diff --git a/src/algorithms/observables/gnuradio_blocks/hybrid_observables_cc.cc b/src/algorithms/observables/gnuradio_blocks/hybrid_observables_cc.cc
index f76681cef..8c29fd840 100644
--- a/src/algorithms/observables/gnuradio_blocks/hybrid_observables_cc.cc
+++ b/src/algorithms/observables/gnuradio_blocks/hybrid_observables_cc.cc
@@ -99,6 +99,10 @@ bool Hybrid_pairCompare_gnss_synchro_Prn_delay_ms( std::pair<int,Gnss_Synchro> a
 }
 
 
+bool Hybrid_pairCompare_gnss_synchro_d_TOW_hybrid_at_current_symbol( std::pair<int,Gnss_Synchro> a, std::pair<int,Gnss_Synchro> b)
+{
+    return (a.second.d_TOW_hybrid_at_current_symbol) < (b.second.d_TOW_hybrid_at_current_symbol);
+}
 
 bool Hybrid_pairCompare_gnss_synchro_d_TOW_at_current_symbol( std::pair<int,Gnss_Synchro> a, std::pair<int,Gnss_Synchro> b)
 {
@@ -106,7 +110,6 @@ bool Hybrid_pairCompare_gnss_synchro_d_TOW_at_current_symbol( std::pair<int,Gnss
 }
 
 
-
 int hybrid_observables_cc::general_work (int noutput_items, gr_vector_int &ninput_items,
         gr_vector_const_void_star &input_items,	gr_vector_void_star &output_items)
 {
@@ -148,30 +151,32 @@ int hybrid_observables_cc::general_work (int noutput_items, gr_vector_int &ninpu
              *  common RX time algorithm
              */
             // what is the most recent symbol TOW in the current set? -> this will be the reference symbol
-//            gnss_synchro_iter = max_element(current_gnss_synchro_map.begin(), current_gnss_synchro_map.end(), Hybrid_pairCompare_gnss_synchro_d_TOW_at_current_symbol);
-//            double d_TOW_reference = gnss_synchro_iter->second.d_TOW_at_current_symbol;
-//            double d_ref_PRN_rx_time_ms = gnss_synchro_iter->second.Prn_timestamp_ms;
+            gnss_synchro_iter = max_element(current_gnss_synchro_map.begin(), current_gnss_synchro_map.end(), Hybrid_pairCompare_gnss_synchro_d_TOW_hybrid_at_current_symbol);
+            double d_TOW_reference = gnss_synchro_iter->second.d_TOW_hybrid_at_current_symbol;
+            std::cout<<"d_TOW_hybrid_reference [ms] = "<< d_TOW_reference*1000 <<std::endl;
+            double d_ref_PRN_rx_time_ms = gnss_synchro_iter->second.Prn_timestamp_ms;
+            std::cout<<"ref_PRN_rx_time_ms [ms] = "<< d_ref_PRN_rx_time_ms <<std::endl;
             //int reference_channel= gnss_synchro_iter->second.Channel_ID;
 
             // Now compute RX time differences due to the PRN alignment in the correlators
-//            double traveltime_ms;
-//            double pseudorange_m;
-//            double delta_rx_time_ms;
-            for(gnss_synchro_iter = current_gnss_synchro_map.begin(); gnss_synchro_iter != current_gnss_synchro_map.end(); gnss_synchro_iter++)
+            double traveltime_ms;
+            double pseudorange_m;
+            double delta_rx_time_ms;
+    	for(gnss_synchro_iter = current_gnss_synchro_map.begin(); gnss_synchro_iter != current_gnss_synchro_map.end(); gnss_synchro_iter++)
                 {
+                    // compute the required symbol history shift in order to match the reference symbol
+                    delta_rx_time_ms = gnss_synchro_iter->second.Prn_timestamp_ms-d_ref_PRN_rx_time_ms;
+                    //compute the pseudorange
+                    traveltime_ms = (d_TOW_reference - gnss_synchro_iter->second.d_TOW_hybrid_at_current_symbol)*1000.0 + delta_rx_time_ms + GALILEO_STARTOFFSET_ms;
+                    pseudorange_m = traveltime_ms * GALILEO_C_m_ms; // [m]
+               		std::cout<<"CH "<<gnss_synchro_iter->second.Channel_ID<<" tracking GNSS System "<<gnss_synchro_iter->second.System<<" has PRN start at= "<<gnss_synchro_iter->second.Prn_timestamp_ms<<" [ms], d_TOW_at_current_symbol = "<<(gnss_synchro_iter->second.d_TOW_at_current_symbol)*1000<<" [ms], d_TOW_hybrid_at_current_symbol = "<<(gnss_synchro_iter->second.d_TOW_hybrid_at_current_symbol)*1000<<"[ms], delta_rx_time_ms = "<< delta_rx_time_ms << "[ms], travel_time = " << traveltime_ms << ", pseudorange[m] = "<< pseudorange_m << std::endl;
+
+                    // update the pseudorange object
+                    //current_gnss_synchro[gnss_synchro_iter->second.Channel_ID] = gnss_synchro_iter->second;
+                    current_gnss_synchro[gnss_synchro_iter->second.Channel_ID].Pseudorange_m = pseudorange_m;
+                    current_gnss_synchro[gnss_synchro_iter->second.Channel_ID].Flag_valid_pseudorange = true;
+                    current_gnss_synchro[gnss_synchro_iter->second.Channel_ID].d_TOW_hybrid_at_current_symbol = round(d_TOW_reference*1000)/1000 + GALILEO_STARTOFFSET_ms/1000.0;
 
