#1340 Updates tuner and frequency controllers to apply locking to ensure multi-threaded access to freuqency control planes doesn't allow center tuned frequency to become indeterminant which can result in channels being mistuned and stop decoding. (#1341)

Co-authored-by: Dennis Sheirer <dsheirer@github.com>

.idea/misc.xml

@@ -4,7 +4,7 @@
   <component name="FrameworkDetectionExcludesConfiguration">
     <file type="web" url="file://$PROJECT_DIR$" />
   </component>
-  <component name="ProjectRootManager" version="2" languageLevel="JDK_19" default="true" project-jdk-name="liberica-19.0.1.fx" project-jdk-type="JavaSDK">
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_17" project-jdk-name="liberica-19.0.1.fx" project-jdk-type="JavaSDK">
     <output url="file://$PROJECT_DIR$/out" />
   </component>
 </project>

src/main/java/io/github/dsheirer/source/SourceEvent.java

@@ -197,7 +197,7 @@ public class SourceEvent
     /**
      * Creates a new locked state change event
      */
-    public static SourceEvent lockedState()
+    public static SourceEvent lockedSampleRateState()
     {
         return new SourceEvent(Event.NOTIFICATION_FREQUENCY_AND_SAMPLE_RATE_LOCKED, 1);
     }
@@ -205,7 +205,7 @@ public class SourceEvent
     /**
      * Creates a new unlocked state change event
      */
-    public static SourceEvent unlockedState()
+    public static SourceEvent unlockedSampleRateState()
     {
         return new SourceEvent(Event.NOTIFICATION_FREQUENCY_AND_SAMPLE_RATE_UNLOCKED, 0);
     }

src/main/java/io/github/dsheirer/source/tuner/TunerController.java

@@ -36,11 +36,11 @@ import io.github.dsheirer.source.tuner.configuration.TunerConfiguration;
 import io.github.dsheirer.source.tuner.frequency.FrequencyController;
 import io.github.dsheirer.source.tuner.frequency.FrequencyController.Tunable;
 import io.github.dsheirer.source.tuner.manager.FrequencyErrorCorrectionManager;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
 import java.text.DecimalFormat;
 import java.util.SortedSet;
+import java.util.concurrent.locks.ReentrantLock;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 public abstract class TunerController implements Tunable, ISourceEventProcessor, ISourceEventListener,
         INativeBufferProvider, Listener<INativeBuffer>, ITunerErrorListener
@@ -70,6 +70,17 @@ public abstract class TunerController implements Tunable, ISourceEventProcessor,
         mFrequencyErrorCorrectionManager = new FrequencyErrorCorrectionManager(this);
     }
 
+    /**
+     * Lock for the frequency controller.  This should only be used by the channel source manager to lock access to the
+     * frequency controller while creating a channel source, to block multi-threaded access to the frequency controller
+     * which might put the center tuned frequency value in an indeterminant state.
+     * @return frequency controller lock
+     */
+    public ReentrantLock getFrequencyControllerLock()
+    {
+        return mFrequencyController.getFrequencyControllerLock();
+    }
+
     /**
      * Frequency correction manager for this tuner controller.
      */
@@ -182,29 +193,30 @@ public abstract class TunerController implements Tunable, ISourceEventProcessor,
     }
 
     /**
-     * Indicates if the frequency and sample rate controls are locked by another process.  User interface controls
+     * Indicates if the sample rate control is locked by another process.  User interface controls should monitor source
-     * should monitor source events and check the locked state via this method to correctly render the enabled state
+     * events and check the locked state via this method to correctly render the enabled state of the sample rate control.
-     * of the frequency and sample rate controls.
      *
      * @return true if the tuner controller is locked.
      */
-    public boolean isLocked()
+    public boolean isLockedSampleRate()
     {
-        return mFrequencyController.isLocked();
+        //Note: this access is not protected by the mFrequencyControllerLock
+        return mFrequencyController.isSampleRateLocked();
     }
 
