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gnss-sdr/src/algorithms/acquisition/gnuradio_blocks/pcps_cccwsr_acquisition_cc.cc

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/*!
* \file pcps_cccwsr_acquisition_cc.cc
* \brief This class implements a Parallel Code Phase Search acquisition
* with Coherent Channel Combining With Sign Recovery scheme.
* \author Marc Molina, 2013. marc.molina.pena(at)gmail.com
*
* D.Borio, C.O'Driscoll, G.Lachapelle, "Coherent, Noncoherent and
* Differentially Coherent Combining Techniques for Acquisition of
* New Composite GNSS Signals", IEEE Transactions On Aerospace and
* Electronic Systems vol. 45 no. 3, July 2009, section IV
*
* -----------------------------------------------------------------------------
*
* GNSS-SDR is a Global Navigation Satellite System software-defined receiver.
* This file is part of GNSS-SDR.
*
* Copyright (C) 2010-2020 (see AUTHORS file for a list of contributors)
* SPDX-License-Identifier: GPL-3.0-or-later
*
* -----------------------------------------------------------------------------
*/
#include "pcps_cccwsr_acquisition_cc.h"
#include "MATH_CONSTANTS.h" // TWO_PI
#include <glog/logging.h>
#include <gnuradio/io_signature.h>
#include <volk/volk.h>
#include <volk_gnsssdr/volk_gnsssdr.h>
#include <exception>
#include <sstream>
#include <utility>
pcps_cccwsr_acquisition_cc_sptr pcps_cccwsr_make_acquisition_cc(
uint32_t sampled_ms,
uint32_t max_dwells,
uint32_t doppler_max,
int64_t fs_in,
int32_t samples_per_ms,
int32_t samples_per_code,
bool dump,
const std::string &dump_filename,
bool enable_monitor_output)
{
return pcps_cccwsr_acquisition_cc_sptr(
new pcps_cccwsr_acquisition_cc(sampled_ms, max_dwells, doppler_max, fs_in,
samples_per_ms, samples_per_code, dump, dump_filename, enable_monitor_output));
}
pcps_cccwsr_acquisition_cc::pcps_cccwsr_acquisition_cc(
uint32_t sampled_ms,
uint32_t max_dwells,
uint32_t doppler_max,
int64_t fs_in,
int32_t samples_per_ms,
int32_t samples_per_code,
bool dump,
const std::string &dump_filename,
bool enable_monitor_output)
: gr::block("pcps_cccwsr_acquisition_cc",
gr::io_signature::make(1, 1, static_cast<int>(sizeof(gr_complex) * sampled_ms * samples_per_ms)),
gr::io_signature::make(0, 1, sizeof(Gnss_Synchro))),
d_dump_filename(dump_filename),
d_gnss_synchro(nullptr),
d_fs_in(fs_in),
d_sample_counter(0ULL),
d_threshold(0),
d_doppler_freq(0),
d_mag(0),
d_input_power(0.0),
d_test_statistics(0),
d_state(0),
d_samples_per_ms(samples_per_ms),
d_samples_per_code(samples_per_code),
d_doppler_resolution(0),
d_doppler_max(doppler_max),
d_doppler_step(0),
d_sampled_ms(sampled_ms),
d_max_dwells(max_dwells),
d_well_count(0),
d_fft_size(d_sampled_ms * d_samples_per_ms),
d_num_doppler_bins(0),
d_code_phase(0),
d_channel(0),
d_active(false),
d_dump(dump),
d_enable_monitor_output(enable_monitor_output)
{
this->message_port_register_out(pmt::mp("events"));
d_fft_code_data = std::vector<gr_complex>(d_fft_size);
d_fft_code_pilot = std::vector<gr_complex>(d_fft_size);
d_data_correlation = std::vector<gr_complex>(d_fft_size);
d_pilot_correlation = std::vector<gr_complex>(d_fft_size);
d_correlation_plus = std::vector<gr_complex>(d_fft_size);
d_correlation_minus = std::vector<gr_complex>(d_fft_size);
d_magnitude = std::vector<float>(d_fft_size);
d_fft_if = gnss_fft_fwd_make_unique(d_fft_size);
d_ifft = gnss_fft_rev_make_unique(d_fft_size);
}
pcps_cccwsr_acquisition_cc::~pcps_cccwsr_acquisition_cc()
{
try
{
if (d_dump)
{
d_dump_file.close();
}
}
catch (const std::ofstream::failure &e)
{
std::cerr << "Problem closing Acquisition dump file: " << d_dump_filename << '\n';
}
catch (const std::exception &e)
{
std::cerr << e.what() << '\n';
}
}
void pcps_cccwsr_acquisition_cc::set_local_code(std::complex<float> *code_data,
