mirror of
https://github.com/f4exb/sdrangel.git
synced 2024-11-23 16:38:37 -05:00
79 lines
2.7 KiB
C++
79 lines
2.7 KiB
C++
///////////////////////////////////////////////////////////////////////////////////
|
|
// Copyright (C) 2015 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/>. //
|
|
///////////////////////////////////////////////////////////////////////////////////
|
|
|
|
#ifndef INCLUDE_DSP_PHASEDISCRI_H_
|
|
#define INCLUDE_DSP_PHASEDISCRI_H_
|
|
|
|
#include "dsp/dsptypes.h"
|
|
|
|
class PhaseDiscriminators
|
|
{
|
|
public:
|
|
/**
|
|
* Reset stored values
|
|
*/
|
|
void reset()
|
|
{
|
|
m_m1Sample = 0;
|
|
m_m2Sample = 0;
|
|
}
|
|
|
|
/**
|
|
* Scaling factor so that resulting excursion maps to [-1,+1]
|
|
*/
|
|
void setFMScaling(Real fmScaling)
|
|
{
|
|
m_fmScaling = fmScaling;
|
|
}
|
|
|
|
/**
|
|
* Standard discriminator using atan2. On modern processors this is as efficient as the non atan2 one.
|
|
* This is better for high fidelity.
|
|
*/
|
|
Real phaseDiscriminator(const Complex& sample)
|
|
{
|
|
Complex d(std::conj(m_m1Sample) * sample);
|
|
m_m1Sample = sample;
|
|
return (std::atan2(d.imag(), d.real()) / M_PI_2) * m_fmScaling;
|
|
}
|
|
|
|
/**
|
|
* Alternative without atan at the expense of a slight distorsion on very wideband signals
|
|
* http://www.embedded.com/design/configurable-systems/4212086/DSP-Tricks--Frequency-demodulation-algorithms-
|
|
* in addition it needs scaling by instantaneous magnitude squared and volume (0..10) adjustment factor
|
|
*/
|
|
Real phaseDiscriminator2(const Complex& sample)
|
|
{
|
|
Real ip = sample.real() - m_m2Sample.real();
|
|
Real qp = sample.imag() - m_m2Sample.imag();
|
|
Real h1 = m_m1Sample.real() * qp;
|
|
Real h2 = m_m1Sample.imag() * ip;
|
|
|
|
m_m2Sample = m_m1Sample;
|
|
m_m1Sample = sample;
|
|
|
|
return ((h1 - h2) / M_PI_2) * m_fmScaling;
|
|
}
|
|
|
|
private:
|
|
Complex m_m1Sample;
|
|
Complex m_m2Sample;
|
|
Real m_fmScaling;
|
|
};
|
|
|
|
#endif /* INCLUDE_DSP_PHASEDISCRI_H_ */
|