     /**
-     * Sets the frequency and sample rate locked state to the locked argument value.  This should only be changed
+     * Sets the sample rate locked state to the locked argument value.  This should only be changed by a downstream
-     * by a downstream consumer of samples to prevent users or other processes from modifying the center frequency
+     * consumer of samples to prevent users or other processes from modifying the sample rate of the tuner while
-     * and/or sample rate of the tuner while processing samples.
+     * processing samples.
      *
      * @param locked true to indicate the tuner controller is in a locked state, otherwise false.
      */
-    public void setLocked(boolean locked)
+    public void setLockedSampleRate(boolean locked)
     {
         try
         {
-            mFrequencyController.setLocked(locked);
+            //Note: this access is not protected by the mFrequencyControllerLock
+            mFrequencyController.setSampleRateLocked(locked);
         }
         catch(SourceException se)
         {
@@ -214,6 +226,7 @@ public abstract class TunerController implements Tunable, ISourceEventProcessor,
 
     public int getBandwidth()
     {
+        //Note: this access is not protected by the mFrequencyControllerLock
         return mFrequencyController.getBandwidth();
     }
 
@@ -225,7 +238,15 @@ public abstract class TunerController implements Tunable, ISourceEventProcessor,
      */
     public void setFrequency(long frequency) throws SourceException
     {
-        mFrequencyController.setFrequency(frequency);
+        try
+        {
+            getFrequencyControllerLock().lock();
+            mFrequencyController.setFrequency(frequency);
+        }
+        finally
+        {
+            getFrequencyControllerLock().unlock();
+        }
     }
 
     /**
@@ -235,28 +256,73 @@ public abstract class TunerController implements Tunable, ISourceEventProcessor,
      */
     public long getFrequency()
     {
-        return mFrequencyController.getFrequency();
+        long frequency;
+
+        try
+        {
+            getFrequencyControllerLock().lock();
+            frequency = mFrequencyController.getFrequency();
+        }
+        finally
+        {
+            getFrequencyControllerLock().unlock();
+        }
+
+        return frequency;
     }
 
     @Override
     public boolean canTune(long frequency)
     {
-        return mFrequencyController.canTune(frequency);
+        boolean canTune;
+
+        try
+        {
+            getFrequencyControllerLock().lock();
+            canTune = mFrequencyController.canTune(frequency);
+        }
+        finally
+        {
+            getFrequencyControllerLock().unlock();
+        }
+
+        return canTune;
     }
 
     public double getSampleRate()
     {
+        //Note: this access is not protected by the mFrequencyControllerLock
         return mFrequencyController.getSampleRate();
     }
 
     public double getFrequencyCorrection()
     {
-        return mFrequencyController.getFrequencyCorrection();
+        double correction;
+
+        try
+        {
+            getFrequencyControllerLock().lock();
+            correction = mFrequencyController.getFrequencyCorrection();
+        }
+        finally
+        {
+            getFrequencyControllerLock().unlock();
+        }
+
+        return correction;
     }
 
     public void setFrequencyCorrection(double correction) throws SourceException
     {
-        mFrequencyController.setFrequencyCorrection(correction);
+        try
+        {
+            getFrequencyControllerLock().lock();
+            mFrequencyController.setFrequencyCorrection(correction);
+        }
+        finally
+        {
+            getFrequencyControllerLock().unlock();
+        }
     }
 
     /**
@@ -265,7 +331,19 @@ public abstract class TunerController implements Tunable, ISourceEventProcessor,
      */
     public long getMinimumFrequency()
     {
-        return mFrequencyController.getMinimumFrequency();
+        long minimum;
+
+        try
+        {
+            getFrequencyControllerLock().lock();
+            minimum = mFrequencyController.getMinimumFrequency();
+        }
+        finally
+        {
+            getFrequencyControllerLock().unlock();
+        }
+
+        return minimum;
     }
 
     /**
@@ -274,7 +352,15 @@ public abstract class TunerController implements Tunable, ISourceEventProcessor,
      */
     public void setMinimumFrequency(long minimum)
     {
-        mFrequencyController.setMinimumFrequency(minimum);
+        try
+        {
+            getFrequencyControllerLock().lock();
+            mFrequencyController.setMinimumFrequency(minimum);
+        }
+        finally
+        {
+            getFrequencyControllerLock().unlock();
+        }
     }
 
