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gnss-sdr/src/algorithms/tracking/gnuradio_blocks/gps_l1_ca_dll_pll_tracking_...

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/*!
* \file gps_l1_ca_dll_pll_tracking_cc.cc
* \brief code DLL + carrier PLL
* \author Carlos Aviles, 2010. carlos.avilesr(at)googlemail.com
* Javier Arribas, 2011. jarribas(at)cttc.es
*
* Code DLL + carrier PLL according to the algorithms described in [1]
* [1] K.Borre, D.M.Akos, N.Bertelsen, P.Rinder, and S.H.Jensen,
* A Software-Defined GPS and Galileo Receiver. A Single-Frequency Approach, Birkha user, 2007
*
* -------------------------------------------------------------------------
*
* Copyright (C) 2010-2011 (see AUTHORS file for a list of contributors)
*
* GNSS-SDR is a software defined Global Navigation
* Satellite Systems receiver
*
* This file is part of GNSS-SDR.
*
* GNSS-SDR is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* at your option) any later version.
*
* GNSS-SDR is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GNSS-SDR. If not, see <http://www.gnu.org/licenses/>.
*
* -------------------------------------------------------------------------
*/
#include "gps_l1_ca_dll_pll_tracking_cc.h"
#include "gps_sdr_signal_processing.h"
#include "tracking_discriminators.h"
#include "CN_estimators.h"
#include "GPS_L1_CA.h"
#include "control_message_factory.h"
#include <boost/lexical_cast.hpp>
#include <iostream>
#include <sstream>
#include <cmath>
#include "math.h"
#include <gnuradio/gr_io_signature.h>
#include <glog/log_severity.h>
#include <glog/logging.h>
/*!
* \todo Include in definition header file
*/
#define CN0_ESTIMATION_SAMPLES 10
using google::LogMessage;
gps_l1_ca_dll_pll_tracking_cc_sptr
gps_l1_ca_dll_pll_make_tracking_cc(unsigned int satellite, long if_freq, long fs_in, unsigned
int vector_length, gr_msg_queue_sptr queue, bool dump, float pll_bw_hz, float dll_bw_hz, float early_late_space_chips) {
return gps_l1_ca_dll_pll_tracking_cc_sptr(new gps_l1_ca_dll_pll_tracking_cc(satellite, if_freq,
fs_in, vector_length, queue, dump, pll_bw_hz, dll_bw_hz, early_late_space_chips));
}
void gps_l1_ca_dll_pll_tracking_cc::forecast (int noutput_items,
gr_vector_int &ninput_items_required){
ninput_items_required[0] =(int)d_vector_length*2; //set the required available samples in each call
}
gps_l1_ca_dll_pll_tracking_cc::gps_l1_ca_dll_pll_tracking_cc(unsigned int satellite, long if_freq, long fs_in, unsigned
int vector_length, gr_msg_queue_sptr queue, bool dump, float pll_bw_hz, float dll_bw_hz, float early_late_space_chips) :
gr_block ("gps_l1_ca_dll_pll_tracking_cc", gr_make_io_signature (1, 1, sizeof(gr_complex)),
gr_make_io_signature(5, 5, sizeof(float))) {
//gr_sync_decimator ("gps_l1_ca_dll_pll_tracking_cc", gr_make_io_signature (1, 1, sizeof(gr_complex)),
// gr_make_io_signature(3, 3, sizeof(float)),vector_length) {
// initialize internal vars
d_queue = queue;
d_dump = dump;
d_satellite = satellite;
d_if_freq = if_freq;
d_fs_in = fs_in;
d_vector_length = vector_length;
//std::cout<<"pll_bw_hz= "<<pll_bw_hz<<"dll_bw_hz="<<dll_bw_hz<<"\r\n";
// Initialize tracking ==========================================
d_code_loop_filter.set_DLL_BW(dll_bw_hz);
d_carrier_loop_filter.set_PLL_BW(pll_bw_hz);
//--- DLL variables --------------------------------------------------------
