mirror of https://github.com/gnss-sdr/gnss-sdr
99 lines
3.7 KiB
C++
99 lines
3.7 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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*
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* GNSS-SDR is a Global Navigation Satellite System software-defined receiver.
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* This file is part of GNSS-SDR.
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*
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* Copyright (C) 2010-2020 (see AUTHORS file for a list of contributors)
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* SPDX-License-Identifier: GPL-3.0-or-later
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*
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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 <algorithm>
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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)
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: 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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noise_power_estimation_(0.0),
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pfa_(pfa),
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length_(length),
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n_segments_(0),
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n_segments_est_(n_segments_est),
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n_segments_reset_(n_segments_reset),
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n_deg_fred_(2 * length),
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last_filtered_(false)
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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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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_ = volk_gnsssdr::vector<gr_complex>(length_);
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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 = volk_gnsssdr::vector<float>(noutput_items);
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volk_32fc_magnitude_squared_32f(magnitude.data(), 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.data() + 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_.data(), 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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consume_each(sample_index);
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return sample_index;
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}
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