     /**
@@ -283,7 +369,19 @@ public abstract class TunerController implements Tunable, ISourceEventProcessor,
      */
     public long getMaximumFrequency()
     {
-        return mFrequencyController.getMaximumFrequency();
+        long maximum;
+
+        try
+        {
+            getFrequencyControllerLock().lock();
+            maximum = mFrequencyController.getMaximumFrequency();
+        }
+        finally
+        {
+            getFrequencyControllerLock().unlock();
+        }
+
+        return maximum;
     }
 
     /**
@@ -292,17 +390,49 @@ public abstract class TunerController implements Tunable, ISourceEventProcessor,
      */
     public void setMaximumFrequency(long maximum)
     {
-        mFrequencyController.setMaximumFrequency(maximum);
+        try
+        {
+            getFrequencyControllerLock().lock();
+            mFrequencyController.setMaximumFrequency(maximum);
+        }
+        finally
+        {
+            getFrequencyControllerLock().unlock();
+        }
     }
 
     public long getMinTunedFrequency() throws SourceException
     {
-        return mFrequencyController.getFrequency() - (getUsableBandwidth() / 2);
+        long minTuned;
+
+        try
+        {
+            getFrequencyControllerLock().lock();
+            minTuned = mFrequencyController.getFrequency() - (getUsableBandwidth() / 2);
+        }
+        finally
+        {
+            getFrequencyControllerLock().unlock();
+        }
+
+        return minTuned;
     }
 
     public long getMaxTunedFrequency() throws SourceException
     {
-        return mFrequencyController.getFrequency() + (getUsableBandwidth() / 2);
+        long maxTuned;
+
+        try
+        {
+            getFrequencyControllerLock().lock();
+            maxTuned = mFrequencyController.getFrequency() + (getUsableBandwidth() / 2);
+        }
+        finally
+        {
+            getFrequencyControllerLock().unlock();
+        }
+
+        return maxTuned;
     }
 
     /**
@@ -425,7 +555,7 @@ public abstract class TunerController implements Tunable, ISourceEventProcessor,
      */
     public void addListener( ISourceEventProcessor processor )
     {
-        mFrequencyController.addListener(processor);
+        mFrequencyController.addSourceEventProcessor(processor);
     }
 
     /**
@@ -433,7 +563,7 @@ public abstract class TunerController implements Tunable, ISourceEventProcessor,
      */
     public void removeListener( ISourceEventProcessor processor )
     {
-        mFrequencyController.removeFrequencyChangeProcessor(processor);
+        mFrequencyController.removeSourceEventProcessor(processor);
     }
 
     /**

src/main/java/io/github/dsheirer/source/tuner/airspy/AirspyTunerEditor.java

@@ -25,6 +25,9 @@ import io.github.dsheirer.source.tuner.manager.DiscoveredTuner;
 import io.github.dsheirer.source.tuner.manager.TunerManager;
 import io.github.dsheirer.source.tuner.manager.TunerStatus;
 import io.github.dsheirer.source.tuner.ui.TunerEditor;
+import java.awt.event.ActionEvent;
+import java.awt.event.ActionListener;
+import java.util.List;
 import net.miginfocom.swing.MigLayout;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -40,9 +43,6 @@ import javax.swing.JSlider;
 import javax.swing.SpinnerNumberModel;
 import javax.swing.event.ChangeEvent;
 import javax.swing.event.ChangeListener;
-import java.awt.event.ActionEvent;
-import java.awt.event.ActionListener;
-import java.util.List;
 
 /**
  * Airspy tuner editor/controller
@@ -102,7 +102,7 @@ public class AirspyTunerEditor extends TunerEditor<AirspyTuner, AirspyTunerConfi
         getTunerStatusLabel().setText(status);
         getButtonPanel().updateControls();
         getFrequencyPanel().updateControls();
-        getSampleRateCombo().setEnabled(hasTuner() && !getTuner().getTunerController().isLocked());
+        getSampleRateCombo().setEnabled(hasTuner() && !getTuner().getTunerController().isLockedSampleRate());
         getTunerInfoButton().setEnabled(hasTuner());
         updateGainComponents((hasTuner() && hasConfiguration()) ? getConfiguration().getGain() : null);
 