d_early_late_spc_chips = early_late_space_chips; // Define early-late offset (in chips)
// Initialization of local code replica
// Get space for a vector with the C/A code replica sampled 1x/chip
d_ca_code=new gr_complex[(int)GPS_L1_CA_CODE_LENGTH_CHIPS+2];
// Get space for the resampled early / prompt / late local replicas
d_early_code= new gr_complex[d_vector_length*2];
d_prompt_code=new gr_complex[d_vector_length*2];
d_late_code=new gr_complex[d_vector_length*2];
// space for carrier wipeoff and signal baseband vectors
d_carr_sign=new gr_complex[d_vector_length*2];
//--- Perform initializations ------------------------------
// define initial code frequency basis of NCO
d_code_freq_hz = GPS_L1_CA_CODE_RATE_HZ;
// define residual code phase (in chips)
d_rem_code_phase_samples = 0.0;
// define residual carrier phase
d_rem_carr_phase_rad = 0.0;
// sample synchronization
d_sample_counter=0;
d_acq_sample_stamp=0;
d_enable_tracking=false;
d_pull_in=false;
d_last_seg=0;
d_current_prn_length_samples=(int)d_vector_length;
// CN0 estimation and lock detector buffers
d_cn0_estimation_counter=0;
d_Prompt_buffer=new gr_complex[CN0_ESTIMATION_SAMPLES];
d_carrier_lock_test=1;
d_CN0_SNV_dB_Hz=0;
d_carrier_lock_fail_counter=0;
d_carrier_lock_threshold=5;
}
void gps_l1_ca_dll_pll_tracking_cc::start_tracking(){
/*!
* correct the code phase according to the delay between acq and trk
*/
unsigned long int acq_trk_diff_samples;
float acq_trk_diff_seconds;
acq_trk_diff_samples=d_sample_counter-d_acq_sample_stamp-d_vector_length;
acq_trk_diff_seconds=acq_trk_diff_samples/(float)d_fs_in;
//doppler effect
// Fd=(C/(C+Vr))*F
float radial_velocity;
radial_velocity=(GPS_L1_FREQ_HZ+d_acq_carrier_doppler_hz)/GPS_L1_FREQ_HZ;
// new chip and prn sequence periods based on acq Doppler
float T_chip_mod_seconds;
float T_prn_mod_seconds;
float T_prn_mod_samples;
d_code_freq_hz=radial_velocity*GPS_L1_CA_CODE_RATE_HZ;
T_chip_mod_seconds=1/d_code_freq_hz;
T_prn_mod_seconds=T_chip_mod_seconds*GPS_L1_CA_CODE_LENGTH_CHIPS;
T_prn_mod_samples=T_prn_mod_seconds*(float)d_fs_in;
d_code_phase_step_chips = d_code_freq_hz / (float)d_fs_in; //[chips]
d_next_prn_length_samples=round(T_prn_mod_samples);
//compute the code phase chips prediction
float delta_T_prn_samples;
float delay_correction_samples;
delta_T_prn_samples=fmod((float)acq_trk_diff_samples,T_prn_mod_samples);
delay_correction_samples=T_prn_mod_samples-delta_T_prn_samples;
d_acq_code_phase_samples=d_acq_code_phase_samples-delay_correction_samples;
if (d_acq_code_phase_samples<0){
d_acq_code_phase_samples=d_acq_code_phase_samples+T_prn_mod_samples;
}
d_carrier_doppler_hz=d_acq_carrier_doppler_hz;
// DLL/PLL filter initialization
d_carrier_loop_filter.initialize(d_carrier_doppler_hz); //initialize the carrier filter
d_code_loop_filter.initialize(d_acq_code_phase_samples); //initialize the code filter
// generate local reference ALWAYS starting at chip 1 (1 sample per chip)
code_gen_conplex(&d_ca_code[1],d_satellite,0);
d_ca_code[0]=d_ca_code[(int)GPS_L1_CA_CODE_LENGTH_CHIPS];
d_ca_code[(int)GPS_L1_CA_CODE_LENGTH_CHIPS+1]=d_ca_code[1];
d_carrier_lock_fail_counter=0;
d_rem_code_phase_samples=0;
d_next_rem_code_phase_samples=0;
d_rem_carr_phase_rad=0;
d_acc_carrier_phase_rad=0;
// ############# ENABLE DATA FILE LOG #################
if (d_dump==true)
{
if (d_dump_file.is_open()==false)
