diff --git a/src/algorithms/acquisition/gnuradio_blocks/pcps_acquisition_fpga.cc b/src/algorithms/acquisition/gnuradio_blocks/pcps_acquisition_fpga.cc
index 7fe87c9f6..af36b9c4a 100644
--- a/src/algorithms/acquisition/gnuradio_blocks/pcps_acquisition_fpga.cc
+++ b/src/algorithms/acquisition/gnuradio_blocks/pcps_acquisition_fpga.cc
@@ -223,7 +223,7 @@ void pcps_acquisition_fpga::set_active(bool active)
                // no CFAR algorithm in the FPGA
                << ", use_CFAR_algorithm_flag: false";
 
-    unsigned long int initial_sample;
+    unsigned long long int initial_sample;
     float input_power_all = 0.0;
     float input_power_computed = 0.0;
 
@@ -325,11 +325,11 @@ void pcps_acquisition_fpga::set_active(bool active)
     if (d_test_statistics > d_threshold)
         {
             d_active = false;
-            printf("##### d_test_statistics = %f\n", d_test_statistics);
-            printf("##### debug_d_max_absolute =%f\n",debug_d_max_absolute);
-            printf("##### debug_d_input_power_absolute =%f\n",debug_d_input_power_absolute);
-            printf("##### initial_sample = %lu\n",initial_sample);
-            printf("##### debug_doppler_index = %d\n",debug_doppler_index);
+//            printf("##### d_test_statistics = %f\n", d_test_statistics);
+//            printf("##### debug_d_max_absolute =%f\n",debug_d_max_absolute);
+//            printf("##### debug_d_input_power_absolute =%f\n",debug_d_input_power_absolute);
+//            printf("##### initial_sample = %llu\n",initial_sample);
+//            printf("##### debug_doppler_index = %d\n",debug_doppler_index);
             send_positive_acquisition();
             d_state = 0;  // Positive acquisition
         }
diff --git a/src/algorithms/acquisition/gnuradio_blocks/pcps_acquisition_fpga.h b/src/algorithms/acquisition/gnuradio_blocks/pcps_acquisition_fpga.h
index e684b0971..7775a14e8 100644
--- a/src/algorithms/acquisition/gnuradio_blocks/pcps_acquisition_fpga.h
+++ b/src/algorithms/acquisition/gnuradio_blocks/pcps_acquisition_fpga.h
@@ -115,7 +115,7 @@ private:
     unsigned int d_doppler_step;
     unsigned int d_fft_size;
     unsigned int d_num_doppler_bins;
-    unsigned long int d_sample_counter;
+    unsigned long long int d_sample_counter;
     Gnss_Synchro* d_gnss_synchro;
     std::shared_ptr<fpga_acquisition> acquisition_fpga;
 
diff --git a/src/algorithms/acquisition/libs/fpga_acquisition.cc b/src/algorithms/acquisition/libs/fpga_acquisition.cc
index 4e74e1779..6bb2ff266 100644
--- a/src/algorithms/acquisition/libs/fpga_acquisition.cc
+++ b/src/algorithms/acquisition/libs/fpga_acquisition.cc
@@ -369,18 +369,20 @@ void fpga_acquisition::set_phase_step(unsigned int doppler_index)
 
 
 void fpga_acquisition::read_acquisition_results(uint32_t *max_index,
-    float *max_magnitude, unsigned long int *initial_sample, float *power_sum, unsigned *doppler_index)
+    float *max_magnitude, unsigned long long int *initial_sample, float *power_sum, unsigned *doppler_index)
 {
-	unsigned long int initial_sample_tmp;
+	unsigned long long int initial_sample_tmp = 0;
+
 
