PhaseLockComplex Class Reference

#include <phaselockcomplex.h>

Collaboration diagram for PhaseLockComplex:

Classes
class	ExpAvg

Public Member Functions
	PhaseLockComplex ()
void	computeCoefficients (Real wn, Real zeta, Real K)
void	setPskOrder (unsigned int order)
void	setSampleRate (unsigned int sampleRate)
void	reset ()
void	feed (float re, float im)
const std::complex< float > &	getComplex () const
float	getReal () const
float	getImag () const
bool	locked () const
float	getFreq () const
float	getDeltaPhi () const
float	getPhiHat () const

Static Private Member Functions
static float	normalizeAngle (float angle)

Private Attributes
float	m_a1
float	m_a2
float	m_b0
float	m_b1
float	m_b2
float	m_v0
float	m_v1
float	m_v2
float	m_deltaPhi
float	m_phiHat
float	m_phiHatPrev
std::complex< float >	m_y
std::complex< float >	m_p
float	m_yRe
float	m_yIm
float	m_freq
float	m_freqPrev
float	m_freqTest
int	m_lockCount
float	m_lockFreq
unsigned int	m_pskOrder
int	m_lockTime
int	m_lockTimeCount
ExpAvg	m_expAvg

Detailed Description

General purpose Phase-locked loop using complex analytic signal input.

Definition at line 31 of file phaselockcomplex.h.

Constructor & Destructor Documentation

PhaseLockComplex()

PhaseLockComplex::PhaseLockComplex

(

)

Definition at line 29 of file phaselockcomplex.cpp.

                                   :
    m_a1(1.0),
    m_a2(1.0),
    m_b0(1.0),
    m_b1(1.0),
    m_b2(1.0),
    m_v0(0.0),
    m_v1(0.0),
    m_v2(0.0),
    m_deltaPhi(0.0),
    m_phiHat(0.0),
    m_phiHatPrev(0.0),
    m_y(1.0, 0.0),
    m_p(1.0, 0.0),
    m_yRe(1.0),
    m_yIm(0.0),
    m_freq(0.0),
    m_freqPrev(0.0),
    m_freqTest(0.0),
    m_lockCount(0),
    m_lockFreq(0.026f),
    m_pskOrder(1),
    m_lockTime(480),
    m_lockTimeCount(0)
{
}

Member Function Documentation

computeCoefficients()

void PhaseLockComplex::computeCoefficients	(	Real	wn,
		Real	zeta,
		Real	K
	)

Compute loop filter parameters (active PI design)

Parameters

wn	PLL bandwidth relative to Nyquist frequency
zeta	PLL damping factor
K	PLL loop gain

Definition at line 56 of file phaselockcomplex.cpp.

References b0, b1, b2, m_a1, m_a2, m_b0, m_b1, m_b2, and reset().

Referenced by AMDemod::AMDemod(), ChannelAnalyzer::ChannelAnalyzer(), and FreqTracker::FreqTracker().

{
    double t1 = K/(wn*wn);          //
    double t2 = 2*zeta/wn - 1/K;   //

    double b0 = 2*K*(1.+t2/2.0f);
    double b1 = 2*K*2.;
    double b2 = 2*K*(1.-t2/2.0f);

    double a0 =  1 + t1/2.0f;
    double a1 = -t1;
    double a2 = -1 + t1/2.0f;

    qDebug("PhaseLockComplex::computeCoefficients: b_raw: %f %f %f", b0, b1, b2);
    qDebug("PhaseLockComplex::computeCoefficients: a_raw: %f %f %f", a0, a1, a2);

    m_b0 = b0 / a0;
    m_b1 = b1 / a0;
    m_b2 = b2 / a0;

    //    a0 =  1.0  is implied
    m_a1 = a1 / a0;
    m_a2 = a2 / a0;

    qDebug("PhaseLockComplex::computeCoefficients: b: %f %f %f", m_b0, m_b1, m_b2);
    qDebug("PhaseLockComplex::computeCoefficients: a: 1.0 %f %f", m_a1, m_a2);

    reset();
}

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feed()

void PhaseLockComplex::feed	(	float	re,
		float	im
	)

Feed PLL with a new signa sample

Definition at line 121 of file phaselockcomplex.cpp.

