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start implementation of class based simulation of a IM/DD communication system. Mostly based on Move-It but cleaned up and with focus on direct detection, however I try to keep the versatility of move-it alive.
2023-05-12 15:28:23 +02:00
parent 69df41340f
commit 6d53823466
109 changed files with 1824 additions and 0 deletions
--- a/comm_tb.asv
+++ b/comm_tb.asv
@@ -0,0 +1,146 @@
+O = 10; %order of prbs
+N = 64; %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;
+% Simulation frequency in "analog domain"
+fsimu = kover * fdac ;
+
+
+
+%SIMULATE
+
+for i = 1:log2(M)
+    [bitpattern(:,i),seed] = prbs(O,N,seed);
+end
+
+pamData     = pam_mapping(bitpattern,M,0);
+
+shapedData  = applyPulseShaping(pamData,fsym,fdac);
+
+
+
+awg = AWG('preset','M8196A','fdac',fdac,'kover',kover,'lpf_active',1);
+awgSignal   = awg.process_channel(shapedData);
+
+fil = Filter('filtdegree',4,"f_cutoff",50e9,"fdac",fdac,"filterType",filtertypes.bessel_bilin);
+filtered = fil.process(awgSignal);
+
+u_pi = 3.5;
+vbias = (0.5*u_pi)-u_pi;
+eml = EML("mode",emlmodes.im_cosinus,"power",10,"fsimu",fsimu,"lambda",1550,"bias",vbias,"u_pi",u_pi,"linewidth",1000000);
+laserfield = eml.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("fiber_length",2,"alpha",0.2,"D",17,"lambda0",1550);
+
+
+figure;
+plot(shapedData);
+hold on
+plot(awgSignal,'DisplayName','skew 0');
+plot(filtered,'DisplayName','filtered');
+plot(abs(laserfield),'DisplayName','laser');
+plot(abs(att_out),'DisplayName','att_out');
+
+hold off
+
+
+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
+
+function yout = applyBandwidthLimitation(xin)
+    data_out=ifft(repmat(state.H,1,size(data_in,1)).*fft(data_in.')).';
+end