Glonass improvements: define resets in telemetry decoders, remove unused async port, fix decoding of some parameters

src/algorithms/PVT/libs/rinex_printer.cc

@@ -2861,7 +2861,9 @@ void Rinex_Printer::log_rinex_nav_glo_gnav(const std::map<int32_t, Glonass_Gnav_
             line.clear();
 
             // -------- BROADCAST ORBIT - 1
-            out << get_nav_broadcast_orbit(&eph.d_Xn, &eph.d_VXn, &eph.d_AXn, &eph.d_B_n, d_version) << '\n';
+            // RINEX expects the health flag in the MSB of the 3-bit Bn word (0 = OK)
+            const auto health_d = static_cast<double>(((static_cast<int32_t>(eph.d_B_n) & 4) == 0) ? 0 : 1);
+            out << get_nav_broadcast_orbit(&eph.d_Xn, &eph.d_VXn, &eph.d_AXn, &health_d, d_version) << '\n';
 
             // -------- BROADCAST ORBIT - 2
             const auto freq_channel_d = static_cast<double>(eph.i_satellite_freq_channel);

src/algorithms/telemetry_decoder/gnuradio_blocks/glonass_l1_ca_telemetry_decoder_gs.cc

@@ -55,7 +55,6 @@ glonass_l1_ca_telemetry_decoder_gs::glonass_l1_ca_telemetry_decoder_gs(const Tlm
           gr::io_signature::make(1, 1, sizeof(Gnss_Synchro)),
           gr::io_signature::make(1, 1, sizeof(Gnss_Synchro))),
       d_dump_filename(conf.dump_filename),
-      d_preamble_time_samples(0),
       d_TOW_at_current_symbol(0),
       d_sample_counter(0ULL),
       d_preamble_index(0ULL),
@@ -73,8 +72,6 @@ glonass_l1_ca_telemetry_decoder_gs::glonass_l1_ca_telemetry_decoder_gs(const Tlm
 {
     configure_basic_outputs();
 
-    this->message_port_register_out(pmt::mp("preamble_timestamp_samples"));
-
     if (d_enable_navdata_monitor)
         {
             // register nav message monitor out
@@ -223,6 +220,28 @@ void glonass_l1_ca_telemetry_decoder_gs::set_channel(int32_t channel)
 }
 
 
+void glonass_l1_ca_telemetry_decoder_gs::reset()
+{
+    gr::thread::scoped_lock lock(d_setlock);  // require mutex with work function called by the scheduler
+    d_symbol_history.clear();
+    d_stat = 0;
+    d_CRC_error_counter = 0;
+    d_flag_frame_sync = false;
+    d_flag_preamble = false;
+    // Invalidate the propagated TOW until a new string 5 is decoded; otherwise
+    // Flag_valid_word would remain true with a TOW offset by the outage duration
+    d_nav.set_flag_TOW_set(false);
+    d_nav.set_flag_TOW_new(false);
+    // Drop partially decoded ephemeris strings so that strings received before
+    // the outage cannot be combined with strings of a different frame
+    d_nav.set_flag_ephemeris_str_1(false);
+    d_nav.set_flag_ephemeris_str_2(false);
+    d_nav.set_flag_ephemeris_str_3(false);
+    d_nav.set_flag_ephemeris_str_4(false);
+    DLOG(INFO) << "Telemetry decoder reset for satellite " << d_satellite;
+}
+
+
 int glonass_l1_ca_telemetry_decoder_gs::general_work(int noutput_items __attribute__((unused)), gr_vector_int &ninput_items __attribute__((unused)),
     gr_vector_const_void_star &input_items, gr_vector_void_star &output_items)
 {
@@ -269,8 +288,6 @@ int glonass_l1_ca_telemetry_decoder_gs::general_work(int noutput_items __attribu
                     LOG(INFO) << "Preamble detection for GLONASS L1 C/A SAT " << this->d_satellite;
                     // Enter into frame pre-detection status
                     d_stat = 1;
-                    d_preamble_time_samples = d_symbol_history[0].Tracking_sample_counter;  // record the preamble sample stamp
-                    // std::cout<< "Preamble detection for GLONASS L1 C/A SAT " << this->d_satellite;
                 }
         }
     else if (d_stat == 1)  // possible preamble lock
@@ -279,14 +296,11 @@ int glonass_l1_ca_telemetry_decoder_gs::general_work(int noutput_items __attribu
                 {
                     // check preamble separation
                     preamble_diff = static_cast<int32_t>(d_sample_counter - d_preamble_index);
-                    // Record the PRN start sample index associated to the preamble
-                    d_preamble_time_samples = static_cast<double>(d_symbol_history[0].Tracking_sample_counter);
                     if (abs(preamble_diff - GLONASS_GNAV_PREAMBLE_PERIOD_BITS) == 0)
                         {
                             // try to decode frame
                             LOG(INFO) << "Starting string decoder for GLONASS L1 C/A SAT " << this->d_satellite;
                             d_preamble_index = d_sample_counter;  // record the preamble sample stamp
-                            this->message_port_pub(pmt::mp("preamble_timestamp_samples"), pmt::mp(d_preamble_time_samples));
                             d_stat = 2;
                         }
                     else

