mirror of https://github.com/gnss-sdr/gnss-sdr
312 lines
11 KiB
C++
312 lines
11 KiB
C++
/*!
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* \file pcps_acquisition_cc.cc
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* \brief This class implements a Parallel Code Phase Search Acquisition
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* \authors <ul>
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* <li> Javier Arribas, 2011. jarribas(at)cttc.es
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* <li> Luis Esteve, 2012. luis(at)epsilon-formacion.com
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* </ul>
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*
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* Detailed description of the file here if needed.
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*
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* -------------------------------------------------------------------------
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*
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* Copyright (C) 2010-2011 (see AUTHORS file for a list of contributors)
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*
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* GNSS-SDR is a software defined Global Navigation
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* Satellite Systems receiver
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*
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* This file is part of GNSS-SDR.
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*
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* GNSS-SDR is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* at your option) any later version.
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*
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* GNSS-SDR is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with GNSS-SDR. If not, see <http://www.gnu.org/licenses/>.
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*
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* -------------------------------------------------------------------------
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*/
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#include "pcps_acquisition_cc.h"
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#include "gnss_signal_processing.h"
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#include "control_message_factory.h"
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#include <gnuradio/gr_io_signature.h>
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#include <sstream>
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#include <glog/log_severity.h>
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#include <glog/logging.h>
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#include <volk/volk.h>
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using google::LogMessage;
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pcps_acquisition_cc_sptr pcps_make_acquisition_cc(
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unsigned int sampled_ms, unsigned int doppler_max, long freq,
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long fs_in, int samples_per_ms, gr_msg_queue_sptr queue, bool dump,
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std::string dump_filename)
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{
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return pcps_acquisition_cc_sptr(
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new pcps_acquisition_cc(sampled_ms, doppler_max, freq,
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fs_in, samples_per_ms, queue, dump, dump_filename));
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}
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pcps_acquisition_cc::pcps_acquisition_cc(
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unsigned int sampled_ms, unsigned int doppler_max, long freq,
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long fs_in, int samples_per_ms, gr_msg_queue_sptr queue, bool dump,
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std::string dump_filename) :
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gr_block("pcps_acquisition_cc", gr_make_io_signature(1, 1,
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sizeof(gr_complex) * sampled_ms *samples_per_ms), gr_make_io_signature(0, 0,
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sizeof(gr_complex) * sampled_ms *samples_per_ms))
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{
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d_sample_counter = 0; // SAMPLE COUNTER
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d_active = false;
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d_queue = queue;
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d_freq = freq;
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d_fs_in = fs_in;
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d_samples_per_ms = samples_per_ms;
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d_sampled_ms = sampled_ms;
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d_doppler_max = doppler_max;
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d_fft_size = d_sampled_ms * d_samples_per_ms;
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d_mag = 0;
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d_input_power = 0.0;
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d_sine_if = new gr_complex[d_fft_size];
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d_fft_codes = (gr_complex*)malloc(sizeof(gr_complex) * d_fft_size);
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// Direct FFT
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d_fft_if = new gri_fft_complex(d_fft_size, true);
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// Inverse FFT
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d_ifft = new gri_fft_complex(d_fft_size, false);
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d_dump = dump;
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d_dump_filename = dump_filename;
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}
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pcps_acquisition_cc::~pcps_acquisition_cc()
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{
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delete[] d_sine_if;
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delete[] d_fft_codes;
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delete d_ifft;
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delete d_fft_if;
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if (d_dump)
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{
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d_dump_file.close();
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}
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}
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void pcps_acquisition_cc::set_local_code(std::complex<float> * code)
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{
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memcpy(d_fft_if->get_inbuf(),code,sizeof(gr_complex)*d_fft_size);
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}
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void pcps_acquisition_cc::init()
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{
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d_gnss_synchro->Acq_delay_samples=0.0;
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d_gnss_synchro->Acq_doppler_hz=0.0;
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d_gnss_synchro->Acq_samplestamp_samples=0;
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d_mag = 0.0;
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d_input_power = 0.0;
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d_fft_if->execute(); // We need the FFT of local code
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//Conjugate the local code
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for (unsigned int i = 0; i < d_fft_size; i++)
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{
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d_fft_codes[i] = std::complex<float>(conj(d_fft_if->get_outbuf()[i]));
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}
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}
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int pcps_acquisition_cc::general_work(int noutput_items,
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gr_vector_int &ninput_items, gr_vector_const_void_star &input_items,
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gr_vector_void_star &output_items)
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{
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/*
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* By J.Arribas and L.Esteve
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* Acquisition strategy (Kay Borre book + CFAR threshold):
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* 1. Compute the input signal power estimation
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* 2. Doppler serial search loop
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* 3. Perform the FFT-based circular convolution (parallel time search)
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* 4. Record the maximum peak and the associated synchronization parameters
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* 5. Compute the test statistics and compare to the threshold
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* 6. Declare positive or negative acquisition using a message queue
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*/
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if (!d_active)
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{
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d_sample_counter += d_fft_size * noutput_items; // sample counter
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consume_each(noutput_items);
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}
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else
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{
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d_sample_counter += d_fft_size; // sample counter
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//restart acquisition variables
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d_gnss_synchro->Acq_delay_samples=0.0;
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d_gnss_synchro->Acq_doppler_hz=0.0;
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d_mag = 0.0;