{
try {
d_dump_filename="track_ch"; //base path and name for the tracking log file
d_dump_filename.append(boost::lexical_cast<std::string>(d_channel));
d_dump_filename.append(".dat");
d_dump_file.exceptions ( std::ifstream::failbit | std::ifstream::badbit );
d_dump_file.open(d_dump_filename.c_str(), std::ios::out | std::ios::binary);
std::cout<<"Tracking dump enabled on channel "<<d_channel<<" Log file: "<<d_dump_filename.c_str()<<std::endl;
}
catch (std::ifstream::failure e) {
std::cout << "channel "<<d_channel <<" Exception opening trk dump file "<<e.what()<<"\r\n";
}
}
}
// DEBUG OUTPUT
std::cout<<"Tracking start on channel "<<d_channel<<" for satellite ID* "<< this->d_satellite<< std::endl;
DLOG(INFO) << "Start tracking for satellite "<<this->d_satellite<<" received ";
// enable tracking
d_pull_in=true;
d_enable_tracking=true;
std::cout<<"PULL-IN Doppler [Hz]= "<<d_carrier_doppler_hz<<" PULL-IN Code Phase [samples]= "<<d_acq_code_phase_samples<<"\r\n";
}
void gps_l1_ca_dll_pll_tracking_cc::update_local_code()
{
float tcode_chips;
float rem_code_phase_chips;
int associated_chip_index;
int code_length_chips=(int)GPS_L1_CA_CODE_LENGTH_CHIPS;
// unified loop for E, P, L code vectors
rem_code_phase_chips=d_rem_code_phase_samples*(d_code_freq_hz/d_fs_in);
tcode_chips=-rem_code_phase_chips;
for (int i=0;i<d_current_prn_length_samples;i++)
{
associated_chip_index=1+round(fmod(tcode_chips-d_early_late_spc_chips,code_length_chips));
d_early_code[i] = d_ca_code[associated_chip_index];
associated_chip_index = 1+round(fmod(tcode_chips, code_length_chips));
d_prompt_code[i] = d_ca_code[associated_chip_index];
associated_chip_index = 1+round(fmod(tcode_chips+d_early_late_spc_chips, code_length_chips));
d_late_code[i] = d_ca_code[associated_chip_index];
tcode_chips=tcode_chips+d_code_phase_step_chips;
}
}
void gps_l1_ca_dll_pll_tracking_cc::update_local_carrier()
{
float phase_rad, phase_step_rad;
phase_step_rad = (float)TWO_PI*d_carrier_doppler_hz/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;
}
d_rem_carr_phase_rad=fmod(phase_rad,TWO_PI);
d_acc_carrier_phase_rad=d_acc_carrier_phase_rad+d_rem_carr_phase_rad;
}
gps_l1_ca_dll_pll_tracking_cc::~gps_l1_ca_dll_pll_tracking_cc() {
d_dump_file.close();
delete d_ca_code;
delete d_early_code;
delete d_prompt_code;
delete d_late_code;
delete d_carr_sign;
delete d_Prompt_buffer;
}
/*! Tracking signal processing
* Notice that this is a class derived from gr_sync_decimator, so each of the ninput_items has vector_length samples
*/
int gps_l1_ca_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) {
if (d_enable_tracking==true){
if (d_pull_in==true)
{
int samples_offset=ceil(d_acq_code_phase_samples);
consume_each(d_acq_code_phase_samples); //shift input to perform alignement with local replica
d_sample_counter+=samples_offset; //count for the processed samples
d_pull_in=false;
return 1;
}
d_current_prn_length_samples=d_next_prn_length_samples;
float carr_error;
float carr_nco;
float code_error;
float code_nco;
const gr_complex* in = (gr_complex*) input_items[0]; //PRN start block alignement
float **out = (float **) &output_items[0];
update_local_code();
update_local_carrier();
gr_complex bb_signal_sample(0,0);
d_Early=gr_complex(0,0);
d_Prompt=gr_complex(0,0);
d_Late=gr_complex(0,0);
// perform Early, Prompt and Late correlation
/*!
* \todo Use SIMD-enabled correlators
*/
for(int i=0;i<d_current_prn_length_samples;i++) {
//Perform the carrier wipe-off
bb_signal_sample = in[i] * d_carr_sign[i];
// Now get early, late, and prompt values for each
d_Early += bb_signal_sample*d_early_code[i];
d_Prompt += bb_signal_sample*d_prompt_code[i];
d_Late += bb_signal_sample*d_late_code[i];
}
// Compute PLL error and update carrier NCO -
carr_error=pll_cloop_two_quadrant_atan(d_Prompt)/ (float)TWO_PI;
// Implement carrier loop filter and generate NCO command
carr_nco=d_carrier_loop_filter.get_carrier_nco(carr_error);
// Modify carrier freq based on NCO command
d_carrier_doppler_hz = d_acq_carrier_doppler_hz + carr_nco;
// Compute DLL error and update code NCO
code_error=dll_nc_e_minus_l_normalized(d_Early,d_Late);
// Implement code loop filter and generate NCO command
code_nco=d_code_loop_filter.get_code_nco(code_error);
// Modify code freq based on NCO command
d_code_freq_hz = GPS_L1_CA_CODE_RATE_HZ - code_nco;
// Update the phasestep based on code freq (variable) and
// sampling frequency (fixed)
d_code_phase_step_chips = d_code_freq_hz / (float)d_fs_in; //[chips]
// variable code PRN sample block size
float T_chip_seconds;
float T_prn_seconds;
float T_prn_samples;
float K_blk_samples;
T_chip_seconds=1/d_code_freq_hz;
T_prn_seconds=T_chip_seconds*GPS_L1_CA_CODE_LENGTH_CHIPS;
T_prn_samples=T_prn_seconds*d_fs_in;
d_rem_code_phase_samples=d_next_rem_code_phase_samples;
K_blk_samples=T_prn_samples+d_rem_code_phase_samples;
d_next_prn_length_samples=round(K_blk_samples);
d_next_rem_code_phase_samples=K_blk_samples-d_next_prn_length_samples;
/*!
* \todo Improve the lock detection algorithm!
*/
// ####### CN0 ESTIMATION AND LOCK DETECTORS ######
if (d_cn0_estimation_counter<CN0_ESTIMATION_SAMPLES)
{
// fill buffer with prompt correlator output values
d_Prompt_buffer[d_cn0_estimation_counter]=d_Prompt;
d_cn0_estimation_counter++;
}else{
d_cn0_estimation_counter=0;
d_CN0_SNV_dB_Hz=gps_l1_ca_CN0_SNV(d_Prompt_buffer, CN0_ESTIMATION_SAMPLES,d_fs_in);
d_carrier_lock_test=carrier_lock_detector(d_Prompt_buffer,CN0_ESTIMATION_SAMPLES);
// ###### TRACKING UNLOCK NOTIFICATION #####
int tracking_message;
if (d_carrier_lock_test<d_carrier_lock_threshold or d_carrier_lock_test>30)
{
d_carrier_lock_fail_counter++;
}else{
if (d_carrier_lock_fail_counter>0) d_carrier_lock_fail_counter--;
}
if (d_carrier_lock_fail_counter>200)
{
std::cout<<"Channel "<<d_channel << " loss of lock!\r\n";
tracking_message=3; //loss of lock
d_channel_internal_queue->push(tracking_message);
d_carrier_lock_fail_counter=0;
d_current_prn_length_samples=(int)d_vector_length; //original dsp block length
d_enable_tracking=false; // TODO: check if disabling tracking is consistent with the channel state machine
}
//std::cout<<"d_carrier_lock_fail_counter"<<d_carrier_lock_fail_counter<<"\r\n";
}
// Output the tracking data to navigation and PVT
// Output channel 1: Prompt correlator output Q
*out[0]=d_Prompt.real();
// Output channel 2: Prompt correlator output I
*out[1]=d_Prompt.imag();
// Output channel 3: Current tracking time [ms]
*out[2]=(float)(((double)d_sample_counter/(double)d_fs_in)*1000.0);
// Output channel 4: Carrier accumulated phase
*out[3]=d_acc_carrier_phase_rad;
if(d_dump) {
// MULTIPLEXED FILE RECORDING - Record results to file
float prompt_I;
float prompt_Q;
float tmp_E,tmp_P,tmp_L;
float tmp_float;
prompt_I=d_Prompt.imag();
