mirror of https://github.com/gnss-sdr/gnss-sdr
130 lines
4.8 KiB
C++
130 lines
4.8 KiB
C++
/*!
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* \file pulse_blanking_cc.cc
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* \brief Implements a pulse blanking algorithm
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* \author Javier Arribas (jarribas(at)cttc.es)
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* Antonio Ramos (antonio.ramosdet(at)gmail.com)
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* -------------------------------------------------------------------------
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*
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* Copyright (C) 2010-2018 (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 <https://www.gnu.org/licenses/>.
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*
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* -------------------------------------------------------------------------
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*/
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#include "pulse_blanking_cc.h"
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#include <boost/math/distributions/chi_squared.hpp>
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#include <gnuradio/io_signature.h>
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#include <volk/volk.h>
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#include <cmath>
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pulse_blanking_cc_sptr make_pulse_blanking_cc(float pfa, int32_t length_,
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int32_t n_segments_est, int32_t n_segments_reset)
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{
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return pulse_blanking_cc_sptr(new pulse_blanking_cc(pfa, length_, n_segments_est, n_segments_reset));
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}
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pulse_blanking_cc::pulse_blanking_cc(float pfa,
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int32_t length_,
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int32_t n_segments_est,
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int32_t n_segments_reset) : gr::block("pulse_blanking_cc",
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gr::io_signature::make(1, 1, sizeof(gr_complex)),
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gr::io_signature::make(1, 1, sizeof(gr_complex)))
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{
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const int32_t alignment_multiple = volk_get_alignment() / sizeof(gr_complex);
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set_alignment(std::max(1, alignment_multiple));
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this->pfa = pfa;
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this->length_ = length_;
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last_filtered = false;
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n_segments = 0;
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this->n_segments_est = n_segments_est;
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this->n_segments_reset = n_segments_reset;
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noise_power_estimation = 0.0;
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n_deg_fred = 2 * length_;
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boost::math::chi_squared_distribution<float> my_dist_(n_deg_fred);
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thres_ = boost::math::quantile(boost::math::complement(my_dist_, pfa));
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zeros_ = static_cast<gr_complex *>(volk_malloc(length_ * sizeof(gr_complex), volk_get_alignment()));
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for (int32_t aux = 0; aux < length_; aux++)
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{
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zeros_[aux] = gr_complex(0.0, 0.0);
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}
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}
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pulse_blanking_cc::~pulse_blanking_cc()
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{
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volk_free(zeros_);
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}
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void pulse_blanking_cc::forecast(int noutput_items __attribute__((unused)), gr_vector_int &ninput_items_required)
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{
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for (int &aux : ninput_items_required)
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{
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aux = length_;
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}
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}
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int pulse_blanking_cc::general_work(int noutput_items, gr_vector_int &ninput_items __attribute__((unused)),
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gr_vector_const_void_star &input_items, gr_vector_void_star &output_items)
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{
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const auto *in = reinterpret_cast<const gr_complex *>(input_items[0]);
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auto *out = reinterpret_cast<gr_complex *>(output_items[0]);
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auto *magnitude = static_cast<float *>(volk_malloc(noutput_items * sizeof(float), volk_get_alignment()));
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volk_32fc_magnitude_squared_32f(magnitude, in, noutput_items);
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int32_t sample_index = 0;
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float segment_energy;
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while ((sample_index + length_) < noutput_items)
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{
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volk_32f_accumulator_s32f(&segment_energy, (magnitude + sample_index), length_);
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if ((n_segments < n_segments_est) && (last_filtered == false))
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{
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noise_power_estimation = (static_cast<float>(n_segments) * noise_power_estimation + segment_energy / static_cast<float>(n_deg_fred)) / static_cast<float>(n_segments + 1);
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memcpy(out, in, sizeof(gr_complex) * length_);
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}
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else
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{
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if ((segment_energy / noise_power_estimation) > thres_)
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{
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memcpy(out, zeros_, sizeof(gr_complex) * length_);
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last_filtered = true;
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}
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else
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{
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memcpy(out, in, sizeof(gr_complex) * length_);
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last_filtered = false;
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if (n_segments > n_segments_reset)
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{
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n_segments = 0;
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}
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}
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}
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in += length_;
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out += length_;
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sample_index += length_;
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n_segments++;
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}
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volk_free(magnitude);
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consume_each(sample_index);
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return sample_index;
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}
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