implemented tracking pull-in tests for the FPGA

solved a bug in which the SW was using the doppler shift index reported by the HW acquisition accelerator plus one, instead of using the doppler shift index as such.

src/algorithms/acquisition/adapters/galileo_e1_pcps_ambiguous_acquisition_fpga.cc

@@ -472,6 +472,24 @@ void GalileoE1PcpsAmbiguousAcquisitionFpga::set_state(int state)
 //    return threshold;
 //}
 
+// this function is only used for the unit tests
+void GalileoE1PcpsAmbiguousAcquisitionFpga::set_single_doppler_flag(unsigned int single_doppler_flag)
+{
+	acquisition_fpga_->set_single_doppler_flag(single_doppler_flag);
+}
+// this function is only used for the unit tests
+void GalileoE1PcpsAmbiguousAcquisitionFpga::read_acquisition_results(uint32_t *max_index,
+    float *max_magnitude, uint64_t *initial_sample, float *power_sum, uint32_t *doppler_index)
+{
+	acquisition_fpga_->read_acquisition_results(max_index, max_magnitude,
+	        initial_sample, power_sum, doppler_index);
+}
+
+// this function is only used for the unit tests
+void GalileoE1PcpsAmbiguousAcquisitionFpga::reset_acquisition(void)
+{
+	acquisition_fpga_->reset_acquisition();
+}
 
 void GalileoE1PcpsAmbiguousAcquisitionFpga::connect(gr::top_block_sptr top_block)
 {

src/algorithms/acquisition/adapters/galileo_e1_pcps_ambiguous_acquisition_fpga.h

@@ -136,6 +136,21 @@ public:
      */
     void set_state(int state) override;
 
+    /*!
+      * \brief This function is only used in the unit tests
+      */
+     void set_single_doppler_flag(unsigned int single_doppler_flag);
+     /*!
+      * \brief This function is only used in the unit tests
+      */
+     void read_acquisition_results(uint32_t *max_index,
+         float *max_magnitude, uint64_t *initial_sample, float *power_sum, uint32_t *doppler_index);
+
+     /*!
+      * \brief This function is only used in the unit tests
+      */
+     void reset_acquisition(void);
+
 private:
     ConfigurationInterface* configuration_;
     //pcps_acquisition_sptr acquisition_;

src/algorithms/acquisition/adapters/galileo_e5a_pcps_acquisition_fpga.cc

@@ -356,6 +356,24 @@ void GalileoE5aPcpsAcquisitionFpga::set_state(int state)
     acquisition_fpga_->set_state(state);
 }
 
+// this function is only used for the unit tests
+void GalileoE5aPcpsAcquisitionFpga::set_single_doppler_flag(unsigned int single_doppler_flag)
+{
+	acquisition_fpga_->set_single_doppler_flag(single_doppler_flag);
+}
+// this function is only used for the unit tests
+void GalileoE5aPcpsAcquisitionFpga::read_acquisition_results(uint32_t *max_index,
+    float *max_magnitude, uint64_t *initial_sample, float *power_sum, uint32_t *doppler_index)
+{
+	acquisition_fpga_->read_acquisition_results(max_index, max_magnitude,
+	        initial_sample, power_sum, doppler_index);
+}
+
+// this function is only used for the unit tests
+void GalileoE5aPcpsAcquisitionFpga::reset_acquisition(void)
+{
+	acquisition_fpga_->reset_acquisition();
+}
 
 void GalileoE5aPcpsAcquisitionFpga::connect(gr::top_block_sptr top_block)
 {

src/algorithms/acquisition/adapters/galileo_e5a_pcps_acquisition_fpga.h

@@ -124,6 +124,21 @@ public:
      */
     void set_state(int state) override;
 
+    /*!
+     * \brief This function is only used in the unit tests
+     */
+    void set_single_doppler_flag(unsigned int single_doppler_flag);
+    /*!
+     * \brief This function is only used in the unit tests
+     */
+    void read_acquisition_results(uint32_t *max_index,
+        float *max_magnitude, uint64_t *initial_sample, float *power_sum, uint32_t *doppler_index);
+
+    /*!
+     * \brief This function is only used in the unit tests
+     */
+    void reset_acquisition(void);
+
 private:
     //float calculate_threshold(float pfa);
 

