ATV Modulator: implemented vestigial sideband

plugins/channeltx/modatv/atvmod.cpp

@@ -57,7 +57,11 @@ ATVMod::ATVMod() :
 	m_cameraIndex(-1),
 	m_showOverlayText(false),
     m_SSBFilter(0),
-    m_SSBFilterBuffer(0)
+    m_DSBFilter(0),
+    m_SSBFilterBuffer(0),
+    m_DSBFilterBuffer(0),
+    m_SSBFilterBufferIndex(0),
+    m_DSBFilterBufferIndex(0)
 {
     setObjectName("ATVMod");
     scanCameras();
@@ -72,6 +76,10 @@ ATVMod::ATVMod() :
     m_SSBFilterBuffer = new Complex[m_ssbFftLen>>1]; // filter returns data exactly half of its size
     memset(m_SSBFilterBuffer, 0, sizeof(Complex)*(m_ssbFftLen>>1));
 
+    m_DSBFilter = new fftfilt((2.0f * m_config.m_rfBandwidth) / m_config.m_outputSampleRate, 2 * m_ssbFftLen);
+    m_DSBFilterBuffer = new Complex[m_ssbFftLen];
+    memset(m_DSBFilterBuffer, 0, sizeof(Complex)*(m_ssbFftLen));
+
     applyStandard();
 
     m_interpolatorDistanceRemain = 0.0f;
@@ -193,6 +201,11 @@ void ATVMod::modulateSample()
         m_modSample = modulateSSB(t);
         m_modSample *= 29204.0f;
         break;
+    case ATVModulationVestigialLSB:
+    case ATVModulationVestigialUSB:
+        m_modSample = modulateVestigialSSB(t);
+        m_modSample *= 29204.0f;
+        break;
     case ATVModulationAM: // AM 90%
     default:
         m_modSample.real((t*1.8f + 0.1f) * 16384.0f); // modulate and scale zero frequency carrier
@@ -219,6 +232,25 @@ Complex& ATVMod::modulateSSB(Real& sample)
     return m_SSBFilterBuffer[m_SSBFilterBufferIndex-1];
 }
 
+Complex& ATVMod::modulateVestigialSSB(Real& sample)
+{
+    int n_out;
+    Complex ci(sample, 0.0f);
+    fftfilt::cmplx *filtered;
+
+    n_out = m_DSBFilter->runVestigial(ci, &filtered, m_running.m_atvModulation == ATVModulationVestigialUSB, 0.15f);
+
+    if (n_out > 0)
+    {
+        memcpy((void *) m_DSBFilterBuffer, (const void *) filtered, n_out*sizeof(Complex));
+        m_DSBFilterBufferIndex = 0;
+    }
+
+    m_DSBFilterBufferIndex++;
+
+    return m_DSBFilterBuffer[m_DSBFilterBufferIndex-1];
+}
+
 void ATVMod::pullVideo(Real& sample)
 {
     int iLine = m_lineCount % m_nbLines2;
@@ -618,6 +650,10 @@ void ATVMod::apply(bool force)
         memset(m_SSBFilterBuffer, 0, sizeof(Complex)*(m_ssbFftLen>>1));
         m_SSBFilterBufferIndex = 0;
 
+        m_DSBFilter->create_dsb_filter(m_config.m_rfBandwidth / m_config.m_outputSampleRate);
+        memset(m_DSBFilterBuffer, 0, sizeof(Complex)*(m_ssbFftLen));
+        m_DSBFilterBufferIndex = 0;
+
         applyStandard(); // set all timings
         m_settingsMutex.unlock();
     }

plugins/channeltx/modatv/atvmod.h

@@ -62,7 +62,9 @@ public:
     	ATVModulationAM,
 		ATVModulationFM,
 		ATVModulationUSB,
-		ATVModulationLSB
+		ATVModulationLSB,
+        ATVModulationVestigialUSB,
+        ATVModulationVestigialLSB
     } ATVModulation;
 
     class MsgConfigureImageFileName : public Message
@@ -532,8 +534,11 @@ private:
     bool m_showOverlayText;
 
     fftfilt* m_SSBFilter;
+    fftfilt* m_DSBFilter;
     Complex* m_SSBFilterBuffer;
+    Complex* m_DSBFilterBuffer;
     int m_SSBFilterBufferIndex;
+    int m_DSBFilterBufferIndex;
     static const int m_ssbFftLen;
 
     static const float m_blackLevel;
@@ -548,6 +553,7 @@ private:
     void calculateLevel(Real& sample);
     void modulateSample();
     Complex& modulateSSB(Real& sample);
+    Complex& modulateVestigialSSB(Real& sample);
     void applyStandard();
     void openImage(const QString& fileName);
     void openVideo(const QString& fileName);

plugins/channeltx/modatv/atvmodgui.cpp

@@ -202,7 +202,9 @@ void ATVModGUI::viewChanged()
 void ATVModGUI::channelizerOutputSampleRateChanged()
 {
     if ((ui->modulation->currentIndex() == (int) ATVMod::ATVModulationLSB) ||
-        (ui->modulation->currentIndex() == (int) ATVMod::ATVModulationUSB))
+        (ui->modulation->currentIndex() == (int) ATVMod::ATVModulationUSB) ||
+        (ui->modulation->currentIndex() == (int) ATVMod::ATVModulationVestigialLSB) ||
+        (ui->modulation->currentIndex() == (int) ATVMod::ATVModulationVestigialUSB))
     {
         ui->rfBW->setMaximum(m_channelizer->getOutputSampleRate() / 200000);
     }
@@ -247,13 +249,15 @@ void ATVModGUI::on_deltaFrequency_changed(quint64 value)
 
