Fixes the replotting update. It's now based on a QTimer so it's in the event buffer as opposed to a best effort based on a hand-made timer. The interval between GUI updates is settable through the qtsink_X objects with set_update_time(newtime). This update makes the plotting much more stable. It also fixes the time scale of the waterfall plot to actually mean the right thing.

18 files changed, 114 insertions, 145 deletions

diff --git a/gr-qtgui/src/lib/ConstellationDisplayPlot.cc b/gr-qtgui/src/lib/ConstellationDisplayPlot.cc
index 80bf4503f..4e6d6da18 100644
--- a/gr-qtgui/src/lib/ConstellationDisplayPlot.cc
+++ b/gr-qtgui/src/lib/ConstellationDisplayPlot.cc
@@ -39,8 +39,6 @@ ConstellationDisplayPlot::ConstellationDisplayPlot(QWidget* parent)
 
   resize(parent->width(), parent->height());
 
-  _displayIntervalTime = (1.0/10.0); // 1/10 of a second between updates
-
   _numPoints = 1024;
   _penSize = 5;
   _realDataPoints = new double[_numPoints];
@@ -148,19 +146,9 @@ ConstellationDisplayPlot::set_axis(double xmin, double xmax,
   set_yaxis(ymin, ymax);
 }
 
-void ConstellationDisplayPlot::replot(){
-
-  const timespec startTime = get_highres_clock();
-  
+void ConstellationDisplayPlot::replot()
+{
   QwtPlot::replot();
-
-  double differenceTime = (diff_timespec(get_highres_clock(), startTime));
-
-  differenceTime *= 99.0;
-  // Require at least a 10% duty cycle
-  if(differenceTime > (1.0/10.0)){
-    _displayIntervalTime = differenceTime;
-  }
 }
 
 void
@@ -171,10 +159,12 @@ ConstellationDisplayPlot::resizeSlot( QSize *s )
 
 void ConstellationDisplayPlot::PlotNewData(const double* realDataPoints,
 					   const double* imagDataPoints,
-					   const int64_t numDataPoints)
+					   const int64_t numDataPoints,
+					   const double timeInterval)
 {
-  if(numDataPoints > 0){
-
+  if((numDataPoints > 0) && 
+     (diff_timespec(get_highres_clock(), _lastReplot) > timeInterval)) {
+    
     if(numDataPoints != _numPoints){
       _numPoints = numDataPoints;
 
@@ -185,17 +175,12 @@ void ConstellationDisplayPlot::PlotNewData(const double* realDataPoints,
       
       _plot_curve->setRawData(_realDataPoints, _imagDataPoints, _numPoints);
     }
+
     memcpy(_realDataPoints, realDataPoints, numDataPoints*sizeof(double));
     memcpy(_imagDataPoints, imagDataPoints, numDataPoints*sizeof(double));
 
-  }
-
-  // Allow at least a 50% duty cycle
-  if(diff_timespec(get_highres_clock(), _lastReplot) > _displayIntervalTime){
-    // Only replot the screen if it is visible
-    if(isVisible()){
-      replot();
-    }
+    replot();
+    
     _lastReplot = get_highres_clock();
   }
 }
diff --git a/gr-qtgui/src/lib/ConstellationDisplayPlot.h b/gr-qtgui/src/lib/ConstellationDisplayPlot.h
index 99ae566e0..a441a8bfe 100644
--- a/gr-qtgui/src/lib/ConstellationDisplayPlot.h
+++ b/gr-qtgui/src/lib/ConstellationDisplayPlot.h
@@ -24,7 +24,8 @@ public:
 
   void PlotNewData(const double* realDataPoints, 
 		   const double* imagDataPoints, 
-		   const int64_t numDataPoints);
+		   const int64_t numDataPoints,
+		   const double timeInterval);
     
   virtual void replot();
 
@@ -55,8 +56,6 @@ private:
 
   int64_t _numPoints;
   int64_t _penSize;
-
-  double _displayIntervalTime;
 };
 
