##2544 bladeRF supports up to 122 MHz sample rate. Adds new 2048 and 4096 half band decimation filters. (#2545)

Co-authored-by: denny <dennis.sheirer@gmail.com>

src/main/java/io/github/dsheirer/dsp/filter/decimate/DecimationFilterFactory.java

@@ -29,12 +29,14 @@ import org.slf4j.LoggerFactory;
 public class DecimationFilterFactory
 {
     private static final Logger mLog = LoggerFactory.getLogger(DecimationFilterFactory.class);
-    private static final int[] SUPPORTED_RATES = new int[]{1,2,4,8,16,32,64,128,256,512,1024};
+    public static final int MAXIMUM_DECIMATION_RATE = 4096;
+    private static final int[] SUPPORTED_RATES = new int[]{1,2,4,8,16,32,64,128,256,512,1024,2048,MAXIMUM_DECIMATION_RATE};
 
     /**
      * Creates a real-valued decimation filter for float array sample buffers providing approximately 70 dB of
      * attenuation for out of band signal aliases, when the signal bandwidth is no more than half of the decimated
-     * sample rate.  Supports power of 2 decimation rates up to 1024.
+     * sample rate.  Supports power of 2 decimation rates up to 4096.  Sample buffers must be an integer multiple of the
+     * decimation rate.
      *
      * @param decimationRate requested @see SUPPORTED_RATES
      * @return constructed decimation filter
@@ -66,6 +68,10 @@ public class DecimationFilterFactory
                 return new RealDecimateX512Filter();
             case 1024:
                 return new RealDecimateX1024Filter();
+            case 2048:
+                return new RealDecimateX2048Filter();
+            case 4096:
+                return new RealDecimateX4096Filter();
             default:
                 throw new IllegalArgumentException("Unsupported decimation rate: " + decimationRate +
                         ".  Supported decimation rates are:" + Arrays.toString(SUPPORTED_RATES));

src/main/java/io/github/dsheirer/dsp/filter/decimate/RealDecimateX2048Filter.java

@@ -0,0 +1,54 @@
+/*
+ * *****************************************************************************
+ * Copyright (C) 2014-2026 Dennis Sheirer
+ *
+ * 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/>
+ * ****************************************************************************
+ */
+
+package io.github.dsheirer.dsp.filter.decimate;
+
+import io.github.dsheirer.dsp.filter.FilterFactory;
+import io.github.dsheirer.dsp.window.WindowType;
+
+/**
+ * Decimate by 2048 filter for real valued sample buffers.
+ */
+public class RealDecimateX2048Filter extends RealDecimateX1024Filter
+{
+    private static final int VALIDATION_LENGTH = 2048;
+    private static final int DECIMATE_BY_2048_FILTER_LENGTH = 11;
+    private static final WindowType DECIMATE_BY_2048_WINDOW_TYPE = WindowType.BLACKMAN;
+    private IRealDecimationFilter mFilter;
+    private float[] mOutput;
+
+    /**
+     * Constructs the decimation filter.
+     */
+    public RealDecimateX2048Filter()
+    {
+        mFilter = FilterFactory.getRealDecimationFilter(DECIMATE_BY_2048_FILTER_LENGTH,
+                DECIMATE_BY_2048_WINDOW_TYPE);
+    }
+
+    @Override
+    public float[] decimateReal(float[] samples)
+    {
+        validate(samples, VALIDATION_LENGTH);
+
+        //Decimate by this filter, then by the parent decimation filter
+        mOutput = getIntermediateOutput(mOutput, samples.length / 2);
+        return super.decimateReal(mFilter.decimateReal(samples, mOutput));
+    }
+}

src/main/java/io/github/dsheirer/dsp/filter/decimate/RealDecimateX4096Filter.java