src/algorithms/acquisition/adapters/gps_l1_ca_pcps_acquisition_fpga.cc

@@ -71,7 +71,7 @@ GpsL1CaPcpsAcquisitionFpga::GpsL1CaPcpsAcquisitionFpga(
 
     //printf("####### DEBUG Acq: fs_in = %d\n", fs_in);
     acq_parameters.fs_in = fs_in;
-    acq_parameters.samples_per_code = static_cast<unsigned int>(ceil(GPS_L1_CA_CHIP_PERIOD * static_cast<float>(acq_parameters.fs_in)));
+    //acq_parameters.samples_per_code = static_cast<unsigned int>(ceil(GPS_L1_CA_CHIP_PERIOD * static_cast<float>(acq_parameters.fs_in)));
     doppler_max_ = configuration_->property(role + ".doppler_max", 5000);
     if (FLAGS_doppler_max != 0) doppler_max_ = FLAGS_doppler_max;
     acq_parameters.doppler_max = doppler_max_;
@@ -258,6 +258,26 @@ void GpsL1CaPcpsAcquisitionFpga::set_state(int state)
     acquisition_fpga_->set_state(state);
 }
 
+
+// this function is only used for the unit tests
+void GpsL1CaPcpsAcquisitionFpga::set_single_doppler_flag(unsigned int single_doppler_flag)
+{
+	acquisition_fpga_->set_single_doppler_flag(single_doppler_flag);
+}
+// this function is only used for the unit tests
+void GpsL1CaPcpsAcquisitionFpga::read_acquisition_results(uint32_t *max_index,
+    float *max_magnitude, uint64_t *initial_sample, float *power_sum, uint32_t *doppler_index)
+{
+	acquisition_fpga_->read_acquisition_results(max_index, max_magnitude,
+	        initial_sample, power_sum, doppler_index);
+}
+
+// this function is only used for the unit tests
+void GpsL1CaPcpsAcquisitionFpga::reset_acquisition(void)
+{
+	acquisition_fpga_->reset_acquisition();
+}
+
 void GpsL1CaPcpsAcquisitionFpga::connect(gr::top_block_sptr top_block)
 {
     // nothing to connect

src/algorithms/acquisition/adapters/gps_l1_ca_pcps_acquisition_fpga.h

@@ -134,6 +134,21 @@ public:
      */
     void set_state(int state) override;
 
+    /*!
+     * \brief This function is only used in the unit tests
+     */
+    void set_single_doppler_flag(unsigned int single_doppler_flag);
+    /*!
+     * \brief This function is only used in the unit tests
+     */
+    void read_acquisition_results(uint32_t *max_index,
+        float *max_magnitude, uint64_t *initial_sample, float *power_sum, uint32_t *doppler_index);
+
+    /*!
+     * \brief This function is only used in the unit tests
+     */
+    void reset_acquisition(void);
+
 private:
     ConfigurationInterface* configuration_;
     pcps_acquisition_fpga_sptr acquisition_fpga_;

src/algorithms/acquisition/adapters/gps_l5i_pcps_acquisition_fpga.cc

@@ -323,6 +323,26 @@ void GpsL5iPcpsAcquisitionFpga::set_state(int state)
 //}
 
 
+// this function is only used for the unit tests
+void GpsL5iPcpsAcquisitionFpga::set_single_doppler_flag(unsigned int single_doppler_flag)
+{
+	acquisition_fpga_->set_single_doppler_flag(single_doppler_flag);
+}
+// this function is only used for the unit tests
+void GpsL5iPcpsAcquisitionFpga::read_acquisition_results(uint32_t *max_index,
+    float *max_magnitude, uint64_t *initial_sample, float *power_sum, uint32_t *doppler_index)
+{
+	acquisition_fpga_->read_acquisition_results(max_index, max_magnitude,
+	        initial_sample, power_sum, doppler_index);
+}
+
+// this function is only used for the unit tests
+void GpsL5iPcpsAcquisitionFpga::reset_acquisition(void)
+{
+	acquisition_fpga_->reset_acquisition();
+}
+
+
 void GpsL5iPcpsAcquisitionFpga::connect(gr::top_block_sptr top_block)
 {
 //    if (item_type_.compare("gr_complex") == 0)

src/algorithms/acquisition/adapters/gps_l5i_pcps_acquisition_fpga.h

@@ -134,6 +134,21 @@ public:
      */
     void set_state(int state) override;
 
