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///////////////////////////////////////////////////////////////////////////////////
// Copyright (C) 2017 F4EXB //
// written by Edouard Griffiths //
// //
// This program is free software; you can redistribute it and/or modify //
// it under the terms of the GNU General Public License as published by //
// the Free Software Foundation as version 3 of the License, or //
// //
// This program is distributed in the hope that it will be useful, //
// but WITHOUT ANY WARRANTY; without even the implied warranty of //
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the //
// GNU General Public License V3 for more details. //
// //
// You should have received a copy of the GNU General Public License //
// along with this program. If not, see <http://www.gnu.org/licenses/>. //
///////////////////////////////////////////////////////////////////////////////////
#include <stdint.h>
#include <vector>
#include "export.h"
namespace DSDcc
{
/** Phase-locked loop. */
class DSDCC_API PhaseLock
{
public:
/**
* Construct phase-locked loop.
*
* freq :: center frequency relative to sample freq
* (0.5 is Nyquist)
* bandwidth :: bandwidth relative to sample frequency
* minsignal :: minimum pilot amplitude
*/
PhaseLock(float freq, float bandwidth, float minsignal);
virtual ~PhaseLock() {}
/**
* Change phase locked loop parameters
*
* freq :: 19 kHz center frequency relative to sample freq
* (0.5 is Nyquist)
* bandwidth :: bandwidth relative to sample frequency
* minsignal :: minimum pilot amplitude
*/
void configure(float freq, float bandwidth, float minsignal);
/**
* Process samples and track a pilot tone. Generate samples for single or multiple phase-locked
* signals. Implement the processPhase virtual method to produce the output samples.
* In flow version. Ex: Use 19 kHz stereo pilot tone to generate 38 kHz (stereo) and 57 kHz
* pilots (see RDSPhaseLock class below).
* This is the in flow version
*/
void process(const float& sample_in, float *samples_out);
/**
* Process samples and extract 19 kHz pilot tone.
* Generate phase-locked 38 kHz tone with unit amplitude.
* Bufferized version with input and output vectors
*/
void process(const std::vector<float>& samples_in, std::vector<float>& samples_out);
/** Return true if the phase-locked loop is locked. */
bool locked() const
{
return m_lock_cnt >= m_lock_delay;
}
protected:
float m_phase;
float m_psin;
float m_pcos;
/**
* Callback method to produce multiple outputs from the current phase value in m_phase
* and/or the sin and cos values in m_psin and m_pcos
*/
virtual void processPhase(float *samples_out) const = 0;
private:
float m_minfreq, m_maxfreq;
float m_phasor_b0, m_phasor_a1, m_phasor_a2;
float m_phasor_i1, m_phasor_i2, m_phasor_q1, m_phasor_q2;
float m_loopfilter_b0, m_loopfilter_b1;
float m_loopfilter_x1;
float m_freq;
float m_minsignal;
int m_lock_delay;
int m_lock_cnt;
uint64_t m_sample_cnt;
};
class DSDCC_API SimplePhaseLock : public PhaseLock
{
public:
SimplePhaseLock(float freq, float bandwidth, float minsignal) :
PhaseLock(freq, bandwidth, minsignal)
{}
protected:
virtual void processPhase(float *samples_out) const
{
samples_out[0] = m_psin; // f Pilot
samples_out[1] = m_pcos; // f Pilot
}
};
} // namespace DSDCc
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