diff --git a/include/dsp/dspcommands.h b/include/dsp/dspcommands.h
index 094c584cc..a3140ea8e 100644
--- a/include/dsp/dspcommands.h
+++ b/include/dsp/dspcommands.h
@@ -28,10 +28,6 @@ class SampleSink;
 class ThreadedSampleSink;
 class AudioFifo;
 
-class SDRANGEL_API DSPPing : public Message {
-	MESSAGE_CLASS_DECLARATION
-};
-
 class SDRANGEL_API DSPExit : public Message {
 	MESSAGE_CLASS_DECLARATION
 };
diff --git a/include/dsp/samplefifo.h b/include/dsp/samplefifo.h
index 58eac0596..f2cfe1648 100644
--- a/include/dsp/samplefifo.h
+++ b/include/dsp/samplefifo.h
@@ -48,7 +48,7 @@ public:
 
 	bool setSize(int size);
 	inline uint size() const { return m_size; }
-	inline uint fill() const { return m_fill; }
+	inline uint fill() { QMutexLocker mutexLocker(&m_mutex); uint fill = m_fill; return fill; }
 
 	uint write(const quint8* data, uint count);
 	uint write(SampleVector::const_iterator begin, SampleVector::const_iterator end);
diff --git a/plugins/samplesource/hackrf/hackrfinput.cpp b/plugins/samplesource/hackrf/hackrfinput.cpp
index 74b27bb8c..fefbb1084 100644
--- a/plugins/samplesource/hackrf/hackrfinput.cpp
+++ b/plugins/samplesource/hackrf/hackrfinput.cpp
@@ -83,12 +83,12 @@ bool HackRFInput::start(int device)
 		return false;
 	}
 
-	m_hackRFThread->startWork();
-
 	mutexLocker.unlock();
 
 	applySettings(m_settings, true);
 
+	m_hackRFThread->startWork();
+
 	qDebug("HackRFInput::startInput: started");
 
 	return true;
diff --git a/plugins/samplesource/hackrf/hackrfthread.cpp b/plugins/samplesource/hackrf/hackrfthread.cpp
index 92045146a..96089860b 100644
--- a/plugins/samplesource/hackrf/hackrfthread.cpp
+++ b/plugins/samplesource/hackrf/hackrfthread.cpp
@@ -43,16 +43,18 @@ HackRFThread::~HackRFThread()
 
 void HackRFThread::startWork()
 {
-	m_startWaitMutex.lock();
+	//m_startWaitMutex.lock();
+	m_running = true;
 	start();
+	/*
 	while(!m_running)
 		m_startWaiter.wait(&m_startWaitMutex, 100);
-	m_startWaitMutex.unlock();
+	m_startWaitMutex.unlock();*/
 }
 
 void HackRFThread::stopWork()
 {
-	qDebug("AirspyThread::stopWork");
+	qDebug("HackRFThread::stopWork");
 	m_running = false;
 	wait();
 }
@@ -76,7 +78,7 @@ void HackRFThread::run()
 {
 	hackrf_error rc;
 
-	m_running = true;
+	//m_running = true;
 	m_startWaiter.wakeAll();
 
 	rc = (hackrf_error) hackrf_start_rx(m_dev, rx_callback, NULL);
@@ -104,7 +106,7 @@ void HackRFThread::run()
 		qDebug("HackRFThread::run: failed to stop HackRF Rx: %s", hackrf_error_name(rc));
 	}
 
-	m_running = false;
+	//m_running = false;
 }
 
 //  Decimate according to specified log2 (ex: log2=4 => decim=16)
diff --git a/sdrbase/dsp/dspcommands.cpp b/sdrbase/dsp/dspcommands.cpp
index f6f8a19b4..e18487e33 100644
--- a/sdrbase/dsp/dspcommands.cpp
+++ b/sdrbase/dsp/dspcommands.cpp
@@ -17,7 +17,6 @@
 
 #include "dsp/dspcommands.h"
 
-MESSAGE_CLASS_DEFINITION(DSPPing, Message)
 MESSAGE_CLASS_DEFINITION(DSPExit, Message)
 MESSAGE_CLASS_DEFINITION(DSPAcquisitionInit, Message)
 MESSAGE_CLASS_DEFINITION(DSPAcquisitionStart, Message)
diff --git a/sdrbase/dsp/dspdeviceengine.cpp b/sdrbase/dsp/dspdeviceengine.cpp
index cd13e5092..2149c096f 100644
--- a/sdrbase/dsp/dspdeviceengine.cpp
+++ b/sdrbase/dsp/dspdeviceengine.cpp
@@ -41,6 +41,9 @@ DSPDeviceEngine::DSPDeviceEngine(QObject* parent) :
 	m_qRange(1 << 16),
 	m_imbalance(65536)
 {
+	connect(&m_inputMessageQueue, SIGNAL(messageEnqueued()), this, SLOT(handleInputMessages()), Qt::QueuedConnection);
+	connect(&m_syncMessenger, SIGNAL(messageSent()), this, SLOT(handleSynchronousMessages()), Qt::QueuedConnection);
+
 	moveToThread(this);
 }
 
@@ -53,21 +56,16 @@ void DSPDeviceEngine::run()
 {
 	qDebug() << "DSPDeviceEngine::run";
 
-	connect(&m_inputMessageQueue, SIGNAL(messageEnqueued()), this, SLOT(handleInputMessages()), Qt::QueuedConnection);
-	connect(&m_syncMessenger, SIGNAL(messageSent()), this, SLOT(handleSynchronousMessages()), Qt::QueuedConnection);
-
 	m_state = StIdle;
 
-    m_syncMessenger.done(); // Release start() that is waiting in main trhead
+    m_syncMessenger.done(); // Release start() that is waiting in main thread
 	exec();
 }
 
 void DSPDeviceEngine::start()
 {
 	qDebug() << "DSPDeviceEngine::start";
-	DSPPing cmd;
 	QThread::start();
-	m_syncMessenger.sendWait(cmd);
 }
 
 void DSPDeviceEngine::stop()