+    /*!
+     * \brief This function is only used in the unit tests
+     */
+    void set_single_doppler_flag(unsigned int single_doppler_flag);
+    /*!
+     * \brief This function is only used in the unit tests
+     */
+    void read_acquisition_results(uint32_t *max_index,
+        float *max_magnitude, uint64_t *initial_sample, float *power_sum, uint32_t *doppler_index);
+
+    /*!
+     * \brief This function is only used in the unit tests
+     */
+    void reset_acquisition(void);
+
 private:
     ConfigurationInterface* configuration_;
     //pcps_acquisition_sptr acquisition_;

src/algorithms/acquisition/gnuradio_blocks/pcps_acquisition_fpga.cc

@@ -130,8 +130,10 @@ void pcps_acquisition_fpga::init()
     d_gnss_synchro->Acq_samplestamp_samples = 0;
     d_mag = 0.0;
     d_input_power = 0.0;
-    d_num_doppler_bins = static_cast<uint32_t>(std::ceil(static_cast<double>(static_cast<int32_t>(acq_parameters.doppler_max) - static_cast<int32_t>(-acq_parameters.doppler_max)) / static_cast<double>(d_doppler_step)));
-
+    d_num_doppler_bins = static_cast<uint32_t>(std::ceil(static_cast<double>(static_cast<int32_t>(acq_parameters.doppler_max) - static_cast<int32_t>(-acq_parameters.doppler_max)) / static_cast<double>(d_doppler_step))) + 1;
+    //printf("acq gnuradioblock doppler_max = %lu\n", (unsigned long) static_cast<int32_t>(acq_parameters.doppler_max));
+    //printf("acq gnuradioblock doppler_step = %lu\n", (unsigned long) d_doppler_step);
+    //printf("acq gnuradioblock d_num_doppler_bins = %lu\n", (unsigned long) d_num_doppler_bins);
     acquisition_fpga->init();
     //  printf("acq init end\n");
 }
@@ -290,15 +292,15 @@ void pcps_acquisition_fpga::set_active(bool active)
 
 
     // debug
-    debug_d_max_absolute = magt;
-    debug_d_input_power_absolute = d_input_power;
-    debug_indext = indext;
-    debug_doppler_index = d_doppler_index;
+    //debug_d_max_absolute = magt;
+    //debug_d_input_power_absolute = d_input_power;
+    //debug_indext = indext;
+    //debug_doppler_index = d_doppler_index;
 
     //  temp_d_input_power = d_input_power;
 
     d_input_power = (d_input_power - d_mag) / (d_fft_size - 1);
-    int32_t doppler = -static_cast<int32_t>(acq_parameters.doppler_max) + d_doppler_step * d_doppler_index;
+    int32_t doppler = -static_cast<int32_t>(acq_parameters.doppler_max) + d_doppler_step * (d_doppler_index - 1);
     //d_gnss_synchro->Acq_delay_samples = static_cast<double>(2*(indext % (2*acq_parameters.samples_per_code)));
 
 
@@ -382,3 +384,26 @@ int pcps_acquisition_fpga::general_work(int noutput_items __attribute__((unused)
     // the general work is not used with the acquisition that uses the FPGA
     return noutput_items;
 }
+
+
+// this function is only used for the unit tests
+void pcps_acquisition_fpga::set_single_doppler_flag(unsigned int single_doppler_flag)
+{
+	acquisition_fpga->set_single_doppler_flag(single_doppler_flag);
+}
+
+// this function is only used for the unit tests
+void pcps_acquisition_fpga::read_acquisition_results(uint32_t *max_index,
+    float *max_magnitude, uint64_t *initial_sample, float *power_sum, uint32_t *doppler_index)
+{
+	acquisition_fpga->read_acquisition_results(max_index, max_magnitude,
+	        initial_sample, power_sum, doppler_index);
+}
+
+// this function is only used for the unit tests
+void pcps_acquisition_fpga::reset_acquisition(void)
+{
+	acquisition_fpga->reset_acquisition();
+}
+
+

src/algorithms/acquisition/gnuradio_blocks/pcps_acquisition_fpga.h

@@ -119,14 +119,16 @@ private:
     std::shared_ptr<fpga_acquisition> acquisition_fpga;
 
     // debug
-    float debug_d_max_absolute;
-    float debug_d_input_power_absolute;
-    int32_t debug_indext;
-    int32_t debug_doppler_index;
+    //float debug_d_max_absolute;
+    //float debug_d_input_power_absolute;
+    //int32_t debug_indext;
+    //int32_t debug_doppler_index;
 
     float d_downsampling_factor;
     uint32_t d_select_queue_Fpga;
 
