function  [output] = imdd_model(varargin)

simulation_mode = 1;

%%% Change folder
curFolder = pwd;
funcFolder=fileparts(mfilename('fullpath'));
if ~isempty(funcFolder)
    cd(funcFolder);
end

%%% Run parameters
% TX
M               = 4;
fsym            = 180e9;

apply_pulsef    = 1;
fdac            = 256e9;
fadc            = 256e9;
random_key      = 1;

rcalpha         = 0.05;
kover           = 16;

vbias_rel       = 0.5;
u_pi            = 3;
vbias           = -vbias_rel*u_pi;

laser_wavelength    = 1293;
laser_linewidth     = 0;
tx_bw_nyquist   = 0.8;

% Channel
link_length     = 1;

% RX
rop = -8;
rx_bw_nyquist = 0.8;

vnle_order1 = 50;
vnle_order2 = 7;
vnle_order3 = 7;

vnle_order=[vnle_order1,vnle_order2,vnle_order3];
dfe_order = [0 0 0];

pf_ncoeffs = 1;

alpha = 0;

len_tr  = 4096*2;

mu_ffe1 = 0.0001;
mu_ffe2 = 0.0008;
mu_ffe3 = 0.001;
mu_dc = 0.005;
% mu_dc = 0;

mu_ffe = [mu_ffe1 mu_ffe3 mu_ffe3];
mu_dfe = 0.0004;


dfe_ = sum(dfe_order)>0;

% duob_mode = db_mode.no_db;

%%% change specific parameter if given in varargin
% Parse optional input arguments
if ~isempty(varargin)
    var_s = varargin{1};
    if isstruct(var_s)
        fields = fieldnames(var_s);
        for i = 1:numel(fields)
            if isnumeric(fields{i})
                eval([fields{i}, ' = ',  num2str( var_s.(fields{i}) ), ';']);
                fprintf("%s <-- %.2f \n", fields{i}, var_s.(fields{i}));
            else
                eval([fields{i}, ' = ',  'var_s.(fields{',num2str(i),'})' , ';']);
            end

        end
    else
        error('Optional variables should be passed as a struct.');
    end
end


fsym_ = floor( bitrate*1e-9./log2(M) ).*1e9;

if fsym_ ~= fsym
    fsym = fsym_;
    % fprintf('Adapted symbolrate to %d GBd, to match provided bitrate of %d GBit/s using PAM %d \n',fsym.*1e-9,bitrate.*1e-9, M);
end





f_nyquist       = fsym/2;

Pform       = Pulseformer("fsym",fsym,"fdac",4*fsym,"pulse","rc","pulselength",16,"alpha",rcalpha);

[Digi_sig,Symbols,Tx_bits] = PAMsource(...
    "fsym",fsym,"M",M,"order",18,"useprbs",0,...
    "fs_out",fdac,...
    "applyclipping",0,"clipfactor",1.5,...
    "applypulseform",apply_pulsef,"pulseformer",Pform,...
    "randkey",random_key,...
    'duobinary_mode',duob_mode,...
    "mrds_code",0,"mrds_blocklength",512).process();

Digi_sig.spectrum("displayname",'Digi Spectrum','fignum',10,'normalizeTo0dB',1);

%%%%% AWG
% El_sig = M8199A("kover",kover).process(Digi_sig);
El_sig = AWG("fdac",fdac,"f_cutoff",fsym,"lpf_active",0,"kover",kover,"bit_resolution",12,"upsampling_method","samplehold","precomp_sinc_rolloff",1).process(Digi_sig);
% El_sig.spectrum("displayname",'Digi Spectrum','fignum',100,'normalizeTo0dB',0);
% El_sig = El_sig.setPower(0,"dBm");

%%%%% Low-pass el. components %%%%%%
tx_bwl = tx_bw_nyquist.*f_nyquist;
% tx_bwl = 80e9;
El_sig = Filter('filtdegree',4,"f_cutoff",tx_bwl,"fs",fdac*kover,"filterType",filtertypes.butterworth,"active",true).process(El_sig);
% El_sig.spectrum("displayname",'Digi Spectrum','fignum',100,'normalizeTo0dB',1);

%%%%% Electrical Driver Amplifier %%%%%%
% El_sig = Amplifier("amp_mode","ideal_no_noise","gain_mode","gain","amplification_db",3).process(El_sig);
El_sig = El_sig.normalize("mode","oneone");
scaling = 0.6*(u_pi/2-abs(vbias-u_pi/2));
El_sig = El_sig .* scaling;

%%%%% MODULATE E/O CONVERSION %%%%%%
[Opt_sig] = EML("mode",eml_mode.im_cosinus,"power",3,"fsimu",El_sig.fs,"lambda",laser_wavelength,"bias",vbias,"u_pi",u_pi,"linewidth",laser_linewidth,"randomkey",random_key+1,"alpha",alpha).process(El_sig);

% Opt_sig.spectrum("displayname",'Opt Spectrum','fignum',10,'normalizeTo0dB',1);

Opt_sig    = Fiber("fsimu",Opt_sig.fs,"fiber_length",link_length,"alpha",0.3,"D",0,"lambda0",1310,"gamma",0,"Dslope",0.07).process(Opt_sig);

%%%%%% ROP %%%%%%
Rx_sig = Amplifier("amp_mode","ideal_no_noise","gain_mode","output_power","amplification_db",rop).process(Opt_sig);

%%%%%% PD Square Law %%%%%%
Rx_sig = Photodiode("fsimu",fdac*kover,"dark_current",2e-08,"responsivity",1,"temperature",20,"nep",1.8e-11).process(Rx_sig);