-            		std::cout<<"CH "<<gnss_synchro_iter->second.Channel_ID<<" tracking GNSS System "<<gnss_synchro_iter->second.System<<" has PRN start at= "<<gnss_synchro_iter->second.Prn_timestamp_ms<<" [ms]"<<std::endl;
-//                    // compute the required symbol history shift in order to match the reference symbol
-//                    delta_rx_time_ms = gnss_synchro_iter->second.Prn_timestamp_ms-d_ref_PRN_rx_time_ms;
-//                    //compute the pseudorange
-//                    traveltime_ms = (d_TOW_reference - gnss_synchro_iter->second.d_TOW_at_current_symbol)*1000.0 + delta_rx_time_ms + GALILEO_STARTOFFSET_ms;
-//                    pseudorange_m = traveltime_ms * GALILEO_C_m_ms; // [m]
-//                    // update the pseudorange object
-//                    //current_gnss_synchro[gnss_synchro_iter->second.Channel_ID] = gnss_synchro_iter->second;
-//                    current_gnss_synchro[gnss_synchro_iter->second.Channel_ID].Pseudorange_m = pseudorange_m;
-//                    current_gnss_synchro[gnss_synchro_iter->second.Channel_ID].Flag_valid_pseudorange = true;
-//                    current_gnss_synchro[gnss_synchro_iter->second.Channel_ID].d_TOW_at_current_symbol = round(d_TOW_reference*1000)/1000 + GALILEO_STARTOFFSET_ms/1000.0;
-//
                 }
             std::cout<<std::endl;
         }
@@ -205,11 +210,11 @@ int hybrid_observables_cc::general_work (int noutput_items, gr_vector_int &ninpu
 
     consume_each(1); //consume one by one
 
-//    for (unsigned int i = 0; i < d_nchannels ; i++)
-//        {
-//            *out[i] = current_gnss_synchro[i];
-//        }
+    for (unsigned int i = 0; i < d_nchannels ; i++)
+        {
+            *out[i] = current_gnss_synchro[i];
+        }
     //todo: enable output when the hybrid algorithm is completed
-    return 0; //Output the observables
+    return 1; //Output the observables
 }
 
diff --git a/src/algorithms/telemetry_decoder/gnuradio_blocks/galileo_e1b_telemetry_decoder_cc.cc b/src/algorithms/telemetry_decoder/gnuradio_blocks/galileo_e1b_telemetry_decoder_cc.cc
index a7a3ec1c6..70e45670f 100644
--- a/src/algorithms/telemetry_decoder/gnuradio_blocks/galileo_e1b_telemetry_decoder_cc.cc
+++ b/src/algorithms/telemetry_decoder/gnuradio_blocks/galileo_e1b_telemetry_decoder_cc.cc
@@ -169,7 +169,7 @@ galileo_e1b_telemetry_decoder_cc::galileo_e1b_telemetry_decoder_cc(
     d_flag_parity = false;
     d_TOW_at_Preamble = 0;
     d_TOW_at_current_symbol = 0;
-
+    delta_t = 0;
     d_CRC_error_counter = 0;
 }
 
@@ -193,7 +193,7 @@ void galileo_e1b_telemetry_decoder_cc::decode_word(double *page_part_symbols,int
 
     // 2. Viterbi decoder
     // 2.1 Take into account the NOT gate in G2 polynomial (Galileo ICD Figure 13, FEC encoder)
-    // 2.2 Take into account the possible inversion of the polarity due to PLL lock at 180¼
+    // 2.2 Take into account the possible inversion of the polarity due to PLL lock at 180�
     for (int i = 0; i < frame_length; i++)
         {
             if ((i + 1) % 2 == 0)
@@ -278,7 +278,7 @@ void galileo_e1b_telemetry_decoder_cc::decode_word(double *page_part_symbols,int
     	std::cout<<"d_TOW_at_current_symbol="<<d_TOW_at_current_symbol<<std::endl;
     	std::cout<<"d_nav.WN_0="<<d_nav.WN_0<<std::endl;
 
