146 lines
3.4 KiB
Matlab
146 lines
3.4 KiB
Matlab
O = 10; %order of prbs
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N = 64; %length of prbs
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[~,seed] = prbs(O,1); %initialize first seed of prbs
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% Modulation
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M = 4;
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bitpattern = zeros(N,log2(M));
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% Symbol Rate
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fsym = 56e9;
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% DAC Rate
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fdac = 120e9;
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% Simulation oversampling rate "k";
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kover = 16;
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% Simulation frequency in "analog domain"
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fsimu = kover * fdac ;
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%SIMULATE
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for i = 1:log2(M)
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[bitpattern(:,i),seed] = prbs(O,N,seed);
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end
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pamData = pam_mapping(bitpattern,M,0);
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shapedData = applyPulseShaping(pamData,fsym,fdac);
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awg = AWG('preset','M8196A','fdac',fdac,'kover',kover,'lpf_active',1);
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awgSignal = awg.process_channel(shapedData);
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fil = Filter('filtdegree',4,"f_cutoff",50e9,"fdac",fdac,"filterType",filtertypes.bessel_bilin);
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filtered = fil.process(awgSignal);
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u_pi = 3.5;
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vbias = (0.5*u_pi)-u_pi;
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eml = EML("mode",emlmodes.im_cosinus,"power",10,"fsimu",fsimu,"lambda",1550,"bias",vbias,"u_pi",u_pi,"linewidth",1000000);
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laserfield = eml.process(filtered);
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att = Amplifier("amplification_db",10,"amp_mode","gain","type","ideal","saturation_mode",0,'saturation_power',10);
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att_out = att.process(laserfield);
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fib = Fiber("fsimu",fdac*kover,"fiber_length",20,"alpha",0.2,"D",17,"lambda0",1550);
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fib_out = fib.process(att_out);
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phdiode = Photodiode("fsimu",fdac*kover,"dark_current",2e-08,"responsivity",1,"temperature",20);
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phdiod_out = phdiode.process(fib_out);
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figure;
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plot(shapedData);
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hold on
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plot(awgSignal,'DisplayName','skew 0');
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plot(filtered,'DisplayName','filtered');
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plot(abs(laserfield),'DisplayName','laser');
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plot(abs(att_out),'DisplayName','att_out');
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plot(abs(fib_out),'DisplayName','att_out');
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hold off
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function pam_sig = pam_mapping(bitpattern, M, unipolar)
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switch log2(M)
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case 1
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% 2-ASK: BPSK / OOK
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pam_sig=bitpattern(:,1);
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if unipolar==0
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pam_sig=2*pam_sig-1;
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end
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case 2
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% 4-ASK:
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pam_sig=2*bitpattern(:,1)+(bitpattern(:,1)==bitpattern(:,2));
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if unipolar==0
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pam_sig=2*pam_sig-3;
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end
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case 3
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% 8-ASK:
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x1 = bitpattern(:,1);
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x2 = (bitpattern(:,1)==bitpattern(:,3));
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x3 = x2~=bitpattern(:,2);
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pam_sig = 4*x1 + 2*x2 + x3;
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if unipolar==0
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pam_sig=2*pam_sig-7;
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end
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case 4
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% 16-ASK:
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x1 = bitpattern(:,1);
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x2 = (bitpattern(:,1)==bitpattern(:,4));
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x3 = x2~=bitpattern(:,3);
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x4 = x3~=bitpattern(:,2);
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pam_sig = 8*x1 + 4*x2 + 2*x3 + x4;
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if unipolar==0
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pam_sig=2*pam_sig-15;
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end
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end
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end
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function yout = applyPulseShaping(xin,fsym,fdac)
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if ~rem(fdac,fsym)
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%ist ein Vielfaches
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sps = fdac / fsym;
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up = sps;
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dn = 1;
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else
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%ist kein Vielfaches
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up = fdac / gcd(fdac, fsym);
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dn = fsym / gcd(fdac, fsym);
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sps= up;
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end
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%Bau das Filter (hier rrc)
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racos_len = 2048;
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alpha = 0.1;
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h = rcosdesign(alpha,racos_len,sps);
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%Apply Filter using Matlab build in fctn.
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yout = upfirdn(xin,h,up,dn);
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%cut signal, which is longer due to fir filter
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st = up/dn*racos_len/2; %we need to cut y_out
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en = st + (length(xin)*up/dn) -1;
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yout = yout(st:en);
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%Check output integrity
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if (up/dn * length(xin)) ~= length(yout)
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warning('Check signal length after pulse shaping');
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end
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end |