 #endif /* CONSTELLATION_DISPLAY_PLOT_HPP */
diff --git a/gr-qtgui/src/lib/FrequencyDisplayPlot.cc b/gr-qtgui/src/lib/FrequencyDisplayPlot.cc
index 5e74dce40..6f09bbc88 100644
--- a/gr-qtgui/src/lib/FrequencyDisplayPlot.cc
+++ b/gr-qtgui/src/lib/FrequencyDisplayPlot.cc
@@ -101,8 +101,6 @@ FrequencyDisplayPlot::FrequencyDisplayPlot(QWidget* parent)
 
   resize(parent->width(), parent->height());
   
-  _displayIntervalTime = (1.0/10.0); // 1/10 of a second between updates
-
   _useCenterFrequencyFlag = false;
 
   _numPoints = 1024;
@@ -299,8 +297,6 @@ FrequencyDisplayPlot::GetStopFrequency() const
 void
 FrequencyDisplayPlot::replot()
 {
-  const timespec startTime = get_highres_clock();
-
   _markerNoiseFloorAmplitude->setYValue(_noiseFloorAmplitude);
   
   // Make sure to take into account the start frequency
@@ -313,14 +309,6 @@ FrequencyDisplayPlot::replot()
   _markerPeakAmplitude->setYValue(_peakAmplitude);
   
   QwtPlot::replot();
-
-  double differenceTime = (diff_timespec(get_highres_clock(), startTime));
-
-  differenceTime *= 99.0;
-  // Require at least a 10% duty cycle
-  if(differenceTime > (1.0/10.0)){
-    _displayIntervalTime = differenceTime;
-  }
 }
  
 void
@@ -332,13 +320,15 @@ FrequencyDisplayPlot::resizeSlot( QSize *s )
 void
 FrequencyDisplayPlot::PlotNewData(const double* dataPoints, const int64_t numDataPoints,
 				  const double noiseFloorAmplitude, const double peakFrequency,
-				  const double peakAmplitude)
+				  const double peakAmplitude, const double timeInterval)
 {
-  if(numDataPoints > 0){
-
-    if(numDataPoints != _numPoints){
+  // Only update plot if there is data and if the time interval has elapsed
+  if((numDataPoints > 0) && 
+     (diff_timespec(get_highres_clock(), _lastReplot) > timeInterval)) {
+    
+    if(numDataPoints != _numPoints) {
       _numPoints = numDataPoints;
-
+      
       delete[] _dataPoints;
       delete[] _minFFTPoints;
       delete[] _maxFFTPoints;
@@ -351,12 +341,12 @@ FrequencyDisplayPlot::PlotNewData(const double* dataPoints, const int64_t numDat
       _fft_plot_curve->setRawData(_xAxisPoints, _dataPoints, _numPoints);
       _min_fft_plot_curve->setRawData(_xAxisPoints, _minFFTPoints, _numPoints);
       _max_fft_plot_curve->setRawData(_xAxisPoints, _maxFFTPoints, _numPoints);
-
+      
       _resetXAxisPoints();
       ClearMaxData();
       ClearMinData();
     }
-
+    
     memcpy(_dataPoints, dataPoints, numDataPoints*sizeof(double));
     for(int64_t point = 0; point < numDataPoints; point++){
       if(dataPoints[point] < _minFFTPoints[point]){
@@ -372,14 +362,9 @@ FrequencyDisplayPlot::PlotNewData(const double* dataPoints, const int64_t numDat
     _peakAmplitude = peakAmplitude;
 
     SetUpperIntensityLevel(_peakAmplitude);
-  }
 
-  // Allow at least a 50% duty cycle
-  if(diff_timespec(get_highres_clock(), _lastReplot) > _displayIntervalTime){
-    // Only replot the screen if it is visible
-    if(isVisible()){
-      replot();
-    }
+    replot();
+    
     _lastReplot = get_highres_clock();
   }
 }
diff --git a/gr-qtgui/src/lib/FrequencyDisplayPlot.h b/gr-qtgui/src/lib/FrequencyDisplayPlot.h
index 785efe694..c78e1667e 100644
--- a/gr-qtgui/src/lib/FrequencyDisplayPlot.h
+++ b/gr-qtgui/src/lib/FrequencyDisplayPlot.h
@@ -30,7 +30,7 @@ public:
 
   void PlotNewData(const double* dataPoints, const int64_t numDataPoints,
 		   const double noiseFloorAmplitude, const double peakFrequency,
-		   const double peakAmplitude);
+		   const double peakAmplitude, const double timeInterval);
   
   void ClearMaxData();
   void ClearMinData();
@@ -86,8 +86,6 @@ private:
   timespec _lastReplot;
 
   bool _useCenterFrequencyFlag;
-
-  double _displayIntervalTime;
 };
 