+
+
 public:
     ~pcps_acquisition_fpga();
 
@@ -228,6 +230,22 @@ public:
     int general_work(int noutput_items, gr_vector_int& ninput_items,
         gr_vector_const_void_star& input_items,
         gr_vector_void_star& output_items);
+
+    /*!
+     * \brief This function is only used for the unit tests
+     */
+    void set_single_doppler_flag(unsigned int single_doppler_flag);
+
+    /*!
+     * \brief This funciton is only used for the unit tests
+     */
+    void read_acquisition_results(uint32_t *max_index,
+        float *max_magnitude, uint64_t *initial_sample, float *power_sum, uint32_t *doppler_index);
+
+    /*!
+     * \brief This funciton is only used for the unit tests
+     */
+    void reset_acquisition(void);
 };
 
 #endif /* GNSS_SDR_PCPS_ACQUISITION_FPGA_H_*/

src/algorithms/acquisition/libs/fpga_acquisition.cc

@@ -156,7 +156,12 @@ fpga_acquisition::fpga_acquisition(std::string device_name,
             //std::cout << "Acquisition test register sanity check success!" << std::endl;
         }
     fpga_acquisition::reset_acquisition();
+
+    // flag used for testing purposes
+    d_single_doppler_flag = 0;
+
     DLOG(INFO) << "Acquisition FPGA class created";
+
 }
 
 
@@ -245,6 +250,8 @@ void fpga_acquisition::run_acquisition(void)
 
 
 void fpga_acquisition::set_doppler_sweep(uint32_t num_sweeps)
+{
+	if (d_single_doppler_flag == 0)
 	{
 		//printf("acq lib set_doppler_sweep called\n");
 	    float phase_step_rad_real;
@@ -290,7 +297,56 @@ void fpga_acquisition::set_doppler_sweep(uint32_t num_sweeps)
 	    //printf("AAA writing num sweeps to d map base 5 = %d\n", num_sweeps);
 	    d_map_base[5] = num_sweeps;
 	}
+	else
+	{
+		//printf("acq lib set_doppler_sweep called\n");
+	    float phase_step_rad_real;
+	    float phase_step_rad_int_temp;
+	    int32_t phase_step_rad_int;
+	    //int32_t doppler = static_cast<int32_t>(-d_doppler_max) + d_doppler_step * doppler_index;
+	    int32_t doppler = static_cast<int32_t>(d_doppler_max);
+	    //float phase_step_rad = GPS_TWO_PI * (d_freq + doppler) / static_cast<float>(d_fs_in);
+	    float phase_step_rad = GPS_TWO_PI * (doppler) / static_cast<float>(d_fs_in);
+	    // The doppler step can never be outside the range -pi to +pi, otherwise there would be aliasing
+	    // The FPGA expects phase_step_rad between -1 (-pi) to +1 (+pi)
+	    // The FPGA also expects the phase to be negative since it produces cos(x) -j*sin(x)
+	    // while the gnss-sdr software (volk_gnsssdr_s32f_sincos_32fc) generates cos(x) + j*sin(x)
+	    phase_step_rad_real = phase_step_rad / (GPS_TWO_PI / 2);
+	    // avoid saturation of the fixed point representation in the fpga
+	    // (only the positive value can saturate due to the 2's complement representation)
 
