[hamradio-commits] [gnss-sdr] 16/251: Faster local carrier update (25% of improvement)

[Carles Fernandez]

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carles_fernandez-guest pushed a commit to branch master
in repository gnss-sdr.

commit 1011bb086367f99a02bf0b7e41066be79d3ef183
Author: Carles Fernandez <carles.fernandez at gmail.com>
Date:   Sun May 3 13:15:17 2015 +0200

    Faster local carrier update (25% of improvement)
---
 .../galileo_e1_dll_pll_veml_tracking_cc.cc               | 16 +++++++++-------
 .../gnuradio_blocks/galileo_e5a_dll_pll_tracking_cc.cc   | 15 ++++++++++-----
 2 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/src/algorithms/tracking/gnuradio_blocks/galileo_e1_dll_pll_veml_tracking_cc.cc b/src/algorithms/tracking/gnuradio_blocks/galileo_e1_dll_pll_veml_tracking_cc.cc
index becfcf9..06f0267 100755
--- a/src/algorithms/tracking/gnuradio_blocks/galileo_e1_dll_pll_veml_tracking_cc.cc
+++ b/src/algorithms/tracking/gnuradio_blocks/galileo_e1_dll_pll_veml_tracking_cc.cc
@@ -259,17 +259,19 @@ void galileo_e1_dll_pll_veml_tracking_cc::update_local_code()
     memcpy(d_very_late_code, &d_very_early_code[2 * very_early_late_spc_samples], d_current_prn_length_samples * sizeof(gr_complex));
 }
 
+
 void galileo_e1_dll_pll_veml_tracking_cc::update_local_carrier()
 {
-    float phase_rad, phase_step_rad;
-    // Compute the carrier phase step for the K-1 carrier doppler estimation
-    phase_step_rad = static_cast<float>(GPS_TWO_PI) * d_carrier_doppler_hz / static_cast<float>(d_fs_in);
-    // Initialize the carrier phase with the remanent carrier phase of the K-2 loop
-    phase_rad = d_rem_carr_phase_rad;
+    float sin_f, cos_f;
+    float phase_step_rad = static_cast<float>(2 * GALILEO_PI) * d_carrier_doppler_hz / static_cast<float>(d_fs_in);
+    int phase_step_rad_i = gr::fxpt::float_to_fixed(phase_step_rad);
+    int phase_rad_i = gr::fxpt::float_to_fixed(d_rem_carr_phase_rad);
+
     for(int i = 0; i < d_current_prn_length_samples; i++)
         {
-            d_carr_sign[i] = gr_complex(cos(phase_rad), -sin(phase_rad));
-            phase_rad += phase_step_rad;
+            gr::fxpt::sincos(phase_rad_i, &sin_f, &cos_f);
+            d_carr_sign[i] = std::complex<float>(cos_f, -sin_f);
+            phase_rad_i += phase_step_rad_i;
         }
 }
 
diff --git a/src/algorithms/tracking/gnuradio_blocks/galileo_e5a_dll_pll_tracking_cc.cc b/src/algorithms/tracking/gnuradio_blocks/galileo_e5a_dll_pll_tracking_cc.cc
index ea7eb5a..88c499e 100644
--- a/src/algorithms/tracking/gnuradio_blocks/galileo_e5a_dll_pll_tracking_cc.cc
+++ b/src/algorithms/tracking/gnuradio_blocks/galileo_e5a_dll_pll_tracking_cc.cc
@@ -40,6 +40,7 @@
 #include <sstream>
 #include <boost/lexical_cast.hpp>
 #include <gnuradio/io_signature.h>
+#include <gnuradio/fxpt.h>  // fixed point sine and cosine
 #include <glog/logging.h>
 #include "gnss_synchro.h"
 #include "galileo_e5_signal_processing.h"
@@ -364,19 +365,23 @@ void Galileo_E5a_Dll_Pll_Tracking_cc::update_local_code()
 
 }
 
+
 void Galileo_E5a_Dll_Pll_Tracking_cc::update_local_carrier()
 {
-    float phase_rad, phase_step_rad;
+    float sin_f, cos_f;
+    float phase_step_rad = static_cast<float>(2 * GALILEO_PI) * d_carrier_doppler_hz / static_cast<float>(d_fs_in);
+    int phase_step_rad_i = gr::fxpt::float_to_fixed(phase_step_rad);
+    int phase_rad_i = gr::fxpt::float_to_fixed(d_rem_carr_phase_rad);
 
-    phase_step_rad = 2 * static_cast<float>(GALILEO_PI) * d_carrier_doppler_hz / static_cast<float>(d_fs_in);
-    phase_rad = d_rem_carr_phase_rad;
     for(int i = 0; i < d_current_prn_length_samples; i++)
         {
-            d_carr_sign[i] = gr_complex(cos(phase_rad), -sin(phase_rad));
-            phase_rad += phase_step_rad;
+            gr::fxpt::sincos(phase_rad_i, &sin_f, &cos_f);
+            d_carr_sign[i] = std::complex<float>(cos_f, -sin_f);
+            phase_rad_i += phase_step_rad_i;
         }
 }
 
+
 int Galileo_E5a_Dll_Pll_Tracking_cc::general_work (int noutput_items, gr_vector_int &ninput_items,
         gr_vector_const_void_star &input_items, gr_vector_void_star &output_items)
 {

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