MagAGC Class Reference

#include <agc.h>

Inheritance diagram for MagAGC:

Collaboration diagram for MagAGC:

Public Member Functions
	MagAGC (int historySize, double R, double threshold)
virtual	~MagAGC ()
void	setSquared (bool squared)
void	resize (int historySize, int stepLength, Real R)
void	setOrder (double R)
virtual void	feed (Complex &ci)
double	feedAndGetValue (const Complex &ci)
double	getMagSq () const
void	setThreshold (double threshold)
void	setThresholdEnable (bool enable)
void	setGate (int gate)
void	setStepDownDelay (int stepDownDelay)
void	setClamping (bool clamping)
void	setClampMax (double clampMax)
int	getStepDownDelay () const
float	getStepValue () const
void	setHardLimiting (bool hardLimiting)
Public Member Functions inherited from AGC
	AGC (int historySize, double R)
virtual	~AGC ()
void	resize (int historySize, double R)
void	setOrder (double R)
Real	getValue ()
Real	getAverage ()

Private Member Functions
double	hardLimiter (double multiplier, double magsq)

Private Attributes
bool	m_squared
	use squared magnitude (power) to compute AGC value More...
double	m_magsq
	current squared magnitude (power) More...
double	m_threshold
	squelch on magsq average More...
bool	m_thresholdEnable
	enable squelch on power threshold More...
int	m_gate
	power threshold gate in number of samples More...
int	m_stepLength
	transition step length in number of samples More...
double	m_stepDelta
	transition step unit by sample More...
int	m_stepUpCounter
	step up transition samples counter More...
int	m_stepDownCounter
	step down transition samples counter More...
int	m_gateCounter
	threshold gate samples counter More...
int	m_stepDownDelay
	delay in samples before cutoff (release) More...
bool	m_clamping
	clamping active More...
double	m_R2
	square of ordered magnitude More...
double	m_clampMax
	maximum to clamp to as power value More...
bool	m_hardLimiting
	hard limit multiplier so that resulting sample magnitude does not exceed 1.0 More...

Additional Inherited Members
Protected Attributes inherited from AGC
double	m_u0
	AGC factor. More...
double	m_R
	ordered magnitude More...
MovingAverage< double >	m_moving_average
	Averaging engine. The stack length conditions the smoothness of AGC. More...
int	m_historySize
	Averaging length (attack) More...
int	m_count
	Samples counter. More...

Detailed Description

Definition at line 36 of file agc.h.

Constructor & Destructor Documentation

MagAGC()

MagAGC::MagAGC	(	int	historySize,
		double	R,
		double	threshold
	)

Definition at line 43 of file agc.cpp.

                                                          :
    AGC(historySize, R),
    m_squared(false),
    m_magsq(0.0),
    m_threshold(threshold),
    m_thresholdEnable(true),
    m_gate(0),
    m_stepLength(std::min(2400, historySize/2)), // max 50 ms (at 48 kHz)
    m_stepDelta(1.0/m_stepLength),
    m_stepUpCounter(0),
    m_stepDownCounter(0),
    m_gateCounter(0),
    m_stepDownDelay(historySize),
    m_clamping(false),
    m_R2(R*R),
    m_clampMax(1.0),
    m_hardLimiting(false)
{}

~MagAGC()

MagAGC::~MagAGC ( )

virtual

Definition at line 62 of file agc.cpp.

{}

Member Function Documentation

feed()

void MagAGC::feed ( Complex &  ci )

virtual

Implements AGC.

Definition at line 94 of file agc.cpp.

References feedAndGetValue().

{
    ci *= feedAndGetValue(ci);
}

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feedAndGetValue()

double MagAGC::feedAndGetValue

(

const Complex &

ci

)

Definition at line 108 of file agc.cpp.

References MovingAverage< Type >::average(), MovingAverage< Type >::feed(), hardLimiter(), m_clamping, m_clampMax, AGC::m_count, m_gate, m_gateCounter, m_magsq, AGC::m_moving_average, AGC::m_R, m_squared, m_stepDelta, m_stepDownCounter, m_stepDownDelay, m_stepLength, m_stepUpCounter, m_threshold, m_thresholdEnable, AGC::m_u0, StepFunctions::smootherstep(), and sqrt().

Referenced by feed(), UDPSink::feed(), AMDemod::processOneSample(), and SSBDemod::processOneSample().