 void ATVModGUI::on_modulation_currentIndexChanged(int index)
 {
-    if (index == (int) ATVMod::ATVModulationLSB)
+    if ((index == (int) ATVMod::ATVModulationLSB) ||
+        (index == (int) ATVMod::ATVModulationVestigialLSB))
     {
         ui->rfBW->setMaximum(m_channelizer->getOutputSampleRate() / 200000);
         m_channelMarker.setBandwidth(-ui->rfBW->value()*200000);
         m_channelMarker.setSidebands(ChannelMarker::lsb);
     }
-    else if (index == (int) ATVMod::ATVModulationUSB)
+    else if ((index == (int) ATVMod::ATVModulationUSB) ||
+             (index == (int) ATVMod::ATVModulationVestigialUSB))
     {
         ui->rfBW->setMaximum(m_channelizer->getOutputSampleRate() / 200000);
         m_channelMarker.setBandwidth(ui->rfBW->value()*200000);
@@ -273,11 +277,13 @@ void ATVModGUI::on_rfBW_valueChanged(int value)
 {
 	ui->rfBWText->setText(QString("%1 MHz").arg(value / 10.0, 0, 'f', 1));
 
-    if (ui->modulation->currentIndex() == (int) ATVMod::ATVModulationLSB)
+    if ((ui->modulation->currentIndex() == (int) ATVMod::ATVModulationLSB) ||
+        (ui->modulation->currentIndex() == (int) ATVMod::ATVModulationVestigialLSB))
     {
         m_channelMarker.setBandwidth(-ui->rfBW->value()*200000);
     }
-    else if (ui->modulation->currentIndex() == (int) ATVMod::ATVModulationUSB)
+    else if ((ui->modulation->currentIndex() == (int) ATVMod::ATVModulationUSB) ||
+            (ui->modulation->currentIndex() == (int) ATVMod::ATVModulationVestigialUSB))
     {
         m_channelMarker.setBandwidth(ui->rfBW->value()*200000);
     }

plugins/channeltx/modatv/atvmodgui.ui

@@ -194,7 +194,7 @@
        <widget class="QComboBox" name="modulation">
         <property name="maximumSize">
          <size>
-          <width>50</width>
+          <width>60</width>
           <height>16777215</height>
          </size>
         </property>
@@ -221,6 +221,16 @@
           <string>LSB</string>
          </property>
         </item>
+        <item>
+         <property name="text">
+          <string>VUSB</string>
+         </property>
+        </item>
+        <item>
+         <property name="text">
+          <string>VLSB</string>
+         </property>
+        </item>
        </widget>
       </item>
       <item>

sdrbase/dsp/fftfilt.cxx

@@ -271,6 +271,64 @@ int fftfilt::runDSB(const cmplx & in, cmplx **out)
 	return flen2;
 }
 
+// Version for vestigial sideband. You have to double the FFT size used for SSB.
+int fftfilt::runVestigial(const cmplx & in, cmplx **out, bool usb, float vf)
+{
+    if (vf < 0.0f) vf = 0.0f;
+    if (vf > 1.0f) vf = 1.0f;
+    if (usb) vf = 1.0f - vf;
+
+    data[inptr++] = in;
+    if (inptr < flen2)
+        return 0;
+    inptr = 0;
+
+    fft->ComplexFFT(data);
+
+    data[0] *= filter[0]; // always keep DC
+
+    if (usb)
+    {
+        for (int i = 1; i < flen2; i++)
+        {
+            data[i] *= filter[i]; // usb
+
+            if (i > (int) (vf * flen2)) { // vestigial lsb
+                data[flen2 + i] *= filter[flen2 + i];
+            } else {
+                data[flen2 + i] = 0;
+            }
+        }
+    }
+    else
+    {
+        for (int i = 1; i < flen2; i++)
+        {
+            if (i < (int) (vf * flen2)) { // vestigial usb
+                data[i] *= filter[i];
+            } else {
+                data[i] = 0;
+            }
+
+            data[flen2 + i] *= filter[flen2 + i]; // lsb
+        }
+    }
+
+    // in-place FFT: freqdata overwritten with filtered timedata
+    fft->InverseComplexFFT(data);
+
+    // overlap and add
+    for (int i = 0; i < flen2; i++) {
+        output[i] = ovlbuf[i] + data[i];
+        ovlbuf[i] = data[i+flen2];
+    }
+
+    memset (data, 0, flen * sizeof(cmplx));
+
+    *out = output;
+    return flen2;
+}
+
 /* Sliding FFT from Fldigi */
 
 struct sfft::vrot_bins_pair {

sdrbase/dsp/fftfilt.h

@@ -1,5 +1,5 @@
 /*
- * Filters from Fldigi. 
+ * Filters from Fldigi.
 */
 
 #ifndef	_FFTFILT_H
@@ -28,6 +28,7 @@ public:
 	int runFilt(const cmplx& in, cmplx **out);
 	int runSSB(const cmplx& in, cmplx **out, bool usb, bool getDC = true);
 	int runDSB(const cmplx& in, cmplx **out);
+	int runVestigial(const cmplx & in, cmplx **out, bool usb, float vf);
 
 protected:
 	int flen;
@@ -43,13 +44,13 @@ protected:
 	int window;
 
 	inline float fsinc(float fc, int i, int len) {
-		return (i == len/2) ? 2.0 * fc: 
+		return (i == len/2) ? 2.0 * fc:
 				sin(2 * M_PI * fc * (i - len/2)) / (M_PI * (i - len/2));
 	}
 
 	inline float _blackman(int i, int len) {
-		return (0.42 - 
+		return (0.42 -
-				 0.50 * cos(2.0 * M_PI * i / len) + 
+				 0.50 * cos(2.0 * M_PI * i / len) +
 				 0.08 * cos(4.0 * M_PI * i / len));
 	}