+	    //printf("AAA  phase_step_rad_real for initial doppler = %f\n", phase_step_rad_real);
+	    if (phase_step_rad_real >= 1.0)
+	        {
+	            phase_step_rad_real = MAX_PHASE_STEP_RAD;
+	        }
+	    //printf("AAA  phase_step_rad_real for initial doppler after checking = %f\n", phase_step_rad_real);
+	    phase_step_rad_int_temp = phase_step_rad_real * POW_2_2;                          // * 2^2
+	    phase_step_rad_int = static_cast<int32_t>(phase_step_rad_int_temp * (POW_2_29));  // * 2^29 (in total it makes x2^31 in two steps to avoid the warnings
+	    //printf("AAA writing phase_step_rad_int for initial doppler = %d to d map base 3\n", phase_step_rad_int);
+	    d_map_base[3] = phase_step_rad_int;
+
+	    // repeat the calculation with the doppler step
+	    doppler = 0;
+	    phase_step_rad = GPS_TWO_PI * (doppler) / static_cast<float>(d_fs_in);
+	    phase_step_rad_real = phase_step_rad / (GPS_TWO_PI / 2);
+	    //printf("AAA  phase_step_rad_real for doppler step = %f\n", phase_step_rad_real);
+	    if (phase_step_rad_real >= 1.0)
+	        {
+	            phase_step_rad_real = MAX_PHASE_STEP_RAD;
+	        }
+	    //printf("AAA  phase_step_rad_real for doppler step after checking = %f\n", phase_step_rad_real);
+	    phase_step_rad_int_temp = phase_step_rad_real * POW_2_2;                          // * 2^2
+	    phase_step_rad_int = static_cast<int32_t>(phase_step_rad_int_temp * (POW_2_29));  // * 2^29 (in total it makes x2^31 in two steps to avoid the warnings
+	    //printf("AAA writing phase_step_rad_int for doppler step = %d to d map base 4\n", phase_step_rad_int);
+	    d_map_base[4] = phase_step_rad_int;
+	    //printf("AAA writing num sweeps to d map base 5 = %d\n", num_sweeps);
+	    d_map_base[5] = 1;  // 1 sweep
+
+	}
+
+}
+/*
 void fpga_acquisition::set_doppler_sweep_debug(uint32_t num_sweeps, uint32_t doppler_index)
 {
 	//printf("acq lib set_doppler_sweep_debug called\n");
@@ -337,7 +393,7 @@ void fpga_acquisition::set_doppler_sweep_debug(uint32_t num_sweeps, uint32_t dop
     //printf("AAAh writing num sweeps to d map base 5 = %d\n", num_sweeps);
     d_map_base[5] = num_sweeps;
 }
-
+*/
 
 void fpga_acquisition::configure_acquisition()
 {
@@ -402,10 +458,10 @@ void fpga_acquisition::read_acquisition_results(uint32_t *max_index,
     *initial_sample = initial_sample_tmp;
     readval = d_map_base[6];
     *max_magnitude = static_cast<float>(readval);
-    //printf("read max_magnitude dmap 2 = %d\n", readval);
+    //printf("acq lib read max_magnitude dmap 2 = %d = %f\n", readval, *max_magnitude);
     readval = d_map_base[4];
     *power_sum = static_cast<float>(readval);
-    //printf("read power sum dmap 4 = %d\n", readval);
+    //printf("acq lib read power sum dmap 4 = %d = %f\n", readval, *power_sum);
     readval = d_map_base[5];  // read doppler index
     *doppler_index = readval;
     //printf("read doppler_index dmap 5 = %d\n", readval);
@@ -446,3 +502,10 @@ void fpga_acquisition::reset_acquisition(void)
 	//printf("acq lib reset acquisition called\n");
     d_map_base[8] = RESET_ACQUISITION;  // writing a 2 to d_map_base[8] resets the multicorrelator
 }
+
+// this function is only used for the unit tests
+void fpga_acquisition::set_single_doppler_flag(unsigned int single_doppler_flag)
+{
+	d_single_doppler_flag = single_doppler_flag;
+}
+

src/algorithms/acquisition/libs/fpga_acquisition.h

@@ -60,7 +60,7 @@ public:
     bool set_local_code(uint32_t PRN);
     bool free();
     void set_doppler_sweep(uint32_t num_sweeps);
-    void set_doppler_sweep_debug(uint32_t num_sweeps, uint32_t doppler_index);
+    //void set_doppler_sweep_debug(uint32_t num_sweeps, uint32_t doppler_index);
     void run_acquisition(void);
     void set_phase_step(uint32_t doppler_index);
     void read_acquisition_results(uint32_t *max_index, float *max_magnitude,
@@ -88,6 +88,16 @@ public:
         d_doppler_step = doppler_step;
     }
 
+    /*!
+     * \brief this function is only used in the unit test
+     */
+    void set_single_doppler_flag(unsigned int single_doppler_flag);
+
+    /*!
+     * \brief this function is only used in the unit test
+     */
+    void reset_acquisition(void);
+
 private:
     int64_t d_fs_in;
     // data related to the hardware module and the driver
@@ -105,8 +115,10 @@ private:
     uint32_t fpga_acquisition_test_register(uint32_t writeval);
     void fpga_configure_acquisition_local_code(lv_16sc_t fft_local_code[]);
     void configure_acquisition();
-    void reset_acquisition(void);
     void close_device();
+
+    // test parameters
+    unsigned int d_single_doppler_flag; // this flag is only used for testing purposes
 };
 