 #endif /* FREQUENCY_DISPLAY_PLOT_HPP */
diff --git a/gr-qtgui/src/lib/SpectrumGUIClass.cc b/gr-qtgui/src/lib/SpectrumGUIClass.cc
index 4cb71a31a..8c1b36703 100644
--- a/gr-qtgui/src/lib/SpectrumGUIClass.cc
+++ b/gr-qtgui/src/lib/SpectrumGUIClass.cc
@@ -111,7 +111,7 @@ SpectrumGUIClass::OpenSpectrumWindow(QWidget* parent,
   timespec_reset(&_lastGUIUpdateTime);
 
   // Draw Blank Display
-  UpdateWindow(false, NULL, 0, NULL, 0, NULL, 0, 1.0, get_highres_clock(), true);
+  UpdateWindow(false, NULL, 0, NULL, 0, NULL, 0, get_highres_clock(), true);
 
   // Set up the initial frequency axis settings
   SetFrequencyRange(_centerFrequency, _startFrequency, _stopFrequency);
@@ -220,7 +220,6 @@ SpectrumGUIClass::UpdateWindow(const bool updateDisplayFlag,
 			       const uint64_t realTimeDomainDataSize,
 			       const float* complexTimeDomainData,
 			       const uint64_t complexTimeDomainDataSize,
-			       const double timePerFFT,
 			       const timespec timestamp,
 			       const bool lastOfMultipleFFTUpdateFlag)
 {
@@ -277,7 +276,7 @@ SpectrumGUIClass::UpdateWindow(const bool updateDisplayFlag,
   const timespec currentTime = get_highres_clock();
   const timespec lastUpdateGUITime = GetLastGUIUpdateTime();
 
-  if((diff_timespec(currentTime, lastUpdateGUITime) > (4*timePerFFT)) &&
+  if((diff_timespec(currentTime, lastUpdateGUITime) > (4*_updateTime)) &&
      (GetPendingGUIUpdateEvents() > 0) && !timespec_empty(&lastUpdateGUITime)) {
     // Do not update the display if too much data is pending to be displayed
     _droppedEntriesCount++;
@@ -290,7 +289,7 @@ SpectrumGUIClass::UpdateWindow(const bool updateDisplayFlag,
 					    _realTimeDomainPoints,
 					    _imagTimeDomainPoints,
 					    timeDomainBufferSize,
-					    timePerFFT, timestamp,
+					    timestamp,
 					    repeatDataFlag,
 					    lastOfMultipleFFTUpdateFlag,
 					    currentTime,
@@ -460,4 +459,12 @@ SpectrumGUIClass::SetFrequencyAxis(double min, double max)
   _spectrumDisplayForm->SetFrequencyAxis(min, max);
 }
 
+void
+SpectrumGUIClass::SetUpdateTime(double t)
+{
+  _updateTime = t;
+  _spectrumDisplayForm->SetUpdateTime(_updateTime);
+}
+
+
 #endif /* SPECTRUM_GUI_CLASS_CPP */
diff --git a/gr-qtgui/src/lib/SpectrumGUIClass.h b/gr-qtgui/src/lib/SpectrumGUIClass.h
index d8dcb2769..17d3a54c1 100644
--- a/gr-qtgui/src/lib/SpectrumGUIClass.h
+++ b/gr-qtgui/src/lib/SpectrumGUIClass.h
@@ -47,7 +47,7 @@ public:
   void UpdateWindow(const bool, const std::complex<float>*,
 		    const uint64_t, const float*,
 		    const uint64_t, const float*,
-		    const uint64_t, const double,
+		    const uint64_t,
 		    const timespec, const bool);
 
   float GetPowerValue()const;
@@ -79,6 +79,8 @@ public:
   void SetConstellationPenSize(int size);
   void SetFrequencyAxis(double min, double max);
 
