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gnss-sdr/src/algorithms/acquisition/gnuradio_blocks/gps_l1_ca_pcps_acquisition_...

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/*!
* \file gps_l1_ca_pcps_acquisition_cc.h
* \brief Brief description of the file here
* \author Javier Arribas, 2011. jarribas(at)cttc.es
* Luis Esteve, 2011. luis(at)epsilon-formacion.com
*
* Detailed description of the file here if needed.
*
* -------------------------------------------------------------------------
*
* 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_pcps_acquisition_cc.h"
#include "gps_sdr_signal_processing.h"
#include "control_message_factory.h"
#include "gps_sdr_x86.h"
#include <gnuradio/gr_io_signature.h>
#include <sstream>
#include <glog/log_severity.h>
#include <glog/logging.h>
using google::LogMessage;
gps_l1_ca_pcps_acquisition_cc_sptr gps_l1_ca_pcps_make_acquisition_cc(
unsigned int sampled_ms, unsigned int doppler_max, long freq,
long fs_in, int samples_per_ms, gr_msg_queue_sptr queue, bool dump,
std::string dump_filename)
{
return gps_l1_ca_pcps_acquisition_cc_sptr(
new gps_l1_ca_pcps_acquisition_cc(sampled_ms, doppler_max, freq,
fs_in, samples_per_ms, queue, dump, dump_filename));
}
gps_l1_ca_pcps_acquisition_cc::gps_l1_ca_pcps_acquisition_cc(
unsigned int sampled_ms, unsigned int doppler_max, long freq,
long fs_in, int samples_per_ms, gr_msg_queue_sptr queue, bool dump,
std::string dump_filename) :
gr_block("gps_l1_ca_pcps_acquisition_cc", gr_make_io_signature(1, 1,
sizeof(gr_complex) * samples_per_ms), gr_make_io_signature(0, 0,
sizeof(gr_complex) * samples_per_ms))
{
d_sample_counter = 0; // SAMPLE COUNTER
d_active = false;
d_queue = queue;
d_freq = freq;
d_fs_in = fs_in;
d_samples_per_ms = samples_per_ms;
d_sampled_ms = sampled_ms;
d_doppler_max = doppler_max;
d_satellite = 0;
d_fft_size = d_sampled_ms * d_samples_per_ms;
d_doppler_freq = 0.0;
d_code_phase = 0;
d_mag = 0;
d_input_power = 0.0;
d_sine_if = new gr_complex[d_fft_size];
d_fft_codes = (gr_complex*)malloc(sizeof(gr_complex) * d_samples_per_ms);
// Direct FFT
d_fft_if = new gri_fft_complex(d_fft_size, true);
// Inverse FFT
d_ifft = new gri_fft_complex(d_fft_size, false);
d_dump = dump;
d_dump_filename = dump_filename;
DLOG(INFO) << "fs in " << d_fs_in;
DLOG(INFO) << "samples per ms " << d_samples_per_ms;
DLOG(INFO) << "doppler max " << d_doppler_max;
DLOG(INFO) << "freq " << d_freq;
DLOG(INFO) << "satellite " << d_satellite;
DLOG(INFO) << "sampled_ms " << d_sampled_ms;
DLOG(INFO) << "fft_size " << d_fft_size;
DLOG(INFO) << "dump filename " << d_dump_filename;
DLOG(INFO) << "dump " << d_dump;
}
gps_l1_ca_pcps_acquisition_cc::~gps_l1_ca_pcps_acquisition_cc()
{
delete[] d_sine_if;
delete[] d_fft_codes;
delete d_ifft;
delete d_fft_if;
if (d_dump)
{
d_dump_file.close();
}
}
void gps_l1_ca_pcps_acquisition_cc::set_satellite(unsigned int satellite)
{
d_satellite = satellite;
d_code_phase = 0;
d_doppler_freq = 0;
d_mag = 0.0;
d_input_power = 0.0;
// Now the GPS codes are generated on the fly using a custom version of the GPS code generator
code_gen_complex_sampled(d_fft_if->get_inbuf(), satellite, d_fs_in, 0);
d_fft_if->execute(); // We need the FFT of GPS C/A code
//Conjugate the local code
//TODO Optimize it ! try conj()
for (unsigned int i = 0; i < d_fft_size; i++)
{
//d_fft_codes[i] = std::complex<float>(
// d_fft_if->get_outbuf()[i].real(),
// -d_fft_if->get_outbuf()[i].imag());
d_fft_codes[i] = std::complex<float>(conj(d_fft_if->get_outbuf()[i]));
d_fft_codes[i] = d_fft_codes[i] / (float)d_fft_size; //to correct the scale factor introduced by FFTW
}
//memcpy(d_fft_codes,d_fft_if->get_outbuf(),sizeof(gr_complex)*d_samples_per_ms);
// std::stringstream filename;
// std::streamsize n = 2*sizeof(float)*(d_fft_size); // complex file write
// filename.str("");
// filename << "./data/code.dat";
// std::cout<<filename.str().c_str();
// std::cout<<".\n";
// d_dump_file.open(filename.str().c_str(), std::ios::out | std::ios::binary);
//
//
// d_dump_file.write((char*)d_ifft->get_inbuf(), n); //write directly |abs(·)|^2 in this Doppler bin