src/algorithms/telemetry_decoder/gnuradio_blocks/glonass_l1_ca_telemetry_decoder_gs.h

@@ -50,7 +50,7 @@ public:
     ~glonass_l1_ca_telemetry_decoder_gs() override;                //!< Class destructor
     void set_satellite(const Gnss_Satellite &satellite) override;  //!< Set satellite PRN
     void set_channel(int32_t channel) override;                    //!< Set receiver's channel
-    inline void reset() override {};
+    void reset() override;                                         //!< Clear synchronization state on channel re-acquisition
 
     /*!
      * \brief This is where all signal processing takes place
@@ -81,7 +81,6 @@ private:
     std::string d_dump_filename;
     std::ofstream d_dump_file;
 
-    double d_preamble_time_samples;
     double d_TOW_at_current_symbol;
 
     // Variables for internal functionality

src/algorithms/telemetry_decoder/gnuradio_blocks/glonass_l2_ca_telemetry_decoder_gs.cc

@@ -55,7 +55,6 @@ glonass_l2_ca_telemetry_decoder_gs::glonass_l2_ca_telemetry_decoder_gs(const Tlm
           gr::io_signature::make(1, 1, sizeof(Gnss_Synchro)),
           gr::io_signature::make(1, 1, sizeof(Gnss_Synchro))),
       d_dump_filename(conf.dump_filename),
-      d_preamble_time_samples(0),
       d_TOW_at_current_symbol(0),
       d_sample_counter(0ULL),
       d_preamble_index(0ULL),
@@ -73,8 +72,6 @@ glonass_l2_ca_telemetry_decoder_gs::glonass_l2_ca_telemetry_decoder_gs(const Tlm
 {
     configure_basic_outputs();
 
-    this->message_port_register_out(pmt::mp("preamble_timestamp_samples"));
-
     if (d_enable_navdata_monitor)
         {
             // register nav message monitor out
@@ -224,6 +221,28 @@ void glonass_l2_ca_telemetry_decoder_gs::set_channel(int32_t channel)
 }
 