References arg(), cos(), PhaseLockComplex::ExpAvg::feed(), m_a1, m_a2, m_b0, m_b1, m_b2, m_deltaPhi, m_expAvg, m_freq, m_freqPrev, m_freqTest, m_lockCount, m_lockFreq, m_lockTime, m_lockTimeCount, m_phiHat, m_phiHatPrev, M_PI, m_pskOrder, m_v0, m_v1, m_v2, m_y, m_yIm, m_yRe, normalizeAngle(), and sin().

Referenced by ChannelAnalyzer::processOneSample(), AMDemod::processOneSample(), and FreqTracker::processOneSample().

{
    m_yRe = cos(m_phiHat);
    m_yIm = sin(m_phiHat);
    m_y.real(m_yRe);
    m_y.imag(m_yIm);
    std::complex<float> x(re, im);
    m_deltaPhi = std::arg(x * std::conj(m_y));

    // bring phase 0 on any of the PSK symbols
    if (m_pskOrder > 1) {
        m_deltaPhi = normalizeAngle(m_pskOrder*m_deltaPhi);
    }

    // advance buffer
    m_v2 = m_v1;  // shift center register to upper register
    m_v1 = m_v0;  // shift lower register to center register

    // compute new lower register
    m_v0 = m_deltaPhi - m_v1*m_a1 - m_v2*m_a2;

    // compute new output
    m_phiHat = m_v0*m_b0 + m_v1*m_b1 + m_v2*m_b2;

    // prevent saturation
    if (m_phiHat > 2.0*M_PI)
    {
        m_v0 *= (m_phiHat - 2.0*M_PI) / m_phiHat;
        m_v1 *= (m_phiHat - 2.0*M_PI) / m_phiHat;
        m_v2 *= (m_phiHat - 2.0*M_PI) / m_phiHat;
        m_phiHat -= 2.0*M_PI;
    }

    if (m_phiHat < -2.0*M_PI)
    {
        m_v0 *= (m_phiHat + 2.0*M_PI) / m_phiHat;
        m_v1 *= (m_phiHat + 2.0*M_PI) / m_phiHat;
        m_v2 *= (m_phiHat + 2.0*M_PI) / m_phiHat;
        m_phiHat += 2.0*M_PI;
    }

    // lock and frequency estimation
    if (m_pskOrder > 1)
    {
        float dPhi = normalizeAngle(m_phiHat - m_phiHatPrev);
        m_freq = m_expAvg.feed(dPhi);

        if (m_lockTimeCount < m_lockTime-1)
        {
            m_lockTimeCount++;
        }
        else
        {
            float dF = m_freq - m_freqTest;

            if ((dF > -m_lockFreq) && (dF < m_lockFreq))
            {
                if (m_lockCount < 20) {
                    m_lockCount++;
                }
            }
            else
            {
                if (m_lockCount > 0) {
                    m_lockCount--;
                }
            }

            m_freqTest = m_freq;
            m_lockTimeCount = 0;
        }

        m_phiHatPrev = m_phiHat;
    }
    else
    {
        m_freqTest = normalizeAngle(m_phiHat - m_phiHatPrev);
        m_freq = m_expAvg.feed(m_freqTest);

        float dFreq = m_freqTest - m_freqPrev;

        if ((dFreq > -0.01) && (dFreq < 0.01))
        {
            if (m_lockCount < (m_lockTime-1)) { // [0..479]
                m_lockCount++;
            }
        }
        else
        {
            m_lockCount = 0;
        }

        m_phiHatPrev = m_phiHat;
        m_freqPrev = m_freqTest;
    }
}

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getComplex()

const std::complex<float>& PhaseLockComplex::getComplex ( ) const

inline

Definition at line 50 of file phaselockcomplex.h.

Referenced by ChannelAnalyzer::processOneSample().

{ return m_y; }

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getDeltaPhi()

float PhaseLockComplex::getDeltaPhi ( ) const

inline

Definition at line 55 of file phaselockcomplex.h.

Referenced by ChannelAnalyzer::getPllDeltaPhase().

