ATV Demod: implemented FFT filter and interpolator (for decimation and DSB filtering)

plugins/channelrx/demodatv/atvdemod.cpp

@@ -29,6 +29,7 @@ MESSAGE_CLASS_DEFINITION(ATVDemod::MsgConfigureATVDemod, Message)
 MESSAGE_CLASS_DEFINITION(ATVDemod::MsgConfigureRFATVDemod, Message)
 
 const float ATVDemod::m_fltSecondToUs = 1000000.0f;
+const int ATVDemod::m_ssbFftLen = 1024;
 
 ATVDemod::ATVDemod() :
     m_objSettingsMutex(QMutex::NonRecursive),
@@ -48,7 +49,12 @@ ATVDemod::ATVDemod() :
     m_fltAmpMax(2000000000.0f),
     m_fltAmpDelta(1.0),
     m_fltAmpLineAverage(0.0f),
-    m_intNumberSamplePerTop(0)
+    m_intNumberSamplePerTop(0),
+    m_interpolatorDistanceRemain(0.0f),
+    m_interpolatorDistance(1.0f),
+    m_DSBFilter(0),
+    m_DSBFilterBuffer(0),
+    m_DSBFilterBufferIndex(0)
 {
     setObjectName("ATVDemod");
 
@@ -60,9 +66,12 @@ ATVDemod::ATVDemod() :
 
     m_objMagSqAverage.resize(32, 1.0);
 
+    m_DSBFilter = new fftfilt((2.0f * m_objRFConfig.m_fltRFBandwidth) / 1000000, 2 * m_ssbFftLen); // arbitrary 1 MS/s sample rate
+    m_DSBFilterBuffer = new Complex[m_ssbFftLen];
+    memset(m_DSBFilterBuffer, 0, sizeof(Complex)*(m_ssbFftLen));
+
     memset((void*)m_fltBufferI,0,6*sizeof(float));
     memset((void*)m_fltBufferQ,0,6*sizeof(float));
-
 }
 
 ATVDemod::~ATVDemod()
@@ -102,13 +111,15 @@ void ATVDemod::configureRF(
         ATVModulation enmModulation,
         float fltRFBandwidth,
         float fltRFOppBandwidth,
-        bool blnFFTFiltering)
+        bool blnFFTFiltering,
+        bool blnDecimatorEnable)
 {
     Message* msgCmd = MsgConfigureRFATVDemod::create(
             enmModulation,
             fltRFBandwidth,
             fltRFOppBandwidth,
-            blnFFTFiltering);
+            blnFFTFiltering,
+            blnDecimatorEnable);
     objMessageQueue->push(msgCmd);
 }
 
@@ -521,7 +532,8 @@ bool ATVDemod::handleMessage(const Message& cmd)
                 << " m_enmModulation" << m_objRFConfig.m_enmModulation
                 << " m_fltRFBandwidth" << m_objRFConfig.m_fltRFBandwidth
                 << " m_fltRFOppBandwidth" << m_objRFConfig.m_fltRFOppBandwidth
-                << " m_blnFFTFiltering" << m_objRFConfig.m_blnFFTFiltering;
+                << " m_blnFFTFiltering" << m_objRFConfig.m_blnFFTFiltering
+                << " m_blnDecimatorEnable" << m_objRFConfig.m_blndecimatorEnable;
 
         applySettings();
 

plugins/channelrx/demodatv/atvdemod.h

@@ -18,16 +18,18 @@
 #ifndef INCLUDE_ATVDEMOD_H
 #define INCLUDE_ATVDEMOD_H
 
-#include <dsp/basebandsamplesink.h>
-#include <dsp/devicesamplesource.h>
-#include <dsp/dspcommands.h>
-#include <dsp/downchannelizer.h>
 #include <QMutex>
 #include <QElapsedTimer>
 #include <vector>
+
+#include "dsp/basebandsamplesink.h"
+#include "dsp/devicesamplesource.h"
+#include "dsp/dspcommands.h"
+#include "dsp/downchannelizer.h"
 #include "dsp/nco.h"
 #include "dsp/interpolator.h"
 #include "dsp/movingaverage.h"
+#include "dsp/fftfilt.h"
 #include "dsp/agc.h"
 #include "audio/audiofifo.h"
 #include "util/message.h"
@@ -41,11 +43,11 @@ class ATVDemod : public BasebandSampleSink
 public:
 
 	enum ATVModulation {
-	    ATV_FM1,
+	    ATV_FM1,  //!< Classical frequency modulation with discriminator #1
-	    ATV_FM2,
+	    ATV_FM2,  //!< Classical frequency modulation with discriminator #2
-        ATV_AM,
+        ATV_AM,   //!< Classical amplitude modulation
-        ATV_VAMU,
+        ATV_VAMU, //!< AM with vestigial lower side band (main signal is in the upper side)
-        ATV_VAML
+        ATV_VAML  //!< AM with vestigial upper side band (main signal is in the lower side)
 	};
 
 	struct ATVConfig
@@ -80,12 +82,14 @@ public:
         float         m_fltRFBandwidth;
         float         m_fltRFOppBandwidth;
         bool          m_blnFFTFiltering;
+        bool          m_blndecimatorEnable;
 
