From f57eecee86ab8474c8be48038e940c5dffb81066 Mon Sep 17 00:00:00 2001
From: f4exb <f4exb06@gmail.com>
Date: Sat, 13 May 2017 12:10:03 +0200
Subject: [PATCH] NFM demod: af squeelch optimization

---
 plugins/channelrx/demodnfm/nfmdemod.cpp    | 37 +++++++++++++---------
 plugins/channelrx/demodnfm/nfmdemodgui.cpp |  4 +--
 sdrbase/dsp/afsquelch.cpp                  |  6 ++++
 3 files changed, 30 insertions(+), 17 deletions(-)

diff --git a/plugins/channelrx/demodnfm/nfmdemod.cpp b/plugins/channelrx/demodnfm/nfmdemod.cpp
index e2713c884..61bbb7f0a 100644
--- a/plugins/channelrx/demodnfm/nfmdemod.cpp
+++ b/plugins/channelrx/demodnfm/nfmdemod.cpp
@@ -15,7 +15,7 @@
 // along with this program. If not, see <http://www.gnu.org/licenses/>.          //
 ///////////////////////////////////////////////////////////////////////////////////
 
-#include "../../channelrx/demodnfm/nfmdemod.h"
+#include "nfmdemod.h"
 
 #include <QTime>
 #include <QDebug>
@@ -25,9 +25,9 @@
 #include "audio/audiooutput.h"
 #include "dsp/pidcontroller.h"
 #include "dsp/dspengine.h"
-#include "../../channelrx/demodnfm/nfmdemodgui.h"
+#include "nfmdemodgui.h"
 
-static const Real afSqTones[2] = {1200.0, 6400.0}; // {1200.0, 8000.0};
+static const Real afSqTones[2] = {1200.0, 8000.0}; // {1200.0, 8000.0};
 
 MESSAGE_CLASS_DEFINITION(NFMDemod::MsgConfigureNFMDemod, Message)
 
@@ -75,7 +75,7 @@ NFMDemod::NFMDemod() :
 	m_movingAverage.resize(32, 0);
 
 	m_ctcssDetector.setCoefficients(3000, 6000.0); // 0.5s / 2 Hz resolution
-	m_afSquelch.setCoefficients(24, 600, 48000.0, 200, 0); // 4000 Hz span, 250us, 100ms attack
+	m_afSquelch.setCoefficients(24, 600, 48000.0, 200, 0); // 0.5ms test period, 300ms average span, 48kS/s SR, 100ms attack, no decay
 
 	DSPEngine::instance()->addAudioSink(&m_audioFifo);
 }
@@ -184,8 +184,23 @@ void NFMDemod::feed(const SampleVector::const_iterator& begin, const SampleVecto
 				if (m_running.m_deltaSquelch)
 				{
 	                if (m_afSquelch.analyze(demod)) {
-	                    m_squelchCount = m_afSquelch.evaluate() ? m_squelchGate + 480 : 0;
+	                    m_afSquelchOpen = m_afSquelch.evaluate() ? m_squelchGate + 480 : 0;
 	                }
+
+                    if (m_afSquelchOpen)
+                    {
+                        if (m_squelchCount < m_squelchGate + 480)
+                        {
+                            m_squelchCount++;
+                        }
+                    }
+                    else
+                    {
+                        if (m_squelchCount > 0)
+                        {
+                            m_squelchCount--;
+                        }
+                    }
 				}
 				else
 				{
@@ -270,16 +285,8 @@ void NFMDemod::feed(const SampleVector::const_iterator& begin, const SampleVecto
 					else
 					{
                         demod = m_bandpass.filter(demod);
-
-                        if (m_running.m_deltaSquelch)
-                        {
-                            sample = demod * m_running.m_volume;
-                        }
-                        else
-                        {
-                            Real squelchFactor = smootherstep((Real) (m_squelchCount - m_squelchGate) / 480.0f);
-                            sample = demod * m_running.m_volume * squelchFactor;
-                        }
+                        Real squelchFactor = smootherstep((Real) (m_squelchCount - m_squelchGate) / 480.0f);
+                        sample = demod * m_running.m_volume * squelchFactor;
 					}
 				}
 				else
diff --git a/plugins/channelrx/demodnfm/nfmdemodgui.cpp b/plugins/channelrx/demodnfm/nfmdemodgui.cpp
index 15fe66b3a..56f3dc0db 100644
--- a/plugins/channelrx/demodnfm/nfmdemodgui.cpp
+++ b/plugins/channelrx/demodnfm/nfmdemodgui.cpp
@@ -208,6 +208,7 @@ void NFMDemodGUI::on_volume_valueChanged(int value)
 
 void NFMDemodGUI::on_squelchGate_valueChanged(int value)
 {
+    ui->squelchGateText->setText(QString("%1").arg(ui->squelchGate->value() * 10.0f, 0, 'f', 0));
 	applySettings();
 }
 
@@ -369,14 +370,13 @@ void NFMDemodGUI::applySettings()
 
 		ui->deltaFrequency->setValue(abs(m_channelMarker.getCenterFrequency()));
 		ui->deltaMinus->setChecked(m_channelMarker.getCenterFrequency() < 0);
-		ui->squelchGateText->setText(QString("%1").arg(ui->squelchGate->value() * 10.0f, 0, 'f', 0));
 
 		m_nfmDemod->configure(m_nfmDemod->getInputMessageQueue(),
 			m_rfBW[ui->rfBW->currentIndex()],
 			ui->afBW->value() * 1000.0f,
 			m_fmDev[ui->rfBW->currentIndex()],
 			ui->volume->value() / 10.0f,
-			ui->squelchGate->value(), // in 10ths of ms
+			ui->squelchGate->value(), // in 10ths of ms 1 -> 50
 			ui->deltaSquelch->isChecked(),
 			ui->squelch->value(), // -1000 -> 0
 			ui->ctcssOn->isChecked(),
diff --git a/sdrbase/dsp/afsquelch.cpp b/sdrbase/dsp/afsquelch.cpp
index e5b7836f2..db9ff9846 100644
--- a/sdrbase/dsp/afsquelch.cpp
+++ b/sdrbase/dsp/afsquelch.cpp
@@ -91,6 +91,12 @@ void AFSquelch::setCoefficients(int N, unsigned int nbAvg, int _samplerate, int
 	m_samplesAttack = _samplesAttack;
 	m_samplesDecay = _samplesDecay;
 	m_movingAverages.resize(m_nTones, MovingAverage<double>(m_nbAvg, 1.0));
+	m_samplesProcessed = 0;
+	m_maxPowerIndex = 0;
+	m_attackCount = 0;
+	m_decayCount = 0;
+	m_isOpen = false;
+	m_threshold = 0.0;
 
 	// for each of the frequencies (tones) of interest calculate
 	// k and the associated filter coefficient as per the Goertzel