prompt_Q=d_Prompt.real();
tmp_E=std::abs<float>(d_Early);
tmp_P=std::abs<float>(d_Prompt);
tmp_L=std::abs<float>(d_Late);
try {
// EPR
d_dump_file.write((char*)&tmp_E, sizeof(float));
d_dump_file.write((char*)&tmp_P, sizeof(float));
d_dump_file.write((char*)&tmp_L, sizeof(float));
// PROMPT I and Q (to analyze navigation symbols)
d_dump_file.write((char*)&prompt_I, sizeof(float));
d_dump_file.write((char*)&prompt_Q, sizeof(float));
// PRN start sample stamp
tmp_float=(float)d_sample_counter;
d_dump_file.write((char*)&tmp_float, sizeof(float));
// accumulated carrier phase
d_dump_file.write((char*)&d_acc_carrier_phase_rad, sizeof(float));
// carrier and code frequency
d_dump_file.write((char*)&d_carrier_doppler_hz, sizeof(float));
d_dump_file.write((char*)&d_code_freq_hz, sizeof(float));
//PLL commands
d_dump_file.write((char*)&carr_error, sizeof(float));
d_dump_file.write((char*)&carr_nco, sizeof(float));
//DLL commands
d_dump_file.write((char*)&code_error, sizeof(float));
d_dump_file.write((char*)&code_nco, sizeof(float));
// CN0 and carrier lock test
d_dump_file.write((char*)&d_CN0_SNV_dB_Hz, sizeof(float));
d_dump_file.write((char*)&d_carrier_lock_test, sizeof(float));
// AUX vars (for debug purposes)
tmp_float=0.0;
d_dump_file.write((char*)&tmp_float, sizeof(float));
tmp_float=0.0;
d_dump_file.write((char*)&tmp_float, sizeof(float));
}
catch (std::ifstream::failure e) {
std::cout << "Exception writing trk dump file "<<e.what()<<"\r\n";
}
}
// ########## DEBUG OUTPUT
// debug: Second counter in channel 0
if (d_channel==0)
{
if (floor(d_sample_counter/d_fs_in)!=d_last_seg)
{
d_last_seg=floor(d_sample_counter/d_fs_in);
std::cout<<"t="<<d_last_seg<<std::endl;
std::cout<<"TRK CH "<<d_channel<<" CN0="<<d_CN0_SNV_dB_Hz<< std::endl;
std::cout<<"TRK CH "<<d_channel<<" Carrier_lock_test="<<d_carrier_lock_test<< std::endl;
}
}else
{
if (floor(d_sample_counter/d_fs_in)!=d_last_seg)
{
d_last_seg=floor(d_sample_counter/d_fs_in);
std::cout<<"TRK CH "<<d_channel<<" CN0="<<d_CN0_SNV_dB_Hz<< std::endl;
std::cout<<"TRK CH "<<d_channel<<" Carrier_lock_test="<<d_carrier_lock_test<< std::endl;
}
}
}
consume_each(d_current_prn_length_samples); // this is necesary in gr_block derivates
d_sample_counter+=d_current_prn_length_samples; //count for the processed samples
return 1; //output tracking result ALWAYS even in the case of d_enable_tracking==false
}
void gps_l1_ca_dll_pll_tracking_cc::set_acq_code_phase(float code_phase) {
d_acq_code_phase_samples = code_phase;
LOG_AT_LEVEL(INFO) << "Tracking code phase set to " << d_acq_code_phase_samples;
}
void gps_l1_ca_dll_pll_tracking_cc::set_acq_doppler(float doppler) {
d_acq_carrier_doppler_hz = doppler;
LOG_AT_LEVEL(INFO) << "Tracking carrier doppler set to " << d_acq_carrier_doppler_hz;
}
void gps_l1_ca_dll_pll_tracking_cc::set_satellite(unsigned int satellite) {
d_satellite = satellite;
LOG_AT_LEVEL(INFO) << "Tracking Satellite set to " << d_satellite;
}
void gps_l1_ca_dll_pll_tracking_cc::set_channel(unsigned int channel) {
d_channel = channel;
LOG_AT_LEVEL(INFO) << "Tracking Channel set to " << d_channel;
}
void gps_l1_ca_dll_pll_tracking_cc::set_acq_sample_stamp(unsigned long int sample_stamp)
{
d_acq_sample_stamp = sample_stamp;
}
void gps_l1_ca_dll_pll_tracking_cc::set_channel_queue(concurrent_queue<int> *channel_internal_queue)
{
d_channel_internal_queue = channel_internal_queue;
}
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