diff --git a/plugins/feature/satellitetracker/satellitetrackerworker.cpp b/plugins/feature/satellitetracker/satellitetrackerworker.cpp
index 7bfaf56e5..193e4fbe0 100644
--- a/plugins/feature/satellitetracker/satellitetrackerworker.cpp
+++ b/plugins/feature/satellitetracker/satellitetrackerworker.cpp
@@ -631,19 +631,6 @@ void SatelliteTrackerWorker::applyDeviceAOSSettings(const QString& name)
                 }
             }
 
-            for (int i = 0; i < m_deviceSettingsList->size(); i++)
-            {
-                SatelliteTrackerSettings::SatelliteDeviceSettings *devSettings = m_deviceSettingsList->at(i);
-
-                // Start file sinks (See issue #782 - currently must occur after starting acqusition)
-                if (devSettings->m_startStopFileSink)
-                {
-                    qDebug() << "SatelliteTrackerWorker::aos: starting file sinks";
-                    int deviceSetIndex = devSettings->m_deviceSet.mid(1).toInt();
-                    ChannelWebAPIUtils::startStopFileSinks(deviceSetIndex, true);
-                }
-            }
-
             // Send AOS message to channels
             SatWorkerState *satWorkerState = m_workerState.value(name);
             ChannelWebAPIUtils::satelliteAOS(name, satWorkerState->m_satState.m_passes[0]->m_northToSouth);
@@ -682,6 +669,23 @@ void SatelliteTrackerWorker::applyDeviceAOSSettings(const QString& name)
                     doppler(satWorkerState);
                 });
             }
+
+            // Start file sinks (need a little delay to ensure sample rate message has been handled in filerecord)
+            QTimer::singleShot(1000, [this, m_deviceSettingsList]()
+            {
+                for (int i = 0; i < m_deviceSettingsList->size(); i++)
+                {
+                    SatelliteTrackerSettings::SatelliteDeviceSettings *devSettings = m_deviceSettingsList->at(i);
+
+                    if (devSettings->m_startStopFileSink)
+                    {
+                        qDebug() << "SatelliteTrackerWorker::aos: starting file sinks";
+                        int deviceSetIndex = devSettings->m_deviceSet.mid(1).toInt();
+                        ChannelWebAPIUtils::startStopFileSinks(deviceSetIndex, true);
+                    }
+                }
+            });
+
         });
     }
     else
diff --git a/plugins/samplesource/fileinput/fileinput.cpp b/plugins/samplesource/fileinput/fileinput.cpp
index 4d8988f52..fc05306a0 100644
--- a/plugins/samplesource/fileinput/fileinput.cpp
+++ b/plugins/samplesource/fileinput/fileinput.cpp
@@ -110,16 +110,21 @@ void FileInput::openFileStream()
 		m_sampleSize = header.sampleSize;
 		QString crcHex = QString("%1").arg(header.crc32 , 0, 16);
 
-	    if (crcOK)
+	    if (crcOK && (m_sampleRate > 0) && (m_sampleSize > 0))
 	    {
 	        qDebug("FileInput::openFileStream: CRC32 OK for header: %s", qPrintable(crcHex));
 	        m_recordLengthMuSec = ((fileSize - sizeof(FileRecord::Header)) * 1000000UL) / ((m_sampleSize == 24 ? 8 : 4) * m_sampleRate);
 	    }
-	    else
+	    else if (!crcOK)
 	    {
 	        qCritical("FileInput::openFileStream: bad CRC32 for header: %s", qPrintable(crcHex));
 	        m_recordLengthMuSec = 0;
 	    }
+            else
+	    {
+	        qCritical("FileInput::openFileStream: invalid header");
+	        m_recordLengthMuSec = 0;
+	    }
 
 		if (getMessageQueueToGUI())
         {
diff --git a/sdrbase/dsp/filerecord.cpp b/sdrbase/dsp/filerecord.cpp
index 0b019d6f8..3e149ea8d 100644
--- a/sdrbase/dsp/filerecord.cpp
+++ b/sdrbase/dsp/filerecord.cpp
@@ -156,6 +156,7 @@ bool FileRecord::handleMessage(const Message& message)
 {
 	if (DSPSignalNotification::match(message))
 	{
+        QMutexLocker mutexLocker(&m_mutex);
 		DSPSignalNotification& notif = (DSPSignalNotification&) message;
 		quint32 sampleRate = notif.getSampleRate();
 		qint64 centerFrequency = notif.getCenterFrequency();