diff --git a/src/utils/matlab/vtl/kf_prototype.m b/src/utils/matlab/vtl/kf_prototype.m
index 422f0ff26..b5c04ca0e 100644
--- a/src/utils/matlab/vtl/kf_prototype.m
+++ b/src/utils/matlab/vtl/kf_prototype.m
@@ -122,7 +122,7 @@ for t=2:length(navSolution.RX_time)
 
         rhoDot_pri(chan,t)=(sat_velX(chan,t)-xDot_u)*a_x(chan,t)...
             +(sat_velY(chan,t)-yDot_u)*a_y(chan,t)...
-            +(sat_velZ(chan,t)-zDot_u)*a_z(chan,t)+cdeltatDot_u;
+            +(sat_velZ(chan,t)-zDot_u)*a_z(chan,t);
     end
 
     for chan=1:5 % Measurement matrix H assembling
@@ -140,7 +140,12 @@ for t=2:length(navSolution.RX_time)
     % Kalman estimation (measurement update)
     for chan=1:5 % Measurement matrix H assembling
         kf_yerr(chan,t)=c_pr_m(chan,t)-sat_prg_m(chan,t);
-        kf_yerr(chan+sat_number,t)=(sat_dopp_hz(chan,t)*Lambda_GPS_L1+cdeltatDot_u)-rhoDot_pri(chan,t);
+        
+        if (t<length(navSolution.RX_time)-point_of_closure)
+            kf_yerr(chan+sat_number,t)=(sat_dopp_hz(chan,t)*Lambda_GPS_L1)-rhoDot_pri(chan,t);
+        else
+            kf_yerr(chan+sat_number,t)=(sat_dopp_hz(chan,t)*Lambda_GPS_L1+cdeltatDot_u)-rhoDot_pri(chan,t);
+        end
     end
 
     % DOUBLES DIFFERENCES
@@ -209,7 +214,8 @@ for t=2:length(navSolution.RX_time)
         pr_m_filt(chan,t)=sat_prg_m(chan,t)+kf_yerr_g(chan,t);% now filtered
         rhoDot_pri_filt(chan,t)=(sat_dopp_hz(chan,t)*Lambda_GPS_L1+corr_kf_state(8,t))-kf_yerr_g(chan+sat_number,t);
         %convert rhoDot_pri to doppler shift!
-        d_dt_clk_drift=(corr_kf_state(8,t)-corr_kf_state(8,t-1));
+%         d_dt_clk_drift=(corr_kf_state(8,t)-corr_kf_state(8,t-1));
+d_dt_clk_drift=0;
 
         if (t<length(navSolution.RX_time)-point_of_closure)   
             sat_dopp_hz_filt(chan,t)=(rhoDot_pri_filt(chan,t)-corr_kf_state(8,t))/Lambda_GPS_L1;