@@ -0,0 +1,54 @@
+/*
+ * *****************************************************************************
+ * Copyright (C) 2014-2026 Dennis Sheirer
+ *
+ * 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/>
+ * ****************************************************************************
+ */
+
+package io.github.dsheirer.dsp.filter.decimate;
+
+import io.github.dsheirer.dsp.filter.FilterFactory;
+import io.github.dsheirer.dsp.window.WindowType;
+
+/**
+ * Decimate by 4096 filter for real valued sample buffers.
+ */
+public class RealDecimateX4096Filter extends RealDecimateX2048Filter
+{
+    private static final int VALIDATION_LENGTH = 4096;
+    private static final int DECIMATE_BY_4096_FILTER_LENGTH = 11;
+    private static final WindowType DECIMATE_BY_4096_WINDOW_TYPE = WindowType.BLACKMAN;
+    private IRealDecimationFilter mFilter;
+    private float[] mOutput;
+
+    /**
+     * Constructs the decimation filter.
+     */
+    public RealDecimateX4096Filter()
+    {
+        mFilter = FilterFactory.getRealDecimationFilter(DECIMATE_BY_4096_FILTER_LENGTH,
+                DECIMATE_BY_4096_WINDOW_TYPE);
+    }
+
+    @Override
+    public float[] decimateReal(float[] samples)
+    {
+        validate(samples, VALIDATION_LENGTH);
+
+        //Decimate by this filter, then by the parent decimation filter
+        mOutput = getIntermediateOutput(mOutput, samples.length / 2);
+        return super.decimateReal(mFilter.decimateReal(samples, mOutput));
+    }
+}

src/main/java/io/github/dsheirer/source/tuner/bladerf/BladeRfSampleRate.java

@@ -23,7 +23,14 @@ import java.util.ArrayList;
 import java.util.List;
 
 /**
- * Sample rates offered for bladeRF tuners.  Each is a multiple of the 25 kHz polyphase channel spacing.
+ * Sample rates offered for bladeRF tuners, up to the 122.88 MHz maximum of the bladeRF 2.0.  Use getRates() to get the
+ * rates supported by a specific device, since the bladeRF 1.0, USB 2.0 connections and older FPGA images have lower
+ * maximums.
+ *
+ * Rates above 61.44 MHz use the AD9361 oversample feature, which requires 8-bit samples.
+ *
+ * Each rate is a multiple of the 25 kHz polyphase channel spacing, except for the 61.44 and 122.88 MHz rates.  The
+ * channelizer uses slightly wider channels at those rates.
  */
 public enum BladeRfSampleRate
 {
@@ -36,7 +43,21 @@ public enum BladeRfSampleRate
     RATE_15_0(15_000_000, "15.00 MHz"),
     RATE_20_0(20_000_000, "20.00 MHz"),
     RATE_25_0(25_000_000, "25.00 MHz"),
-    RATE_30_0(30_000_000, "30.00 MHz");
+    RATE_30_0(30_000_000, "30.00 MHz"),
+    RATE_35_0(35_000_000, "35.00 MHz"),
+    RATE_40_0(40_000_000, "40.00 MHz"),
+    RATE_45_0(45_000_000, "45.00 MHz"),
+    RATE_50_0(50_000_000, "50.00 MHz"),
+    RATE_55_0(55_000_000, "55.00 MHz"),
+    RATE_60_0(60_000_000, "60.00 MHz"),
+    RATE_61_44(61_440_000, "61.44 MHz"),
+    RATE_70_0(70_000_000, "70.00 MHz (8-bit)"),
+    RATE_80_0(80_000_000, "80.00 MHz (8-bit)"),
+    RATE_90_0(90_000_000, "90.00 MHz (8-bit)"),
+    RATE_100_0(100_000_000, "100.00 MHz (8-bit)"),
+    RATE_110_0(110_000_000, "110.00 MHz (8-bit)"),
+    RATE_120_0(120_000_000, "120.00 MHz (8-bit)"),
+    RATE_122_88(122_880_000, "122.88 MHz (8-bit)");
 
     public static final BladeRfSampleRate DEFAULT = RATE_10_0;
     private final int mRate;
@@ -56,6 +77,14 @@ public enum BladeRfSampleRate
         return mRate;
     }
 
