Significantly improved performance of the Qt Gui sinks. This removes a number of redundant loops and memcopies by combining operations and reduces the CPU load greatly to run much more smoothly.

git-svn-id: http://gnuradio.org/svn/gnuradio/trunk@11559 221aa14e-8319-0410-a670-987f0aec2ac5

11 files changed, 184 insertions, 161 deletions

diff --git a/gr-qtgui/src/lib/FrequencyDisplayPlot.cc b/gr-qtgui/src/lib/FrequencyDisplayPlot.cc
index 154c8d234..e299157f5 100644
--- a/gr-qtgui/src/lib/FrequencyDisplayPlot.cc
+++ b/gr-qtgui/src/lib/FrequencyDisplayPlot.cc
@@ -76,7 +76,9 @@ public:
 protected:
   virtual QwtText trackerText( const QwtDoublePoint& p ) const 
   {
-    QwtText t(QString("%1 %2, %3 dB").arg(p.x(), 0, 'f', GetFrequencyPrecision()).arg( (GetFrequencyPrecision() == 0) ? "Hz" : "kHz").arg(p.y(), 0, 'f', 2));
+    QString strunits = (GetFrequencyPrecision() == 0) ? "Hz" : "kHz";
+    QwtText t(QString("%1 %2, %3 dB").arg(p.x(), 0, 'f', 
+					  GetFrequencyPrecision()).arg(strunits).arg(p.y(), 0, 'f', 2));
 
     return t;
   }
@@ -260,10 +262,11 @@ FrequencyDisplayPlot::SetFrequencyRange(const double constStartFreq,
   _stopFrequency = stopFreq;
   _resetXAxisPoints();
 
+  double display_units = ceil(log10(units)/2.0);
   setAxisScale(QwtPlot::xBottom, _startFrequency, _stopFrequency);
-  setAxisScaleDraw(QwtPlot::xBottom, new FreqDisplayScaleDraw(2));
+  setAxisScaleDraw(QwtPlot::xBottom, new FreqDisplayScaleDraw(display_units));
   setAxisTitle(QwtPlot::xBottom, QString("Frequency (%1)").arg(strunits.c_str()));
-  ((FreqDisplayZoomer*)_zoomer)->SetFrequencyPrecision(2);
+  ((FreqDisplayZoomer*)_zoomer)->SetFrequencyPrecision(display_units);
 
   // Load up the new base zoom settings
   _zoomer->setZoomBase();
@@ -339,6 +342,7 @@ FrequencyDisplayPlot::PlotNewData(const double* dataPoints, const int64_t numDat
       ClearMaxData();
       ClearMinData();
     }
+
     memcpy(_dataPoints, dataPoints, numDataPoints*sizeof(double));
     for(int64_t point = 0; point < numDataPoints; point++){
       if(dataPoints[point] < _minFFTPoints[point]){
@@ -369,7 +373,7 @@ void
 FrequencyDisplayPlot::ClearMaxData()
 {
   for(int64_t number = 0; number < _numPoints; number++){
-    _maxFFTPoints[number] = _maxYAxis;
+    _maxFFTPoints[number] = _minYAxis;
   }
 }
 
@@ -377,7 +381,7 @@ void
 FrequencyDisplayPlot::ClearMinData()
 {
   for(int64_t number = 0; number < _numPoints; number++){
-    _minFFTPoints[number] = _minYAxis;
+    _minFFTPoints[number] = _maxYAxis;
   }
 }
 
diff --git a/gr-qtgui/src/lib/SpectrumGUIClass.cc b/gr-qtgui/src/lib/SpectrumGUIClass.cc
index f196d7c5f..34062209e 100644
--- a/gr-qtgui/src/lib/SpectrumGUIClass.cc
+++ b/gr-qtgui/src/lib/SpectrumGUIClass.cc
@@ -30,7 +30,6 @@ SpectrumGUIClass::SpectrumGUIClass(const uint64_t maxDataSize,
   _startFrequency = newStartFrequency;
   _stopFrequency = newStopFrequency;
 
