From c7436c946f387c08ad9b1fe1a6cebd61642a86dd Mon Sep 17 00:00:00 2001
From: srcejon <jon@beniston.com>
Date: Fri, 17 Nov 2023 16:44:47 +0000
Subject: [PATCH] Fix M17 FM frequency deviation to work at +/-2.4kHz.

---
 plugins/channelrx/demodm17/m17demodsettings.cpp | 2 +-
 plugins/channelrx/demodm17/m17demodsink.cpp     | 2 +-
 plugins/channeltx/modm17/m17modgui.cpp          | 6 +++---
 plugins/channeltx/modm17/m17modsettings.cpp     | 4 ++--
 plugins/channeltx/modm17/m17modsource.cpp       | 2 +-
 5 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/plugins/channelrx/demodm17/m17demodsettings.cpp b/plugins/channelrx/demodm17/m17demodsettings.cpp
index a71a4fbe3..f729bde9a 100644
--- a/plugins/channelrx/demodm17/m17demodsettings.cpp
+++ b/plugins/channelrx/demodm17/m17demodsettings.cpp
@@ -34,7 +34,7 @@ void M17DemodSettings::resetToDefaults()
 {
     m_inputFrequencyOffset = 0;
     m_rfBandwidth = 12500.0;
-    m_fmDeviation = 3500.0;
+    m_fmDeviation = 2400.0;
     m_volume = 2.0;
     m_baudRate = 4800;
     m_squelchGate = 5; // 10s of ms at 48000 Hz sample rate. Corresponds to 2400 for AGC attack
diff --git a/plugins/channelrx/demodm17/m17demodsink.cpp b/plugins/channelrx/demodm17/m17demodsink.cpp
index 8031f563f..ae650c059 100644
--- a/plugins/channelrx/demodm17/m17demodsink.cpp
+++ b/plugins/channelrx/demodm17/m17demodsink.cpp
@@ -334,7 +334,7 @@ void M17DemodSink::applySettings(const M17DemodSettings& settings, const QList<Q
     }
 
     if (settingsKeys.contains("fmDeviation") || force) {
-        m_phaseDiscri.setFMScaling(48000.0f / (2.0f*settings.m_fmDeviation));
+        m_phaseDiscri.setFMScaling(48000.0f / (2.0f*M_PI*settings.m_fmDeviation));
     }
 
     if (settingsKeys.contains("squelchGate") || force)
diff --git a/plugins/channeltx/modm17/m17modgui.cpp b/plugins/channeltx/modm17/m17modgui.cpp
index 0b2fee88a..68b7fcc61 100644
--- a/plugins/channeltx/modm17/m17modgui.cpp
+++ b/plugins/channeltx/modm17/m17modgui.cpp
@@ -164,7 +164,7 @@ void M17ModGUI::on_rfBW_valueChanged(int value)
 void M17ModGUI::on_fmDev_valueChanged(int value)
 {
 	ui->fmDevText->setText(QString("%1%2k").arg(QChar(0xB1, 0x00)).arg(value / 10.0, 0, 'f', 1));
-	m_settings.m_fmDeviation = value * 200.0;
+	m_settings.m_fmDeviation = value * 100.0;
 	applySettings(QList<QString>{"fmDeviation"});
 }
 
@@ -570,8 +570,8 @@ void M17ModGUI::displaySettings()
     ui->rfBWText->setText(QString("%1k").arg(m_settings.m_rfBandwidth / 1000.0, 0, 'f', 1));
     ui->rfBW->setValue(m_settings.m_rfBandwidth / 100.0);
 
-    ui->fmDevText->setText(QString("%1%2k").arg(QChar(0xB1, 0x00)).arg(m_settings.m_fmDeviation / 2000.0, 0, 'f', 1));
-    ui->fmDev->setValue(m_settings.m_fmDeviation / 200.0);
+    ui->fmDevText->setText(QString("%1%2k").arg(QChar(0xB1, 0x00)).arg(m_settings.m_fmDeviation / 1000.0, 0, 'f', 1));
+    ui->fmDev->setValue(m_settings.m_fmDeviation / 100.0);
 
     ui->volumeText->setText(QString("%1").arg(m_settings.m_volumeFactor, 0, 'f', 1));
     ui->volume->setValue(m_settings.m_volumeFactor * 10.0);
diff --git a/plugins/channeltx/modm17/m17modsettings.cpp b/plugins/channeltx/modm17/m17modsettings.cpp
index c150a2c81..ba58a521a 100644
--- a/plugins/channeltx/modm17/m17modsettings.cpp
+++ b/plugins/channeltx/modm17/m17modsettings.cpp
@@ -35,7 +35,7 @@ void M17ModSettings::resetToDefaults()
 {
     m_inputFrequencyOffset = 0;
     m_rfBandwidth = 16000.0f;
-    m_fmDeviation = 10000.0f; //!< full deviation
+    m_fmDeviation = 2400.0; //!< peak deviation
     m_toneFrequency = 1000.0f;
     m_volumeFactor = 1.0f;
     m_channelMute = false;
@@ -146,7 +146,7 @@ bool M17ModSettings::deserialize(const QByteArray& data)
         d.readS32(1, &tmp, 0);
         m_inputFrequencyOffset = tmp;
         d.readReal(2, &m_rfBandwidth, 12500.0);
-        d.readReal(4, &m_fmDeviation, 10000.0);
+        d.readReal(4, &m_fmDeviation, 2400.0);
         d.readU32(5, &m_rgbColor);
         d.readReal(6, &m_toneFrequency, 1000.0);
         d.readReal(7, &m_volumeFactor, 1.0);
diff --git a/plugins/channeltx/modm17/m17modsource.cpp b/plugins/channeltx/modm17/m17modsource.cpp
index 9901bd209..7a76d4e2b 100644
--- a/plugins/channeltx/modm17/m17modsource.cpp
+++ b/plugins/channeltx/modm17/m17modsource.cpp
@@ -177,7 +177,7 @@ void M17ModSource::modulateSample()
         calculateLevel(t);
         t1 = m_lowpass.filter(t) * 1.5f;
 
-        m_modPhasor += (m_settings.m_fmDeviation / (float) m_audioSampleRate) * t1;
+        m_modPhasor += ((2.0f * M_PI * m_settings.m_fmDeviation) / (float) m_audioSampleRate) * t1;
 
         // limit phasor range to ]-pi,pi]
         if (m_modPhasor > M_PI) {