diff --git a/mainwindow.cpp b/mainwindow.cpp
index 0b4d5ae..f6dc151 100644
--- a/mainwindow.cpp
+++ b/mainwindow.cpp
@@ -23,7 +23,7 @@
 #include "mainwindow.h"
 #include "util.h"
 
-MainWindow::MainWindow()
+MainWindow::MainWindow() : spectrogram(nullptr)
 {
     setWindowTitle(tr("inspectrum"));
     scrollArea.viewport()->installEventFilter(this);
diff --git a/plotview.cpp b/plotview.cpp
index 1bf0442..b01e2dd 100644
--- a/plotview.cpp
+++ b/plotview.cpp
@@ -40,6 +40,9 @@ void PlotView::refreshSources()
 {
     plots.clear();
 
+    auto sp = new SpectrogramPlot(mainSampleSource);
+    plots.emplace_back(sp);
+
     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);
diff --git a/spectrogramplot.cpp b/spectrogramplot.cpp
index d1fa864..e72aa33 100644
--- a/spectrogramplot.cpp
+++ b/spectrogramplot.cpp
@@ -29,10 +29,11 @@
 #include "util.h"
 
 
-SpectrogramPlot::SpectrogramPlot()
+SpectrogramPlot::SpectrogramPlot(SampleSource<std::complex<float>> *src)
 {
+    inputSource = src;
     sampleRate = 8000000;
-    setFFTSize(1024);
+    setFFTSize(512);
     zoomLevel = 0;
     powerMax = 0.0f;
     powerMin = -50.0f;
@@ -66,7 +67,6 @@ void SpectrogramPlot::openFile(QString fileName)
             pixmapCache.clear();
             fftCache.clear();
             inputSource = newFile;
-            setHeight(fftSize);
         } catch (std::runtime_error e) {
             // TODO: display error
         }
diff --git a/spectrogramplot.h b/spectrogramplot.h
index b6c8b9e..cc11272 100644
--- a/spectrogramplot.h
+++ b/spectrogramplot.h
@@ -37,7 +37,7 @@ class SpectrogramPlot : public Plot
     Q_OBJECT
 
 public:
-    SpectrogramPlot();
+    SpectrogramPlot(SampleSource<std::complex<float>> *src);
     ~SpectrogramPlot();
 
     void paintMid(QPainter &painter, QRect &rect, range_t<off_t> sampleRange);
@@ -48,7 +48,7 @@ public:
     int getStride();
     off_t lineToSample(off_t line);
 
-    InputSource *inputSource = nullptr;
+    SampleSource<std::complex<float>> *inputSource = nullptr;
 
 signals:
     void cursorFrequencyChanged(QString);