-    	double delta_t;
+    	//double delta_t; declared out of this function to be used in the observable block
     	delta_t=almanac.A_0G_10+almanac.A_1G_10*(d_TOW_at_current_symbol-almanac.t_0G_10+604800*(fmod((d_nav.WN_0-almanac.WN_0G_10),64)));
 
     	std::cout<<"delta_t="<<delta_t<<"[s]"<<std::endl;
@@ -445,9 +445,10 @@ int galileo_e1b_telemetry_decoder_cc::general_work (int noutput_items, gr_vector
                 }
             else
                 {
-                    //this page has no timming information
+                    //this page has no timing information
                     d_TOW_at_Preamble = d_TOW_at_Preamble + GALILEO_INAV_PAGE_SECONDS;
                     d_TOW_at_current_symbol =  d_TOW_at_current_symbol + GALIELO_E1_CODE_PERIOD;// + GALILEO_INAV_PAGE_PART_SYMBOLS*GALIELO_E1_CODE_PERIOD;
+
                 }
 
         }
@@ -457,6 +458,14 @@ int galileo_e1b_telemetry_decoder_cc::general_work (int noutput_items, gr_vector
         }
 
     //if (d_flag_frame_sync == true and d_nav.flag_TOW_set==true and d_nav.flag_CRC_test == true)
+
+    if(d_nav.flag_GGTO_1 == true  and  d_nav.flag_GGTO_2 == true and  d_nav.flag_GGTO_3 == true and  d_nav.flag_GGTO_4 == true) //all GGTO parameters arrived
+        {
+    	delta_t=d_nav.A_0G_10+d_nav.A_1G_10*(d_TOW_at_current_symbol-d_nav.t_0G_10+604800*(fmod((d_nav.WN_0-d_nav.WN_0G_10),64)));
+        }
+
+
+
     if (d_flag_frame_sync == true and d_nav.flag_TOW_set == true)
         {
             current_synchro_data.Flag_valid_word = true;
@@ -466,8 +475,12 @@ int galileo_e1b_telemetry_decoder_cc::general_work (int noutput_items, gr_vector
             current_synchro_data.Flag_valid_word = false;
         }
 
+
+
     current_synchro_data.d_TOW = d_TOW_at_Preamble;
     current_synchro_data.d_TOW_at_current_symbol = d_TOW_at_current_symbol;
+    current_synchro_data.d_TOW_hybrid_at_current_symbol= current_synchro_data.d_TOW_at_current_symbol - delta_t; //delta_t = t_gal - t_gps  ---->  t_gps = t_gal -delta_t
+    std::cout<< "delta_t = " << delta_t << std::endl;
     current_synchro_data.Flag_preamble = d_flag_preamble;
     current_synchro_data.Prn_timestamp_ms = in[0][0].Tracking_timestamp_secs * 1000.0;
     current_synchro_data.Prn_timestamp_at_preamble_ms = Prn_timestamp_at_preamble_ms;
diff --git a/src/algorithms/telemetry_decoder/gnuradio_blocks/galileo_e1b_telemetry_decoder_cc.h b/src/algorithms/telemetry_decoder/gnuradio_blocks/galileo_e1b_telemetry_decoder_cc.h
index 899ba68c3..19a7964bb 100644
--- a/src/algorithms/telemetry_decoder/gnuradio_blocks/galileo_e1b_telemetry_decoder_cc.h
+++ b/src/algorithms/telemetry_decoder/gnuradio_blocks/galileo_e1b_telemetry_decoder_cc.h
@@ -138,6 +138,8 @@ private:
     double d_TOW_at_current_symbol;
     double Prn_timestamp_at_preamble_ms;
     bool flag_TOW_set;
+    double delta_t; //GPS-GALILEO time offset
+
 
     std::string d_dump_filename;
     std::ofstream d_dump_file;
diff --git a/src/algorithms/telemetry_decoder/gnuradio_blocks/gps_l1_ca_telemetry_decoder_cc.cc b/src/algorithms/telemetry_decoder/gnuradio_blocks/gps_l1_ca_telemetry_decoder_cc.cc
index 34de57449..9c40c2dd7 100644
--- a/src/algorithms/telemetry_decoder/gnuradio_blocks/gps_l1_ca_telemetry_decoder_cc.cc
+++ b/src/algorithms/telemetry_decoder/gnuradio_blocks/gps_l1_ca_telemetry_decoder_cc.cc
@@ -318,6 +318,8 @@ int gps_l1_ca_telemetry_decoder_cc::general_work (int noutput_items, gr_vector_i
 