std::complex<float> *code_pilot)
{
// Data code (E1B)
memcpy(d_fft_if->get_inbuf(), code_data, sizeof(gr_complex) * d_fft_size);
d_fft_if->execute(); // We need the FFT of local code
// Conjugate the local code
volk_32fc_conjugate_32fc(d_fft_code_data.data(), d_fft_if->get_outbuf(), d_fft_size);
// Pilot code (E1C)
memcpy(d_fft_if->get_inbuf(), code_pilot, sizeof(gr_complex) * d_fft_size);
d_fft_if->execute(); // We need the FFT of local code
// Conjugate the local code,
volk_32fc_conjugate_32fc(d_fft_code_pilot.data(), d_fft_if->get_outbuf(), d_fft_size);
}
void pcps_cccwsr_acquisition_cc::init()
{
d_gnss_synchro->Flag_valid_acquisition = false;
d_gnss_synchro->Flag_valid_symbol_output = false;
d_gnss_synchro->Flag_valid_pseudorange = false;
d_gnss_synchro->Flag_valid_word = false;
d_gnss_synchro->Acq_doppler_step = 0U;
d_gnss_synchro->Acq_delay_samples = 0.0;
d_gnss_synchro->Acq_doppler_hz = 0.0;
d_gnss_synchro->Acq_samplestamp_samples = 0ULL;
d_mag = 0.0;
d_input_power = 0.0;
// Count the number of bins
d_num_doppler_bins = 0;
for (auto doppler = static_cast<int32_t>(-d_doppler_max);
doppler <= static_cast<int32_t>(d_doppler_max);
doppler += d_doppler_step)
{
d_num_doppler_bins++;
}
// Create the carrier Doppler wipeoff signals
d_grid_doppler_wipeoffs = std::vector<std::vector<gr_complex>>(d_num_doppler_bins, std::vector<gr_complex>(d_fft_size));
for (uint32_t doppler_index = 0; doppler_index < d_num_doppler_bins; doppler_index++)
{
int32_t doppler = -static_cast<int32_t>(d_doppler_max) + d_doppler_step * doppler_index;
float phase_step_rad = static_cast<float>(TWO_PI) * doppler / static_cast<float>(d_fs_in);
std::array<float, 1> _phase{};
volk_gnsssdr_s32f_sincos_32fc(d_grid_doppler_wipeoffs[doppler_index].data(), -phase_step_rad, _phase.data(), d_fft_size);
}
}
void pcps_cccwsr_acquisition_cc::set_state(int32_t state)
{
d_state = state;
if (d_state == 1)
{
d_gnss_synchro->Acq_delay_samples = 0.0;
d_gnss_synchro->Acq_doppler_hz = 0.0;
d_gnss_synchro->Acq_samplestamp_samples = 0ULL;
d_gnss_synchro->Acq_doppler_step = 0U;
d_well_count = 0;
d_mag = 0.0;
d_input_power = 0.0;
d_test_statistics = 0.0;
}
else if (d_state == 0)
{
}
else
{
LOG(ERROR) << "State can only be set to 0 or 1";
}
}
int pcps_cccwsr_acquisition_cc::general_work(int noutput_items,
gr_vector_int &ninput_items, gr_vector_const_void_star &input_items,
gr_vector_void_star &output_items)
{
int32_t acquisition_message = -1; // 0=STOP_CHANNEL 1=ACQ_SUCCEES 2=ACQ_FAIL
switch (d_state)
{
case 0:
{
if (d_active)
{
// restart acquisition variables
d_gnss_synchro->Acq_delay_samples = 0.0;
d_gnss_synchro->Acq_doppler_hz = 0.0;
d_gnss_synchro->Acq_samplestamp_samples = 0ULL;
d_gnss_synchro->Acq_doppler_step = 0U;
d_well_count = 0;
d_mag = 0.0;
d_input_power = 0.0;
d_test_statistics = 0.0;
d_state = 1;
}
d_sample_counter += static_cast<uint64_t>(d_fft_size * ninput_items[0]); // sample counter
consume_each(ninput_items[0]);
break;
}
case 1:
{
// initialize acquisition algorithm
int32_t doppler;
uint32_t indext = 0;
uint32_t indext_plus = 0;
uint32_t indext_minus = 0;
float magt = 0.0;
float magt_plus = 0.0;
float magt_minus = 0.0;
const auto *in = reinterpret_cast<const gr_complex *>(input_items[0]); // Get the input samples pointer
float fft_normalization_factor = static_cast<float>(d_fft_size) * static_cast<float>(d_fft_size);
d_sample_counter += static_cast<uint64_t>(d_fft_size); // sample counter
d_well_count++;
DLOG(INFO) << "Channel: " << d_channel
<< " , doing acquisition of satellite: " << d_gnss_synchro->System << " " << d_gnss_synchro->PRN
<< " ,sample stamp: " << d_sample_counter << ", threshold: "
<< d_threshold << ", doppler_max: " << d_doppler_max
<< ", doppler_step: " << d_doppler_step;