+  void SetUpdateTime(double t);
+
 protected:
 
 private:
@@ -98,6 +100,7 @@ private:
   unsigned int _pendingGUIUpdateEventsCount;
   int _droppedEntriesCount;
   bool _fftBuffersCreatedFlag;
+  double _updateTime;
 
   SpectrumDisplayForm* _spectrumDisplayForm;
 
diff --git a/gr-qtgui/src/lib/TimeDomainDisplayPlot.cc b/gr-qtgui/src/lib/TimeDomainDisplayPlot.cc
index cb18b4418..708ac1661 100644
--- a/gr-qtgui/src/lib/TimeDomainDisplayPlot.cc
+++ b/gr-qtgui/src/lib/TimeDomainDisplayPlot.cc
@@ -32,13 +32,12 @@ protected:
   }
 };
 
-TimeDomainDisplayPlot::TimeDomainDisplayPlot(QWidget* parent):QwtPlot(parent){
+TimeDomainDisplayPlot::TimeDomainDisplayPlot(QWidget* parent):QwtPlot(parent)
+{
   timespec_reset(&_lastReplot);
 
   resize(parent->width(), parent->height());
 
-  _displayIntervalTime = (1.0/10.0); // 1/10 of a second between updates
-
   _numPoints = 1024;
   _realDataPoints = new double[_numPoints];
   _imagDataPoints = new double[_numPoints];
@@ -114,7 +113,8 @@ TimeDomainDisplayPlot::TimeDomainDisplayPlot(QWidget* parent):QwtPlot(parent){
   legendDisplay->setItemMode(QwtLegend::CheckableItem);
   insertLegend(legendDisplay);
 
-  connect(this, SIGNAL( legendChecked(QwtPlotItem *, bool ) ), this, SLOT( LegendEntryChecked(QwtPlotItem *, bool ) ));
+  connect(this, SIGNAL( legendChecked(QwtPlotItem *, bool ) ), 
+	  this, SLOT( LegendEntryChecked(QwtPlotItem *, bool ) ));
 }
 
 TimeDomainDisplayPlot::~TimeDomainDisplayPlot(){
@@ -143,17 +143,7 @@ TimeDomainDisplayPlot::set_xaxis(double min, double max)
 
 void TimeDomainDisplayPlot::replot()
 {
-  const timespec startTime = get_highres_clock();
-  
   QwtPlot::replot();
-
-  double differenceTime = (diff_timespec(get_highres_clock(), startTime));
-
-  differenceTime *= 99.0;
-  // Require at least a 10% duty cycle
-  if(differenceTime > (1.0/10.0)){
-    _displayIntervalTime = differenceTime;
-  }
 }
 
 void
@@ -164,10 +154,12 @@ TimeDomainDisplayPlot::resizeSlot( QSize *s )
 
 void TimeDomainDisplayPlot::PlotNewData(const double* realDataPoints,
 					const double* imagDataPoints,
-					const int64_t numDataPoints)
+					const int64_t numDataPoints,
+					const double timeInterval)
 {
-  if(numDataPoints > 0){
-
+  if((numDataPoints > 0) && 
+     (diff_timespec(get_highres_clock(), _lastReplot) > timeInterval)) {
+  
     if(numDataPoints != _numPoints){
       _numPoints = numDataPoints;
 
@@ -185,17 +177,12 @@ void TimeDomainDisplayPlot::PlotNewData(const double* realDataPoints,
 
       _resetXAxisPoints();
     }
+
     memcpy(_realDataPoints, realDataPoints, numDataPoints*sizeof(double));
     memcpy(_imagDataPoints, imagDataPoints, numDataPoints*sizeof(double));
 
-  }
+    replot();
 