@@ -626,7 +626,7 @@ public class AirspyTunerEditor extends TunerEditor<AirspyTuner, AirspyTunerConfi
      */
     private void updateSampleRateToolTip()
     {
-        if(hasTuner() && getTuner().getController().isLocked())
+        if(hasTuner() && getTuner().getController().isLockedSampleRate())
         {
             mSampleRateCombo.setToolTipText("Sample Rate is locked.  Disable decoding channels to unlock.");
         }

src/main/java/io/github/dsheirer/source/tuner/frequency/FrequencyController.java

@@ -22,12 +22,11 @@ import io.github.dsheirer.source.ISourceEventProcessor;
 import io.github.dsheirer.source.InvalidFrequencyException;
 import io.github.dsheirer.source.SourceEvent;
 import io.github.dsheirer.source.SourceException;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
 import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.locks.ReentrantLock;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 public class FrequencyController
 {
@@ -40,8 +39,12 @@ public class FrequencyController
     private long mMaximumFrequency = 0;
     private double mFrequencyCorrection = 0.0d;
     private double mSampleRate = 0.0d;
-    private boolean mLocked = false;
+    private boolean mSampleRateLocked = false;
     private List<ISourceEventProcessor> mProcessors = new ArrayList<>();
+
+    /**
+     * Lock protecting access to frequency control plane, source event processor subscriptions and event broadcasting
+     */
     private ReentrantLock mLock = new ReentrantLock();
 
     /**
@@ -53,6 +56,15 @@ public class FrequencyController
         mTunable = tunable;
     }
 
+
+    /**
+     * Lock for controlling access to frequency control plane, event processor subscriptions and source event broadcasts.
+     */
+    public ReentrantLock getFrequencyControllerLock()
+    {
+        return mLock;
+    }
+
     /**
      * Prepare for disposal of this instance.
      */
@@ -63,36 +75,36 @@ public class FrequencyController
     }
 
     /**
-     * Indicates if this frequency controller is locked by a remote process.  A locked state indicates that neither
+     * Indicates if the sample rate for this frequency controller is locked by a remote process.  A locked state
-     * the frequency nor the sample rate should be changed.  The remote process will typically be a downstream
+     * indicates that the sample rate cannot be changed.  The remote process will typically be a downstream
      * consumer of the data produced by the device being controlled (ie polyphase channelizer) that does not want
-     * the sample rate or frequency to be changed while processing is ongoing.
+     * the sample rate to be changed while processing (ie channels have been allocated) is ongoing.
      *
      * @return true if locked or false if not locked.
      */
-    public boolean isLocked()
+    public boolean isSampleRateLocked()
     {
-        return mLocked;
+        return mSampleRateLocked;
     }
 
     /**
      * Sets the lock state for this frequency controller.  Set to true when a consumer process requires that the
-     * frequency and sample rate controls be locked so that only the singular consumer process makes changes.  This
+     * sample rate control be locked so that only the single consumer process makes changes to the sample rate.  This
      * is primarily to lock down user interface controls when the polyphase channelizer is producing channels.
      *
-     * @param locked state
+     * @param sampleRateLocked state
      */
-    public void setLocked(boolean locked) throws SourceException
+    public void setSampleRateLocked(boolean sampleRateLocked) throws SourceException
     {
-        mLocked = locked;
+        mSampleRateLocked = sampleRateLocked;
 
-        if(mLocked)
+        if(mSampleRateLocked)
         {
-            broadcast(SourceEvent.lockedState());
+            broadcast(SourceEvent.lockedSampleRateState());
         }
         else
         {
-            broadcast(SourceEvent.unlockedState());
+            broadcast(SourceEvent.unlockedSampleRateState());
         }
     }
 
@@ -111,7 +123,7 @@ public class FrequencyController
     {
         if(sampleRate != mSampleRate)
         {
-            if(!mLocked)
+            if(!mSampleRateLocked)
             {
                 mSampleRate = sampleRate;
 