+    /**
+     * Indicates if this rate requires the oversample feature and 8-bit samples.
+     */
+    public boolean isOversampled()
+    {
+        return mRate > RATE_61_44.mRate;
+    }
+
     @Override
     public String toString()
     {
@@ -63,7 +92,7 @@ public enum BladeRfSampleRate
     }
 
     /**
-     * Sample rates within the device maximum, which is the lower of the hardware limit and what the USB link sustains.
+     * Sample rates within the device maximum, which is the lower of what the hardware, FPGA image and USB link support.
      * @param maximumRate in Hertz
      * @return rates, lowest to highest
      */

src/main/java/io/github/dsheirer/source/tuner/bladerf/BladeRfTuner.java

@@ -30,6 +30,8 @@ import io.github.dsheirer.source.tuner.TunerClass;
 public class BladeRfTuner extends Tuner
 {
     private static final int BITS_PER_SAMPLE = 32;
+    private static final double SAMPLE_SIZE_12_BIT = 12.0;
+    private static final double SAMPLE_SIZE_8_BIT = 8.0;
 
     /**
      * Constructs an instance
@@ -72,12 +74,13 @@ public class BladeRfTuner extends Tuner
     @Override
     public double getSampleSize()
     {
-        return 12.0;
+        BladeRfSampleRate rate = getController().getBladeRfSampleRate();
+        return rate != null && rate.isOversampled() ? SAMPLE_SIZE_8_BIT : SAMPLE_SIZE_12_BIT;
     }
 
     @Override
     public int getMaximumUSBBitsPerSecond()
     {
-        return BladeRfSampleRate.RATE_30_0.getRate() * BITS_PER_SAMPLE;
+        return BladeRfSampleRate.RATE_61_44.getRate() * BITS_PER_SAMPLE;
     }
 }

src/main/java/io/github/dsheirer/source/tuner/bladerf/BladeRfTunerController.java

@@ -28,14 +28,17 @@ import io.github.dsheirer.bladerf.Channel;
 import io.github.dsheirer.bladerf.ChannelLayout;
 import io.github.dsheirer.bladerf.DeviceInfo;
 import io.github.dsheirer.bladerf.DeviceSpeed;
+import io.github.dsheirer.bladerf.Feature;
 import io.github.dsheirer.bladerf.GainMode;
 import io.github.dsheirer.bladerf.GainModeInfo;
 import io.github.dsheirer.bladerf.Range;
 import io.github.dsheirer.bladerf.SampleBuffer;
 import io.github.dsheirer.bladerf.SampleFormat;
 import io.github.dsheirer.bladerf.StreamConfig;
+import io.github.dsheirer.bladerf.Version;
 import io.github.dsheirer.buffer.FloatNativeBuffer;
 import io.github.dsheirer.buffer.INativeBuffer;
+import io.github.dsheirer.buffer.SignedByteNativeBuffer;
 import io.github.dsheirer.sample.Listener;
 import io.github.dsheirer.source.SourceException;
 import io.github.dsheirer.source.tuner.ITunerErrorListener;
@@ -62,6 +65,12 @@ import org.usb4java.LibUsb;
  *
  * Only the first receive channel (RX1 connector) is used.  The bladeRF 2.0 has a second receive channel, but it shares
  * the local oscillator and sample rate with the first, so it couldn't be tuned as an independent tuner.
+ *
+ * Sample rates above 61.44 MHz use the AD9361 oversample feature with 8-bit samples.  These are only offered with FPGA
+ * version 0.15.0 or later, because starting an 8-bit sample stream on an older FPGA crashes in libbladeRF.
+ *
+ * The device is reopened when changing between oversampled and normal sample rates.  Disabling the oversample feature
+ * doesn't fully restore the RFIC.  The device reports the correct settings, but streams at the wrong rate or times out.
  */
 public class BladeRfTunerController extends TunerController
 {
@@ -75,10 +84,16 @@ public class BladeRfTunerController extends TunerController
     private static final Channel CHANNEL = Channel.RX0;
     private static final float SAMPLE_SCALE = 1.0f / 2048.0f;
     private static final SampleFormat SAMPLE_FORMAT = SampleFormat.SC16_Q11;
+    private static final SampleFormat OVERSAMPLE_SAMPLE_FORMAT = SampleFormat.SC8_Q7;
+    private static final int OVERSAMPLE_MINIMUM_FPGA_MAJOR = 0;
+    private static final int OVERSAMPLE_MINIMUM_FPGA_MINOR = 15;
     private static final int BUFFER_SAMPLE_COUNT = 65536;
     private static final StreamConfig STREAM_CONFIG = new StreamConfig(32, BUFFER_SAMPLE_COUNT, 16);
+    private static final StreamConfig OVERSAMPLE_STREAM_CONFIG = new StreamConfig(64, BUFFER_SAMPLE_COUNT, 32);
     private static final long USB2_MAXIMUM_BYTES_PER_SECOND = 32_000_000L;
     private static final double MAXIMUM_USABLE_BANDWIDTH_PERCENT = 0.90;
+    //Measured with a carrier swept across the band at 122.88 MHz.  The analog filter is 3 dB down at about +/- 33 MHz.
+    private static final double OVERSAMPLE_USABLE_BANDWIDTH_HZ = 66_000_000.0;
     private static final long STREAM_CHECK_INTERVAL_SECONDS = 1;
 