// 1- Compute the input signal power estimation
volk_32fc_magnitude_squared_32f(d_magnitude.data(), in, d_fft_size);
volk_32f_accumulator_s32f(&d_input_power, d_magnitude.data(), d_fft_size);
d_input_power /= static_cast<float>(d_fft_size);
// 2- Doppler frequency search loop
for (uint32_t doppler_index = 0; doppler_index < d_num_doppler_bins; doppler_index++)
{
// doppler search steps
doppler = -static_cast<int32_t>(d_doppler_max) + d_doppler_step * doppler_index;
volk_32fc_x2_multiply_32fc(d_fft_if->get_inbuf(), in,
d_grid_doppler_wipeoffs[doppler_index].data(), d_fft_size);
// 3- Perform the FFT-based convolution (parallel time search)
// Compute the FFT of the carrier wiped--off incoming signal
d_fft_if->execute();
// Multiply carrier wiped--off, Fourier transformed incoming signal
// with the local FFT'd data code reference (E1B) using SIMD operations
// with VOLK library
volk_32fc_x2_multiply_32fc(d_ifft->get_inbuf(),
d_fft_if->get_outbuf(), d_fft_code_data.data(), d_fft_size);
// compute the inverse FFT
d_ifft->execute();
// Copy the result of the correlation between wiped--off signal and data code in
// d_data_correlation.
memcpy(d_data_correlation.data(), d_ifft->get_outbuf(), sizeof(gr_complex) * d_fft_size);
// Multiply carrier wiped--off, Fourier transformed incoming signal
// with the local FFT'd pilot code reference (E1C) using SIMD operations
// with VOLK library
volk_32fc_x2_multiply_32fc(d_ifft->get_inbuf(),
d_fft_if->get_outbuf(), d_fft_code_pilot.data(), d_fft_size);
// Compute the inverse FFT
d_ifft->execute();
// Copy the result of the correlation between wiped--off signal and pilot code in
// d_data_correlation.
memcpy(d_pilot_correlation.data(), d_ifft->get_outbuf(), sizeof(gr_complex) * d_fft_size);
for (uint32_t i = 0; i < d_fft_size; i++)
{
d_correlation_plus[i] = std::complex<float>(
d_data_correlation[i].real() - d_pilot_correlation[i].imag(),
d_data_correlation[i].imag() + d_pilot_correlation[i].real());
d_correlation_minus[i] = std::complex<float>(
d_data_correlation[i].real() + d_pilot_correlation[i].imag(),
d_data_correlation[i].imag() - d_pilot_correlation[i].real());
}
volk_32fc_magnitude_squared_32f(d_magnitude.data(), d_correlation_plus.data(), d_fft_size);
volk_gnsssdr_32f_index_max_32u(&indext_plus, d_magnitude.data(), d_fft_size);
magt_plus = d_magnitude[indext_plus] / (fft_normalization_factor * fft_normalization_factor);
volk_32fc_magnitude_squared_32f(d_magnitude.data(), d_correlation_minus.data(), d_fft_size);
volk_gnsssdr_32f_index_max_32u(&indext_minus, d_magnitude.data(), d_fft_size);
magt_minus = d_magnitude[indext_minus] / (fft_normalization_factor * fft_normalization_factor);
if (magt_plus >= magt_minus)
{
magt = magt_plus;
indext = indext_plus;
}
else
{
magt = magt_minus;
indext = indext_minus;
}
// 4- record the maximum peak and the associated synchronization parameters
if (d_mag < magt)
{
d_mag = magt;
d_gnss_synchro->Acq_delay_samples = static_cast<double>(indext % d_samples_per_code);
d_gnss_synchro->Acq_doppler_hz = static_cast<double>(doppler);
d_gnss_synchro->Acq_samplestamp_samples = d_sample_counter;
d_gnss_synchro->Acq_doppler_step = d_doppler_step;
}
// Record results to file if required
if (d_dump)
{
std::stringstream filename;
std::streamsize n = 2 * sizeof(float) * (d_fft_size); // complex file write
filename.str("");
filename << "../data/test_statistics_" << d_gnss_synchro->System
<< "_" << d_gnss_synchro->Signal[0] << d_gnss_synchro->Signal[1] << "_sat_"
<< d_gnss_synchro->PRN << "_doppler_" << doppler << ".dat";
d_dump_file.open(filename.str().c_str(), std::ios::out | std::ios::binary);
d_dump_file.write(reinterpret_cast<char *>(d_ifft->get_outbuf()), n); // write directly |abs(x)|^2 in this Doppler bin?
