diff --git a/src/algorithms/libs/gnss_circular_deque.h b/src/algorithms/libs/gnss_circular_deque.h
index e1b73c87d..d9694e722 100644
--- a/src/algorithms/libs/gnss_circular_deque.h
+++ b/src/algorithms/libs/gnss_circular_deque.h
@@ -2,7 +2,7 @@
  * \file gnss_circular_deque.h
  * \brief This class implements a circular deque for Gnss_Synchro
  *
- * \author Luis Esteve, 2018. antonio.ramos(at)cttc.es
+ * \author Antonio Ramos, 2018. antonio.ramosdet(at)gmail.com
  *
  * Detailed description of the file here if needed.
  *
diff --git a/src/algorithms/telemetry_decoder/gnuradio_blocks/gps_l1_ca_telemetry_decoder_cc.cc b/src/algorithms/telemetry_decoder/gnuradio_blocks/gps_l1_ca_telemetry_decoder_cc.cc
index 09f4e2621..0c79165c2 100644
--- a/src/algorithms/telemetry_decoder/gnuradio_blocks/gps_l1_ca_telemetry_decoder_cc.cc
+++ b/src/algorithms/telemetry_decoder/gnuradio_blocks/gps_l1_ca_telemetry_decoder_cc.cc
@@ -107,6 +107,8 @@ gps_l1_ca_telemetry_decoder_cc::gps_l1_ca_telemetry_decoder_cc(
     d_TOW_at_current_symbol_ms = 0;
     d_symbol_history.resize(GPS_CA_PREAMBLE_LENGTH_SYMBOLS + 1);  // Change fixed buffer size
     d_symbol_history.clear();                                     // Clear all the elements in the buffer
+    d_make_correlation = true;
+    d_symbol_counter_corr = 0;
 }
 
 
@@ -170,7 +172,7 @@ int gps_l1_ca_telemetry_decoder_cc::general_work(int noutput_items __attribute__
     unsigned int required_symbols = GPS_CA_PREAMBLE_LENGTH_SYMBOLS;
     d_flag_preamble = false;
 
-    if (d_symbol_history.size() > required_symbols)
+    if ((d_symbol_history.size() > required_symbols) and (d_make_correlation or !d_flag_frame_sync))
         {
             //******* preamble correlation ********
             for (unsigned int i = 0; i < GPS_CA_PREAMBLE_LENGTH_SYMBOLS; i++)
@@ -179,19 +181,22 @@ int gps_l1_ca_telemetry_decoder_cc::general_work(int noutput_items __attribute__
                         {
                             if (d_symbol_history.at(i).Prompt_I < 0)  // symbols clipping
                                 {
-                                    corr_value -= d_preambles_symbols[i] * d_symbol_history.at(i).correlation_length_ms;
+                                    corr_value -= d_preambles_symbols[i];
                                 }
                             else
                                 {
-                                    corr_value += d_preambles_symbols[i] * d_symbol_history.at(i).correlation_length_ms;
+                                    corr_value += d_preambles_symbols[i];
                                 }
                         }
-                    if (corr_value >= GPS_CA_PREAMBLE_LENGTH_SYMBOLS) break;
+                }
+            if (std::abs(corr_value) >= GPS_CA_PREAMBLE_LENGTH_SYMBOLS)
+                {
+                    d_symbol_counter_corr++;
                 }
         }
 
     //******* frame sync ******************
-    if (abs(corr_value) == GPS_CA_PREAMBLE_LENGTH_SYMBOLS)
+    if (std::abs(corr_value) == GPS_CA_PREAMBLE_LENGTH_SYMBOLS)
         {
             //TODO: Rewrite with state machine
             if (d_stat == 0)
@@ -208,12 +213,14 @@ int gps_l1_ca_telemetry_decoder_cc::general_work(int noutput_items __attribute__
                 }
             else if (d_stat == 1)  //check 6 seconds of preamble separation
                 {
-                    preamble_diff_ms = round(((static_cast<double>(d_symbol_history.at(0).Tracking_sample_counter) - d_preamble_time_samples) / static_cast<double>(d_symbol_history.at(0).fs)) * 1000.0);
-                    if (abs(preamble_diff_ms - GPS_SUBFRAME_MS) < 1)
+                    preamble_diff_ms = std::round(((static_cast<double>(d_symbol_history.at(0).Tracking_sample_counter) - d_preamble_time_samples) / static_cast<double>(d_symbol_history.at(0).fs)) * 1000.0);
+                    if (std::abs(preamble_diff_ms - GPS_SUBFRAME_MS) < 1)
                         {
                             DLOG(INFO) << "Preamble confirmation for SAT " << this->d_satellite;
                             d_GPS_FSM.Event_gps_word_preamble();
                             d_flag_preamble = true;
+                            d_make_correlation = false;
+                            d_symbol_counter_corr = 0;
                             d_preamble_time_samples = d_symbol_history.at(0).Tracking_sample_counter;  // record the PRN start sample index associated to the preamble
                             if (!d_flag_frame_sync)
                                 {
@@ -238,6 +245,11 @@ int gps_l1_ca_telemetry_decoder_cc::general_work(int noutput_items __attribute__
         }
     else
         {
+            d_symbol_counter_corr++;
+            if (d_symbol_counter_corr > (GPS_SUBFRAME_MS - GPS_CA_TELEMETRY_SYMBOLS_PER_BIT))
+                {
+                    d_make_correlation = true;
+                }
             if (d_stat == 1)
                 {
                     preamble_diff_ms = round(((static_cast<double>(d_symbol_history.at(0).Tracking_sample_counter) - static_cast<double>(d_preamble_time_samples)) / static_cast<double>(d_symbol_history.at(0).fs)) * 1000.0);
@@ -247,6 +259,8 @@ int gps_l1_ca_telemetry_decoder_cc::general_work(int noutput_items __attribute__
                             d_stat = 0;  //lost of frame sync
                             d_flag_frame_sync = false;
                             flag_TOW_set = false;
+                            d_make_correlation = true;
+                            d_symbol_counter_corr = 0;
                         }
                 }
         }
diff --git a/src/algorithms/telemetry_decoder/gnuradio_blocks/gps_l1_ca_telemetry_decoder_cc.h b/src/algorithms/telemetry_decoder/gnuradio_blocks/gps_l1_ca_telemetry_decoder_cc.h
index 22a9526a2..8e3600e3a 100644
--- a/src/algorithms/telemetry_decoder/gnuradio_blocks/gps_l1_ca_telemetry_decoder_cc.h
+++ b/src/algorithms/telemetry_decoder/gnuradio_blocks/gps_l1_ca_telemetry_decoder_cc.h
@@ -84,6 +84,10 @@ private:
     double d_symbol_accumulator;
     short int d_symbol_accumulator_counter;
 
+    // symbol counting
+    bool d_make_correlation;
+    unsigned int d_symbol_counter_corr;
+
     //bits and frame
     unsigned short int d_frame_bit_index;
     unsigned int d_GPS_frame_4bytes;