diff --git a/inputsource.h b/inputsource.h
index 552264a..ff7ea76 100644
--- a/inputsource.h
+++ b/inputsource.h
@@ -50,4 +50,7 @@ public:
     };
     void setSampleRate(off_t rate);
     off_t rate();
+    float relativeBandwidth() {
+        return 1;
+    }
 };
diff --git a/plotview.cpp b/plotview.cpp
index ad12c35..7210d21 100644
--- a/plotview.cpp
+++ b/plotview.cpp
@@ -248,7 +248,7 @@ void PlotView::exportSamples(std::shared_ptr<AbstractSampleSource> src)
 
     QGroupBox groupBox2("Decimation");
     QSpinBox decimation(&groupBox2);
-    decimation.setValue(1);
+    decimation.setValue(1 / complexSrc->relativeBandwidth());
 
     QVBoxLayout vbox2;
     vbox2.addWidget(&decimation);
diff --git a/samplebuffer.h b/samplebuffer.h
index 32847ec..8cb4438 100644
--- a/samplebuffer.h
+++ b/samplebuffer.h
@@ -43,4 +43,8 @@ public:
     off_t rate() {
         return src->rate();
     };
+
+    float relativeBandwidth() {
+        return 1;
+    }
 };
diff --git a/samplesource.h b/samplesource.h
index 14243ef..7662b09 100644
--- a/samplesource.h
+++ b/samplesource.h
@@ -36,6 +36,7 @@ public:
     virtual void invalidateEvent() { };
     virtual off_t count() = 0;
     virtual off_t rate() = 0;
+    virtual float relativeBandwidth() = 0;
     std::type_index sampleType() override;
     void subscribe(Subscriber *subscriber);
     int subscriberCount();
diff --git a/spectrogramplot.cpp b/spectrogramplot.cpp
index 330f1ca..f1091a1 100644
--- a/spectrogramplot.cpp
+++ b/spectrogramplot.cpp
@@ -34,7 +34,7 @@
 SpectrogramPlot::SpectrogramPlot(std::shared_ptr<SampleSource<std::complex<float>>> src) : Plot(src), inputSource(src), tuner(this)
 {
     setFFTSize(512);
-    zoomLevel = 0;
+    zoomLevel = 1;
     powerMax = 0.0f;
     powerMin = -50.0f;
 
@@ -236,6 +236,7 @@ void SpectrogramPlot::tunerMoved()
 {
     tunerTransform->setFrequency(getTunerPhaseInc());
     tunerTransform->setTaps(getTunerTaps());
+    tunerTransform->setRelativeBandwith(tuner.deviation() * 2.0 / getStride());
 
     // TODO: for invalidating traceplot cache, this shouldn't really go here
     QPixmapCache::clear();
diff --git a/tunertransform.cpp b/tunertransform.cpp
index e5f9842..daa1aa3 100644
--- a/tunertransform.cpp
+++ b/tunertransform.cpp
@@ -61,3 +61,13 @@ void TunerTransform::setTaps(std::vector<float> taps)
 {
     this->taps = taps;
 }
+
+float TunerTransform::relativeBandwidth() {
+    return bandwidth;
+}
+
+void TunerTransform::setRelativeBandwith(float bandwidth)
+{
+    this->bandwidth = bandwidth;
+}
+
diff --git a/tunertransform.h b/tunertransform.h
index 0655b7c..abc77f6 100644
--- a/tunertransform.h
+++ b/tunertransform.h
@@ -27,10 +27,13 @@ class TunerTransform : public SampleBuffer<std::complex<float>, std::complex<flo
 private:
     float frequency;
     std::vector<float> taps;
+    float bandwidth;
 
 public:
     TunerTransform(SampleSource<std::complex<float>> *src);
     void work(void *input, void *output, int count, off_t sampleid) override;
     void setFrequency(float frequency);
     void setTaps(std::vector<float> taps);
+    void setRelativeBandwith(float bandwidth);
+    float relativeBandwidth();
 };