 #endif /* GNSS_SDR_FPGA_ACQUISITION_H_ */

src/algorithms/tracking/adapters/galileo_e1_dll_pll_veml_tracking_fpga.cc

@@ -123,7 +123,7 @@ GalileoE1DllPllVemlTrackingFpga::GalileoE1DllPllVemlTrackingFpga(
     std::string default_device_name = "/dev/uio";
     std::string device_name = configuration->property(role + ".devicename", default_device_name);
     trk_param_fpga.device_name = device_name;
-    unsigned int device_base = configuration->property(role + ".device_base", 1);
+    unsigned int device_base = configuration->property(role + ".device_base", 15);
     trk_param_fpga.device_base = device_base;
     //unsigned int multicorr_type = configuration->property(role + ".multicorr_type", 1);
     trk_param_fpga.multicorr_type = 1; // 0 -> 3 correlators, 1 -> 5 correlators

src/algorithms/tracking/adapters/galileo_e5a_dll_pll_tracking_fpga.cc

@@ -123,7 +123,7 @@ GalileoE5aDllPllTrackingFpga::GalileoE5aDllPllTrackingFpga(
     std::string default_device_name = "/dev/uio";
     std::string device_name = configuration->property(role + ".devicename", default_device_name);
     trk_param_fpga.device_name = device_name;
-    unsigned int device_base = configuration->property(role + ".device_base", 1);
+    unsigned int device_base = configuration->property(role + ".device_base", 27);
     trk_param_fpga.device_base = device_base;
     //unsigned int multicorr_type = configuration->property(role + ".multicorr_type", 1);
     trk_param_fpga.multicorr_type = 1; // 0 -> 3 correlators, 1 -> up to 5+1 correlators

src/algorithms/tracking/adapters/gps_l1_ca_dll_pll_tracking_fpga.cc

@@ -127,7 +127,7 @@ GpsL1CaDllPllTrackingFpga::GpsL1CaDllPllTrackingFpga(
     std::string default_device_name = "/dev/uio";
     std::string device_name = configuration->property(role + ".devicename", default_device_name);
     trk_param_fpga.device_name = device_name;
-    unsigned int device_base = configuration->property(role + ".device_base", 1);
+    unsigned int device_base = configuration->property(role + ".device_base", 3);
     trk_param_fpga.device_base = device_base;
     //unsigned int multicorr_type = configuration->property(role + ".multicorr_type", 0);
     trk_param_fpga.multicorr_type = 0; //multicorr_type : 0 -> 3 correlators, 1 -> 5 correlators

src/algorithms/tracking/adapters/gps_l5_dll_pll_tracking_fpga.cc

@@ -123,7 +123,7 @@ GpsL5DllPllTrackingFpga::GpsL5DllPllTrackingFpga(
     std::string default_device_name = "/dev/uio";
     std::string device_name = configuration->property(role + ".devicename", default_device_name);
     trk_param_fpga.device_name = device_name;
-    unsigned int device_base = configuration->property(role + ".device_base", 1);
+    unsigned int device_base = configuration->property(role + ".device_base", 27);
     trk_param_fpga.device_base = device_base;
     //unsigned int multicorr_type = configuration->property(role + ".multicorr_type", 0);
     trk_param_fpga.multicorr_type = 0; //multicorr_type : 0 -> 3 correlators, 1 -> 5 correlators

src/algorithms/tracking/gnuradio_blocks/dll_pll_veml_tracking_fpga.cc

@@ -1218,6 +1218,7 @@ void dll_pll_veml_tracking_fpga::set_gnss_synchro(Gnss_Synchro *p_gnss_synchro)
 int dll_pll_veml_tracking_fpga::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)
 {
+
     // Block input data and block output stream pointers
     Gnss_Synchro **out = reinterpret_cast<Gnss_Synchro **>(&output_items[0]);
 