-#warning SPECIFY THIS LATER...
   _windowType = 5;
 
   timespec_reset(&_lastGUIUpdateTime);
diff --git a/gr-qtgui/src/lib/TimeDomainDisplayPlot.cc b/gr-qtgui/src/lib/TimeDomainDisplayPlot.cc
index 42f827d9a..6d8ef6ee4 100644
--- a/gr-qtgui/src/lib/TimeDomainDisplayPlot.cc
+++ b/gr-qtgui/src/lib/TimeDomainDisplayPlot.cc
@@ -44,6 +44,8 @@ TimeDomainDisplayPlot::TimeDomainDisplayPlot(QWidget* parent):QwtPlot(parent){
   _imagDataPoints = new double[_numPoints];
   _xAxisPoints = new double[_numPoints];
 
+  _zoomer = new TimeDomainDisplayZoomer(canvas());
+
   // Disable polygon clipping
   QwtPainter::setDeviceClipping(false);
   
@@ -56,7 +58,7 @@ TimeDomainDisplayPlot::TimeDomainDisplayPlot(QWidget* parent):QwtPlot(parent){
   canvas()->setPalette(palette);  
 
   setAxisScaleEngine(QwtPlot::xBottom, new QwtLinearScaleEngine);
-  setAxisScale(QwtPlot::xBottom, 0, _numPoints);
+  set_xaxis(0, _numPoints);
   setAxisTitle(QwtPlot::xBottom, "Sample Number");
 
   setAxisScaleEngine(QwtPlot::yLeft, new QwtLinearScaleEngine);
@@ -83,7 +85,6 @@ TimeDomainDisplayPlot::TimeDomainDisplayPlot(QWidget* parent):QwtPlot(parent){
 
   replot();
 
-  _zoomer = new TimeDomainDisplayZoomer(canvas());
 #if QT_VERSION < 0x040000
   _zoomer->setMousePattern(QwtEventPattern::MouseSelect2,
 			  Qt::RightButton, Qt::ControlModifier);
@@ -129,8 +130,17 @@ void
 TimeDomainDisplayPlot::set_yaxis(double min, double max)
 {
   setAxisScale(QwtPlot::yLeft, min, max);
+  _zoomer->setZoomBase();
+}
+
+void
+TimeDomainDisplayPlot::set_xaxis(double min, double max)
+{
+  setAxisScale(QwtPlot::xBottom, min, max);
+  _zoomer->setZoomBase();
 }
 
+
 void TimeDomainDisplayPlot::replot(){
 
   const timespec startTime = get_highres_clock();
@@ -146,7 +156,9 @@ void TimeDomainDisplayPlot::replot(){
   }
 }
 
-void TimeDomainDisplayPlot::PlotNewData(const double* realDataPoints, const double* imagDataPoints, const int64_t numDataPoints){
+void TimeDomainDisplayPlot::PlotNewData(const double* realDataPoints,
+					const double* imagDataPoints,
+					const int64_t numDataPoints){
   if(numDataPoints > 0){
 
     if(numDataPoints != _numPoints){
@@ -162,6 +174,8 @@ void TimeDomainDisplayPlot::PlotNewData(const double* realDataPoints, const doub
       _real_plot_curve->setRawData(_xAxisPoints, _realDataPoints, _numPoints);
       _imag_plot_curve->setRawData(_xAxisPoints, _imagDataPoints, _numPoints);
 
+      set_xaxis(0, numDataPoints);
+
       _resetXAxisPoints();
     }
     memcpy(_realDataPoints, realDataPoints, numDataPoints*sizeof(double));
diff --git a/gr-qtgui/src/lib/TimeDomainDisplayPlot.h b/gr-qtgui/src/lib/TimeDomainDisplayPlot.h
index 9c6364af2..56d44539d 100644
--- a/gr-qtgui/src/lib/TimeDomainDisplayPlot.h
+++ b/gr-qtgui/src/lib/TimeDomainDisplayPlot.h
@@ -28,6 +28,7 @@ public:
   virtual void replot();
 
   void set_yaxis(double min, double max);
+  void set_xaxis(double min, double max);
 
 protected slots:
   void LegendEntryChecked(QwtPlotItem *plotItem, bool on);
diff --git a/gr-qtgui/src/lib/qtgui_sink_c.cc b/gr-qtgui/src/lib/qtgui_sink_c.cc
index b1fd60d34..bfb464119 100644
--- a/gr-qtgui/src/lib/qtgui_sink_c.cc
+++ b/gr-qtgui/src/lib/qtgui_sink_c.cc
@@ -78,8 +78,6 @@ qtgui_sink_c::qtgui_sink_c (int fftsize, int wintype,
 
   d_fft = new gri_fft_complex (d_fftsize, true);
 
