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/* -*- c++ -*- */
/*
* Copyright (C) 2011,2013,2016-2017 Free Software Foundation, Inc.
*
* This file is part of GNU Radio
*
* SPDX-License-Identifier: GPL-3.0-or-later
*
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "clock_tracking_loop.h"
#include <gnuradio/math.h>
#include <stdexcept>
namespace gr {
namespace digital {
clock_tracking_loop::clock_tracking_loop(float loop_bw,
float max_period,
float min_period,
float nominal_period,
float damping,
float ted_gain)
: d_avg_period(nominal_period),
d_max_avg_period(max_period),
d_min_avg_period(min_period),
d_nom_avg_period(nominal_period),
d_inst_period(nominal_period),
d_phase(0.0f),
d_zeta(damping),
d_omega_n_norm(loop_bw),
d_ted_gain(ted_gain),
d_alpha(0.0f),
d_beta(0.0f),
d_prev_avg_period(nominal_period),
d_prev_inst_period(nominal_period),
d_prev_phase(0.0f)
{
set_max_avg_period(max_period);
set_min_avg_period(min_period);
set_nom_avg_period(nominal_period);
set_avg_period(d_nom_avg_period);
set_inst_period(d_nom_avg_period);
if (d_zeta < 0.0f)
throw std::out_of_range("clock_tracking_loop: damping factor must be > 0.0");
if (d_omega_n_norm < 0.0f)
throw std::out_of_range(
"clock_tracking_loop: loop bandwidth must be greater than 0.0");
if (d_ted_gain <= 0.0f)
throw std::out_of_range(
"clock_tracking_loop: expected ted gain must be greater than 0.0");
update_gains();
}
clock_tracking_loop::~clock_tracking_loop() {}
void clock_tracking_loop::update_gains()
{
float omega_n_T, omega_d_T, zeta_omega_n_T, cosx_omega_d_T;
float k0, k1, sinh_zeta_omega_n_T;
float alpha, beta;
omega_n_T = d_omega_n_norm;
zeta_omega_n_T = d_zeta * omega_n_T;
k0 = 2.0f / d_ted_gain;
k1 = expf(-zeta_omega_n_T);
sinh_zeta_omega_n_T = sinhf(zeta_omega_n_T);
if (d_zeta > 1.0f) { // Over-damped (or critically-damped too)
omega_d_T = omega_n_T * sqrtf(d_zeta * d_zeta - 1.0f);
cosx_omega_d_T = coshf(omega_d_T);
// cosh ---------^^^^
} else if (d_zeta == 1.0f) { // Critically-damped
omega_d_T = 0.0f;
cosx_omega_d_T = 1.0f;
// cosh(omega_d_T) & cos(omega_d_T) are both 1 for omega_d_T == 0
} else { // Under-damped (or critically-damped too)
omega_d_T = omega_n_T * sqrtf(1.0 - d_zeta * d_zeta);
cosx_omega_d_T = cosf(omega_d_T);
// cos ----------^^^
}
alpha = k0 * k1 * sinh_zeta_omega_n_T;
beta = k0 * (1 - k1 * (sinh_zeta_omega_n_T + cosx_omega_d_T));
set_alpha(alpha);
set_beta(beta);
}
/*******************************************************************
* SET FUNCTIONS
*******************************************************************/
void clock_tracking_loop::set_loop_bandwidth(float bw)
{
if (bw < 0.0f)
throw std::out_of_range(
"clock_tracking_loop: loop bandwidth must be greater than 0.0");
d_omega_n_norm = bw;
update_gains();
}
void clock_tracking_loop::set_damping_factor(float df)
{
if (df < 0.0f)
throw std::out_of_range("clock_tracking_loop: damping factor must be > 0.0");
d_zeta = df;
update_gains();
}
void clock_tracking_loop::set_ted_gain(float ted_gain)
{
if (ted_gain <= 0.0f)
throw std::out_of_range("clock_tracking_loop: expected ted gain must be > 0.0");
d_ted_gain = ted_gain;
update_gains();
}
void clock_tracking_loop::set_alpha(float alpha) { d_alpha = alpha; }
void clock_tracking_loop::set_beta(float beta) { d_beta = beta; }
void clock_tracking_loop::set_avg_period(float period)
{
d_avg_period = period;
d_prev_avg_period = period;
}
void clock_tracking_loop::set_inst_period(float period)
{
d_inst_period = period;
d_prev_inst_period = period;
}
void clock_tracking_loop::set_phase(float phase)
{
// This previous phase is likely inconsistent with the tracking,
// but if the caller is setting the phase, the odds of
// revert_loop() being called are slim.
d_prev_phase = phase;
d_phase = phase;
}
void clock_tracking_loop::set_max_avg_period(float period) { d_max_avg_period = period; }
void clock_tracking_loop::set_min_avg_period(float period) { d_min_avg_period = period; }
void clock_tracking_loop::set_nom_avg_period(float period)
{
if (period < d_min_avg_period || period > d_max_avg_period) {
d_nom_avg_period = (d_max_avg_period + d_min_avg_period) / 2.0f;
} else {
d_nom_avg_period = period;
}
}
/*******************************************************************
* GET FUNCTIONS
*******************************************************************/
float clock_tracking_loop::get_loop_bandwidth() const { return d_omega_n_norm; }
float clock_tracking_loop::get_damping_factor() const { return d_zeta; }
float clock_tracking_loop::get_ted_gain() const { return d_ted_gain; }
float clock_tracking_loop::get_alpha() const { return d_alpha; }
float clock_tracking_loop::get_beta() const { return d_beta; }
float clock_tracking_loop::get_avg_period() const { return d_avg_period; }
float clock_tracking_loop::get_inst_period() const { return d_inst_period; }
float clock_tracking_loop::get_phase() const { return d_phase; }
float clock_tracking_loop::get_max_avg_period() const { return d_max_avg_period; }
float clock_tracking_loop::get_min_avg_period() const { return d_min_avg_period; }
float clock_tracking_loop::get_nom_avg_period() const { return d_nom_avg_period; }
} /* namespace digital */
} /* namespace gr */
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