%%%%%% Low-pass RX (PD, El. Connectors and Scope %%%%%%
rx_bwl = rx_bw_nyquist.*f_nyquist;
% rx_bwl = 80e9;
Rx_sig = Filter('filtdegree',4,"f_cutoff",rx_bwl,"fs",fdac*kover,"filterType",filtertypes.butterworth,"active",true).process(Rx_sig);

% %%%%%% Low-pass Scope %%%%%%
Lp_scpe = Filter('filtdegree',4,"f_cutoff",110e9,"fs",fadc,"filterType",filtertypes.butterworth,"active",true);

% Rx_sig.spectrum("displayname",'Analog Rx Spectrum','fignum',100,'normalizeTo0dB',1);

%%%%%% Scope %%%%%%
Scpe_sig = Scope("fsimu",fdac*kover,"fadc",fadc,...
    "delay",0,"fixed_delay",0,"filtertype",filtertypes.butterworth,...
    "samplingdelay",0,"rand_samplingdelay",0,"freq_offset",0,"samp_jitter",0,...
    "adcresolution",8,"quantbuffer",0.1,'block_dc',1,'lpf_active',1,'H_lpf',Lp_scpe).process(Rx_sig);

output = struct();

%%%%%% Sample to 2x fsym %%%%%%
Scpe_sig =  Scpe_sig.resample("fs_out",2*fsym);
Scpe_sig.signal = Scpe_sig.signal(1:2*length(Symbols));

%%%%%% Sync Rx signal with reference %%%%%%
[Scpe_sig,~] = Scpe_sig.tsynch("reference",Symbols,"fs_ref",fsym,"debug_plots",0);

Scpe_sig = Filter('filtdegree',4,"f_cutoff",Symbols.fs.*0.5,"fs",Scpe_sig.fs,"filterType",filtertypes.gaussian,"active",true).process(Scpe_sig);

Scpe_sig = Scpe_sig - mean(Scpe_sig.signal);

%%% EQUALIZING


% % -------------------- FFE --------------------
% ffe_order   = [50, 0, 0];
% eq_ffe      = EQ("Ne",ffe_order,"Nb",[0,0,0], ...
%     "training_length",len_tr,"training_loops",5,"dd_loops",5, ...
%     "K",2,"DCmu",mu_dc,"DDmu",[mu_ffe mu_dfe],"DFEmu",0.005, ...
%     "FFEmu",0,"plotfinal",0,"ideal_dfe",0);
% 
% output.ffe_results = ffe(eq_ffe,M,Scpe_sig,Symbols,Tx_bits, ...
%     "precode_mode",duob_mode,'showAnalysis',0,"postFFE",[], ...
%     "eth_style_symbol_mapping",0);
% 
% output.ffe_results.metrics.print

% % -------------------- DFE --------------------
% eq_dfe      = EQ("Ne",ffe_order,"Nb",[2,0,0], ...
%     "training_length",len_tr,"training_loops",5,"dd_loops",5, ...
%     "K",2,"DCmu",mu_dc,"DDmu",[mu_ffe mu_dfe],"DFEmu",0.005, ...
%     "FFEmu",0,"plotfinal",0,"ideal_dfe",0);
% 
% output.dfe_results = ffe(eq_dfe,M,Scpe_sig,Symbols,Tx_bits, ...
%     "precode_mode",duob_mode,'showAnalysis',0,"postFFE",[], ...
%     "eth_style_symbol_mapping",0);
% 
% output.dfe_results.metrics.print("description",'DFE');


% % -------------------- VNLE + MLSE --------------------
% pf_ncoeffs  = 1;
% ffe_order3  = [200, 0, 0];
% eq_v        = EQ("Ne",ffe_order3,"Nb",dfe_order, ...
%     "training_length",len_tr,"training_loops",5,"dd_loops",5, ...
%     "K",2,"DCmu",mu_dc,"DDmu",[mu_ffe mu_dfe],"DFEmu",0.005, ...
%     "FFEmu",0,"plotfinal",0,"ideal_dfe",1);
% pf_         = Postfilter("ncoeff",pf_ncoeffs,"useBurg",1);
% 
% mlse_ = MLSE("duobinary_output",0,'M',M,'trellis_states',PAMmapper(M,0).levels);
% 
% [output.vnle_results, output.mlse_results] = vnle_postfilter_mlse(eq_v, pf_, mlse_, M, Scpe_sig, Symbols, Tx_bits, ...
%     "precode_mode", duob_mode, 'showAnalysis', 0, "postFFE", [], "eth_style_symbol_mapping", 0);


% -------------------- DB target --------------------
mlse_db_ = MLSE("DIR",[1,1],"duobinary_output",0,"M",M,'trellis_states',PAMmapper(M,0).levels);
ffe_order = [50, 0, 0];
eq_       = EQ("Ne",ffe_order,"Nb",dfe_order,"training_length",len_tr,"training_loops",5,"dd_loops",5, ...
    "K",2,"DCmu",mu_dc,"DDmu",[mu_ffe mu_dfe],"DFEmu",0.005,"FFEmu",0,"plotfinal",0,"ideal_dfe",1);
output.dbt_results = duobinary_target(eq_,mlse_db_, M, Scpe_sig, Symbols, Tx_bits, ...
    "precode_mode", duob_mode, 'showAnalysis', 0, "postFFE", [], "decoding_mode", decoding_mode);

output.dbt_results.metrics.print("description",'Duobinary');


disp('- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ')
fprintf('\n')

end