-  // Allow at least a 50% duty cycle
-  if(diff_timespec(get_highres_clock(), _lastReplot) > _displayIntervalTime){
-    // Only replot the screen if it is visible
-    if(isVisible()){
-      replot();
-    }
     _lastReplot = get_highres_clock();
   }
 }
diff --git a/gr-qtgui/src/lib/TimeDomainDisplayPlot.h b/gr-qtgui/src/lib/TimeDomainDisplayPlot.h
index 8d98abac6..88f97cb80 100644
--- a/gr-qtgui/src/lib/TimeDomainDisplayPlot.h
+++ b/gr-qtgui/src/lib/TimeDomainDisplayPlot.h
@@ -21,7 +21,8 @@ public:
   TimeDomainDisplayPlot(QWidget*);
   virtual ~TimeDomainDisplayPlot();
 
-  void PlotNewData(const double* realDataPoints, const double* imagDataPoints, const int64_t numDataPoints);
+  void PlotNewData(const double* realDataPoints, const double* imagDataPoints, 
+		   const int64_t numDataPoints, const double timeInterval);
     
   void SetImaginaryDataVisible(const bool);
 				   
@@ -54,8 +55,6 @@ private:
   timespec _lastReplot;
 
   int64_t _numPoints;
-
-  double _displayIntervalTime;
 };
 
 #endif /* TIME_DOMAIN_DISPLAY_PLOT_HPP */
diff --git a/gr-qtgui/src/lib/WaterfallDisplayPlot.cc b/gr-qtgui/src/lib/WaterfallDisplayPlot.cc
index b23612524..3d173cfe3 100644
--- a/gr-qtgui/src/lib/WaterfallDisplayPlot.cc
+++ b/gr-qtgui/src/lib/WaterfallDisplayPlot.cc
@@ -224,8 +224,6 @@ WaterfallDisplayPlot::WaterfallDisplayPlot(QWidget* parent)
   resize(parent->width(), parent->height());
   _numPoints = 1024;
 
-  _displayIntervalTime = (1.0/5.0); // 1/5 of a second between updates
-
   _waterfallData = new WaterfallData(_startFrequency, _stopFrequency, _numPoints, 200);
 
   QPalette palette;
@@ -370,50 +368,46 @@ WaterfallDisplayPlot::GetStopFrequency() const
 
 void
 WaterfallDisplayPlot::PlotNewData(const double* dataPoints, 
-				       const int64_t numDataPoints,
-				       const double timePerFFT,
-				       const timespec timestamp,
-				       const int droppedFrames)
+				  const int64_t numDataPoints,
+				  const double timePerFFT,
+				  const timespec timestamp,
+				  const int droppedFrames)
 {
   if(numDataPoints > 0){
     if(numDataPoints != _numPoints){
       _numPoints = numDataPoints;
-
+      
       Reset();
-
+      
       d_spectrogram->invalidateCache();
       d_spectrogram->itemChanged();
-
+      
       if(isVisible()){
 	replot();
       }
-
+      
       _lastReplot = get_highres_clock();
     }
 
-    _waterfallData->addFFTData(dataPoints, numDataPoints, droppedFrames);
-    _waterfallData->IncrementNumLinesToUpdate();
-
-    QwtTimeScaleDraw* timeScale = (QwtTimeScaleDraw*)axisScaleDraw(QwtPlot::yLeft);
-    timeScale->SetSecondsPerLine(timePerFFT);
-    timeScale->SetZeroTime(timestamp);
-
-    ((WaterfallZoomer*)_zoomer)->SetSecondsPerLine(timePerFFT);
-    ((WaterfallZoomer*)_zoomer)->SetZeroTime(timestamp);
-  }
-
-  // Allow at least a 50% duty cycle
-  if(diff_timespec(get_highres_clock(), _lastReplot) > _displayIntervalTime){
-
-    d_spectrogram->invalidateCache();
-    d_spectrogram->itemChanged();
-
-    // Only update when window is visible
-    if(isVisible()){
+    if(diff_timespec(get_highres_clock(), _lastReplot) > timePerFFT) {
+      //FIXME: We may want to average the data between these updates to smooth display
+      _waterfallData->addFFTData(dataPoints, numDataPoints, droppedFrames);
+      _waterfallData->IncrementNumLinesToUpdate();
+      
+      QwtTimeScaleDraw* timeScale = (QwtTimeScaleDraw*)axisScaleDraw(QwtPlot::yLeft);
+      timeScale->SetSecondsPerLine(timePerFFT);
+      timeScale->SetZeroTime(timestamp);
+      
+      ((WaterfallZoomer*)_zoomer)->SetSecondsPerLine(timePerFFT);
+      ((WaterfallZoomer*)_zoomer)->SetZeroTime(timestamp);
+      
+      d_spectrogram->invalidateCache();
+      d_spectrogram->itemChanged();
+      
       replot();
-    }
 