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d_input_power = 0.0;
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// initialize acquisition algorithm
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int doppler;
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unsigned int indext = 0;
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float magt = 0.0;
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float tmp_magt = 0.0;
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const gr_complex *in = (const gr_complex *)input_items[0]; //Get the input samples pointer
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bool positive_acquisition = false;
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int acquisition_message = -1; //0=STOP_CHANNEL 1=ACQ_SUCCEES 2=ACQ_FAIL
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//aux vars
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unsigned int i;
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float fft_normalization_factor;
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DLOG(INFO) << "Channel: " << d_channel
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<< " , doing acquisition of satellite: " << d_gnss_synchro->System << " "<< d_gnss_synchro->PRN
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<< " ,sample stamp: " << d_sample_counter << ", threshold: "
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<< d_threshold << ", doppler_max: " << d_doppler_max
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<< ", doppler_step: " << d_doppler_step;
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// 1- Compute the input signal power estimation
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for (i = 0; i < d_fft_size; i++)
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{
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d_input_power += std::norm(in[i]);
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}
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d_input_power = d_input_power / (float)d_fft_size;
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// 2- Doppler frequency search loop
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for (doppler = (int)(-d_doppler_max); doppler < (int)d_doppler_max; doppler += d_doppler_step)
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{
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//doppler search steps
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//Perform the carrier wipe-off
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complex_exp_gen(d_sine_if, d_freq + doppler, d_fs_in, d_fft_size);
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for (i = 0; i < d_fft_size; i++)
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{
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d_fft_if->get_inbuf()[i] = in[i] * d_sine_if[i];
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}
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//3- Perform the FFT-based circular convolution (parallel time search)
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d_fft_if->execute();
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// Using plain C++ operations
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// for (i = 0; i < d_fft_size; i++)
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// {
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// d_ifft->get_inbuf()[i] = (d_fft_if->get_outbuf()[i]
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// * d_fft_codes[i]) / (float)d_fft_size;
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// }
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// Using SIMD operations with VOLK library
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volk_32fc_x2_multiply_32fc_a(d_ifft->get_inbuf(), d_fft_if->get_outbuf(), d_fft_codes, d_fft_size);
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d_ifft->execute();
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// Search maximum
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indext = 0;
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magt = 0;
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fft_normalization_factor=(float)d_fft_size*(float)d_fft_size;
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for (i = 0; i < d_fft_size; i++)
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{
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tmp_magt = std::norm(d_ifft->get_outbuf()[i]);
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if (tmp_magt > magt)
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{
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magt = tmp_magt;
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indext = i;
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}
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}
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// Normalize the maximum value to correct the scale factor introduced by FFTW
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magt=magt/(fft_normalization_factor*fft_normalization_factor);
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// Record results to files
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if (d_dump)
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{
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std::stringstream filename;
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std::streamsize n = 2 * sizeof(float) * (d_fft_size); // complex file write
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filename.str("");
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filename << "../data/test_statistics_"<<d_gnss_synchro->System<<"_"<<d_gnss_synchro->Signal<<"_sat_" << d_gnss_synchro->PRN << "_doppler_"<< doppler << ".dat";
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d_dump_file.open(filename.str().c_str(), std::ios::out
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| std::ios::binary);
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d_dump_file.write((char*)d_ifft->get_outbuf(), n); //write directly |abs(x)|^2 in this Doppler bin?
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d_dump_file.close();
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}
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// 4- record the maximum peak and the associated synchronization parameters
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if (d_mag < magt)
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{
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d_mag = magt;
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d_gnss_synchro->Acq_delay_samples= (double)indext;
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d_gnss_synchro->Acq_doppler_hz= (double)doppler;
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}
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}
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// 5- Compute the test statistics and compare to the threshold
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d_test_statistics = 2 * d_fft_size * d_mag / d_input_power;
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// 6- Declare positive or negative acquisition using a message queue
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if (d_test_statistics > d_threshold)
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{
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positive_acquisition = true;
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d_gnss_synchro->Acq_samplestamp_samples = d_sample_counter;
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DLOG(INFO) << "positive acquisition";
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DLOG(INFO) << "satellite " << d_gnss_synchro->System << " "<< d_gnss_synchro->PRN;
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DLOG(INFO) << "sample_stamp " << d_sample_counter;
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DLOG(INFO) << "test statistics value " << d_test_statistics;
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DLOG(INFO) << "test statistics threshold " << d_threshold;
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DLOG(INFO) << "code phase " << d_gnss_synchro->Acq_delay_samples;
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DLOG(INFO) << "doppler " << d_gnss_synchro->Acq_doppler_hz;
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DLOG(INFO) << "magnitude " << d_mag;
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DLOG(INFO) << "input signal power " << d_input_power;
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}
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else
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{
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DLOG(INFO) << "negative acquisition";
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DLOG(INFO) << "satellite " << d_gnss_synchro->System << " "<< d_gnss_synchro->PRN;
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DLOG(INFO) << "sample_stamp " << d_sample_counter;
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DLOG(INFO) << "test statistics value " << d_test_statistics;
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DLOG(INFO) << "test statistics threshold " << d_threshold;
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DLOG(INFO) << "code phase " << d_gnss_synchro->Acq_delay_samples;
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DLOG(INFO) << "doppler " << d_gnss_synchro->Acq_doppler_hz;
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DLOG(INFO) << "magnitude " << d_mag;
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DLOG(INFO) << "input signal power " << d_input_power;
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}
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d_active = false;
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if (positive_acquisition)
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{
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acquisition_message = 1;
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}
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else
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{
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acquisition_message = 2;
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}
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d_channel_internal_queue->push(acquisition_message);
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consume_each(1);
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}
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return 0;
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}
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