diff --git a/CMakeLists.txt b/CMakeLists.txt
index d664df3..ca6c214 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -38,6 +38,7 @@ list(APPEND inspectrum_sources
     plot.cpp
     plotview.cpp
     samplebuffer.cpp
+    samplesource.cpp
     spectrogramcontrols.cpp
     spectrogramplot.cpp
     traceplot.cpp
diff --git a/samplebuffer.cpp b/samplebuffer.cpp
index a34a2f8..b4c6f65 100644
--- a/samplebuffer.cpp
+++ b/samplebuffer.cpp
@@ -19,6 +19,12 @@
 
 #include "samplebuffer.h"
 
+template <typename Tin, typename Tout>
+SampleBuffer<Tin, Tout>::SampleBuffer(SampleSource<Tin> *src) : src(src)
+{
+	src->subscribe(this);
+}
+
 template <typename Tin, typename Tout>
 std::unique_ptr<Tout[]> SampleBuffer<Tin, Tout>::getSamples(off_t start, off_t length)
 {
@@ -28,5 +34,11 @@ std::unique_ptr<Tout[]> SampleBuffer<Tin, Tout>::getSamples(off_t start, off_t l
     return dest;
 }
 
+template <typename Tin, typename Tout>
+void SampleBuffer<Tin, Tout>::invalidEvent()
+{
+	SampleSource<Tout>::invalidate();
+}
+
 template class SampleBuffer<std::complex<float>, std::complex<float>>;
 template class SampleBuffer<std::complex<float>, float>;
diff --git a/samplebuffer.h b/samplebuffer.h
index 93fc135..511d14a 100644
--- a/samplebuffer.h
+++ b/samplebuffer.h
@@ -24,13 +24,14 @@
 #include "samplesource.h"
 
 template <typename Tin, typename Tout>
-class SampleBuffer : public SampleSource<Tout>
+class SampleBuffer : public SampleSource<Tout>, public Subscriber
 {
 private:
     SampleSource<Tin> *src;
 
 public:
-    SampleBuffer(SampleSource<Tin> *src) : src(src) {};
+    SampleBuffer(SampleSource<Tin> *src);
+	void invalidEvent();
     virtual std::unique_ptr<Tout[]> getSamples(off_t start, off_t length);
     virtual void work(void *input, void *output, int count) = 0;
     virtual off_t count() {
diff --git a/samplesource.cpp b/samplesource.cpp
new file mode 100644
index 0000000..123a203
--- /dev/null
+++ b/samplesource.cpp
@@ -0,0 +1,43 @@
+/*
+ *  Copyright (C) 2015, Mike Walters <mike@flomp.net>
+ *
+ *  This file is part of inspectrum.
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "samplesource.h"
+
+template<typename T>
+void SampleSource<T>::subscribe(Subscriber *subscriber)
+{
+	subscribers.insert(subscriber);
+}
+
+template<typename T>
+void SampleSource<T>::invalidate()
+{
+	for (auto subscriber : subscribers) {
+		subscriber->invalidateEvent();
+	}
+}
+
+template<typename T>
+void SampleSource<T>::unsubscribe(Subscriber *subscriber)
+{
+	subscribers.erase(subscriber);
+}
+
+template class SampleSource<std::complex<float>>;
+template class SampleSource<float>;
diff --git a/samplesource.h b/samplesource.h
index 22d5bbd..7035218 100644
--- a/samplesource.h
+++ b/samplesource.h
@@ -21,7 +21,9 @@
 
 #include <complex>
 #include <memory>
+#include <set>
 #include "abstractsamplesource.h"
+#include "subscriber.h"
 
 template<typename T>
 class SampleSource : public AbstractSampleSource
@@ -31,5 +33,14 @@ public:
     virtual ~SampleSource() {};
 
     virtual std::unique_ptr<T[]> getSamples(off_t start, off_t length) = 0;
+    virtual void invalidateEvent() { };
     virtual off_t count() = 0;
+    void subscribe(Subscriber *subscriber);
+    void unsubscribe(Subscriber *subscriber);
+
+protected:
+	virtual void invalidate();
+
+private:
+	std::set<Subscriber*> subscribers;
 };
diff --git a/subscriber.h b/subscriber.h
new file mode 100644
index 0000000..bbf4c67
--- /dev/null
+++ b/subscriber.h
@@ -0,0 +1,27 @@
+/*
+ *  Copyright (C) 2016, Mike Walters <mike@flomp.net>
+ *
+ *  This file is part of inspectrum.
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+
+class Subscriber
+{
+public:
+    virtual void invalidateEvent() = 0;
+};