-  d_fftdata = new gr_complex[d_fftsize];
-
   d_index = 0;
   d_residbuf = new gr_complex[d_fftsize];
 
@@ -91,11 +89,19 @@ qtgui_sink_c::qtgui_sink_c (int fftsize, int wintype,
 qtgui_sink_c::~qtgui_sink_c()
 {
   delete d_object;
-  delete [] d_fftdata;
   delete [] d_residbuf;
   delete d_fft;
 }
 
+void
+qtgui_sink_c::forecast(int noutput_items, gr_vector_int &ninput_items_required)
+{
+  unsigned int ninputs = ninput_items_required.size();
+  for (unsigned int i = 0; i < ninputs; i++) {
+    ninput_items_required[i] = std::min(d_fftsize, 8191);
+  }
+}
+
 void qtgui_sink_c::lock()
 {
   pthread_mutex_lock(&d_pmutex);
@@ -195,7 +201,7 @@ qtgui_sink_c::set_frequency_axis(double min, double max)
 }
 
 void
-qtgui_sink_c::fft(const gr_complex *data_in, int size, gr_complex *data_out)
+qtgui_sink_c::fft(const gr_complex *data_in, int size)
 {
   if (d_window.size()) {
     gr_complex *dst = d_fft->get_inbuf();
@@ -208,20 +214,6 @@ qtgui_sink_c::fft(const gr_complex *data_in, int size, gr_complex *data_out)
   }
 
   d_fft->execute ();     // compute the fft
-
-  for(int i=0; i < size; i++) {
-    d_fft->get_outbuf()[i] /= size;
-  }
-
-  // copy result to our output
-  if(d_shift) {  // apply a fft shift on the data
-    unsigned int len = (unsigned int)(ceil(size/2.0));
-    memcpy(&data_out[0], &d_fft->get_outbuf()[len], sizeof(gr_complex)*(size - len));
-    memcpy(&data_out[size - len], &d_fft->get_outbuf()[0], sizeof(gr_complex)*len);
-  }
-  else {
-    memcpy(data_out, d_fft->get_outbuf(), sizeof(gr_complex)*size);
-  }
 }
 
 void 
@@ -250,10 +242,6 @@ qtgui_sink_c::fftresize()
 
   if(newfftsize != d_fftsize) {
 
-    // Resize the fftdata buffer; no need to preserve old data
-    delete [] d_fftdata;
-    d_fftdata = new gr_complex[newfftsize];
-
     // Resize residbuf and replace data
     delete [] d_residbuf;
     d_residbuf = new gr_complex[newfftsize];
@@ -279,7 +267,7 @@ qtgui_sink_c::general_work (int noutput_items,
 			    gr_vector_const_void_star &input_items,
 			    gr_vector_void_star &output_items)
 {
-  int i=0, j=0;
+  int j=0;
   const gr_complex *in = (const gr_complex*)input_items[0];
 
   pthread_mutex_lock(&d_pmutex);
@@ -287,49 +275,36 @@ qtgui_sink_c::general_work (int noutput_items,
   // Update the FFT size from the application
   fftresize();
   windowreset();
- 
-  const timespec currentTime = get_highres_clock();
-  const timespec lastUpdateGUITime = d_main_gui->GetLastGUIUpdateTime();
 
-  if(diff_timespec(currentTime, lastUpdateGUITime) > 0.05) {
+  for(int i=0; i < noutput_items; i+=d_fftsize) {
+    unsigned int datasize = noutput_items - i;
+    unsigned int resid = d_fftsize-d_index;
 
-    if(d_index) {
-      int filler = std::min(d_fftsize - d_index, noutput_items);
+    // If we have enough input for one full FFT, do it
+    if(datasize >= resid) {
+      const timespec currentTime = get_highres_clock();
       
-      memcpy(&d_residbuf[d_index], &in[0], sizeof(gr_complex)*filler);
-      d_index += filler;
-      i = filler;
-      j = filler;
-    }
-    
-    if(d_index == d_fftsize) {
+      // Fill up residbuf with d_fftsize number of items
+      memcpy(d_residbuf+d_index, &in[j], sizeof(gr_complex)*resid);
       d_index = 0;
-      fft(d_residbuf, d_fftsize, d_fftdata);
+
+      j += resid;
+      fft(d_residbuf, d_fftsize);
       