     private final int mBus;
@@ -89,6 +104,7 @@ public class BladeRfTunerController extends TunerController
     private ScheduledFuture<?> mStreamCheck;
     private List<BladeRfSampleRate> mSampleRates = List.of();
     private BladeRfSampleRate mSampleRate;
+    private boolean mOversampled;
     private List<GainModeInfo> mGainModes = List.of();
     private Range mGainRange;
     private long mMinimumTunableFrequency = MINIMUM_TUNABLE_FREQUENCY_HZ;
@@ -136,6 +152,8 @@ public class BladeRfTunerController extends TunerController
         try
         {
             mDevice = BladeRf.open(findDevice());
+            mSampleRate = null;
+            mOversampled = false;
 
             if(!mDevice.isFpgaConfigured())
             {
@@ -270,12 +288,69 @@ public class BladeRfTunerController extends TunerController
 
         if(device.speed() != DeviceSpeed.SUPER)
         {
-            maximum = Math.min(maximum, USB2_MAXIMUM_BYTES_PER_SECOND / SAMPLE_FORMAT.bytesPerSample());
+            return Math.min(maximum, USB2_MAXIMUM_BYTES_PER_SECOND / SAMPLE_FORMAT.bytesPerSample());
+        }
+
+        if(isOversampleSupported(device.fpgaVersion()))
+        {
+            maximum = Math.max(maximum, getOversampleMaximumSampleRate(device));
+        }
+        else
+        {
+            mLog.info("bladeRF sample rates limited to [" + maximum + "] Hz - FPGA version [" + device.fpgaVersion() +
+                    "] doesn't support 8-bit samples.  Upgrade to FPGA version 0.15.0 or later for higher sample rates.");
         }
 