@@ -1247,15 +1248,29 @@ int dll_pll_veml_tracking_fpga::general_work(int noutput_items __attribute__((un
                 multicorrelator_fpga->lock_channel();
                 uint64_t counter_value = multicorrelator_fpga->read_sample_counter();
                 //printf("333333 counter_value = %llu\n", counter_value);
-                //printf("333333 current_synchro_data.Acq_samplestamp_samples = %d\n", current_synchro_data.Acq_samplestamp_samples);
+                //printf("333333 current_synchro_data.Acq_samplestamp_samples = %llu\n", current_synchro_data.Acq_samplestamp_samples);
                 //printf("333333 current_synchro_data.Acq_delay_samples = %f\n", current_synchro_data.Acq_delay_samples);
                 //printf("333333 d_correlation_length_samples = %d\n", d_correlation_length_samples);
+
+                uint64_t absolute_samples_offset;
+
+                if (counter_value > (current_synchro_data.Acq_samplestamp_samples + current_synchro_data.Acq_delay_samples))
+                {
+                	// normal operation
                     uint32_t num_frames = ceil((counter_value - current_synchro_data.Acq_samplestamp_samples - current_synchro_data.Acq_delay_samples) / d_correlation_length_samples);
                     //uint32_t num_frames = ceil((counter_value - current_synchro_data.Acq_samplestamp_samples*2 - current_synchro_data.Acq_delay_samples*2) / d_correlation_length_samples);
                     //printf("333333 num_frames = %d\n", num_frames);
-                uint64_t absolute_samples_offset = static_cast<uint64_t>(current_synchro_data.Acq_delay_samples + current_synchro_data.Acq_samplestamp_samples + num_frames * d_correlation_length_samples);
+                    absolute_samples_offset = static_cast<uint64_t>(current_synchro_data.Acq_delay_samples + current_synchro_data.Acq_samplestamp_samples + num_frames * d_correlation_length_samples);
                     //uint64_t absolute_samples_offset = static_cast<uint64_t>(current_synchro_data.Acq_delay_samples*2 + current_synchro_data.Acq_samplestamp_samples*2 + num_frames * d_correlation_length_samples);
                     //printf("333333 absolute_samples_offset = %llu\n", absolute_samples_offset);
+                }
+                else
+                {
+                	// during the unit tests the counter value may be reset after the acquisition process. We have to take this into account
+                	absolute_samples_offset = static_cast<uint64_t>(current_synchro_data.Acq_delay_samples + current_synchro_data.Acq_samplestamp_samples);
+                	//printf("333333 absolute_samples_offset = %llu\n", absolute_samples_offset);
+                }
+
                 multicorrelator_fpga->set_initial_sample(absolute_samples_offset);
                 d_absolute_samples_offset = absolute_samples_offset;
                 d_sample_counter = absolute_samples_offset;
@@ -1268,6 +1283,7 @@ int dll_pll_veml_tracking_fpga::general_work(int noutput_items __attribute__((un
 
         case 2:
             {
+            	//printf("trk state 2 counter value = %" PRIu64 "\n", multicorrelator_fpga->read_sample_counter());
                 d_sample_counter = d_sample_counter_next;
                 d_sample_counter_next = d_sample_counter + static_cast<uint64_t>(d_current_prn_length_samples);
 
@@ -1481,6 +1497,7 @@ int dll_pll_veml_tracking_fpga::general_work(int noutput_items __attribute__((un
 
         case 3:
             {
+            	//printf("trk state 3 counter value = %" PRIu64 "\n", multicorrelator_fpga->read_sample_counter());
                 d_sample_counter = d_sample_counter_next;
                 d_sample_counter_next = d_sample_counter + static_cast<uint64_t>(d_current_prn_length_samples);
 
@@ -1541,6 +1558,7 @@ int dll_pll_veml_tracking_fpga::general_work(int noutput_items __attribute__((un
 
         case 4:  // narrow tracking
             {
+            	//printf("trk state 4 counter value = %" PRIu64 "\n", multicorrelator_fpga->read_sample_counter());
                 d_sample_counter = d_sample_counter_next;
                 d_sample_counter_next = d_sample_counter + static_cast<uint64_t>(d_current_prn_length_samples);
 

src/algorithms/tracking/libs/fpga_multicorrelator.cc

@@ -320,7 +320,7 @@ bool fpga_multicorrelator_8sc::free()
 
 void fpga_multicorrelator_8sc::set_channel(uint32_t channel)
 {
-    //printf("www trk set channel\n");
+    //printf("www trk set channel channel=%lu\n", (unsigned long) channel);
     char device_io_name[MAX_LENGTH_DEVICEIO_NAME];  // driver io name
     d_channel = channel;