-      d_main_gui->UpdateWindow(true, d_fftdata, d_fftsize, NULL, 0, 
-			       (float*)d_residbuf, d_fftsize,
-			       1.0/4.0, convert_to_timespec(0.0), true);
-    }
-    
-    for(; i < noutput_items; i+=d_fftsize) {
-      if(noutput_items - i > d_fftsize) {
-	j += d_fftsize;
-	fft(&in[i], d_fftsize, d_fftdata);
-	
-	d_main_gui->UpdateWindow(true, d_fftdata, d_fftsize, NULL, 0, 
-				 (float*)&in[i], d_fftsize,
-				 1.0/4.0, convert_to_timespec(0.0), true);
-      }
-    }
-    
-    if(noutput_items > j) {
-      d_index = noutput_items - j;
-      memcpy(d_residbuf, &in[j], sizeof(gr_complex)*d_index);
+      d_main_gui->UpdateWindow(true, d_fft->get_outbuf(), d_fftsize,
+			       NULL, 0, (float*)d_residbuf, d_fftsize,
+			       1.0/4.0, currentTime, true);
     }
+    // Otherwise, copy what we received into the residbuf for next time
+    else {
+      memcpy(d_residbuf+d_index, &in[j], sizeof(gr_complex)*datasize);
+      d_index += datasize;
+      j += datasize;
+    }   
   }
 
   pthread_mutex_unlock(&d_pmutex);
 
-  consume_each(noutput_items);
-  return noutput_items;
+  consume_each(j);
+  return j;
 }
diff --git a/gr-qtgui/src/lib/qtgui_sink_c.h b/gr-qtgui/src/lib/qtgui_sink_c.h
index 1c9d59200..e36c8c9b0 100644
--- a/gr-qtgui/src/lib/qtgui_sink_c.h
+++ b/gr-qtgui/src/lib/qtgui_sink_c.h
@@ -63,6 +63,8 @@ private:
 		bool use_openGL,
 		QWidget *parent);
 
+  void forecast(int noutput_items, gr_vector_int &ninput_items_required);
+
   // use opengl to force OpenGL on or off
   // this might be necessary for sessions over SSH
   void initialize(const bool opengl=true);
@@ -78,7 +80,6 @@ private:
 
   bool d_shift;
   gri_fft_complex *d_fft;
-  gr_complex *d_fftdata;
 
   int d_index;
   gr_complex *d_residbuf;
@@ -91,7 +92,7 @@ private:
   void windowreset();
   void buildwindow();
   void fftresize();
-  void fft(const gr_complex *data_in, int size, gr_complex *data_out);
+  void fft(const gr_complex *data_in, int size);
   
 public:
   ~qtgui_sink_c();
diff --git a/gr-qtgui/src/lib/qtgui_sink_f.cc b/gr-qtgui/src/lib/qtgui_sink_f.cc
index 4c526f09f..d0ce24274 100644
--- a/gr-qtgui/src/lib/qtgui_sink_f.cc
+++ b/gr-qtgui/src/lib/qtgui_sink_f.cc
@@ -78,8 +78,6 @@ qtgui_sink_f::qtgui_sink_f (int fftsize, int wintype,
 
   d_fft = new gri_fft_complex (d_fftsize, true);
 
-  d_fftdata = new gr_complex[d_fftsize];
-
   d_index = 0;
   d_residbuf = new float[d_fftsize];
 
@@ -91,11 +89,19 @@ qtgui_sink_f::qtgui_sink_f (int fftsize, int wintype,
 qtgui_sink_f::~qtgui_sink_f()
 {
   delete d_object;
-  delete [] d_fftdata;
   delete [] d_residbuf;
   delete d_fft;
 }
 
+void
+qtgui_sink_f::forecast(int noutput_items, gr_vector_int &ninput_items_required)
+{
+  unsigned int ninputs = ninput_items_required.size();
+  for (unsigned int i = 0; i < ninputs; i++) {
+    ninput_items_required[i] = std::min(d_fftsize, 8191);
+  }
+}
+
 void qtgui_sink_f::lock()
 {
   pthread_mutex_lock(&d_pmutex);
@@ -189,7 +195,7 @@ qtgui_sink_f::set_frequency_axis(double min, double max)
 }
 
