From 8a16e99e48b6332f1e9d6d11300af92db31e930e Mon Sep 17 00:00:00 2001
From: f4exb <f4exb06@gmail.com>
Date: Sun, 20 Aug 2017 22:18:33 +0200
Subject: [PATCH] UDP source plugin: new AM mode with 300 Hz low cutoff
 bandpass filter

---
 plugins/channelrx/udpsrc/udpsrc.cpp    | 19 +++++++++++++++++++
 plugins/channelrx/udpsrc/udpsrc.h      |  3 +++
 plugins/channelrx/udpsrc/udpsrcgui.cpp |  4 ++++
 plugins/channelrx/udpsrc/udpsrcgui.ui  |  5 +++++
 4 files changed, 31 insertions(+)

diff --git a/plugins/channelrx/udpsrc/udpsrc.cpp b/plugins/channelrx/udpsrc/udpsrc.cpp
index 187fcbdbd..0bcea5780 100644
--- a/plugins/channelrx/udpsrc/udpsrc.cpp
+++ b/plugins/channelrx/udpsrc/udpsrc.cpp
@@ -286,6 +286,23 @@ void UDPSrc::feed(const SampleVector::const_iterator& begin, const SampleVector:
                     m_udpBufferMono->write(0);
                     m_outMovingAverage.feed(0);
                 }
+            }
+            else if (m_running.m_sampleFormat == FormatAMBPFMono)
+            {
+                if (m_squelchOpen)
+                {
+                    double demodf = sqrt(inMagSq);
+                    demodf = m_bandpass.filter(demodf);
+                    demodf /= 301.0;
+                    FixReal demod = (FixReal) (demodf * agcFactor * m_running.m_gain);
+                    m_udpBufferMono->write(demod);
+                    m_outMovingAverage.feed((demod * demod) / 1073741824.0);
+                }
+                else
+                {
+                    m_udpBufferMono->write(0);
+                    m_outMovingAverage.feed(0);
+                }
             }
 			else // Raw I/Q samples
 			{
@@ -437,6 +454,8 @@ void UDPSrc::apply(bool force)
         m_agc.setStepDownDelay( m_config.m_outputSampleRate * (m_config.m_squelchGate == 0 ? 0.01 : m_config.m_squelchGate));
         m_agc.setGate(m_config.m_outputSampleRate * 0.02);
 
+        m_bandpass.create(301, m_config.m_outputSampleRate, 300.0, m_config.m_rfBandwidth / 2.0f);
+
         m_inMovingAverage.resize(m_config.m_outputSampleRate * 0.01, 1e-10);  // 10 ms
         m_amMovingAverage.resize(m_config.m_outputSampleRate * 0.005, 1e-10); //  5 ms
         m_outMovingAverage.resize(m_config.m_outputSampleRate * 0.01, 1e-10); // 10 ms
diff --git a/plugins/channelrx/udpsrc/udpsrc.h b/plugins/channelrx/udpsrc/udpsrc.h
index 1ff443dfc..3f5257274 100644
--- a/plugins/channelrx/udpsrc/udpsrc.h
+++ b/plugins/channelrx/udpsrc/udpsrc.h
@@ -27,6 +27,7 @@
 #include "dsp/phasediscri.h"
 #include "dsp/movingaverage.h"
 #include "dsp/agc.h"
+#include "dsp/bandpass.h"
 #include "util/udpsink.h"
 #include "util/message.h"
 #include "audio/audiofifo.h"
@@ -49,6 +50,7 @@ public:
 		FormatUSBMono,
 		FormatAMMono,
 		FormatAMNoDCMono,
+		FormatAMBPFMono,
 		FormatNone
 	};
 
@@ -341,6 +343,7 @@ protected:
     int m_squelchThreshold; //!< number of samples computed from given gate
 
     MagAGC m_agc;
+    Bandpass<double> m_bandpass;
 
 	QMutex m_settingsMutex;
 
diff --git a/plugins/channelrx/udpsrc/udpsrcgui.cpp b/plugins/channelrx/udpsrc/udpsrcgui.cpp
index 272f3ba88..6d44bdbf8 100644
--- a/plugins/channelrx/udpsrc/udpsrcgui.cpp
+++ b/plugins/channelrx/udpsrc/udpsrcgui.cpp
@@ -453,6 +453,10 @@ void UDPSrcGUI::applySettings(bool force)
             case 8:
                 sampleFormat = UDPSrc::FormatAMNoDCMono;
                 ui->fmDeviation->setEnabled(false);
+                break;
+            case 9:
+                sampleFormat = UDPSrc::FormatAMBPFMono;
+                ui->fmDeviation->setEnabled(false);
                 break;
 			default:
 				sampleFormat = UDPSrc::FormatS16LE;
diff --git a/plugins/channelrx/udpsrc/udpsrcgui.ui b/plugins/channelrx/udpsrc/udpsrcgui.ui
index 8a22f117b..5daae8808 100644
--- a/plugins/channelrx/udpsrc/udpsrcgui.ui
+++ b/plugins/channelrx/udpsrc/udpsrcgui.ui
@@ -522,6 +522,11 @@
           <string>S16LE AM !DC Mono</string>
          </property>
         </item>
+        <item>
+         <property name="text">
+          <string>S16LE AM BPF Mono</string>
+         </property>
+        </item>
        </widget>
       </item>
      </layout>