         return maximum;
     }
 
+    /**
+     * Indicates if the FPGA version supports the 8-bit samples that are required for the oversample feature.
+     * @param fpga version
+     * @return true if supported
+     */
+    static boolean isOversampleSupported(Version fpga)
+    {
+        return fpga.major() > OVERSAMPLE_MINIMUM_FPGA_MAJOR ||
+                (fpga.major() == OVERSAMPLE_MINIMUM_FPGA_MAJOR && fpga.minor() >= OVERSAMPLE_MINIMUM_FPGA_MINOR);
+    }
+
+    /**
+     * Usable portion of an oversampled rate, which is limited by the analog filter that stays in the signal path.
+     * @param rate that is oversampled
+     * @return usable bandwidth percentage
+     */
+    static double getOversampleUsableBandwidthPercentage(BladeRfSampleRate rate)
+    {
+        return Math.min(MAXIMUM_USABLE_BANDWIDTH_PERCENT, OVERSAMPLE_USABLE_BANDWIDTH_HZ / rate.getRate());
+    }
+
+    /**
+     * Highest sample rate that the device reports while the oversample feature is enabled.
+     * @return maximum rate, or zero if the device doesn't have the oversample feature, such as the bladeRF 1.0.
+     */
+    private static long getOversampleMaximumSampleRate(BladeRfDevice device) throws BladeRfException
+    {
+        try
+        {
+            device.enableFeature(Feature.OVERSAMPLE, true);
+        }
+        catch(BladeRfException e)
+        {
+            mLog.info("bladeRF oversample feature isn't available - " + e.getMessage());
+            return 0;
+        }
+
+        try
+        {
+            return device.sampleRateRange(CHANNEL).max();
+        }
+        finally
+        {
+            device.enableFeature(Feature.DEFAULT, true);
+        }
+    }
+
     /**
      * Finds the libbladeRF description of the device at this controller's USB bus and port.
      */
@@ -450,11 +525,33 @@ public class BladeRfTunerController extends TunerController
 
                 try
                 {
+                    if(rate.isOversampled() != mOversampled)
+                    {
+                        reopenDevice();
+
+                        if(rate.isOversampled())
+                        {
+                            //Bandwidth has to be set first since it can't be reliably set with oversample enabled.
+                            mDevice.setBandwidth(CHANNEL, mDevice.bandwidthRange(CHANNEL).max());
+                            mDevice.enableFeature(Feature.OVERSAMPLE, true);
+                            mOversampled = true;
+                        }
+                    }
+
                     mDevice.setSampleRate(CHANNEL, rate.getRate());
-                    long requested = (long)(rate.getRate() * MAXIMUM_USABLE_BANDWIDTH_PERCENT);
-                    long bandwidth = mDevice.setBandwidth(CHANNEL, requested);
-                    setUsableBandwidthPercentage(Math.min(MAXIMUM_USABLE_BANDWIDTH_PERCENT,
-                            (double)bandwidth / rate.getRate()));
+
+                    if(rate.isOversampled())
+                    {
+                        setUsableBandwidthPercentage(getOversampleUsableBandwidthPercentage(rate));
+                    }
+                    else
+                    {
+                        long requested = (long)(rate.getRate() * MAXIMUM_USABLE_BANDWIDTH_PERCENT);
+                        long bandwidth = mDevice.setBandwidth(CHANNEL, requested);
+                        setUsableBandwidthPercentage(Math.min(MAXIMUM_USABLE_BANDWIDTH_PERCENT,
+                                (double)bandwidth / rate.getRate()));
+                    }
+
                     mSampleRate = rate;
                     mSamplesPerMillisecond = rate.getRate() / 1000.0f;
                     mFrequencyController.setSampleRate(rate.getRate());
@@ -465,7 +562,7 @@ public class BladeRfTunerController extends TunerController
                 }
                 finally
                 {
-                    if(streaming)
+                    if(streaming && mDevice != null)
                     {
                         startStream();
                     }
@@ -478,6 +575,33 @@ public class BladeRfTunerController extends TunerController
         }
     }
 