-    _lastReplot = get_highres_clock();
+      _lastReplot = get_highres_clock();
+    }
   }
 }
 
@@ -432,8 +426,6 @@ WaterfallDisplayPlot::SetIntensityRange(const double minIntensity,
 void
 WaterfallDisplayPlot::replot()
 {
-  const timespec startTime = get_highres_clock();
-
   QwtTimeScaleDraw* timeScale = (QwtTimeScaleDraw*)axisScaleDraw(QwtPlot::yLeft);
   timeScale->initiateUpdate();
 
@@ -455,14 +447,6 @@ WaterfallDisplayPlot::replot()
   }
 
   QwtPlot::replot();
-
-  double differenceTime = (diff_timespec(get_highres_clock(), startTime));
-  
-  // Require at least a 5% duty cycle
-  differenceTime *= 19.0;
-  if(differenceTime > (1.0/5.0)){
-    _displayIntervalTime = differenceTime;
-  }
 }
 
 void
diff --git a/gr-qtgui/src/lib/WaterfallDisplayPlot.h b/gr-qtgui/src/lib/WaterfallDisplayPlot.h
index 18e10aae9..a5ccaec40 100644
--- a/gr-qtgui/src/lib/WaterfallDisplayPlot.h
+++ b/gr-qtgui/src/lib/WaterfallDisplayPlot.h
@@ -73,8 +73,6 @@ private:
 
   int64_t _numPoints;
 
-  double _displayIntervalTime;
-
   int _intensityColorMapType;
   QColor _userDefinedLowIntensityColor;
   QColor _userDefinedHighIntensityColor;
diff --git a/gr-qtgui/src/lib/qtgui_sink_c.cc b/gr-qtgui/src/lib/qtgui_sink_c.cc
index 7340141a6..fefa98704 100644
--- a/gr-qtgui/src/lib/qtgui_sink_c.cc
+++ b/gr-qtgui/src/lib/qtgui_sink_c.cc
@@ -145,6 +145,9 @@ qtgui_sink_c::initialize(const bool opengl)
 				 d_plotconst,
 				 opengl);
 
+  // initialize update time to 10 times a second
+  set_update_time(0.1);
+
   d_object = new qtgui_obj(d_qApplication);
   qApp->postEvent(d_object, new qtgui_event(&d_pmutex));
 }
@@ -208,6 +211,13 @@ qtgui_sink_c::set_frequency_axis(double min, double max)
 }
 
 void
+qtgui_sink_c::set_update_time(double t)
+{
+  d_update_time = t;
+  d_main_gui->SetUpdateTime(d_update_time);
+}
+
+void
 qtgui_sink_c::fft(const gr_complex *data_in, int size)
 {
   if (d_window.size()) {
@@ -300,7 +310,7 @@ qtgui_sink_c::general_work (int noutput_items,
       
       d_main_gui->UpdateWindow(true, d_fft->get_outbuf(), d_fftsize,
 			       NULL, 0, (float*)d_residbuf, d_fftsize,
-			       1.0/4.0, currentTime, true);
+			       currentTime, true);
     }
     // Otherwise, copy what we received into the residbuf for next time
     else {
diff --git a/gr-qtgui/src/lib/qtgui_sink_c.h b/gr-qtgui/src/lib/qtgui_sink_c.h
index 91c6b03e6..1f6c28473 100644
--- a/gr-qtgui/src/lib/qtgui_sink_c.h
+++ b/gr-qtgui/src/lib/qtgui_sink_c.h
@@ -86,6 +86,8 @@ private:
 
   bool d_plotfreq, d_plotwaterfall, d_plotwaterfall3d, d_plottime, d_plotconst;
   