         ATVRFConfig() :
             m_enmModulation(ATV_FM1),
             m_fltRFBandwidth(0),
             m_fltRFOppBandwidth(0),
-            m_blnFFTFiltering(false)
+            m_blnFFTFiltering(false),
+            m_blndecimatorEnable(false)
         {
         }
     };
@@ -107,7 +111,8 @@ public:
             ATVModulation enmModulation,
             float fltRFBandwidth,
             float fltRFOppBandwidth,
-            bool blnFFTFiltering);
+            bool blnFFTFiltering,
+            bool blndecimatorEnable);
 
 	virtual void feed(const SampleVector::const_iterator& begin, const SampleVector::const_iterator& end, bool po);
 	virtual void start();
@@ -180,13 +185,15 @@ private:
                     ATVModulation enmModulation,
                     float fltRFBandwidth,
                     float fltRFOppBandwidth,
-                    bool blnFFTFiltering)
+                    bool blnFFTFiltering,
+                    bool blndecimatorEnable)
             {
                 return new MsgConfigureRFATVDemod(
                         enmModulation,
                         fltRFBandwidth,
                         fltRFOppBandwidth,
-                        blnFFTFiltering);
+                        blnFFTFiltering,
+                        blndecimatorEnable);
             }
 
             ATVRFConfig m_objMsgConfig;
@@ -196,7 +203,8 @@ private:
                     ATVModulation enmModulation,
                     float fltRFBandwidth,
                     float fltRFOppBandwidth,
-                    bool blnFFTFiltering) :
+                    bool blnFFTFiltering,
+                    bool blndecimatorEnable) :
                 Message()
             {
                 m_objMsgConfig.m_enmModulation = enmModulation;
@@ -244,6 +252,17 @@ private:
 
     MovingAverage<double> m_objMagSqAverage;
 
+    // Interpolator group for decimation and/or double sideband RF filtering
+    Interpolator m_interpolator;
+    Real m_interpolatorDistance;
+    Real m_interpolatorDistanceRemain;
+
+    // Used for vestigial SSB with asymmetrical filtering (needs double sideband scheme)
+    fftfilt* m_DSBFilter;
+    Complex* m_DSBFilterBuffer;
+    int m_DSBFilterBufferIndex;
+    static const int m_ssbFftLen;
+
     //QElapsedTimer m_objTimer;
 
     ATVConfig m_objRunning;

plugins/channelrx/demodatv/atvdemodgui.cpp

@@ -361,7 +361,8 @@ void ATVDemodGUI::applyRFSettings()
                 (ATVDemod::ATVModulation) ui->modulation->currentIndex(),
                 ui->rfBW->value() * 100000.0f,
                 ui->rfOppBW->value() * 100000.0f,
-                ui->rfFiltering->isChecked());
+                ui->rfFiltering->isChecked(),
+                ui->decimator->isChecked());
     }
 }
 
@@ -577,3 +578,9 @@ void ATVDemodGUI::on_rfFiltering_toggled(bool checked)
     m_blnDoApplySettings = true;
     applyRFSettings();
 }
+
+void ATVDemodGUI::on_decimator_toggled(bool checked)
+{
+    applyRFSettings();
+}
+

plugins/channelrx/demodatv/atvdemodgui.h

@@ -75,6 +75,7 @@ private slots:
     void on_rfBW_valueChanged(int value);
     void on_rfOppBW_valueChanged(int value);
     void on_rfFiltering_toggled(bool checked);
+    void on_decimator_toggled(bool checked);
 
 private:
 	Ui::ATVDemodGUI* ui;

plugins/channelrx/demodatv/atvdemodgui.ui

@@ -99,9 +99,16 @@
        </layout>
       </item>
       <item>
-       <widget class="Line" name="line">
+       <widget class="ButtonSwitch" name="decimator">
-        <property name="orientation">
+        <property name="text">
-         <enum>Qt::Vertical</enum>
+         <string/>
+        </property>
+        <property name="icon">
+         <iconset resource="../../../sdrbase/resources/res.qrc">
+          <normaloff>:/arrow_down.png</normaloff>:/arrow_down.png</iconset>
+        </property>
+        <property name="checkable">
+         <bool>true</bool>
         </property>
        </widget>
       </item>