 
+void glonass_l2_ca_telemetry_decoder_gs::reset()
+{
+    gr::thread::scoped_lock lock(d_setlock);  // require mutex with work function called by the scheduler
+    d_symbol_history.clear();
+    d_stat = 0;
+    d_CRC_error_counter = 0;
+    d_flag_frame_sync = false;
+    d_flag_preamble = false;
+    // Invalidate the propagated TOW until a new string 5 is decoded; otherwise
+    // Flag_valid_word would remain true with a TOW offset by the outage duration
+    d_nav.set_flag_TOW_set(false);
+    d_nav.set_flag_TOW_new(false);
+    // Drop partially decoded ephemeris strings so that strings received before
+    // the outage cannot be combined with strings of a different frame
+    d_nav.set_flag_ephemeris_str_1(false);
+    d_nav.set_flag_ephemeris_str_2(false);
+    d_nav.set_flag_ephemeris_str_3(false);
+    d_nav.set_flag_ephemeris_str_4(false);
+    DLOG(INFO) << "Telemetry decoder reset for satellite " << d_satellite;
+}
+
+
 int glonass_l2_ca_telemetry_decoder_gs::general_work(int noutput_items __attribute__((unused)), gr_vector_int &ninput_items __attribute__((unused)),
     gr_vector_const_void_star &input_items, gr_vector_void_star &output_items)
 {
@@ -269,7 +288,6 @@ int glonass_l2_ca_telemetry_decoder_gs::general_work(int noutput_items __attribu
                     LOG(INFO) << "Preamble detection for GLONASS L2 C/A SAT " << this->d_satellite;
                     // Enter into frame pre-detection status
                     d_stat = 1;
-                    d_preamble_time_samples = d_symbol_history[0].Tracking_sample_counter;  // record the preamble sample stamp
                 }
         }
     else if (d_stat == 1)  // possible preamble lock
@@ -278,14 +296,11 @@ int glonass_l2_ca_telemetry_decoder_gs::general_work(int noutput_items __attribu
                 {
                     // check preamble separation
                     preamble_diff = static_cast<int32_t>(d_sample_counter - d_preamble_index);
-                    // Record the PRN start sample index associated to the preamble
-                    d_preamble_time_samples = static_cast<double>(d_symbol_history[0].Tracking_sample_counter);
                     if (abs(preamble_diff - GLONASS_GNAV_PREAMBLE_PERIOD_BITS) == 0)
                         {
                             // try to decode frame
                             LOG(INFO) << "Starting string decoder for GLONASS L2 C/A SAT " << this->d_satellite;
                             d_preamble_index = d_sample_counter;  // record the preamble sample stamp
-                            this->message_port_pub(pmt::mp("preamble_timestamp_samples"), pmt::mp(d_preamble_time_samples));
                             d_stat = 2;
                         }
                     else

src/algorithms/telemetry_decoder/gnuradio_blocks/glonass_l2_ca_telemetry_decoder_gs.h

@@ -49,7 +49,7 @@ public:
     ~glonass_l2_ca_telemetry_decoder_gs() override;                //!< Class destructor
     void set_satellite(const Gnss_Satellite &satellite) override;  //!< Set satellite PRN
     void set_channel(int32_t channel) override;                    //!< Set receiver's channel
-    inline void reset() override {};
+    void reset() override;                                         //!< Clear synchronization state on channel re-acquisition
 
     /*!
      * \brief This is where all signal processing takes place
@@ -78,7 +78,6 @@ private:
     std::string d_dump_filename;
     std::ofstream d_dump_file;
 
-    double d_preamble_time_samples;
     double d_TOW_at_current_symbol;
 
     uint64_t d_sample_counter;  // Sample counter as an index (1,2,3,..etc) indicating number of samples processed

src/core/system_parameters/glonass_gnav_ephemeris.cc

@@ -119,8 +119,7 @@ void Glonass_Gnav_Ephemeris::glot_to_gpst(double tod_offset, double glot2utc_cor
     const boost::gregorian::date d1(d_yr - J + 1.0, 1, 1);
     const boost::gregorian::days d2(d_N_T - 1);
     const boost::posix_time::ptime utc_time(d1 + d2, t);
-    const boost::gregorian::date utc_date = utc_time.date();
-    boost::posix_time::ptime gps_time;
+    boost::posix_time::ptime gps_time = utc_time;
 
     // Adjust for leap second correction
     for (i = 0; GLONASS_LEAP_SECONDS[i][0] > 0; i++)
@@ -136,10 +135,9 @@ void Glonass_Gnav_Ephemeris::glot_to_gpst(double tod_offset, double glot2utc_cor
                 }
         }
 
-    // Total number of days
-    days = static_cast<double>((utc_date - gps_epoch).days());
-
-    // Total number of seconds
+    // Days and seconds of day must be taken from the same (GPS) timestamp,
+    // since the leap second adjustment may roll gps_time over a day boundary
+    days = static_cast<double>((gps_time.date() - gps_epoch).days());
     sec_of_day = static_cast<double>((gps_time.time_of_day()).total_seconds());
     total_sec = days * 86400 + sec_of_day;
 