+  double d_update_time;
+
   QWidget *d_parent;
   SpectrumGUIClass *d_main_gui;
 
@@ -111,6 +113,8 @@ public:
   void set_constellation_pen_size(int size);
   void set_frequency_axis(double min, double max);
 
+  void set_update_time(double t);
+
   QApplication *d_qApplication;
   qtgui_obj *d_object;
 
diff --git a/gr-qtgui/src/lib/qtgui_sink_f.cc b/gr-qtgui/src/lib/qtgui_sink_f.cc
index 6fbb2f381..a088e28e9 100644
--- a/gr-qtgui/src/lib/qtgui_sink_f.cc
+++ b/gr-qtgui/src/lib/qtgui_sink_f.cc
@@ -140,6 +140,9 @@ qtgui_sink_f::initialize(const bool opengl)
 				 d_plotconst,
 				 opengl);
 
+  // initialize update time to 10 times a second
+  set_update_time(100);
+
   d_object = new qtgui_obj(d_qApplication);
   qApp->postEvent(d_object, new qtgui_event(&d_pmutex));
 }
@@ -202,6 +205,13 @@ qtgui_sink_f::set_frequency_axis(double min, double max)
 }
 
 void
+qtgui_sink_f::set_update_time(double t)
+{
+  d_update_time = t;
+  d_main_gui->SetUpdateTime(d_update_time);
+}
+
+void
 qtgui_sink_f::fft(const float *data_in, int size)
 {
   if (d_window.size()) {
@@ -295,7 +305,7 @@ qtgui_sink_f::general_work (int noutput_items,
       
       d_main_gui->UpdateWindow(true, d_fft->get_outbuf(), d_fftsize,
 			       (float*)d_residbuf, d_fftsize, NULL, 0,
-			       1.0/4.0, currentTime, true);
+			       currentTime, true);
     }
     // Otherwise, copy what we received into the residbuf for next time
     else {
diff --git a/gr-qtgui/src/lib/qtgui_sink_f.h b/gr-qtgui/src/lib/qtgui_sink_f.h
index 47c928d17..f603da7b6 100644
--- a/gr-qtgui/src/lib/qtgui_sink_f.h
+++ b/gr-qtgui/src/lib/qtgui_sink_f.h
@@ -84,6 +84,8 @@ private:
 
   bool d_plotfreq, d_plotwaterfall, d_plotwaterfall3d, d_plottime, d_plotconst;
 
+  double d_update_time;
+
   QWidget *d_parent;
   SpectrumGUIClass *d_main_gui; 
 
@@ -109,6 +111,8 @@ public:
   void set_constellation_pen_size(int size);
   void set_frequency_axis(double min, double max);
 
+  void set_update_time(double t);
+
   QApplication *d_qApplication;
   qtgui_obj *d_object;
 
diff --git a/gr-qtgui/src/lib/spectrumUpdateEvents.cc b/gr-qtgui/src/lib/spectrumUpdateEvents.cc
index 2da37d350..350e3eeb2 100644
--- a/gr-qtgui/src/lib/spectrumUpdateEvents.cc
+++ b/gr-qtgui/src/lib/spectrumUpdateEvents.cc
@@ -8,7 +8,6 @@ SpectrumUpdateEvent::SpectrumUpdateEvent(const std::complex<float>* fftPoints,
 					 const double* realTimeDomainPoints,
 					 const double* imagTimeDomainPoints,
 					 const uint64_t numTimeDomainDataPoints,
-					 const double timePerFFT,
 					 const timespec dataTimestamp,
 					 const bool repeatDataFlag,
 					 const bool lastOfMultipleUpdateFlag,
@@ -44,7 +43,6 @@ SpectrumUpdateEvent::SpectrumUpdateEvent(const std::complex<float>* fftPoints,
 	   numTimeDomainDataPoints*sizeof(double));
   }
   _dataTimestamp = dataTimestamp;
-  _timePerFFT = timePerFFT;
   _repeatDataFlag = repeatDataFlag;
   _lastOfMultipleUpdateFlag = lastOfMultipleUpdateFlag;
   _eventGeneratedTimestamp = generatedTimestamp;
@@ -87,12 +85,6 @@ SpectrumUpdateEvent::getNumTimeDomainDataPoints() const
   return _numTimeDomainDataPoints;
 }
 