// //d_dump_file.write((char*)d_sine_if, n); //to be read with read_complex_binary() -> test OK
// d_dump_file.close();
}
signed int gps_l1_ca_pcps_acquisition_cc::prn_code_phase()
{
return d_code_phase;
}
int gps_l1_ca_pcps_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)
{
/*
* By J.Arribas
* Acquisition strategy (Kay Borre book + CFAR threshold):
* 1. Compute the input signal power estimation
* 2. Doppler serial search loop
* 3. Perform the FFT-based circular convolution (parallel time search)
* 4. Record the maximum peak and the associated synchronization parameters
* 5. Compute the test statistics and compare to the threshold
* 6. Declare positive or negative acquisition using a message queue
*/
if (!d_active)
{
d_sample_counter += d_fft_size * noutput_items; // sample counter
consume_each(noutput_items);
}
else
{
d_sample_counter += d_fft_size; // sample counter
//restart acquisition variables
d_code_phase = 0;
d_doppler_freq = 0;
d_mag = 0.0;
d_input_power = 0.0;
// initialize acquisition algorithm
int doppler;
unsigned int indext = 0;
float magt = 0.0;
float tmp_magt = 0.0;
const gr_complex *in = (const gr_complex *)input_items[0]; //Get the input samples pointer
bool positive_acquisition = false;
int acquisition_message = -1; //0=STOP_CHANNEL 1=ACQ_SUCCEES 2=ACQ_FAIL
//aux vars
unsigned int i;
DLOG(INFO) << "Channel: " << d_channel
<< " , doing acquisition of satellite: " << d_satellite
<< " ,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
for (i = 0; i < d_fft_size; i++)
{
d_input_power += std::norm(in[i]);
}
d_input_power = d_input_power / (float)d_fft_size;
// 2- Doppler frequency search loop
for (doppler = (int)(-d_doppler_max); doppler < (int)d_doppler_max; doppler += d_doppler_step)
{
// doppler search steps
//Perform the carrier wipe-off
sine_gen_complex(d_sine_if, d_freq + doppler, d_fs_in, d_fft_size);
for (i = 0; i < d_fft_size; i++)
{
d_fft_if->get_inbuf()[i] = in[i] * d_sine_if[i];
}
//3- Perform the FFT-based circular convolution (parallel time search)
d_fft_if->execute();
for (i = 0; i < d_fft_size; i++)
{
d_ifft->get_inbuf()[i] = (d_fft_if->get_outbuf()[i]
* d_fft_codes[i]) / (float)d_fft_size;
}
d_ifft->execute();
// Search maximum
indext = 0;
magt = 0;
for (i = 0; i < d_fft_size; i++)
{
tmp_magt = std::norm(d_ifft->get_outbuf()[i]);
if (tmp_magt > magt)
{
magt = tmp_magt;
indext = i;
}
}
// Record results to files
if (d_dump)
{
std::stringstream filename;
std::streamsize n = 2 * sizeof(float) * (d_fft_size); // complex file write
filename.str("");
filename << "./data/fft_" << doppler << "_.dat";
std::cout << filename.str().c_str();
std::cout << ".\n";
d_dump_file.open(filename.str().c_str(), std::ios::out
| std::ios::binary);
d_dump_file.write((char*)d_ifft->get_outbuf(), n); //write directly |abs(<28>)|^2 in this Doppler bin?
d_dump_file.close();
}
// 4- record the maximum peak and the associated synchronization parameters
if (d_mag < magt)
{
d_mag = magt;
d_code_phase = indext;
d_doppler_freq = doppler;
}
}
// 5- Compute the test statistics and compare to the threshold
d_test_statistics = 2 * d_fft_size * d_mag / d_input_power;
// 6- Declare positive or negative acquisition using a message queue
if (d_test_statistics > d_threshold)
{
positive_acquisition = true;
d_acq_sample_stamp = d_sample_counter;
DLOG(INFO) << "positive acquisition";
DLOG(INFO) << "satellite " << d_satellite;
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_code_phase;
DLOG(INFO) << "doppler " << d_doppler_freq;
DLOG(INFO) << "magnitude " << d_mag;
DLOG(INFO) << "input signal power " << d_input_power;
}
else
{
DLOG(INFO) << "negative acquisition";
DLOG(INFO) << "satellite " << d_satellite;
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_code_phase;
DLOG(INFO) << "doppler " << d_doppler_freq;
DLOG(INFO) << "magnitude " << d_mag;
DLOG(INFO) << "input signal power " << d_input_power;
}
d_active = false;
if (positive_acquisition)
{
acquisition_message = 1;
}
else
{
acquisition_message = 2;
}
d_channel_internal_queue->push(acquisition_message);
consume_each(1);
}
return 0;
}
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