{
    m_magsq = ci.real()*ci.real() + ci.imag()*ci.imag();
    m_moving_average.feed(m_magsq);

    if (m_clamping)
    {
        if (m_squared)
        {
            if (m_magsq > m_clampMax) {
                m_u0 = m_clampMax / m_magsq;
            } else {
                m_u0 = m_R / m_moving_average.average();
            }
        }
        else
        {
            if (sqrt(m_magsq) > m_clampMax) {
                m_u0 = m_clampMax / sqrt(m_magsq);
            } else {
                m_u0 = m_R / sqrt(m_moving_average.average());
            }
        }
    }
    else
    {
        m_u0 = m_R / (m_squared ? m_moving_average.average() : sqrt(m_moving_average.average()));
    }

    if (m_thresholdEnable)
    {
        bool open = false;

        if (m_magsq > m_threshold)
        {
            if (m_gateCounter < m_gate) {
                m_gateCounter++;
            } else {
                open = true;
            }
        }
        else
        {
            m_gateCounter = 0;
        }

        if (open)
        {
            m_count = m_stepDownDelay; // delay before step down (grace delay)
        }
        else
        {
            m_count--;
            m_gateCounter = m_gate; // keep gate open during grace
        }

        if (m_count > 0) // up phase
        {
            m_stepDownCounter = m_stepUpCounter; // prepare for step down

            if (m_stepUpCounter < m_stepLength) // step up
            {
                m_stepUpCounter++;
                return hardLimiter(m_u0 * StepFunctions::smootherstep(m_stepUpCounter * m_stepDelta), m_magsq);
            }
            else // steady open
            {
                return hardLimiter(m_u0, m_magsq);
            }
        }
        else // down phase
        {
            m_stepUpCounter = m_stepDownCounter; // prepare for step up

            if (m_stepDownCounter > 0) // step down
            {
                m_stepDownCounter--;
                return hardLimiter(m_u0 * StepFunctions::smootherstep(m_stepDownCounter * m_stepDelta), m_magsq);
            }
            else // steady closed
            {
                return 0.0;
            }
        }
    }
    else
    {
        return hardLimiter(m_u0, m_magsq);
    }
}

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getMagSq()

double MagAGC::getMagSq ( ) const

inline

Definition at line 46 of file agc.h.

Referenced by UDPSink::feed().

{ return m_magsq; }

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getStepDownDelay()

int MagAGC::getStepDownDelay ( ) const

inline

Definition at line 53 of file agc.h.

Referenced by SSBDemod::processOneSample().

{ return m_stepDownDelay; }

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getStepValue()

float MagAGC::getStepValue

(

)

const

Definition at line 199 of file agc.cpp.

References AGC::m_count, m_stepDelta, m_stepDownCounter, m_stepUpCounter, and StepFunctions::smootherstep().

Referenced by SSBDemod::processOneSample().

{
    if (m_count > 0) // up phase
    {
        return StepFunctions::smootherstep(m_stepUpCounter * m_stepDelta); // step up
    }
    else // down phase
    {
        return StepFunctions::smootherstep(m_stepDownCounter * m_stepDelta); // step down
    }
}

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hardLimiter()

double MagAGC::hardLimiter ( double  multiplier, double  magsq  )

private

Definition at line 99 of file agc.cpp.

References m_hardLimiting, and sqrt().

Referenced by feedAndGetValue().

{
    if ((m_hardLimiting) && (multiplier*multiplier*magsq > 1.0)) {
        return 1.0 / (multiplier*sqrt(magsq));
    } else {
        return multiplier;
    }
}

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resize()

void MagAGC::resize	(	int	historySize,
		int	stepLength,
		Real	R
	)

Definition at line 65 of file agc.cpp.

References MovingAverage< Type >::fill(), AGC::m_moving_average, m_R2, m_stepDelta, m_stepDownCounter, m_stepLength, m_stepUpCounter, and AGC::resize().

Referenced by AMDemod::AMDemod(), AMDemod::applyAudioSampleRate(), SSBDemod::applyAudioSampleRate(), UDPSink::applySettings(), and SSBDemod::applySettings().

{
    m_R2 = R*R;
    m_stepLength = stepLength;
    m_stepDelta = 1.0 / m_stepLength;
    m_stepUpCounter = 0;
    m_stepDownCounter = 0;
    AGC::resize(historySize, R);
    m_moving_average.fill(0);
}

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setClamping()

void MagAGC::setClamping ( bool  clamping )

inline

Definition at line 51 of file agc.h.

Referenced by SSBDemod::applySettings(), SSBDemod::SSBDemod(), and UDPSink::UDPSink().

{ m_clamping = clamping; }

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setClampMax()

void MagAGC::setClampMax ( double  clampMax )

inline

Definition at line 52 of file agc.h.

Referenced by SSBDemod::SSBDemod(), and UDPSink::UDPSink().

{ m_clampMax = clampMax; }

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setGate()

void MagAGC::setGate ( int  gate )

inline

Definition at line 49 of file agc.h.

Referenced by SSBDemod::applyAudioSampleRate(), UDPSink::applySettings(), and SSBDemod::applySettings().