     unsigned readval = 0;
-    unsigned long int readval_long = 0;
+    unsigned long long int readval_long = 0;
+    unsigned long long int readval_long_shifted = 0;
     readval = d_map_base[1];
     initial_sample_tmp = readval;
-    //*initial_sample = readval;
-    //printf("read initial sample dmap 1 = %d\n", readval);
     readval_long = d_map_base[2];
-    initial_sample_tmp = initial_sample_tmp + (readval_long * (2^32));
+    readval_long_shifted = readval_long << 32; // 2^32
+    initial_sample_tmp = initial_sample_tmp + readval_long_shifted; // 2^32
+    //printf("----------------------------------------------------------------> acq initial sample TOTAL = %llu\n", initial_sample_tmp);
     *initial_sample = initial_sample_tmp;
     readval = d_map_base[6];
     *max_magnitude = static_cast<float>(readval);
diff --git a/src/algorithms/acquisition/libs/fpga_acquisition.h b/src/algorithms/acquisition/libs/fpga_acquisition.h
index 8219037a7..36bb4df0e 100644
--- a/src/algorithms/acquisition/libs/fpga_acquisition.h
+++ b/src/algorithms/acquisition/libs/fpga_acquisition.h
@@ -61,7 +61,7 @@ public:
     void run_acquisition(void);
     void set_phase_step(unsigned int doppler_index);
     void read_acquisition_results(uint32_t *max_index, float *max_magnitude,
-    		unsigned long int *initial_sample, float *power_sum, unsigned *doppler_index);
+    		unsigned long long int *initial_sample, float *power_sum, unsigned *doppler_index);
     void block_samples();
     void unblock_samples();
 
diff --git a/src/algorithms/tracking/gnuradio_blocks/dll_pll_veml_tracking_fpga.cc b/src/algorithms/tracking/gnuradio_blocks/dll_pll_veml_tracking_fpga.cc
index 7ea045401..a04d9fede 100644
--- a/src/algorithms/tracking/gnuradio_blocks/dll_pll_veml_tracking_fpga.cc
+++ b/src/algorithms/tracking/gnuradio_blocks/dll_pll_veml_tracking_fpga.cc
@@ -1251,15 +1251,15 @@ int dll_pll_veml_tracking_fpga::general_work (int noutput_items __attribute__((u
             {
                 d_pull_in = 0;
                 multicorrelator_fpga->lock_channel();
-                unsigned long int counter_value = multicorrelator_fpga->read_sample_counter();
-                //printf("333333 counter_value = %d\n", counter_value);
+                unsigned long long int 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_delay_samples = %f\n", current_synchro_data.Acq_delay_samples);
                 //printf("333333 d_correlation_length_samples = %d\n", d_correlation_length_samples);
                 unsigned num_frames = ceil((counter_value - current_synchro_data.Acq_samplestamp_samples - current_synchro_data.Acq_delay_samples)/d_correlation_length_samples);
                 //printf("333333 num_frames = %d\n", num_frames);
-                unsigned long int absolute_samples_offset = current_synchro_data.Acq_delay_samples + current_synchro_data.Acq_samplestamp_samples + num_frames*d_correlation_length_samples;
-                //printf("333333 absolute_samples_offset = %d\n", absolute_samples_offset);
+                unsigned long long int absolute_samples_offset = current_synchro_data.Acq_delay_samples + current_synchro_data.Acq_samplestamp_samples + num_frames*d_correlation_length_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;
diff --git a/src/algorithms/tracking/gnuradio_blocks/dll_pll_veml_tracking_fpga.h b/src/algorithms/tracking/gnuradio_blocks/dll_pll_veml_tracking_fpga.h
index a58e4b04a..c5419c93c 100644
--- a/src/algorithms/tracking/gnuradio_blocks/dll_pll_veml_tracking_fpga.h
+++ b/src/algorithms/tracking/gnuradio_blocks/dll_pll_veml_tracking_fpga.h
@@ -213,9 +213,9 @@ private:
     // PRN period in samples
     int d_current_prn_length_samples;
     // processing samples counters
-    unsigned long int d_sample_counter;
-    unsigned long int d_acq_sample_stamp;
-    unsigned long int d_absolute_samples_offset;
+    unsigned long long int d_sample_counter;
+    unsigned long long int d_acq_sample_stamp;
+    unsigned long long int d_absolute_samples_offset;
 
