mirror of https://github.com/gnss-sdr/gnss-sdr
167 lines
6.8 KiB
C++
167 lines
6.8 KiB
C++
/*!
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* \file notch_lite_cc.cc
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* \brief Implements a multi state notch filter algorithm
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* \author Antonio Ramos (antonio.ramosdet(at)gmail.com)
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*
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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 "notch_lite_cc.h"
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#include <boost/math/distributions/chi_squared.hpp>
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#include <glog/logging.h>
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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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#include <cstring>
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using google::LogMessage;
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notch_lite_sptr make_notch_filter_lite(float p_c_factor, float pfa, int32_t length_, int32_t n_segments_est, int32_t n_segments_reset, int32_t n_segments_coeff)
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{
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return notch_lite_sptr(new NotchLite(p_c_factor, pfa, length_, n_segments_est, n_segments_reset, n_segments_coeff));
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}
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NotchLite::NotchLite(float p_c_factor,
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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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int32_t n_segments_coeff) : gr::block("NotchLite",
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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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set_history(2);
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this->p_c_factor = gr_complex(p_c_factor, 0.0);
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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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this->n_segments_coeff_reset = n_segments_coeff;
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this->n_segments_coeff = 0;
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this->length_ = length_;
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set_output_multiple(length_);
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this->pfa = pfa;
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n_segments = 0;
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n_deg_fred = 2 * length_;
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noise_pow_est = 0.0;
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filter_state_ = false;
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z_0 = gr_complex(0.0, 0.0);
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last_out = gr_complex(0.0, 0.0);
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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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c_samples1 = gr_complex(0.0, 0.0);
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c_samples2 = gr_complex(0.0, 0.0);
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angle1 = 0.0;
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angle2 = 0.0;
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power_spect = static_cast<float *>(volk_malloc(length_ * sizeof(float), volk_get_alignment()));
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d_fft = std::unique_ptr<gr::fft::fft_complex>(new gr::fft::fft_complex(length_, true));
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}
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NotchLite::~NotchLite()
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{
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volk_free(power_spect);
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}
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void NotchLite::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 NotchLite::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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int32_t index_out = 0;
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float sig2dB = 0.0;
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float sig2lin = 0.0;
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lv_32fc_t dot_prod_;
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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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in++;
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while ((index_out + length_) < noutput_items)
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{
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if ((n_segments < n_segments_est) && (filter_state_ == false))
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{
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memcpy(d_fft->get_inbuf(), in, sizeof(gr_complex) * length_);
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d_fft->execute();
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volk_32fc_s32f_power_spectrum_32f(power_spect, d_fft->get_outbuf(), 1.0, length_);
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volk_32f_s32f_calc_spectral_noise_floor_32f(&sig2dB, power_spect, 15.0, length_);
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sig2lin = std::pow(10.0, (sig2dB / 10.0)) / static_cast<float>(n_deg_fred);
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noise_pow_est = (static_cast<float>(n_segments) * noise_pow_est + sig2lin) / 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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volk_32fc_x2_conjugate_dot_prod_32fc(&dot_prod_, in, in, length_);
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if ((lv_creal(dot_prod_) / noise_pow_est) > thres_)
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{
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if (filter_state_ == false)
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{
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filter_state_ = true;
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last_out = gr_complex(0, 0);
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n_segments_coeff = 0;
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}
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if (n_segments_coeff == 0)
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{
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volk_32fc_x2_multiply_conjugate_32fc(&c_samples1, (in + 1), in, 1);
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volk_32fc_s32f_atan2_32f(&angle1, &c_samples1, static_cast<float>(1.0), 1);
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volk_32fc_x2_multiply_conjugate_32fc(&c_samples2, (in + length_ - 1), (in + length_ - 2), 1);
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volk_32fc_s32f_atan2_32f(&angle2, &c_samples2, static_cast<float>(1.0), 1);
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float angle_ = (angle1 + angle2) / 2.0;
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z_0 = std::exp(gr_complex(0, 1) * angle_);
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}
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for (int32_t aux = 0; aux < length_; aux++)
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{
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*(out + aux) = *(in + aux) - z_0 * (*(in + aux - 1)) + p_c_factor * z_0 * last_out;
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last_out = *(out + aux);
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}
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n_segments_coeff++;
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n_segments_coeff = n_segments_coeff % n_segments_coeff_reset;
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}
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else
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{
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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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filter_state_ = false;
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memcpy(out, in, sizeof(gr_complex) * length_);
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}
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}
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index_out += length_;
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n_segments++;
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in += length_;
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out += length_;
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}
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consume_each(index_out);
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return index_out;
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}
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