{ m_gate = gate; m_gateCounter = 0; m_count = 0; }

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setHardLimiting()

void MagAGC::setHardLimiting ( bool  hardLimiting )

inline

Definition at line 55 of file agc.h.

{ m_hardLimiting = hardLimiting; }

setOrder()

void MagAGC::setOrder

(

double

R

)

Definition at line 76 of file agc.cpp.

References MovingAverage< Type >::fill(), AGC::m_moving_average, m_R2, and AGC::setOrder().

{
    m_R2 = R*R;
    AGC::setOrder(R);
    m_moving_average.fill(0);
}

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setSquared()

void MagAGC::setSquared ( bool  squared )

inline

Definition at line 41 of file agc.h.

References AGC::feed(), AGC::resize(), and AGC::setOrder().

{ m_squared = squared; }

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setStepDownDelay()

void MagAGC::setStepDownDelay ( int  stepDownDelay )

inline

Definition at line 50 of file agc.h.

Referenced by SSBDemod::applyAudioSampleRate(), UDPSink::applySettings(), and SSBDemod::applySettings().

{ m_stepDownDelay = stepDownDelay; m_gateCounter = 0; m_count = 0; }

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setThreshold()

void MagAGC::setThreshold ( double  threshold )

inline

Definition at line 47 of file agc.h.

Referenced by UDPSink::applySettings(), and SSBDemod::applySettings().

{ m_threshold = threshold; }

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setThresholdEnable()

void MagAGC::setThresholdEnable

(

bool

enable

)

Definition at line 83 of file agc.cpp.

References m_stepDownCounter, m_stepUpCounter, and m_thresholdEnable.

Referenced by AMDemod::AMDemod(), and SSBDemod::applySettings().

{
    if (m_thresholdEnable != enable)
    {
        m_stepUpCounter = 0;
        m_stepDownCounter = 0;
    }

    m_thresholdEnable = enable;
}

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Member Data Documentation

m_clamping

bool MagAGC::m_clamping

private

clamping active

Definition at line 69 of file agc.h.

Referenced by feedAndGetValue().

m_clampMax

double MagAGC::m_clampMax

private

maximum to clamp to as power value

Definition at line 71 of file agc.h.

Referenced by feedAndGetValue().

m_gate

int MagAGC::m_gate

private

power threshold gate in number of samples

Definition at line 62 of file agc.h.

Referenced by feedAndGetValue().

m_gateCounter

int MagAGC::m_gateCounter

private

threshold gate samples counter

Definition at line 67 of file agc.h.

Referenced by feedAndGetValue().

m_hardLimiting

bool MagAGC::m_hardLimiting

private

hard limit multiplier so that resulting sample magnitude does not exceed 1.0

Definition at line 72 of file agc.h.

Referenced by hardLimiter().

m_magsq

double MagAGC::m_magsq

private

current squared magnitude (power)

Definition at line 59 of file agc.h.

Referenced by feedAndGetValue().

m_R2

double MagAGC::m_R2

private

square of ordered magnitude

Definition at line 70 of file agc.h.

Referenced by resize(), and setOrder().

m_squared

bool MagAGC::m_squared

private

use squared magnitude (power) to compute AGC value

Definition at line 58 of file agc.h.

Referenced by feedAndGetValue().

m_stepDelta

double MagAGC::m_stepDelta

private

transition step unit by sample

Definition at line 64 of file agc.h.

Referenced by feedAndGetValue(), getStepValue(), and resize().

m_stepDownCounter

int MagAGC::m_stepDownCounter

private

step down transition samples counter

Definition at line 66 of file agc.h.

Referenced by feedAndGetValue(), getStepValue(), resize(), and setThresholdEnable().

m_stepDownDelay

int MagAGC::m_stepDownDelay

private

delay in samples before cutoff (release)

Definition at line 68 of file agc.h.

Referenced by feedAndGetValue().

m_stepLength

int MagAGC::m_stepLength

private

transition step length in number of samples

Definition at line 63 of file agc.h.

Referenced by feedAndGetValue(), and resize().

m_stepUpCounter

int MagAGC::m_stepUpCounter

private

step up transition samples counter

Definition at line 65 of file agc.h.

Referenced by feedAndGetValue(), getStepValue(), resize(), and setThresholdEnable().

m_threshold

double MagAGC::m_threshold

private

squelch on magsq average

Definition at line 60 of file agc.h.

Referenced by feedAndGetValue().

m_thresholdEnable

bool MagAGC::m_thresholdEnable

private

enable squelch on power threshold

Definition at line 61 of file agc.h.

Referenced by feedAndGetValue(), and setThresholdEnable().

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

• sdrbase/dsp/agc.h
• sdrbase/dsp/agc.cpp