VE7UWU/sdrangel
1
0
Fork 0
mirror of https://github.com/f4exb/sdrangel.git synced 2024-12-23 01:55:48 -05:00
Code Issues Projects Releases Wiki Activity

SSB demod: mitigate AGC steep transitions causing audio clicks

Browse Source
This commit is contained in:
f4exb 2023-11-30 14:11:36 +01:00
parent 3b969ac058
commit b402739db6
3 changed files with 24 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
plugins/channelrx/demodssb/ssbdemodsink.cpp
View File

@ -69,10 +69,12 @@ SSBDemodSink::SSBDemodSink() :
m_demodBufferFill = 0;
m_usb = true;
m_magsq = 0.0f;
m_magsqSum = 0.0f;
m_magsqPeak = 0.0f;
m_magsq = 0.0;
m_magsqSum = 0.0;
m_magsqPeak = 0.0;
m_magsqCount = 0;
m_magsqCur = 0.0;
m_magsqPrev = 0.0;
m_agc.setClampMax(SDR_RX_SCALED/100.0);
m_agc.setClamping(m_agcClamping);
@ -170,10 +172,24 @@ void SSBDemodSink::processOneSample(Complex &ci)
m_sum.imag(0.0);
}
float agcVal = m_agcActive ? m_agc.feedAndGetValue(sideband[i]) : 0.1;
float agcVal = m_agcActive ? m_agc.feedAndGetValue(sideband[i]) : 1.0;
fftfilt::cmplx& delayedSample = m_squelchDelayLine.readBack(m_agc.getStepDownDelay());
m_audioActive = delayedSample.real() != 0.0;
m_squelchDelayLine.write(sideband[i]*agcVal);
m_magsqCur = std::norm(sideband[i]*agcVal);
// Prevent overload if squared magnitude variation is 90% full scale (0.9*.0.9 = 0.81)
// Only if AGC is active
if (m_agcActive && (m_magsqCur - m_magsqPrev > m_agcTarget*m_agcTarget*8.1))
{
m_agc.reset(m_agcTarget*100.0); // Quench AGC at -20dB the target
m_squelchDelayLine.write(sideband[i]);
}
else
{
m_squelchDelayLine.write(sideband[i]*agcVal);
}
m_magsqPrev = m_magsqCur;
if (m_audioMute)
{

2
plugins/channelrx/demodssb/ssbdemodsink.h
View File

@ -101,6 +101,8 @@ private:
double m_magsqSum;
double m_magsqPeak;
int m_magsqCount;
double m_magsqCur;
double m_magsqPrev;
MagSqLevelsStore m_magSqLevelStore;
MagAGC m_agc;
bool m_agcActive;

1
sdrbase/dsp/agc.h
View File

@ -32,6 +32,7 @@ public:
void setOrder(double R) { m_R = R; }
Real getValue();
Real getAverage();
void reset(double R) { m_moving_average.fill(R); }
virtual void feed(Complex& ci) = 0;
protected: