Simultaneous multi-GNSS system acquisition, tracking and telemetry

decoding: Changes in the flowgraph and in the configuration files to mix
channels from different GNSS systems in the same receiver. Hybrid
observables and PVT under construction.

The changes in the configuration file parameter names are NOT backward
compatible. The receiver can still work as usual in single GNSS system
mode but some modification on configuration files are required. Use the
example provided of Hybrid configuration file.

src/algorithms/telemetry_decoder/gnuradio_blocks/galileo_e1b_telemetry_decoder_cc.cc

@@ -492,6 +492,8 @@ int galileo_e1b_telemetry_decoder_cc::general_work (int noutput_items, gr_vector
         }
     //3. Make the output (copy the object contents to the GNURadio reserved memory)
     *out[0] = current_synchro_data;
+
+    //std::cout<<"Galileo TLM output on CH="<<this->d_channel << " SAMPLE STAMP="<<d_sample_counter<<std::endl;
     return 1;
 }
 

src/algorithms/telemetry_decoder/gnuradio_blocks/gps_l1_ca_telemetry_decoder_cc.cc

@@ -130,7 +130,7 @@ gps_l1_ca_telemetry_decoder_cc::gps_l1_ca_telemetry_decoder_cc(
     d_TOW_at_Preamble = 0;
     d_TOW_at_current_symbol = 0;
     flag_TOW_set = false;
-
+    d_average_count=0;
     //set_history(d_samples_per_bit*8); // At least a history of 8 bits are needed to correlate with the preamble
 }
 
@@ -341,12 +341,28 @@ int gps_l1_ca_telemetry_decoder_cc::general_work (int noutput_items, gr_vector_i
                     LOG(WARNING) << "Exception writing observables dump file " << e.what();
             }
         }
-    //3. Make the output (copy the object contents to the GNURadio reserved memory)
-    *out[0] = current_synchro_data;
-    return 1;
+
+    //todo: implement averaging
+    d_average_count++;
+    if (d_average_count==d_decimation_output_factor)
+    {
+    	d_average_count=0;
+        //3. Make the output (copy the object contents to the GNURadio reserved memory)
+        *out[0] = current_synchro_data;
+        //std::cout<<"GPS TLM output on CH="<<this->d_channel << " SAMPLE STAMP="<<d_sample_counter/d_decimation_output_factor<<std::endl;
+        return 1;
+    }else{
+    	return 0;
+    }
+
 }
 
 
+void gps_l1_ca_telemetry_decoder_cc::set_decimation(int decimation)
+{
+	d_decimation_output_factor=decimation;
+}
+
 void gps_l1_ca_telemetry_decoder_cc::set_satellite(Gnss_Satellite satellite)
 {
     d_satellite = Gnss_Satellite(satellite.get_system(), satellite.get_PRN());

src/algorithms/telemetry_decoder/gnuradio_blocks/gps_l1_ca_telemetry_decoder_cc.h

@@ -61,6 +61,12 @@ public:
     void set_satellite(Gnss_Satellite satellite);  //!< Set satellite PRN
     void set_channel(int channel);                 //!< Set receiver's channel
 
+
+    /*!
+     * \brief Set decimation factor to average the GPS synchronization estimation output from the tracking module.
+     */
+    void set_decimation(int decimation);
+
     /*!
      * \brief Set the satellite data queue
      */
@@ -114,6 +120,10 @@ private:
     bool d_flag_preamble;
     int d_word_number;
 
+    // output averaging and decimation
+    int d_average_count;
+    int d_decimation_output_factor;
+
     long d_fs_in;
     //double d_preamble_duration_seconds;
     // navigation message vars