 4;
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 ;


%SIMULATE

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

Bits = Informationsignal(bitpattern);

Bits.signal  = pam_mapping(Bits.signal,M,0);

Bits.signal  = applyPulseShaping(Bits.signal,fsym,fdac);


awg = AWG('preset','M8196A','fdac',fdac,'kover',kover,'lpf_active',1);
awgSignal   = awg.process_channel(Bits);

fil = Filter('filtdegree',4,"f_cutoff",50e9,"fsamp",fdac,"filterType",filtertypes.bessel_bilin);
filtered = fil.process(awgSignal);

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",1000000);
laserfield = extmodlaser.process(filtered); 

att = Amplifier("amplification_db",10,"amp_mode","gain","type","ideal","saturation_mode",0,'saturation_power',10);
att_out = att.process(laserfield);

fib = Fiber("fsimu",fdac*kover,"fiber_length",0,"alpha",0.2,"D",17,"lambda0",1550);
fib_out = fib.process(att_out);

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

fil = Filter('filtdegree',4,"f_cutoff",70e9,"fsamp",fdac,"filterType",filtertypes.bessel_bilin);
phdiod_out2 = fil.process(phdiod_out);


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);

scope_out = scp.process(phdiod_out2);

figure;
hold on
plot( nmlze(resample(shapedData,fadc,fdac)),'DisplayName','shapedData Data');
plot( nmlze(resample(awgSignal,fadc,fdac*kover)),'DisplayName','AWG Data');
plot( nmlze(scope_out),'DisplayName','scope out out');
hold off

resample_out = resample(scope_out,fsym,fadc);


% figure;
% hold on
% plot(awgSignal,'DisplayName','skew 0');
% plot(filtered,'DisplayName','filtered');
% plot(abs(laserfield),'DisplayName','laser');
% plot(abs(att_out),'DisplayName','att_out');
% plot(abs(fib_out),'DisplayName','fiber_out');
% plot(abs(phdiod_out),'DisplayName','photo diode out');
% hold off

% figure;
% hold on
% plot(nmlze(pamData),'DisplayName','PAM Data');
% plot(nmlze(resample_out),'DisplayName','system out');
% hold off


function y = nmlze(x)
    y = (x-min(x)) / max((x-min(x)));
end

function pam_sig = pam_mapping(bitpattern, M, unipolar)

switch log2(M)
    case 1
        % 2-ASK: BPSK / OOK
        pam_sig=bitpattern(:,1);

        if unipolar==0
            pam_sig=2*pam_sig-1;
        end

    case 2
        % 4-ASK:
        pam_sig=2*bitpattern(:,1)+(bitpattern(:,1)==bitpattern(:,2));

        if unipolar==0
            pam_sig=2*pam_sig-3;
        end


    case 3
        % 8-ASK:
        x1 = bitpattern(:,1);
        x2 = (bitpattern(:,1)==bitpattern(:,3));
        x3 = x2~=bitpattern(:,2);

        pam_sig = 4*x1 + 2*x2 + x3;

        if unipolar==0
            pam_sig=2*pam_sig-7;
        end


    case 4
        % 16-ASK:
        x1 = bitpattern(:,1);
        x2 = (bitpattern(:,1)==bitpattern(:,4));
        x3 = x2~=bitpattern(:,3);
        x4 = x3~=bitpattern(:,2);

        pam_sig = 8*x1 + 4*x2 + 2*x3 + x4;

        if unipolar==0
            pam_sig=2*pam_sig-15;
        end

end
end

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 = up/dn*racos_len/2; %we need to cut y_out 
    en = st + (length(xin)*up/dn) -1;

    yout = yout(st:en);

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

end