 void
-qtgui_sink_f::fft(const float *data_in, int size, gr_complex *data_out)
+qtgui_sink_f::fft(const float *data_in, int size)
 {
   if (d_window.size()) {
     gr_complex *dst = d_fft->get_inbuf();
@@ -203,20 +209,6 @@ qtgui_sink_f::fft(const float *data_in, int size, gr_complex *data_out)
   }
   
   d_fft->execute ();     // compute the fft
-
-  for(int i=0; i < size; i++) {
-    d_fft->get_outbuf()[i] /= size;
-  }
-
-  // copy result to our output
-  if(d_shift) {  // apply a fft shift on the data
-    unsigned int len = (unsigned int)(ceil(size/2.0));
-    memcpy(&data_out[0], &d_fft->get_outbuf()[len], sizeof(gr_complex)*(size - len));
-    memcpy(&data_out[size - len], &d_fft->get_outbuf()[0], sizeof(gr_complex)*len);
-  }
-  else {
-    memcpy(data_out, d_fft->get_outbuf(), sizeof(gr_complex)*size);
-  }
 }
 
 void 
@@ -245,10 +237,6 @@ qtgui_sink_f::fftresize()
 
   if(newfftsize != d_fftsize) {
 
-    // Resize the fftdata buffer; no need to preserve old data
-    delete [] d_fftdata;
-    d_fftdata = new gr_complex[newfftsize];
-
     // Resize residbuf and replace data
     delete [] d_residbuf;
     d_residbuf = new float[newfftsize];
@@ -274,46 +262,44 @@ qtgui_sink_f::general_work (int noutput_items,
 			    gr_vector_const_void_star &input_items,
 			    gr_vector_void_star &output_items)
 {
-  int i=0, j=0;
+  int j=0;
   const float *in = (const float*)input_items[0];
 
   pthread_mutex_lock(&d_pmutex);
 
-  if(d_index) {
-    int filler = std::min(d_fftsize - d_index, noutput_items);
-    memcpy(&d_residbuf[d_index], &in[0], sizeof(float)*filler);
-    d_index += filler;
-    i = filler;
-    j = filler;
-  }
+  // Update the FFT size from the application
+  fftresize();
+  windowreset();
 
-  if(d_index == d_fftsize) {
-    d_index = 0;
-    fft(d_residbuf, d_fftsize, d_fftdata);
-    
-    d_main_gui->UpdateWindow(true, d_fftdata, d_fftsize,
-			     d_residbuf, d_fftsize, NULL, 0,
-			     1.0/4.0, convert_to_timespec(0.0), true);
-  }
-  
-  for(; i < noutput_items; i+=d_fftsize) {
-    if(noutput_items - i > d_fftsize) {
-      j += d_fftsize;
-      fft(&in[i], d_fftsize, d_fftdata);
+  for(int i=0; i < noutput_items; i+=d_fftsize) {
+    unsigned int datasize = noutput_items - i;
+    unsigned int resid = d_fftsize-d_index;
+
+    // If we have enough input for one full FFT, do it
+    if(datasize >= resid) {
+      const timespec currentTime = get_highres_clock();
       
-      d_main_gui->UpdateWindow(true, d_fftdata, d_fftsize, &in[i],
-			       d_fftsize, NULL, 0, 1.0/4.0,
-			       convert_to_timespec(0.0), true);
-    }
-  }
+      // Fill up residbuf with d_fftsize number of items
+      memcpy(d_residbuf+d_index, &in[j], sizeof(float)*resid);
+      d_index = 0;
 
-  if(noutput_items > j) {
-    d_index = noutput_items - j;
-    memcpy(d_residbuf, &in[j], sizeof(float)*d_index);
+      j += resid;
+      fft(d_residbuf, d_fftsize);
+      
+      d_main_gui->UpdateWindow(true, d_fft->get_outbuf(), d_fftsize,
+			       (float*)d_residbuf, d_fftsize, NULL, 0,
+			       1.0/4.0, currentTime, true);
+    }
+    // Otherwise, copy what we received into the residbuf for next time
+    else {
+      memcpy(d_residbuf+d_index, &in[j], sizeof(float)*datasize);
+      d_index += datasize;
+      j += datasize;
+    }   
   }
 
   pthread_mutex_unlock(&d_pmutex);
 
-  consume_each(noutput_items);
-  return noutput_items;
+  consume_each(j);
+  return j;
 }
diff --git a/gr-qtgui/src/lib/qtgui_sink_f.h b/gr-qtgui/src/lib/qtgui_sink_f.h
index 4c24b4983..027b89bea 100644
--- a/gr-qtgui/src/lib/qtgui_sink_f.h
+++ b/gr-qtgui/src/lib/qtgui_sink_f.h
@@ -63,6 +63,8 @@ private:
 		bool use_openGL,
 		QWidget *parent);
 