src/core/system_parameters/glonass_gnav_navigation_message.cc

@@ -560,8 +560,9 @@ int32_t Glonass_Gnav_Navigation_Message::string_decoder(const std::string& frame
             // parameters instead of almanac data
             if (d_frame_ID == 5)
                 {
-                    gnav_utc_model.d_B1 = static_cast<double>(read_navigation_unsigned(string_bits, B1));
-                    gnav_utc_model.d_B2 = static_cast<double>(read_navigation_unsigned(string_bits, B2));
+                    // B1 and B2 are sign-magnitude values (GLONASS ICD Table 4.9)
+                    gnav_utc_model.d_B1 = static_cast<double>(read_navigation_signed(string_bits, B1)) * TWO_N10;
+                    gnav_utc_model.d_B2 = static_cast<double>(read_navigation_signed(string_bits, B2)) * TWO_N16;
                 }
             else if (d_frame_ID != 0)
                 {

src/core/system_parameters/glonass_gnav_navigation_message.h

@@ -148,6 +148,11 @@ public:
         return flag_TOW_set;
     }
 
+    inline void set_flag_TOW_set(bool tow_set)
+    {
+        flag_TOW_set = tow_set;
+    }
+
     inline void set_flag_ephemeris_str_1(bool ephemeris_str_1)
     {
         flag_ephemeris_str_1 = ephemeris_str_1;

src/core/system_parameters/glonass_gnav_utc_model.cc

@@ -20,8 +20,10 @@
 
 double Glonass_Gnav_Utc_Model::utc_time(double glonass_time_corrected) const
 {
-    // GLONASS Time is relative to UTC Moscow, so we simply add its time difference
-    double t_utc = glonass_time_corrected + 3.0 * 3600.0 + d_tau_c;
+    // GLONASS Time runs 3 hours ahead of UTC(SU): tUTC + 3h = tGLO + tau_c
+    // (GLONASS ICD Edition 5.1, Section 4.5). The result may be negative,
+    // meaning the UTC epoch falls in the previous day
+    double t_utc = glonass_time_corrected - 3.0 * 3600.0 + d_tau_c;
 
     return t_utc;
 }

tests/unit-tests/system-parameters/glonass_gnav_ephemeris_test.cc

@@ -19,6 +19,7 @@
 
 #include "GLONASS_L1_L2_CA.h"
 #include "glonass_gnav_ephemeris.h"
+#include "glonass_gnav_utc_model.h"
 #include "gnss_satellite.h"
 #include "gnss_signal_replica.h"
 
@@ -243,3 +244,40 @@ TEST(GlonassGnavEphemerisTest, ConvertGlonassT2GpsT5)
     ASSERT_TRUE(week - true_week < FLT_EPSILON);
     ASSERT_TRUE(tow - true_tow < FLT_EPSILON);
 }
+
+
+/*!
+ * \brief Testing conversion from GLONASST to GPST across the UTC day boundary
+ * \test The GLONASS time of day falls less than one leap-second interval
+ * before 03:00:00, so the UTC epoch lies just before midnight and the leap
+ * second correction rolls the GPS time into the next day
+ */
+TEST(GlonassGnavEphemerisTest, ConvertGlonassT2GpsT6)
+{
+    Glonass_Gnav_Ephemeris gnav_eph;
+    gnav_eph.d_yr = 2019;
+    gnav_eph.d_N_T = 1366;  // 2019-09-27 in the GLONASS day scale
+
+    int week = 0;
+    double tow = 0.0;
+
+    // GLONASS tod 02:59:50 -> UTC 2019-09-26 23:59:50 -> GPST 2019-09-27 00:00:08
+    gnav_eph.glot_to_gpst(10790, 0.0, 0.0, &week, &tow);
+
+    EXPECT_EQ(week, 2072);
+    EXPECT_DOUBLE_EQ(tow, 432008.0);
+}
+
+
+/*!
+ * \brief Testing the GLONASST to UTC(SU) conversion of the UTC model:
+ * tUTC = tGLO + tau_c - 3 hrs (GLONASS ICD Edition 5.1, Section 4.5)
+ */
+TEST(GlonassGnavEphemerisTest, UtcModelUtcTime)
+{
+    Glonass_Gnav_Utc_Model gnav_utc_model;
+    gnav_utc_model.d_tau_c = -1.0 / 1024.0;
+
+    // GLONASS tod 12:00:00 -> UTC 09:00:00 (minus tau_c correction)
+    EXPECT_DOUBLE_EQ(gnav_utc_model.utc_time(43200.0), 32400.0 - 1.0 / 1024.0);
+}