@@ -284,7 +296,7 @@ public class FrequencyController
     /**
      * Adds listener to receive frequency change events
      */
-    public void addListener(ISourceEventProcessor processor)
+    public void addSourceEventProcessor(ISourceEventProcessor processor)
     {
         mLock.lock();
 
@@ -304,7 +316,7 @@ public class FrequencyController
     /**
      * Removes listener from receiving frequency change events
      */
-    public void removeFrequencyChangeProcessor(ISourceEventProcessor processor)
+    public void removeSourceEventProcessor(ISourceEventProcessor processor)
     {
         mLock.lock();
 

src/main/java/io/github/dsheirer/source/tuner/hackrf/HackRFTunerEditor.java

@@ -120,7 +120,7 @@ public class HackRFTunerEditor extends TunerEditor<HackRFTuner,HackRFTunerConfig
         getTunerStatusLabel().setText(status);
         getButtonPanel().updateControls();
         getFrequencyPanel().updateControls();
-        getSampleRateCombo().setEnabled(hasTuner() && !getTuner().getTunerController().isLocked());
+        getSampleRateCombo().setEnabled(hasTuner() && !getTuner().getTunerController().isLockedSampleRate());
         updateSampleRateToolTip();
         getTunerInfoButton().setEnabled(hasTuner());
 
@@ -295,7 +295,7 @@ public class HackRFTunerEditor extends TunerEditor<HackRFTuner,HackRFTunerConfig
      */
     private void updateSampleRateToolTip()
     {
-        if(hasTuner() && getTuner().getController().isLocked())
+        if(hasTuner() && getTuner().getController().isLockedSampleRate())
         {
             mSampleRateCombo.setToolTipText("Sample Rate is locked.  Disable decoding channels to unlock.");
         }

src/main/java/io/github/dsheirer/source/tuner/manager/HeterodyneChannelSourceManager.java

@@ -93,38 +93,48 @@ public class HeterodyneChannelSourceManager extends ChannelSourceManager
             return null;
         }
 
-        if(CenterFrequencyCalculator.canTune(tunerChannel, mTunerController, mTunerChannels))
+        TunerChannelSource source = null;
+
+        try
         {
-            try
+            mTunerController.getFrequencyControllerLock().lock();
+            if(CenterFrequencyCalculator.canTune(tunerChannel, mTunerController, mTunerChannels))
             {
-                //Attempt to create the channel source first, in case we get a filter design exception
+                try
-                HalfBandTunerChannelSource tunerChannelSource = new HalfBandTunerChannelSource(mChannelSourceEventProcessor,
+                {
-                        tunerChannel, mTunerController.getSampleRate(), channelSpecification);
+                    //Attempt to create the channel source first, in case we get a filter design exception
+                    HalfBandTunerChannelSource tunerChannelSource = new HalfBandTunerChannelSource(mChannelSourceEventProcessor,
+                            tunerChannel, mTunerController.getSampleRate(), channelSpecification);
 
-                //Add to the list of channel sources so that it will receive the tuner frequency change
+                    //Add to the list of channel sources so that it will receive the tuner frequency change
-                mChannelSources.add(tunerChannelSource);
+                    mChannelSources.add(tunerChannelSource);
 
-                //Set the current tuner frequency
+                    //Set the current tuner frequency
-                tunerChannelSource.setFrequency(mTunerController.getFrequency());
+                    tunerChannelSource.setFrequency(mTunerController.getFrequency());
 
-                //Add to the channel list and update the tuner center frequency as needed
+                    //Add to the channel list and update the tuner center frequency as needed
-                mTunerChannels.add(tunerChannel);
+                    mTunerChannels.add(tunerChannel);
-                updateTunerFrequency();
+                    updateTunerFrequency();
 
-                //Lock the tuner controller frequency and sample rate
+                    //Lock the tuner controller frequency and sample rate
-                mTunerController.setLocked(true);
+                    mTunerController.setLockedSampleRate(true);
 