+  void forecast(int noutput_items, gr_vector_int &ninput_items_required);
+
   void initialize(const bool opengl=true);
 
   int d_fftsize;
@@ -76,7 +78,6 @@ private:
 
   bool d_shift;
   gri_fft_complex *d_fft;
-  gr_complex *d_fftdata;
 
   int d_index;
   float *d_residbuf;
@@ -89,7 +90,7 @@ private:
   void windowreset();
   void buildwindow();
   void fftresize();
-  void fft(const float *data_in, int size, gr_complex *data_out);
+  void fft(const float *data_in, int size);
   
 public:
   ~qtgui_sink_f();
diff --git a/gr-qtgui/src/lib/spectrumdisplayform.cc b/gr-qtgui/src/lib/spectrumdisplayform.cc
index 427e70a27..36097d975 100644
--- a/gr-qtgui/src/lib/spectrumdisplayform.cc
+++ b/gr-qtgui/src/lib/spectrumdisplayform.cc
@@ -110,6 +110,7 @@ SpectrumDisplayForm::setSystem( SpectrumGUIClass * newSystem,
 void
 SpectrumDisplayForm::newFrequencyData( const SpectrumUpdateEvent* spectrumUpdateEvent)
 {
+  //_lastSpectrumEvent = (SpectrumUpdateEvent)(*spectrumUpdateEvent);
   const std::complex<float>* complexDataPoints = spectrumUpdateEvent->getFFTPoints();
   const uint64_t numFFTDataPoints = spectrumUpdateEvent->getNumFFTDataPoints();
   const double* realTimeDomainDataPoints = spectrumUpdateEvent->getRealTimeDomainPoints();
@@ -125,23 +126,34 @@ SpectrumDisplayForm::newFrequencyData( const SpectrumUpdateEvent* spectrumUpdate
   ResizeBuffers(numFFTDataPoints, numTimeDomainDataPoints);
 
   // Calculate the Magnitude of the complex point
-  const std::complex<float>* complexDataPointsPtr = complexDataPoints;
+  const std::complex<float>* complexDataPointsPtr = complexDataPoints+numFFTDataPoints/2;
   double* realFFTDataPointsPtr = _realFFTDataPoints;
-  for(uint64_t point = 0; point < numFFTDataPoints; point++){
+
+  // Run this twice to perform the fftshift operation on the data here as well
+  for(uint64_t point = 0; point < numFFTDataPoints/2; point++){
     // Calculate dBm
     // 50 ohm load assumption
     // 10 * log10 (v^2 / (2 * 50.0 * .001)) = 10 * log10( v^2 * 10)
     // 75 ohm load assumption
     // 10 * log10 (v^2 / (2 * 75.0 * .001)) = 10 * log10( v^2 * 15)
-    
-    *realFFTDataPointsPtr = 10.0*log10((((*complexDataPointsPtr).real() * (*complexDataPointsPtr).real()) +
-					((*complexDataPointsPtr).imag()*(*complexDataPointsPtr).imag())) + 1e-20);
+
+    // perform scaling here
+    std::complex<float> pt = (*complexDataPointsPtr) / std::complex<float>((float)numFFTDataPoints);
+    *realFFTDataPointsPtr = 10.0*log10((pt.real() * pt.real() + pt.imag()*pt.imag()) + 1e-20);
+
+    complexDataPointsPtr++;
+    realFFTDataPointsPtr++;
+  }
+  
+  // This loop takes the first half of the input data and puts it in the second half of the plotted data
+  complexDataPointsPtr = complexDataPoints;
+  for(uint64_t point = 0; point < numFFTDataPoints/2; point++){
+    std::complex<float> pt = (*complexDataPointsPtr) / std::complex<float>((float)numFFTDataPoints);
+    *realFFTDataPointsPtr = 10.0*log10((pt.real() * pt.real() + pt.imag()*pt.imag()) + 1e-20);
 
     complexDataPointsPtr++;
     realFFTDataPointsPtr++;
   }
- 
-  int tabindex = SpectrumTypeTab->currentIndex();
 
