mirror of https://github.com/gnss-sdr/gnss-sdr
101 lines
3.0 KiB
C++
101 lines
3.0 KiB
C++
/*!
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* \file tracking_loop_filter.h
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* \brief Generic 1st to 3rd order loop filter implementation
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* \author Cillian O'Driscoll, 2015. cillian.odriscoll(at)gmail.com
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*
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* Class implementing a generic 1st, 2nd or 3rd order loop filter. Based
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* on the bilinear transform of the standard Weiner filter.
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*
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* -------------------------------------------------------------------------
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*
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* Copyright (C) 2010-2015 (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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#ifndef GNSS_SDR_TRACKING_LOOP_FILTER_H_
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#define GNSS_SDR_TRACKING_LOOP_FILTER_H_
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#define MAX_LOOP_ORDER 3
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#define MAX_LOOP_HISTORY_LENGTH 4
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#include <vector>
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/*!
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* \brief This class implements a generic 1st, 2nd or 3rd order loop filter
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*
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*/
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class Tracking_loop_filter
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{
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private:
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// Store the last inputs and outputs:
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std::vector<float> d_inputs;
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std::vector<float> d_outputs;
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// Store the filter coefficients:
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std::vector<float> d_input_coefficients;
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std::vector<float> d_output_coefficients;
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// The loop order:
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int d_loop_order;
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// The current index in the i/o arrays:
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int d_current_index;
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// Should the last integrator be included?
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bool d_include_last_integrator;
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// The noise bandwidth (in Hz)
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// Note this is an approximation only valid when the product of this
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// number and the update interval (T) is small.
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float d_noise_bandwidth;
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// Loop update interval
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float d_update_interval;
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// Compute the filter coefficients:
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void update_coefficients(void);
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public:
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float get_noise_bandwidth(void) const;
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float get_update_interval(void) const;
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bool get_include_last_integrator(void) const;
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int get_order(void) const;
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void set_noise_bandwidth(float noise_bandwidth);
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void set_update_interval(float update_interval);
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void set_include_last_integrator(bool include_last_integrator);
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void set_order(int loop_order);
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void initialize(float initial_output = 0.0);
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float apply(float current_input);
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Tracking_loop_filter(float update_interval, float noise_bandwidth,
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int loop_order = 2,
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bool include_last_integrator = false);
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Tracking_loop_filter();
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~Tracking_loop_filter();
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};
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#endif
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