halfway merged and pulled?!

Classes/02_optical/dp_fiber_lib/lin_step.m

@@ -0,0 +1,125 @@
+
+%function [rOpt,state] = lin_step(state,aOpt,aStepSize)
+
+function [rOpt_x,rOpt_y,z_prop,lin_z_test,...
+    corr_length,n_plates_done,missing_dz,n_step,test_plates,...
+    test_plate_numbers,brf,common_beta_x,common_beta_y,alpha_lin_x,alpha_lin_y]...
+    = lin_step(...
+    opt_x,opt_y,z_prop,lin_z_test,aStepSize,corr_length,...
+    n_plates_done,missing_dz,n_step,test_plates,test_plate_numbers,...
+    brf,common_beta_x,common_beta_y,alpha_lin_x,alpha_lin_y)
+
+%%%%%% 1) Update and Check Distances etc. %%%%%%
+
+% update propgated distance z_prop
+z_prop = z_prop + aStepSize;
+
+% calculate the number of plates needed for the so far propagated fiber length
+n_plates = ceil(z_prop/corr_length);
+
+% subtract the number of plates which were already processed
+n_plates_left = n_plates - n_plates_done;
+
+% compute last plate size ( if it fits, it should be 0)
+if missing_dz > aStepSize
+    
+    last_plate = aStepSize;
+    missing_dz = missing_dz-aStepSize;
+    plate_sizes = last_plate;
+    plate_numbers = n_plates;
+    
+else
+    
+    last_plate = aStepSize - missing_dz - (n_plates_left-1)*corr_length;
+    
+    if missing_dz == 0
+        missing_dz = [];
+    end
+    
+    %build vector of plate lengths with missing plate part from prev.
+    %iterartion , then some normal plates and finally a fraction of a plate
+    %to fit into the step length
+    plate_sizes = [missing_dz corr_length*ones(1,n_plates_left-1) last_plate];
+    
+    if n_plates_done == 0
+        plate_numbers =[(n_plates_done+1):(n_plates-1) n_plates];
+    else
+        plate_numbers = [n_plates_done (n_plates_done+1):(n_plates-1) n_plates];  % not wrking yet
+    end
+    
+    %remember for next step 
+    missing_dz = corr_length - last_plate;
+    
+end
+
+plate_steps = repmat(n_step,1,length(plate_sizes));
+
+%
+%figure;stem(plate_sizes);
+test_plates = [test_plates,plate_sizes];
+
+test_plate_numbers = [test_plate_numbers, plate_numbers];
+
+%%%%%% 2) Apply Waveplate Model %%%%%%
+
+% transfer optical envelope to frequency domain for effective convolution with transfer function h
+opt_x=fft(opt_x);
+opt_y=fft(opt_y);
+
+% db1 = gpuArray(brf.db1);
+% db0 = gpuArray(brf.db0);
+% common_beta_x = gpuArray(common_beta_x);
+% common_beta_y = gpuArray(common_beta_y);
+
+db1 = (brf.db1);
+db0 = (brf.db0);
+common_beta_x = (common_beta_x);
+common_beta_y = (common_beta_y);
+
+% process every waveplate with given sizes in plate_sizes
+for n=1:length(plate_sizes)
+    dz = plate_sizes(n);
+    
+    %         figure(87);subplot(2,1,1);plot(real(x(900:1150)));subplot(2,1,2);plot(real(y(900:1150)));
+    %         MOV1=[MOV1 getframe(87)];
+    
+    % extract rotation matrix from pre calculated matrices
+    matR = brf.matR{plate_numbers(n)};
+    
+    % transform to eigenvalue of of fiber segment
+    tOpt.X = conj(matR(1,1))*opt_x + conj(matR(2,1))*opt_y;
+    tOpt.Y = conj(matR(1,2))*opt_x + conj(matR(2,2))*opt_y;
+    
+    % calculate statistical delta beta for pmd
+    delta_beta = 0.5*(db1+db0(n))/corr_length;
+    % build transfer function with delta beta
+    %common.beta = beta1+beta2*omega^2
+    
+    %accumulate delta beta for log...
+    brf.simdgd = brf.simdgd + (db1(length(db1)/2+1)+db0(n))/corr_length;
+    
+    h.X = exp(-1j*(common_beta_x-delta_beta)*dz);
+    h.Y = exp(-1j*(common_beta_y+delta_beta)*dz);
+    % delta_beta has to be added to the transfer function
+    
+    % process with transfer function
+    tOpt.X = h.X.*tOpt.X ;
+    tOpt.Y = h.Y.*tOpt.Y ;
+    
+    % rotate back
+    opt_x = matR(1,1)*tOpt.X + matR(1,2)*tOpt.Y;
+    opt_y = matR(2,1)*tOpt.X + matR(2,2)*tOpt.Y;
+    
+end
+
+lin_z_test = lin_z_test + sum(plate_sizes,2);
+
+%update the number of processed plates so far
+n_plates_done = n_plates_done + n_plates_left;
+
+% attanuate the signal each linear state with alpha
+% ( 0.2dB = 4.6052e-05 )
+rOpt_x=ifft(exp(-alpha_lin_x*aStepSize/2).*opt_x); % /2 not sure why (have to find it in formulas) 
+rOpt_y=ifft(exp(-alpha_lin_y*aStepSize/2).*opt_y); % but not relevant for now
+
+end