   // Don't update the averaging history if this is repeated data
   if(!repeatDataFlag){
@@ -157,7 +169,8 @@ SpectrumDisplayForm::newFrequencyData( const SpectrumUpdateEvent* spectrumUpdate
     for(uint64_t number = 0; number < numFFTDataPoints; number++){
       // find peak
       if(_realFFTDataPoints[number] > _peakAmplitude){
-        _peakFrequency = (static_cast<float>(number) * fft_bin_size);  // Calculate the frequency relative to the local bw, adjust for _startFrequency later
+	// Calculate the frequency relative to the local bw, adjust for _startFrequency later
+        _peakFrequency = (static_cast<float>(number) * fft_bin_size);
         _peakAmplitude = _realFFTDataPoints[number];
         // _peakBin = number;
       }
@@ -187,6 +200,7 @@ SpectrumDisplayForm::newFrequencyData( const SpectrumUpdateEvent* spectrumUpdate
   }
 
   if(lastOfMultipleUpdatesFlag){
+    int tabindex = SpectrumTypeTab->currentIndex();
     if(tabindex == d_plot_fft) {
       _frequencyDisplayPlot->PlotNewData(_averagedValues, numFFTDataPoints, 
 					 _noiseFloorAmplitude, _peakFrequency, 
@@ -219,6 +233,7 @@ SpectrumDisplayForm::newFrequencyData( const SpectrumUpdateEvent* spectrumUpdate
       }
     }
 
+    
     // Tell the system the GUI has been updated
     if(_systemSpecifiedFlag){
       _system->SetLastGUIUpdateTime(generatedTimestamp);
@@ -449,6 +464,13 @@ SpectrumDisplayForm::MaxHoldResetBtn_clicked()
 