-                broadcast(SourceEvent.channelCountChange(getTunerChannelCount()));
+                    broadcast(SourceEvent.channelCountChange(getTunerChannelCount()));
 
-                return tunerChannelSource;
+                    source = tunerChannelSource;
-            }
+                }
-            catch(FilterDesignException fde)
+                catch(FilterDesignException fde)
-            {
+                {
-                mLog.error("Error creating CIC tuner channel source - couldn't design cleanup filter", fde);
+                    mLog.error("Error creating CIC tuner channel source - couldn't design cleanup filter", fde);
+                }
             }
         }
+        finally
+        {
+            mTunerController.getFrequencyControllerLock().unlock();
+        }
 
-        return null;
+        return source;
     }
 
     @Override
@@ -294,7 +304,7 @@ public class HeterodyneChannelSourceManager extends ChannelSourceManager
                         //Unlock the tuner controller if there are no more channels
                         if(getTunerChannelCount() == 0)
                         {
-                            mTunerController.setLocked(false);
+                            mTunerController.setLockedSampleRate(false);
                         }
                         broadcast(SourceEvent.channelCountChange(getTunerChannelCount()));
                     }

src/main/java/io/github/dsheirer/source/tuner/manager/PassThroughSourceManager.java

@@ -82,18 +82,30 @@ public class PassThroughSourceManager extends ChannelSourceManager
     @Override
     public TunerChannelSource getSource(TunerChannel tunerChannel, ChannelSpecification channelSpecification)
     {
+
         if(!mRunning)
         {
             return null;
         }
 
-        PassThroughChannelSource channelSource = new PassThroughChannelSource(new SourceEventProxy(),
+        TunerChannelSource source = null;
-                mTunerController, tunerChannel);
 
-        mTunerChannels.add(tunerChannel);
+        try
-        mTunerChannelSources.add(channelSource);
+        {
+            mTunerController.getFrequencyControllerLock().lock();
+            PassThroughChannelSource channelSource = new PassThroughChannelSource(new SourceEventProxy(),
+                    mTunerController, tunerChannel);
 
-        return channelSource;
+            mTunerChannels.add(tunerChannel);
+            mTunerChannelSources.add(channelSource);
+            source = channelSource;
+        }
+        finally
+        {
+            mTunerController.getFrequencyControllerLock().unlock();
+        }
+
+        return source;
     }
 
     @Override

src/main/java/io/github/dsheirer/source/tuner/manager/PolyphaseChannelSourceManager.java

@@ -25,12 +25,11 @@ import io.github.dsheirer.source.tuner.TunerController;
 import io.github.dsheirer.source.tuner.channel.ChannelSpecification;
 import io.github.dsheirer.source.tuner.channel.TunerChannel;
 import io.github.dsheirer.source.tuner.channel.TunerChannelSource;
+import java.util.SortedSet;
 import org.apache.commons.math3.util.FastMath;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import java.util.SortedSet;
-
 /**
  * PolyphaseChannelSourceManager is responsible for managing the tuner's center tuned frequency and providing access to
  * polyphase tuner channel sources (ie DDCs).  This class is responsible for determining IF a requested channel can
@@ -416,48 +415,56 @@ public class PolyphaseChannelSourceManager extends ChannelSourceManager
     @Override
     public TunerChannelSource getSource(TunerChannel tunerChannel, ChannelSpecification channelSpecification)
     {
-        if(isTunable(tunerChannel))
+        TunerChannelSource tunerChannelSource = null;
+
+        try
         {
-            //Get a new set of currently tuned channels
+            mTunerController.getFrequencyControllerLock().lock();
-            SortedSet<TunerChannel> tunerChannels = getTunerChannels();
+            if(isTunable(tunerChannel))
-
-            //Add the requested channel to the list
-            tunerChannels.add(tunerChannel);
-
-            if(canTune(tunerChannels))
             {
-                long currentCenterFrequency = mTunerController.getFrequency();
+                //Get a new set of currently tuned channels
-                long updatedCenterFrequency = 0;
+                SortedSet<TunerChannel> tunerChannels = getTunerChannels();
 
