Add mechanism for back-propagation of TOW from telemetry to tracking in GPS L1

src/algorithms/telemetry_decoder/gnuradio_blocks/gps_l1_ca_telemetry_decoder_gs.cc

@@ -24,6 +24,7 @@
 #include "gps_iono.h"              // for Gps_Iono
 #include "gps_utc_model.h"         // for Gps_Utc_Model
 #include "tlm_utils.h"
+#include "tow_to_trk.h"
 #include <gnuradio/io_signature.h>
 #include <pmt/pmt.h>        // for make_any
 #include <pmt/pmt_sugar.h>  // for mp
@@ -695,6 +696,15 @@ int gps_l1_ca_telemetry_decoder_gs::general_work(int noutput_items __attribute__
                         }
                 }
 
+            // SEND TOW TO THE TRACKING BLOCK
+            const std::shared_ptr<TOW_to_trk> tmp_tow_obj = std::make_shared<TOW_to_trk>(TOW_to_trk(
+                std::string("1C"),
+                d_channel,
+                d_TOW_at_current_symbol_ms,
+                current_symbol.Tracking_sample_counter,
+                d_nav.get_GPS_week(), d_nav.get_satellite_PRN()));
+            this->message_port_pub(pmt::mp("telemetry_to_trk"), pmt::make_any(tmp_tow_obj));
+
             // 3. Make the output (move the object contents to the GNU Radio reserved memory)
             *out[0] = std::move(current_symbol);
 

src/algorithms/tracking/gnuradio_blocks/dll_pll_veml_tracking.cc

@@ -606,6 +606,7 @@ dll_pll_veml_tracking::dll_pll_veml_tracking(const Dll_Pll_Conf &conf_)
     d_last_timetag_samplecounter = 0;
     d_timetag_waiting = false;
     set_tag_propagation_policy(TPP_DONT);  // no tag propagation, the time tag will be adjusted and regenerated in work()
+    d_last_tow_received = std::make_shared<TOW_to_trk>();
 }
 
 
@@ -623,7 +624,7 @@ void dll_pll_veml_tracking::msg_handler_telemetry_to_trk(const pmt::pmt_t &msg)
 {
     try
         {
-            if (pmt::any_ref(msg).type().hash_code() == int_type_hash_code)
+            if (pmt::any_ref(msg).type().hash_code() == d_int_type_hash_code)
                 {
                     const int tlm_event = wht::any_cast<int>(pmt::any_ref(msg));
                     if (tlm_event == 1)
@@ -633,6 +634,14 @@ void dll_pll_veml_tracking::msg_handler_telemetry_to_trk(const pmt::pmt_t &msg)
                             d_carrier_lock_fail_counter = 200000;  // force loss-of-lock condition
                         }
                 }
+            if (pmt::any_ref(msg).type().hash_code() == d_tow_to_trk_type_hash_code)
+                {
+                    const auto tow_event = wht::any_cast<const std::shared_ptr<TOW_to_trk>>(pmt::any_ref(msg));
+                    if (tow_event->signal == d_signal_type && tow_event->channel == static_cast<int32_t>(d_channel) && tow_event->prn == d_acquisition_gnss_synchro->PRN)
+                        {
+                            d_last_tow_received = tow_event;
+                        }
+                }
         }
     catch (const wht::bad_any_cast &e)
         {
@@ -2103,6 +2112,11 @@ int dll_pll_veml_tracking::general_work(int noutput_items __attribute__((unused)
                     add_item_tag(0, this->nitems_written(0) + 1, tag.key, tag.value);
                 }
 
+            // Estimate TOW if received from telemetry
+            if (d_last_tow_received->prn == current_synchro_data.PRN)  // ensure we have received async messages
+                {
+                    // TODO: Estimate TOW from d_last_tow_received and store it in current_synchro_data.TOW_at_current_symbol_ms
+                }
             *out[0] = std::move(current_synchro_data);
             return 1;
         }

src/algorithms/tracking/gnuradio_blocks/dll_pll_veml_tracking.h

@@ -22,7 +22,8 @@
 #include "dll_pll_conf.h"
 #include "exponential_smoother.h"
 #include "gnss_block_interface.h"
-#include "gnss_time.h"                // for timetags produced by File_Timestamp_Signal_Source
+#include "gnss_time.h"  // for timetags produced by File_Timestamp_Signal_Source
+#include "tow_to_trk.h"
 #include "tracking_FLL_PLL_filter.h"  // for PLL/FLL filter
 #include "tracking_loop_filter.h"     // for DLL filter
 #include <boost/circular_buffer.hpp>
@@ -112,7 +113,8 @@ private:
     boost::circular_buffer<std::pair<double, double>> d_carr_ph_history;
     boost::circular_buffer<gr_complex> d_Prompt_circular_buffer;
 
-    const size_t int_type_hash_code = typeid(int).hash_code();
+    const size_t d_int_type_hash_code = typeid(int).hash_code();
+    const size_t d_tow_to_trk_type_hash_code = typeid(std::shared_ptr<TOW_to_trk>).hash_code();
 
     double d_signal_carrier_freq;
     double d_code_period;
@@ -168,6 +170,7 @@ private:
     // uint64_t d_sample_counter;
     uint64_t d_acq_sample_stamp;
     GnssTime d_last_timetag{};
+    std::shared_ptr<TOW_to_trk> d_last_tow_received;
     uint64_t d_last_timetag_samplecounter;
     bool d_timetag_waiting;
 

src/core/system_parameters/CMakeLists.txt

@@ -96,6 +96,7 @@ set(SYSTEM_PARAMETERS_HEADERS
     Galileo_OSNMA.h
     osnma_data.h
     osnma_dsm_reader.h
+    tow_to_trk.h
 )
 
 list(SORT SYSTEM_PARAMETERS_HEADERS)

src/core/system_parameters/tow_to_trk.h

@@ -0,0 +1,48 @@
+/*!
+ * \file tow_to_trk.h
+ * \brief Class to inform about TOW from Telemetry to Tracking blocks
+ * \author Carles Fernandez, 2025. cfernandez(at)cttc.es
+ *
+ * -----------------------------------------------------------------------------
+ *
+ * GNSS-SDR is a Global Navigation Satellite System software-defined receiver.
+ * This file is part of GNSS-SDR.
+ *
+ * Copyright (C) 2010-2025  (see AUTHORS file for a list of contributors)
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ * -----------------------------------------------------------------------------
+ */
+
+#ifndef GNSS_SDR_TOW_TO_TRK_H
+#define GNSS_SDR_TOW_TO_TRK_H
+
+#include <cstdint>
+#include <string>
+
+
+/** \addtogroup Core
+ * \{ */
+/** \addtogroup System_Parameters
+ * \{ */
+
+class TOW_to_trk
+{
+public:
+    TOW_to_trk() = default;
+
+    // Constructor with all parameters
+    TOW_to_trk(const std::string& sig, int32_t ch, uint32_t t, uint64_t stamp, int32_t w, uint32_t p)
+        : signal(sig), channel(ch), tow(t), sample_stamp(stamp), wn(w), prn(p) {}
+
+    std::string signal;
+    int32_t channel{0};
+    uint32_t tow{0};
+    uint64_t sample_stamp{0};
+    int32_t wn{0};
+    uint32_t prn{0};
+};
+
+/** \} */
+/** \} */
+#endif  // GNSS_SDR_TOW_TO_TRK_H