 
 void
+SpectrumDisplayForm::TabChanged(int index)
+{
+  _frequencyDisplayPlot->replot();
+  
+}
+
+void
 SpectrumDisplayForm::PowerLineEdit_textChanged( const QString &valueString )
 {
   if(_systemSpecifiedFlag){
diff --git a/gr-qtgui/src/lib/spectrumdisplayform.h b/gr-qtgui/src/lib/spectrumdisplayform.h
index bf8023209..dbbf2567e 100644
--- a/gr-qtgui/src/lib/spectrumdisplayform.h
+++ b/gr-qtgui/src/lib/spectrumdisplayform.h
@@ -41,6 +41,8 @@ public slots:
   void MinHoldCheckBox_toggled( bool newState );
   void MinHoldResetBtn_clicked();
   void MaxHoldResetBtn_clicked();
+  void TabChanged(int index);
+
   void PowerLineEdit_textChanged( const QString& valueString );
   void SetFrequencyRange( const double newCenterFrequency,
 			  const double newStartFrequency,
@@ -99,7 +101,9 @@ private:
   double _peakAmplitude;
   static int _openGLWaterfall3DFlag;
   double _stopFrequency;
-
+  
+  //SpectrumUpdateEvent _lastSpectrumEvent;
+  
   // whether or not to use a particular display
   int d_plot_fft;
   int d_plot_waterfall;
diff --git a/gr-qtgui/src/lib/spectrumdisplayform.ui b/gr-qtgui/src/lib/spectrumdisplayform.ui
index 96096030d..9324f150b 100644
--- a/gr-qtgui/src/lib/spectrumdisplayform.ui
+++ b/gr-qtgui/src/lib/spectrumdisplayform.ui
@@ -729,8 +729,8 @@
    <slot>MaxHoldCheckBox_toggled(bool)</slot>
    <hints>
     <hint type="sourcelabel" >
-     <x>20</x>
-     <y>20</y>
+     <x>22</x>
+     <y>324</y>
     </hint>
     <hint type="destinationlabel" >
      <x>20</x>
@@ -745,8 +745,8 @@
    <slot>MaxHoldResetBtn_clicked()</slot>
    <hints>
     <hint type="sourcelabel" >
-     <x>20</x>
-     <y>20</y>
+     <x>107</x>
+     <y>324</y>
     </hint>
     <hint type="destinationlabel" >
      <x>20</x>
@@ -761,8 +761,8 @@
    <slot>MinHoldCheckBox_toggled(bool)</slot>
    <hints>
     <hint type="sourcelabel" >
-     <x>20</x>
-     <y>20</y>
+     <x>22</x>
+     <y>349</y>
     </hint>
     <hint type="destinationlabel" >
      <x>20</x>
@@ -777,8 +777,8 @@
    <slot>MinHoldResetBtn_clicked()</slot>
    <hints>
     <hint type="sourcelabel" >
-     <x>20</x>
-     <y>20</y>
+     <x>107</x>
+     <y>349</y>
     </hint>
     <hint type="destinationlabel" >
      <x>20</x>
@@ -793,8 +793,8 @@
    <slot>AvgLineEdit_textChanged(QString)</slot>
    <hints>
     <hint type="sourcelabel" >
-     <x>20</x>
-     <y>20</y>
+     <x>552</x>
+     <y>344</y>
     </hint>
     <hint type="destinationlabel" >
      <x>20</x>
@@ -809,8 +809,8 @@
    <slot>PowerLineEdit_textChanged(QString)</slot>
    <hints>
     <hint type="sourcelabel" >
-     <x>20</x>
-     <y>20</y>
+     <x>482</x>
+     <y>344</y>
     </hint>
     <hint type="destinationlabel" >
      <x>20</x>
@@ -857,8 +857,8 @@
    <slot>waterfallMaximumIntensityChangedCB(double)</slot>
    <hints>
     <hint type="sourcelabel" >
-     <x>20</x>
-     <y>20</y>
+     <x>217</x>
+     <y>44</y>
     </hint>
     <hint type="destinationlabel" >
      <x>20</x>
@@ -873,8 +873,8 @@
    <slot>waterfallMinimumIntensityChangedCB(double)</slot>
    <hints>
     <hint type="sourcelabel" >
-     <x>20</x>
-     <y>20</y>
+     <x>217</x>
+     <y>349</y>
     </hint>
     <hint type="destinationlabel" >
      <x>20</x>
@@ -889,8 +889,8 @@
    <slot>waterfall3DMaximumIntensityChangedCB(double)</slot>
    <hints>
     <hint type="sourcelabel" >
-     <x>20</x>
-     <y>20</y>
+     <x>217</x>
+     <y>44</y>
     </hint>
     <hint type="destinationlabel" >
      <x>20</x>
@@ -905,8 +905,8 @@
    <slot>waterfall3DMinimumIntensityChangedCB(double)</slot>
    <hints>
     <hint type="sourcelabel" >
-     <x>20</x>
-     <y>20</y>
+     <x>217</x>
+     <y>349</y>
     </hint>
     <hint type="destinationlabel" >
      <x>20</x>
@@ -937,8 +937,8 @@
    <slot>WaterfallAutoScaleBtnCB()</slot>
    <hints>
     <hint type="sourcelabel" >
-     <x>20</x>
-     <y>20</y>
+     <x>22</x>
+     <y>349</y>
     </hint>
     <hint type="destinationlabel" >
      <x>20</x>
@@ -953,8 +953,8 @@
    <slot>Waterfall3DAutoScaleBtnCB()</slot>
    <hints>
     <hint type="sourcelabel" >
-     <x>20</x>
-     <y>20</y>
+     <x>22</x>
+     <y>349</y>
     </hint>
     <hint type="destinationlabel" >
      <x>20</x>
@@ -969,8 +969,8 @@
    <slot>WaterfallIntensityColorTypeChanged(int)</slot>
    <hints>
     <hint type="sourcelabel" >
-     <x>20</x>
-     <y>20</y>
+     <x>92</x>
+     <y>44</y>
     </hint>
     <hint type="destinationlabel" >
      <x>20</x>
@@ -985,8 +985,8 @@
    <slot>Waterfall3DIntensityColorTypeChanged(int)</slot>
    <hints>
     <hint type="sourcelabel" >
-     <x>20</x>
-     <y>20</y>
+     <x>92</x>
+     <y>44</y>
     </hint>
     <hint type="destinationlabel" >
      <x>20</x>
@@ -994,5 +994,21 @@
     </hint>
    </hints>
   </connection>
+  <connection>
+   <sender>SpectrumTypeTab</sender>
+   <signal>currentChanged(int)</signal>
+   <receiver>SpectrumDisplayForm</receiver>
+   <slot>TabChanged(int)</slot>
+   <hints>
+    <hint type="sourcelabel" >
+     <x>314</x>
+     <y>189</y>
+    </hint>
+    <hint type="destinationlabel" >
+     <x>316</x>
+     <y>217</y>
+    </hint>
+   </hints>
+  </connection>
  </connections>
 </ui>