diff --git a/plotview.cpp b/plotview.cpp
index 7822696..b860241 100644
--- a/plotview.cpp
+++ b/plotview.cpp
@@ -29,7 +29,6 @@
 #include "grsamplebuffer.h"
 #include "memory_sink.h"
 #include "memory_source.h"
-#include "traceplot.h"
 
 PlotView::PlotView(InputSource *input) : cursors(this), viewRange({0, 0})
 {
@@ -37,18 +36,18 @@ PlotView::PlotView(InputSource *input) : cursors(this), viewRange({0, 0})
     setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
     enableCursors(false);
 
-    mainSampleSource->subscribe(this);
-}
-
-void PlotView::refreshSources()
-{
-    plots.clear();
-    if (mainSampleSource == nullptr)
-        return;
-
     spectrogramPlot = new SpectrogramPlot(mainSampleSource);
     plots.emplace_back(spectrogramPlot);
 
+    iqPlot = createIQPlot(mainSampleSource);
+    plots.emplace_back(iqPlot);
+    plots.emplace_back(createQuadratureDemodPlot(static_cast<SampleSource<std::complex<float>>*>(iqPlot->source().get())));
+
+    mainSampleSource->subscribe(this);
+}
+
+TracePlot* PlotView::createIQPlot(SampleSource<std::complex<float>> *src)
+{
     gr::top_block_sptr iq_tb = gr::make_top_block("multiply");
     auto iq_mem_source = gr::blocks::memory_source::make(8);
     auto iq_mem_sink = gr::blocks::memory_sink::make(8);
@@ -67,6 +66,12 @@ void PlotView::refreshSources()
         iq_tb->connect(multiply, 0, iq_mem_sink, 0);
     }
 
+    auto iq_src = std::make_shared<GRSampleBuffer<std::complex<float>, std::complex<float>>>(mainSampleSource, iq_tb, iq_mem_source, iq_mem_sink);
+    return new TracePlot(iq_src);
+}
+
+TracePlot* PlotView::createQuadratureDemodPlot(SampleSource<std::complex<float>> *src)
+{
     gr::top_block_sptr quad_demod_tb = gr::make_top_block("quad_demod");
     auto quad_demod_mem_source = gr::blocks::memory_source::make(8);
     auto quad_demod_mem_sink = gr::blocks::memory_sink::make(4);
@@ -74,17 +79,11 @@ void PlotView::refreshSources()
     quad_demod_tb->connect(quad_demod_mem_source, 0, quad_demod, 0);
     quad_demod_tb->connect(quad_demod, 0, quad_demod_mem_sink, 0);
 
-    auto iq_src = std::make_shared<GRSampleBuffer<std::complex<float>, std::complex<float>>>(mainSampleSource, iq_tb, iq_mem_source, iq_mem_sink);
-    plots.emplace_back(new TracePlot(iq_src));
-
-    plots.emplace_back(
-        new TracePlot(
-            std::make_shared<GRSampleBuffer<std::complex<float>, float>>(
-                dynamic_cast<SampleSource<std::complex<float>>*>(iq_src.get()), quad_demod_tb, quad_demod_mem_source, quad_demod_mem_sink
-            )
+    return new TracePlot(
+        std::make_shared<GRSampleBuffer<std::complex<float>, float>>(
+            dynamic_cast<SampleSource<std::complex<float>>*>(src), quad_demod_tb, quad_demod_mem_source, quad_demod_mem_sink
         )
     );
-    update();
 }
 
 void PlotView::enableCursors(bool enabled)
@@ -97,8 +96,6 @@ void PlotView::enableCursors(bool enabled)
 
 void PlotView::invalidateEvent()
 {
-    refreshSources();
-
     horizontalScrollBar()->setMinimum(0);
     horizontalScrollBar()->setMaximum(mainSampleSource->count());
 }
@@ -108,13 +105,11 @@ void PlotView::selectionChanged(std::pair<off_t, off_t> selectionTime, std::pair
     this->selectionTime = selectionTime;
     this->selectionFreq = selectionFreq;
     selection = true;
-    refreshSources();
 }
 
 void PlotView::selectionCleared()
 {
     selection = false;
-    refreshSources();
 }
 
 void PlotView::setFFTSize(int size)
diff --git a/plotview.h b/plotview.h
index 3b204f2..5983b1c 100644
--- a/plotview.h
+++ b/plotview.h
@@ -25,7 +25,9 @@
 #include "cursors.h"
 #include "inputsource.h"
 #include "plot.h"
+#include "samplesource.h"
 #include "spectrogramplot.h"
+#include "traceplot.h"
 
 class PlotView : public QAbstractScrollArea, Subscriber
 {
@@ -51,6 +53,7 @@ private:
     Cursors cursors;
     SampleSource<std::complex<float>> *mainSampleSource = nullptr;
     SpectrogramPlot *spectrogramPlot = nullptr;
+    TracePlot *iqPlot = nullptr;
     std::vector<std::unique_ptr<Plot>> plots;
     std::pair<off_t, off_t> viewRange;
     bool selection = false;
@@ -60,6 +63,7 @@ private:
     int fftSize;
     int zoomLevel;
 
-    void refreshSources();
+    TracePlot* createIQPlot(SampleSource<std::complex<float>> *src);
+    TracePlot* createQuadratureDemodPlot(SampleSource<std::complex<float>> *src);
     void updateView();
 };
\ No newline at end of file
diff --git a/spectrogramplot.cpp b/spectrogramplot.cpp
index d7c0d3c..41f5585 100644
--- a/spectrogramplot.cpp
+++ b/spectrogramplot.cpp
@@ -102,6 +102,9 @@ void SpectrogramPlot::mousePressEvent(QMouseEvent *event)
 
 void SpectrogramPlot::paintMid(QPainter &painter, QRect &rect, range_t<off_t> sampleRange)
 {
+    if (!inputSource || inputSource->count() == 0)
+        return;
+
     for (int x = rect.left(); x < rect.right(); x += linesPerTile()) {
         QPixmap *tile = getPixmapTile(sampleRange.minimum + x * getStride());
         painter.drawPixmap(QRect(x, rect.y(), linesPerTile(), fftSize), *tile);
diff --git a/traceplot.h b/traceplot.h
index 4a7097e..bae457d 100644
--- a/traceplot.h
+++ b/traceplot.h
@@ -32,6 +32,7 @@ public:
 
     void paintMid(QPainter &painter, QRect &rect, range_t<off_t> sampleRange);
     void paintFront(QPainter &painter, QRect &rect, range_t<off_t> sampleRange);
+    std::shared_ptr<AbstractSampleSource> source() { return sampleSource; };
 
 private:
 	std::shared_ptr<AbstractSampleSource> sampleSource;