useprbs = 0;
M = 4;
randkey = 2;
fsym = 112e9;

%%%%% PRBS Generation in correct shape for Modulation Format %%%%%%
O = 18; %order of prbs
N = 2^(O-1); %length of prbs
[~,seed] = prbs(O,1); %initialize first seed of prbs
bitpattern=[];

if useprbs
    for i = 1:log2(M)
        [bitpattern(:,i),seed] = prbs(O,N,seed);
    end
else
    s = RandStream('twister','Seed',randkey);
    for i = 1:log2(M)
        bitpattern(:,i) = randi(s,[0 1], N, 1);
    end
end

if M == 6
    bitpattern = reshape(bitpattern,[],1);
    bitpattern = bitpattern(1:end-mod(length(bitpattern),5));
end

Tx_bits = Informationsignal(bitpattern);

Digi_Mod = PAMmapper(M,0);
Symbols_tx = Digi_Mod.map(Tx_bits);
Symbols_tx.fs = fsym;

if 0

    Symbols = Duobinary().precode(Symbols_tx);

    Symbols = Duobinary().encode(Symbols);

    Symbols = MLSE("DIR",[1 1],"duobinary_output",1,"trellis_states",Digi_Mod.levels,"M",M).process(Symbols);

    Symbols = Duobinary().decode(Symbols);

else
    cnt = 1;

    Symbols = Symbols_tx;

    coeff = [1,0.5,0.2,0.1];

    Symbols.signal = filter(coeff, 1, Symbols.signal);

    Symbols.spectrum("fignum",129,"displayname",['coeff:',num2str(coeff)]);

    Symbols = MLSE("DIR",coeff,"duobinary_output",0,"trellis_states",Digi_Mod.levels,"M",M).process(Symbols);

    Rx_bits = PAMmapper(M,0).demap(Symbols);

    [~,error_num,ber,error_pos] = calc_ber(Tx_bits.signal,Rx_bits.signal,"skip_front",0,"skip_end",0,"returnErrorLocation",1);

    disp(['BER: ',sprintf('%.1E',ber),' - - PAM-',num2str(M)]);

end


%
figure(494)
clf
subplot(2,1,1)
title('Bits Compare')
hold on
stairs(Rx_bits.signal(1:100,1),'LineWidth',2,'DisplayName','Rx Bits')
stairs(Tx_bits.signal(1:100,1),'LineStyle',':','LineWidth',2,'DisplayName','Tx Bits');
legend
subplot(2,1,2)
hold on
title('Symbols Compare')
stairs(Symbols.signal(1:100,1),'LineStyle','-','LineWidth',2,'DisplayName','Rx Symbols');
stairs(Symbols_tx.signal(1:100,1),'LineWidth',2,'DisplayName','Tx Symbols','LineStyle',':')
legend