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NFM demod: revised AF squelch completely

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This commit is contained in:
f4exb
2015-09-13 11:56:14 +02:00
parent 34942340a3
commit 4246fb6381
8 changed files with 64 additions and 38 deletions
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sdrbase/dsp/afsquelch.cpp
+28 -12
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@@ -18,6 +18,7 @@
#include "dsp/afsquelch.h"
AFSquelch::AFSquelch() :
m_nbAvg(128),
m_N(0),
m_sampleRate(0),
m_samplesProcessed(0),
@@ -36,20 +37,22 @@ AFSquelch::AFSquelch() :
m_u0 = new double[m_nTones];
m_u1 = new double[m_nTones];
m_power = new double[m_nTones];
m_movingAverages.resize(m_nTones, MovingAverage<Real>(m_nbAvg, 0.0));
m_toneSet[0] = 2000.0;
m_toneSet[1] = 10000.0;
}
AFSquelch::AFSquelch(unsigned int nbTones, const Real *tones, int samplesAttack, int samplesDecay) :
AFSquelch::AFSquelch(unsigned int nbTones, const Real *tones) :
m_N(0),
m_nbAvg(0),
m_sampleRate(0),
m_samplesProcessed(0),
m_maxPowerIndex(0),
m_nTones(nbTones),
m_samplesAttack(samplesAttack),
m_samplesAttack(0),
m_attackCount(0),
m_samplesDecay(samplesDecay),
m_samplesDecay(0),
m_decayCount(0),
m_isOpen(false),
m_threshold(0.0)
@@ -79,12 +82,14 @@ AFSquelch::~AFSquelch()
}
void AFSquelch::setCoefficients(int _N, int _samplerate, int _samplesAttack, int _samplesDecay )
void AFSquelch::setCoefficients(int _N, unsigned int nbAvg, int _samplerate, int _samplesAttack, int _samplesDecay )
{
m_N = _N; // save the basic parameters for use during analysis
m_nbAvg = nbAvg;
m_sampleRate = _samplerate;
m_samplesAttack = _samplesAttack;
m_samplesDecay = _samplesDecay;
m_movingAverages.resize(m_nTones, MovingAverage<Real>(m_nbAvg, 0.0));
// for each of the frequencies (tones) of interest calculate
// k and the associated filter coefficient as per the Goertzel
@@ -102,10 +107,10 @@ void AFSquelch::setCoefficients(int _N, int _samplerate, int _samplesAttack, int
// Analyze an input signal
bool AFSquelch::analyze(Real *sample)
bool AFSquelch::analyze(Real sample)
{
feedback(*sample); // Goertzel feedback
feedback(sample); // Goertzel feedback
m_samplesProcessed += 1;
if (m_samplesProcessed == m_N) // completed a block of N
@@ -140,6 +145,7 @@ void AFSquelch::feedForward()
for (int j = 0; j < m_nTones; ++j)
{
m_power[j] = (m_u0[j] * m_u0[j]) + (m_u1[j] * m_u1[j]) - (m_coef[j] * m_u0[j] * m_u1[j]);
m_movingAverages[j].feed(m_power[j]);
m_u0[j] = m_u1[j] = 0.0; // reset for next block.
}
@@ -152,6 +158,7 @@ void AFSquelch::reset()
for (int j = 0; j < m_nTones; ++j)
{
m_power[j] = m_u0[j] = m_u1[j] = 0.0; // reset
m_movingAverages[j].fill(0.0);
}
m_samplesProcessed = 0;
@@ -160,7 +167,7 @@ void AFSquelch::reset()
}
void AFSquelch::evaluate()
bool AFSquelch::evaluate()
{
double maxPower = 0.0;
double minPower;
@@ -168,8 +175,9 @@ void AFSquelch::evaluate()
for (int j = 0; j < m_nTones; ++j)
{
if (m_power[j] > maxPower) {
maxPower = m_power[j];
if (m_movingAverages[j].sum() > maxPower)
{
maxPower = m_movingAverages[j].sum();
maxIndex = j;
}
}
@@ -178,14 +186,14 @@ void AFSquelch::evaluate()
for (int j = 0; j < m_nTones; ++j)
{
if (m_power[j] < minPower) {
minPower = m_power[j];
if (m_movingAverages[j].sum() < minPower) {
minPower = m_movingAverages[j].sum();
minIndex = j;
}
}
// principle is to open if power is uneven because noise gives even power
bool open = ((maxPower - minPower) > m_threshold); // && (minIndex > maxIndex);
bool open = (minPower/maxPower < m_threshold) && (minIndex > maxIndex);
if (open)
{
@@ -213,4 +221,12 @@ void AFSquelch::evaluate()
m_attackCount = 0;
}
}
return m_isOpen;
}
void AFSquelch::setThreshold(double threshold)
{
qDebug("AFSquelch::setThreshold: threshold: %f", threshold);
m_threshold = threshold;
}