-                //Attempt to adjust the center frequency before we allocate the channel
+                //Add the requested channel to the list
-                try
+                tunerChannels.add(tunerChannel);
+
+                if(canTune(tunerChannels))
                 {
-                    updatedCenterFrequency = getCenterFrequency(tunerChannels, currentCenterFrequency);
+                    long currentCenterFrequency = mTunerController.getFrequency();
+                    long updatedCenterFrequency = 0;
 
-                    if(updatedCenterFrequency != currentCenterFrequency && updatedCenterFrequency != 0)
+                    //Attempt to adjust the center frequency before we allocate the channel
+                    try
                     {
-                        mTunerController.setFrequency(updatedCenterFrequency);
+                        updatedCenterFrequency = getCenterFrequency(tunerChannels, currentCenterFrequency);
-                    }
 
-                    //If we're successful to here, allocate the channel
+                        if(updatedCenterFrequency != currentCenterFrequency && updatedCenterFrequency != 0)
-                    return mPolyphaseChannelManager.getChannel(tunerChannel);
+                        {
-                }
+                            mTunerController.setFrequency(updatedCenterFrequency);
-                catch(SourceException se)
+                        }
-                {
+
-                    //Tuner controller threw an error trying to tune to the updated frequency
+                        //If we're successful to here, allocate the channel
-                    mLog.error("Error while updating tuner controller with new center frequency [" +
+                        tunerChannelSource = mPolyphaseChannelManager.getChannel(tunerChannel);
-                        updatedCenterFrequency + "] - unable to allocate new tuner channel", se);
+                    }
-                }
+                    catch(SourceException se)
-                catch(IllegalArgumentException iae)
+                    {
-                {
+                        //Tuner controller threw an error trying to tune to the updated frequency
-                    //Center frequency calculation failed
+                        mLog.error("Error while updating tuner controller with new center frequency [" +
-//                    mLog.debug("Couldn't calculate new tuner center frequency for new tuner channel [" +
+                                updatedCenterFrequency + "] - unable to allocate new tuner channel", se);
-//                        tunerChannel + "] unable to allocate new tuner channel");
+                    }
+                    catch(IllegalArgumentException iae)
+                    {
+                        //Center frequency calculation failed
+                    }
                 }
             }
         }
+        finally
+        {
+            mTunerController.getFrequencyControllerLock().unlock();
+        }
 
-        return null;
+        return tunerChannelSource;
     }
 
     /**
@@ -474,7 +481,7 @@ public class PolyphaseChannelSourceManager extends ChannelSourceManager
                 broadcast(sourceEvent);
                 //Lock the frequency and sample rate controls on the tuner controller so users can't change them
                 //when the polyphase manager has channels allocated
-                mTunerController.setLocked(getTunerChannelCount() > 0);
+                mTunerController.setLockedSampleRate(getTunerChannelCount() > 0);
                 break;
             case NOTIFICATION_MEASURED_FREQUENCY_ERROR_SYNC_LOCKED:
                 //Rebroadcast these frequency measurement errors to the tuner and tuner controller

src/main/java/io/github/dsheirer/source/tuner/rtl/e4k/E4KTunerEditor.java

@@ -29,6 +29,8 @@ import io.github.dsheirer.source.tuner.rtl.e4k.E4KEmbeddedTuner.E4KGain;
 import io.github.dsheirer.source.tuner.rtl.e4k.E4KEmbeddedTuner.E4KLNAGain;
 import io.github.dsheirer.source.tuner.rtl.e4k.E4KEmbeddedTuner.E4KMixerGain;
 import io.github.dsheirer.source.tuner.ui.TunerEditor;
+import java.awt.event.ActionEvent;
+import java.awt.event.ActionListener;
 import net.miginfocom.swing.MigLayout;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -41,8 +43,6 @@ import javax.swing.JOptionPane;
 import javax.swing.JSeparator;
 import javax.swing.SpinnerNumberModel;
 import javax.usb.UsbException;
-import java.awt.event.ActionEvent;
-import java.awt.event.ActionListener;
 