{ return m_deltaPhi; }

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getFreq()

float PhaseLockComplex::getFreq ( ) const

inline

Definition at line 54 of file phaselockcomplex.h.

Referenced by FreqTracker::getFrequency(), ChannelAnalyzer::getPllFrequency(), and AMDemod::getPllFrequency().

{ return m_freq; }

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getImag()

float PhaseLockComplex::getImag ( ) const

inline

Definition at line 52 of file phaselockcomplex.h.

Referenced by AMDemod::processOneSample().

{ return m_yIm; }

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getPhiHat()

float PhaseLockComplex::getPhiHat ( ) const

inline

Definition at line 56 of file phaselockcomplex.h.

Referenced by ChannelAnalyzer::getPllPhase().

{ return m_phiHat; }

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getReal()

float PhaseLockComplex::getReal ( ) const

inline

Definition at line 51 of file phaselockcomplex.h.

Referenced by AMDemod::processOneSample().

{ return m_yRe; }

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locked()

bool PhaseLockComplex::locked ( ) const

inline

Definition at line 53 of file phaselockcomplex.h.

Referenced by AMDemod::getPllLocked(), FreqTracker::getPllLocked(), and ChannelAnalyzer::isPllLocked().

{ return m_pskOrder > 1 ? m_lockCount > 10 : m_lockCount > m_lockTime-2; }

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normalizeAngle()

float PhaseLockComplex::normalizeAngle ( float  angle )

staticprivate

Normalize angle in radians into the [-pi,+pi] region

Definition at line 218 of file phaselockcomplex.cpp.

References M_PI.

Referenced by feed().

{
    while (angle <= -M_PI) {
        angle += 2.0*M_PI;
    }
    while (angle > M_PI) {
        angle -= 2.0*M_PI;
    }
    return angle;
}

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reset()

void PhaseLockComplex::reset

(

)

Definition at line 99 of file phaselockcomplex.cpp.

References m_deltaPhi, m_freq, m_freqPrev, m_freqTest, m_lockCount, m_lockTimeCount, m_p, m_phiHat, m_phiHatPrev, m_v0, m_v1, m_v2, m_y, m_yIm, and m_yRe.

Referenced by ChannelAnalyzer::applySettings(), FreqTracker::applySettings(), computeCoefficients(), setPskOrder(), and setSampleRate().

{
    // reset filter accumulators and phase
    m_v0 = 0.0f;
    m_v1 = 0.0f;
    m_v2 = 0.0f;
    m_deltaPhi = 0.0f;
    m_phiHat = 0.0f;
    m_phiHatPrev = 0.0f;
    m_y.real(1.0);
    m_y.imag(0.0);
    m_p.real(1.0);
    m_p.imag(0.0);
    m_yRe = 1.0f;
    m_yIm = 0.0f;
    m_freq = 0.0f;
    m_freqPrev = 0.0f;
    m_freqTest = 0.0f;
    m_lockCount = 0;
    m_lockTimeCount = 0;
}

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setPskOrder()

void PhaseLockComplex::setPskOrder

(

unsigned int

order

)

Set the PSK order for the phase comparator

Parameters

order

0,1: no PSK (CW), 2: BPSK, 4: QPSK, 8: 8-PSK, ... use powers of two for real cases

Definition at line 86 of file phaselockcomplex.cpp.

References m_pskOrder, and reset().

Referenced by ChannelAnalyzer::applySettings(), and FreqTracker::applySettings().

{
    m_pskOrder = order > 0 ? order : 1;
    reset();
}

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setSampleRate()

void PhaseLockComplex::setSampleRate

(

unsigned int

sampleRate

)

Set sample rate information only for frequency and lock condition calculation

Definition at line 92 of file phaselockcomplex.cpp.

References m_lockFreq, m_lockTime, M_PI, m_pskOrder, and reset().

Referenced by AMDemod::applyAudioSampleRate(), ChannelAnalyzer::applyChannelSettings(), ChannelAnalyzer::applySettings(), and FreqTracker::configureChannelizer().

