GLONASS Observables: Fixes bug in TOW updating

Fixes bug in TOW update when a new value has been computed. This adds a
new flag to keep track of TOW update given the tk component. The code
fix improves the pseudorange measurement for code

conf/gnss-sdr_GLONASS_L1_CA_ibyte.conf

@@ -62,6 +62,8 @@ TelemetryDecoder_1G.implementation=GLONASS_L1_CA_Telemetry_Decoder
 
 ;######### OBSERVABLES CONFIG ############
 Observables.implementation=Hybrid_Observables
+Observables.dump=true;
+Observables.dump_filename=/archive/glo_observables.dat
 
 ;######### PVT CONFIG ############
 PVT.implementation=RTKLIB_PVT

src/algorithms/telemetry_decoder/gnuradio_blocks/glonass_l1_ca_telemetry_decoder_cc.cc

@@ -351,10 +351,11 @@ int glonass_l1_ca_telemetry_decoder_cc::general_work (int noutput_items __attrib
 
     // UPDATE GNSS SYNCHRO DATA
     //2. Add the telemetry decoder information
-    if (this->d_flag_preamble == true and d_nav.flag_TOW_set == true)
+    if (this->d_flag_preamble == true and d_nav.flag_TOW_new == true)
         //update TOW at the preamble instant
         {
-            d_TOW_at_current_symbol = floor((d_nav.d_TOW + 2*GLONASS_L1_CA_CODE_PERIOD + GLONASS_GNAV_PREAMBLE_DURATION_S)*1000.0)/1000.0;
+            d_TOW_at_current_symbol = floor((d_nav.d_TOW - GLONASS_GNAV_PREAMBLE_DURATION_S)*1000.0)/1000.0;
+            d_nav.flag_TOW_new = false;
 
         }
     else //if there is not a new preamble, we define the TOW of the current symbol

src/core/system_parameters/glonass_gnav_navigation_message.cc

@@ -73,12 +73,8 @@ void Glonass_Gnav_Navigation_Message::reset()
 
     //broadcast orbit 1
     flag_TOW_set = false;
+    flag_TOW_new = false;
     d_TOW = 0.0;           //!< Time of GPS Week of the ephemeris set (taken from subframes TOW) [s]
-    d_TOW_F1 = 0.0;        //!< Time of GPS Week from HOW word of Subframe 1 [s]
-    d_TOW_F2 = 0.0;        //!< Time of GPS Week from HOW word of Subframe 2 [s]
-    d_TOW_F3 = 0.0;        //!< Time of GPS Week from HOW word of Subframe 3 [s]
-    d_TOW_F4 = 0.0;        //!< Time of GPS Week from HOW word of Subframe 4 [s]
-    d_TOW_F5 = 0.0;        //!< Time of GPS Week from HOW word of Subframe 5 [s]
 
     flag_CRC_test = false;
     d_frame_ID = 0;
@@ -366,7 +362,8 @@ double Glonass_Gnav_Navigation_Message::get_TOW()
     int i = 0;
 
     // tk is relative to UTC(SU) + 3.00 hrs, so we need to convert to utc and add corrections
-    TOD = gnav_ephemeris.d_t_k - glot2utcsu - utcsu2utc + gnav_utc_model.d_tau_c + gnav_utc_model.d_tau_gps;
+    // tk plus 10 sec is the true tod since get_TOW is called when in str5
+    TOD = (gnav_ephemeris.d_t_k + 10) - glot2utcsu - utcsu2utc + gnav_utc_model.d_tau_c + gnav_utc_model.d_tau_gps;
 
 
     boost::gregorian::date glo_date(gnav_ephemeris.d_yr, 1, 1);
@@ -521,6 +518,7 @@ int Glonass_Gnav_Navigation_Message::string_decoder(std::string frame_string)
                         gnav_ephemeris.d_TOW = d_TOW;
                         gnav_ephemeris.d_WN = get_WN();
                         flag_TOW_set = true;
+                        flag_TOW_new = true;
                     }
 
                 }

src/core/system_parameters/glonass_gnav_navigation_message.h

@@ -95,13 +95,9 @@ public:
     bool flag_utc_model_str_5;      //!< Clock info send in string 5 of navigation data
     bool flag_utc_model_str_15;     //!< Clock info send in string 15 of frame 5 of navigation data
 
-    bool flag_TOW_set;
+    bool flag_TOW_set;      //!< Flag indicating when the TOW has been set
+    bool flag_TOW_new;      //!< Flag indicating when a new TOW has been computed
     double d_TOW;           //!< Time of GPS Week of the ephemeris set (taken from subframes TOW) [s]
-    double d_TOW_F1;        //!< Time of GPS Week from HOW word of Subframe 1 [s]
-    double d_TOW_F2;        //!< Time of GPS Week from HOW word of Subframe 2 [s]
-    double d_TOW_F3;        //!< Time of GPS Week from HOW word of Subframe 3 [s]
-    double d_TOW_F4;        //!< Time of GPS Week from HOW word of Subframe 4 [s]
-    double d_TOW_F5;        //!< Time of GPS Week from HOW word of Subframe 5 [s]
 
     // Clock terms
     double d_satClkCorr;     // Satellite clock error

src/utils/matlab/hybrid_observables_plot_sample.m

@@ -7,16 +7,17 @@ addpath('./libs');
 samplingFreq       = 6625000;     %[Hz]
 channels=5;
 path='/archive/';
-observables_log_path=[path 'glo_observables'];
+observables_log_path=[path 'glo_observables.dat'];
 GNSS_observables= read_hybrid_observables_dump(channels,observables_log_path);
 
+%%
 %optional:
 %search all channels having good satellite simultaneously
 min_idx=1;
 for n=1:1:channels
     idx=find(GNSS_observables.valid(n,:)>0,1,'first');
     if min_idx<idx
-        min_idx=idx;
+        min_idx=idx
     end
 end