 /**
  * E4000 tuner editor
@@ -383,7 +383,7 @@ public class E4KTunerEditor extends TunerEditor<RTL2832Tuner, E4KTunerConfigurat
      */
     private void updateSampleRateToolTip()
     {
-        if(hasTuner() && getTuner().getTunerController().isLocked())
+        if(hasTuner() && getTuner().getTunerController().isLockedSampleRate())
         {
             getSampleRateCombo().setToolTipText("Sample Rate is locked.  Disable decoding channels to unlock.");
         }

src/main/java/io/github/dsheirer/source/tuner/rtl/r820t/R820TTunerEditor.java

@@ -416,7 +416,7 @@ public class R820TTunerEditor extends TunerEditor<RTL2832Tuner,R820TTunerConfigu
      */
     private void updateSampleRateToolTip()
     {
-        if(hasTuner() && getTuner().getTunerController().isLocked())
+        if(hasTuner() && getTuner().getTunerController().isLockedSampleRate())
         {
             getSampleRateCombo().setToolTipText("Sample Rate is locked.  Disable decoding channels to unlock.");
         }

src/main/java/io/github/dsheirer/source/tuner/ui/DiscoveredTunerModel.java

@@ -25,10 +25,6 @@ import io.github.dsheirer.source.tuner.manager.DiscoveredTuner;
 import io.github.dsheirer.source.tuner.manager.DiscoveredUSBTuner;
 import io.github.dsheirer.source.tuner.manager.IDiscoveredTunerStatusListener;
 import io.github.dsheirer.source.tuner.manager.TunerStatus;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
-import javax.swing.table.AbstractTableModel;
 import java.awt.EventQueue;
 import java.text.DecimalFormat;
 import java.util.ArrayList;
@@ -36,6 +32,10 @@ import java.util.List;
 import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.concurrent.locks.Lock;
 import java.util.concurrent.locks.ReentrantLock;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import javax.swing.table.AbstractTableModel;
 
 /**
  * Model for discovered tuners
@@ -449,7 +449,7 @@ public class DiscoveredTunerModel extends AbstractTableModel implements Listener
                     if(discoveredTuner.hasTuner())
                     {
                         int channelCount = discoveredTuner.getTuner().getChannelSourceManager().getTunerChannelCount();
-                        return channelCount + " (" + (discoveredTuner.getTuner().getTunerController().isLocked() ? "LOCKED)" : "UNLOCKED)");
+                        return channelCount + " (" + (discoveredTuner.getTuner().getTunerController().isLockedSampleRate() ? "LOCKED)" : "UNLOCKED)");
                     }
                     else
                     {

src/main/java/io/github/dsheirer/source/tuner/ui/TunerEditor.java

@@ -619,8 +619,8 @@ public abstract class TunerEditor<T extends Tuner,C extends TunerConfiguration>
         {
             getFrequencyControl().clearListeners();
             getFrequencyControl().addListener(mFrequencyAndCorrectionChangeListener);
-            getFrequencyControl().setEnabled(hasTuner() && !getTuner().getTunerController().isLocked());
+            getFrequencyControl().setEnabled(hasTuner() && !getTuner().getTunerController().isLockedSampleRate());
-            getTunerLockedStatusLabel().setVisible(hasTuner() && getTuner().getTunerController().isLocked());
+            getTunerLockedStatusLabel().setVisible(hasTuner() && getTuner().getTunerController().isLockedSampleRate());
             getFrequencyCorrectionSpinner().setEnabled(hasTuner());
             getAutoPPMCheckBox().setEnabled(hasTuner());
 

src/main/java/io/github/dsheirer/source/tuner/ui/TunerViewPanel.java

@@ -143,7 +143,7 @@ public class TunerViewPanel extends JPanel
 
                             if(selectedTuner != null && selectedTuner.hasTuner() && tunerEvent.getTuner() == selectedTuner.getTuner())
                             {
-                                mDiscoveredTunerEditor.setTunerLockState(selectedTuner.getTuner().getTunerController().isLocked());
+                                mDiscoveredTunerEditor.setTunerLockState(selectedTuner.getTuner().getTunerController().isLockedSampleRate());
                             }
                         }
                     }