     // CN0 estimation and lock detector
     int d_cn0_estimation_counter;
@@ -232,7 +232,7 @@ private:
     // extra
     int d_correlation_length_samples;
     int d_next_prn_length_samples;
-    unsigned long int d_sample_counter_next;
+    unsigned long long int d_sample_counter_next;
     unsigned int d_pull_in = 0;
     
 
diff --git a/src/algorithms/tracking/libs/fpga_multicorrelator.cc b/src/algorithms/tracking/libs/fpga_multicorrelator.cc
index 5fa8f06fd..a1a051d55 100644
--- a/src/algorithms/tracking/libs/fpga_multicorrelator.cc
+++ b/src/algorithms/tracking/libs/fpga_multicorrelator.cc
@@ -84,17 +84,18 @@
 #define LOCAL_CODE_FPGA_ENABLE_WRITE_MEMORY 0x0C000000
 #define TEST_REGISTER_TRACK_WRITEVAL 0x55AA
 
-unsigned long int fpga_multicorrelator_8sc::read_sample_counter()
+unsigned long long int fpga_multicorrelator_8sc::read_sample_counter()
 {
-	unsigned long int sample_counter_tmp, sample_counter_msw_tmp;
+	unsigned long long int sample_counter_tmp, sample_counter_msw_tmp;
 	sample_counter_tmp = d_map_base[d_SAMPLE_COUNTER_REG_ADDR_LSW];
 	sample_counter_msw_tmp = d_map_base[d_SAMPLE_COUNTER_REG_ADDR_MSW];
-	sample_counter_tmp = sample_counter_tmp + (sample_counter_msw_tmp * (2^32));
+	sample_counter_msw_tmp = sample_counter_msw_tmp << 32;
+	sample_counter_tmp = sample_counter_tmp + sample_counter_msw_tmp; // 2^32
 	//return d_map_base[d_SAMPLE_COUNTER_REG_ADDR];
 	return sample_counter_tmp;
 }
 
-void fpga_multicorrelator_8sc::set_initial_sample(unsigned long int samples_offset)
+void fpga_multicorrelator_8sc::set_initial_sample(unsigned long long int samples_offset)
 {
     d_initial_sample_counter = samples_offset;
     //printf("www writing d map base %d = d_initial_sample_counter = %d\n", d_INITIAL_COUNTER_VALUE_REG_ADDR, d_initial_sample_counter);
diff --git a/src/algorithms/tracking/libs/fpga_multicorrelator.h b/src/algorithms/tracking/libs/fpga_multicorrelator.h
index 563433297..13c4d21f9 100644
--- a/src/algorithms/tracking/libs/fpga_multicorrelator.h
+++ b/src/algorithms/tracking/libs/fpga_multicorrelator.h
@@ -68,8 +68,8 @@ public:
             float rem_code_phase_chips, float code_phase_step_chips,
             int signal_length_samples);bool free();
     void set_channel(unsigned int channel);
-    void set_initial_sample(unsigned long int samples_offset);
-    unsigned long int read_sample_counter();
+    void set_initial_sample(unsigned long long int samples_offset);
+    unsigned long long int read_sample_counter();
     void lock_channel(void);
     void unlock_channel(void);
     //void read_sample_counters(int *sample_counter, int *secondary_sample_counter, int *counter_corr_0_in, int *counter_corr_0_out); // debug
@@ -103,7 +103,7 @@ private:
     unsigned d_code_phase_step_chips_num;
     int d_rem_carr_phase_rad_int;
     int d_phase_step_rad_int;
-    unsigned long int d_initial_sample_counter;
+    unsigned long long int d_initial_sample_counter;
 
     // driver
     std::string d_device_name;