     current_synchro_data.d_TOW = d_TOW_at_Preamble;
     current_synchro_data.d_TOW_at_current_symbol = d_TOW_at_current_symbol;
+
+    current_synchro_data.d_TOW_hybrid_at_current_symbol= current_synchro_data.d_TOW_at_current_symbol; // to be  used in the hybrid configuration
     current_synchro_data.Flag_valid_word = (d_flag_frame_sync == true and d_flag_parity == true and flag_TOW_set==true);
     current_synchro_data.Flag_preamble = d_flag_preamble;
     current_synchro_data.Prn_timestamp_ms = in[0][0].Tracking_timestamp_secs * 1000.0;
diff --git a/src/core/system_parameters/galileo_navigation_message.cc b/src/core/system_parameters/galileo_navigation_message.cc
index 76048f019..b9d014924 100644
--- a/src/core/system_parameters/galileo_navigation_message.cc
+++ b/src/core/system_parameters/galileo_navigation_message.cc
@@ -66,6 +66,12 @@ void Galileo_Navigation_Message::reset()
     flag_TOW_5 = 0;
     flag_TOW_set = false;
 
+    flag_GGTO= false;
+    flag_GGTO_1= false;
+    flag_GGTO_2= false;
+    flag_GGTO_3= false;
+    flag_GGTO_4= false;
+
     IOD_ephemeris = 0;
     /*Word type 1: Ephemeris (1/4)*/
     IOD_nav_1 = 0;
@@ -974,14 +980,18 @@ int Galileo_Navigation_Message::page_jk_decoder(const char *data_jk)
         DLOG(INFO) << "E1B_HS_10= " << E1B_HS_10;
         A_0G_10 = (double)read_navigation_signed(data_jk_bits, A_0G_10_bit);
         A_0G_10 = A_0G_10 * A_0G_10_LSB;
+        flag_GGTO_1=true;
         DLOG(INFO) << "A_0G_10= " << A_0G_10;
         A_1G_10 = (double)read_navigation_signed(data_jk_bits, A_1G_10_bit);
         A_1G_10 = A_1G_10 * A_1G_10_LSB;
+        flag_GGTO_2=true;
         DLOG(INFO) << "A_1G_10= " << A_1G_10;
         t_0G_10 = (double)read_navigation_unsigned(data_jk_bits, t_0G_10_bit);
         t_0G_10 = t_0G_10 * t_0G_10_LSB;
+        flag_GGTO_3=true;
         DLOG(INFO) << "t_0G_10= " << t_0G_10;
         WN_0G_10 = (double)read_navigation_unsigned(data_jk_bits, WN_0G_10_bit);
+        flag_GGTO_4=true;
         DLOG(INFO) << "WN_0G_10= " << WN_0G_10;
         flag_almanac_4 = true;
         DLOG(INFO) << "flag_tow_set" << flag_TOW_set;
diff --git a/src/core/system_parameters/galileo_navigation_message.h b/src/core/system_parameters/galileo_navigation_message.h
index e56c0a1dc..f11672541 100644
--- a/src/core/system_parameters/galileo_navigation_message.h
+++ b/src/core/system_parameters/galileo_navigation_message.h
@@ -87,6 +87,12 @@ public:
 
     int IOD_ephemeris;
 
+    bool flag_GGTO;
+    bool flag_GGTO_1;
+    bool flag_GGTO_2;
+    bool flag_GGTO_3;
+    bool flag_GGTO_4;
+
     /*Word type 1: Ephemeris (1/4)*/
     int IOD_nav_1;            //!< IOD_nav page 1
     double t0e_1;             //!< Ephemeris reference time [s]
diff --git a/src/core/system_parameters/gnss_synchro.h b/src/core/system_parameters/gnss_synchro.h
index 2bb2ffa02..4672afb71 100644
--- a/src/core/system_parameters/gnss_synchro.h
+++ b/src/core/system_parameters/gnss_synchro.h
@@ -70,6 +70,8 @@ public:
     bool Flag_preamble;     //!< Set by Telemetry Decoder processing block
     double d_TOW;           //!< Set by Telemetry Decoder processing block
     double d_TOW_at_current_symbol;
+    double d_TOW_hybrid_at_current_symbol; //Galileo TOW is expressed in the GPS time scale (it will be the same for any other constellation)
+
     // Pseudorange
     double Pseudorange_m;
     bool Flag_valid_pseudorange;