d_dump_file.close();
}
}
// 5- Compute the test statistics and compare to the threshold
// d_test_statistics = 2 * d_fft_size * d_mag / d_input_power;
d_test_statistics = d_mag / d_input_power;
// 6- Declare positive or negative acquisition using a message port
if (d_test_statistics > d_threshold)
{
d_state = 2; // Positive acquisition
}
else if (d_well_count == d_max_dwells)
{
d_state = 3; // Negative acquisition
}
consume_each(1);
break;
}
case 2:
{
// 6.1- Declare positive acquisition using a message port
DLOG(INFO) << "positive acquisition";
DLOG(INFO) << "satellite " << d_gnss_synchro->System << " " << d_gnss_synchro->PRN;
DLOG(INFO) << "sample_stamp " << d_sample_counter;
DLOG(INFO) << "test statistics value " << d_test_statistics;
DLOG(INFO) << "test statistics threshold " << d_threshold;
DLOG(INFO) << "code phase " << d_gnss_synchro->Acq_delay_samples;
DLOG(INFO) << "doppler " << d_gnss_synchro->Acq_doppler_hz;
DLOG(INFO) << "magnitude " << d_mag;
DLOG(INFO) << "input signal power " << d_input_power;
d_active = false;
d_state = 0;
d_sample_counter += static_cast<uint64_t>(d_fft_size * ninput_items[0]); // sample counter
consume_each(ninput_items[0]);
acquisition_message = 1;
this->message_port_pub(pmt::mp("events"), pmt::from_long(acquisition_message));
// Copy and push current Gnss_Synchro to monitor queue
if (d_enable_monitor_output)
{
auto **out = reinterpret_cast<Gnss_Synchro **>(&output_items[0]);
Gnss_Synchro current_synchro_data = Gnss_Synchro();
current_synchro_data = *d_gnss_synchro;
*out[0] = current_synchro_data;
noutput_items = 1; // Number of Gnss_Synchro objects produced
}
break;
}
case 3:
{
// 6.2- Declare negative acquisition using a message port
DLOG(INFO) << "negative acquisition";
DLOG(INFO) << "satellite " << d_gnss_synchro->System << " " << d_gnss_synchro->PRN;
DLOG(INFO) << "sample_stamp " << d_sample_counter;
DLOG(INFO) << "test statistics value " << d_test_statistics;
DLOG(INFO) << "test statistics threshold " << d_threshold;
DLOG(INFO) << "code phase " << d_gnss_synchro->Acq_delay_samples;
DLOG(INFO) << "doppler " << d_gnss_synchro->Acq_doppler_hz;
DLOG(INFO) << "magnitude " << d_mag;
DLOG(INFO) << "input signal power " << d_input_power;
d_active = false;
d_state = 0;
d_sample_counter += static_cast<uint64_t>(d_fft_size * ninput_items[0]); // sample counter
consume_each(ninput_items[0]);
acquisition_message = 2;
this->message_port_pub(pmt::mp("events"), pmt::from_long(acquisition_message));
break;
}
}
return noutput_items;
}
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