{
    m_lockTime = sampleRate / 100; // 10ms for order 1
    m_lockFreq = (2.0*M_PI*(m_pskOrder > 1 ? 6.0 : 1.0)) / sampleRate; // +/- 6 Hz frequency swing
    reset();
}

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Member Data Documentation

m_a1

float PhaseLockComplex::m_a1

private

Definition at line 85 of file phaselockcomplex.h.

Referenced by computeCoefficients(), and feed().

m_a2

float PhaseLockComplex::m_a2

private

Definition at line 86 of file phaselockcomplex.h.

Referenced by computeCoefficients(), and feed().

m_b0

float PhaseLockComplex::m_b0

private

Definition at line 87 of file phaselockcomplex.h.

Referenced by computeCoefficients(), and feed().

m_b1

float PhaseLockComplex::m_b1

private

Definition at line 88 of file phaselockcomplex.h.

Referenced by computeCoefficients(), and feed().

m_b2

float PhaseLockComplex::m_b2

private

Definition at line 89 of file phaselockcomplex.h.

Referenced by computeCoefficients(), and feed().

m_deltaPhi

float PhaseLockComplex::m_deltaPhi

private

Definition at line 93 of file phaselockcomplex.h.

Referenced by feed(), and reset().

m_expAvg

ExpAvg PhaseLockComplex::m_expAvg

private

Definition at line 108 of file phaselockcomplex.h.

Referenced by feed().

m_freq

float PhaseLockComplex::m_freq

private

Definition at line 100 of file phaselockcomplex.h.

Referenced by feed(), and reset().

m_freqPrev

float PhaseLockComplex::m_freqPrev

private

Definition at line 101 of file phaselockcomplex.h.

Referenced by feed(), and reset().

m_freqTest

float PhaseLockComplex::m_freqTest

private

Definition at line 102 of file phaselockcomplex.h.

Referenced by feed(), and reset().

m_lockCount

int PhaseLockComplex::m_lockCount

private

Definition at line 103 of file phaselockcomplex.h.

Referenced by feed(), and reset().

m_lockFreq

float PhaseLockComplex::m_lockFreq

private

Definition at line 104 of file phaselockcomplex.h.

Referenced by feed(), and setSampleRate().

m_lockTime

int PhaseLockComplex::m_lockTime

private

Definition at line 106 of file phaselockcomplex.h.

Referenced by feed(), and setSampleRate().

m_lockTimeCount

int PhaseLockComplex::m_lockTimeCount

private

Definition at line 107 of file phaselockcomplex.h.

Referenced by feed(), and reset().

m_p

std::complex<float> PhaseLockComplex::m_p

private

Definition at line 97 of file phaselockcomplex.h.

Referenced by reset().

m_phiHat

float PhaseLockComplex::m_phiHat

private

Definition at line 94 of file phaselockcomplex.h.

Referenced by feed(), and reset().

m_phiHatPrev

float PhaseLockComplex::m_phiHatPrev

private

Definition at line 95 of file phaselockcomplex.h.

Referenced by feed(), and reset().

m_pskOrder

unsigned int PhaseLockComplex::m_pskOrder

private

Definition at line 105 of file phaselockcomplex.h.

Referenced by feed(), setPskOrder(), and setSampleRate().

m_v0

float PhaseLockComplex::m_v0

private

Definition at line 90 of file phaselockcomplex.h.

Referenced by feed(), and reset().

m_v1

float PhaseLockComplex::m_v1

private

Definition at line 91 of file phaselockcomplex.h.

Referenced by feed(), and reset().

m_v2

float PhaseLockComplex::m_v2

private

Definition at line 92 of file phaselockcomplex.h.

Referenced by feed(), and reset().

m_y

std::complex<float> PhaseLockComplex::m_y

private

Definition at line 96 of file phaselockcomplex.h.

Referenced by feed(), and reset().

m_yIm

float PhaseLockComplex::m_yIm

private

Definition at line 99 of file phaselockcomplex.h.

Referenced by feed(), and reset().

m_yRe

float PhaseLockComplex::m_yRe

private

Definition at line 98 of file phaselockcomplex.h.

Referenced by feed(), and reset().

---

The documentation for this class was generated from the following files:

• sdrbase/dsp/phaselockcomplex.h
• sdrbase/dsp/phaselockcomplex.cpp