-double
-SpectrumUpdateEvent::getTimePerFFT() const
-{
-  return _timePerFFT;
-}
-
 timespec
 SpectrumUpdateEvent::getDataTimestamp() const
 {
diff --git a/gr-qtgui/src/lib/spectrumUpdateEvents.h b/gr-qtgui/src/lib/spectrumUpdateEvents.h
index 75fa27324..9c46d4bf3 100644
--- a/gr-qtgui/src/lib/spectrumUpdateEvents.h
+++ b/gr-qtgui/src/lib/spectrumUpdateEvents.h
@@ -10,14 +10,13 @@
 class SpectrumUpdateEvent:public QEvent{
 
 public:
-  SpectrumUpdateEvent(const std::complex<float>* fftPoints, const uint64_t numFFTDataPoints, const double* realTimeDomainPoints, const double* imagTimeDomainPoints, const uint64_t numTimeDomainDataPoints, const double timePerFFT, const timespec dataTimestamp, const bool repeatDataFlag, const bool lastOfMultipleUpdateFlag, const timespec generatedTimestamp, const int droppedFFTFrames);
+  SpectrumUpdateEvent(const std::complex<float>* fftPoints, const uint64_t numFFTDataPoints, const double* realTimeDomainPoints, const double* imagTimeDomainPoints, const uint64_t numTimeDomainDataPoints, const timespec dataTimestamp, const bool repeatDataFlag, const bool lastOfMultipleUpdateFlag, const timespec generatedTimestamp, const int droppedFFTFrames);
   ~SpectrumUpdateEvent();
   const std::complex<float>* getFFTPoints()const;
   const double* getRealTimeDomainPoints()const;
   const double* getImagTimeDomainPoints()const;
   uint64_t getNumFFTDataPoints()const;
   uint64_t getNumTimeDomainDataPoints()const;
-  double getTimePerFFT()const;
   timespec getDataTimestamp()const;
   bool getRepeatDataFlag()const;
   bool getLastOfMultipleUpdateFlag()const;
@@ -32,7 +31,6 @@ private:
   double* _imagDataTimeDomainPoints;
   uint64_t _numFFTDataPoints;
   uint64_t _numTimeDomainDataPoints;
-  double _timePerFFT;
   timespec _dataTimestamp;
   bool _repeatDataFlag;
   bool _lastOfMultipleUpdateFlag;
diff --git a/gr-qtgui/src/lib/spectrumdisplayform.cc b/gr-qtgui/src/lib/spectrumdisplayform.cc
index 141fc0e33..0170f7862 100644
--- a/gr-qtgui/src/lib/spectrumdisplayform.cc
+++ b/gr-qtgui/src/lib/spectrumdisplayform.cc
diff --git a/gr-qtgui/src/lib/spectrumdisplayform.h b/gr-qtgui/src/lib/spectrumdisplayform.h
index b596b0495..bf2af7033 100644
--- a/gr-qtgui/src/lib/spectrumdisplayform.h
+++ b/gr-qtgui/src/lib/spectrumdisplayform.h
@@ -13,6 +13,7 @@ class SpectrumGUIClass;
 #include <TimeDomainDisplayPlot.h>
 #include <ConstellationDisplayPlot.h>
 #include <QValidator>
+#include <QTimer>
 #include <vector>
 
 class SpectrumDisplayForm : public QWidget, public Ui::SpectrumDisplayForm
@@ -70,9 +71,11 @@ public slots:
 			    double ymin, double ymax);
   void SetConstellationPenSize(int size);
   void SetFrequencyAxis(double min, double max);
+  void SetUpdateTime(double t);
 
 private slots:
   void newFrequencyData( const SpectrumUpdateEvent* );
+  void UpdateGuiTimer();
 
 protected:
 
@@ -110,6 +113,9 @@ private:
   int d_plot_waterfall3d;
   int d_plot_time;
   int d_plot_constellation;
+
+  QTimer *displayTimer;
+  double d_update_time;
 };
 
 #endif /* SPECTRUM_DISPLAY_FORM_H */