+    /**
+     * Closes and reopens the device and restores the settings that were reset, except for the sample rate and bandwidth
+     * which the caller sets.  The sample stream must be stopped.
+     */
+    private void reopenDevice() throws SourceException, BladeRfException
+    {
+        long frequency = mFrequencyController.getTunedFrequency();
+        BladeRfDevice device = mDevice;
+        mDevice = null;
+        mOversampled = false;
+        closeDevice(device, false);
+
+        mDevice = BladeRf.open(findDevice());
+        mDevice.setFrequency(CHANNEL, frequency);
+        mDevice.setGainMode(CHANNEL, mGainMode);
+
+        if(mGainMode == GainMode.MANUAL)
+        {
+            mDevice.setGain(CHANNEL, mGain);
+        }
+
+        if(mBiasT)
+        {
+            mDevice.setBiasTee(CHANNEL, true);
+        }
+    }
+
     /**
      * Gain modes supported by the device.
      */
@@ -679,7 +803,9 @@ public class BladeRfTunerController extends TunerController
     {
         try
         {
-            mStream = mDevice.startRx(ChannelLayout.RX_X1, SAMPLE_FORMAT, STREAM_CONFIG, this::receive);
+            mStream = mOversampled ?
+                    mDevice.startRx(ChannelLayout.RX_X1, OVERSAMPLE_SAMPLE_FORMAT, OVERSAMPLE_STREAM_CONFIG, this::receive) :
+                    mDevice.startRx(ChannelLayout.RX_X1, SAMPLE_FORMAT, STREAM_CONFIG, this::receive);
             mStreamCheck = ThreadPool.SCHEDULED.scheduleAtFixedRate(this::checkStream, STREAM_CHECK_INTERVAL_SECONDS,
                     STREAM_CHECK_INTERVAL_SECONDS, TimeUnit.SECONDS);
         }
@@ -746,7 +872,16 @@ public class BladeRfTunerController extends TunerController
     {
         try
         {
-            broadcast(new FloatNativeBuffer(scale(buffer.copyShorts()), System.currentTimeMillis(), mSamplesPerMillisecond));
+            long timestamp = System.currentTimeMillis();
+
+            if(buffer.format() == OVERSAMPLE_SAMPLE_FORMAT)
+            {
+                broadcast(new SignedByteNativeBuffer(buffer.copyBytes(), timestamp, 0.0f, 0.0f, mSamplesPerMillisecond));
+            }
+            else
+            {
+                broadcast(new FloatNativeBuffer(scale(buffer.copyShorts()), timestamp, mSamplesPerMillisecond));
+            }
         }
         catch(RuntimeException e)
         {

src/main/java/io/github/dsheirer/source/tuner/bladerf/BladeRfTunerEditor.java

@@ -90,7 +90,7 @@ public class BladeRfTunerEditor extends TunerEditor<BladeRfTuner, BladeRfTunerCo
 
     private void init()
     {
-        setLayout(new MigLayout("fill,wrap 3", "[right][grow,fill][fill]", "[][][][][][][][][][grow]"));
+        setLayout(new MigLayout("fill,wrap 3", "[right][grow,fill][fill]", "[][][][][][][][][][][][grow]"));
 
         add(new JLabel("Tuner:"));
         add(getTunerIdLabel());
@@ -101,7 +101,7 @@ public class BladeRfTunerEditor extends TunerEditor<BladeRfTuner, BladeRfTunerCo
 
         add(getButtonPanel(), "span,align left");
 
-        add(new JSeparator(), "span,growx,push");
+        add(new JSeparator(), "span,growx");
 
         add(new JLabel("Frequency (MHz):"));
         add(getFrequencyPanel(), "wrap");
@@ -112,7 +112,7 @@ public class BladeRfTunerEditor extends TunerEditor<BladeRfTuner, BladeRfTunerCo
         add(new JLabel());
         add(getBiasTCheckBox(), "wrap");
 
-        add(new JSeparator(), "span,growx,push");
+        add(new JSeparator(), "span,growx");
         add(new JLabel("Gain Control"), "wrap");
 
         add(new JLabel("Mode:"));
@@ -121,6 +121,9 @@ public class BladeRfTunerEditor extends TunerEditor<BladeRfTuner, BladeRfTunerCo
         add(new JLabel("Gain:"));
         add(getGainSlider());
         add(getGainValueLabel());
+
+        //Empty row that takes all extra vertical space so that the controls stay stacked at the top of the editor.
+        add(new JLabel(), "span,pushy");
     }
 
     @Override

src/main/java/io/github/dsheirer/source/tuner/channel/HalfBandTunerChannelSource.java

@@ -46,6 +46,16 @@ public class HalfBandTunerChannelSource<T extends INativeBuffer> extends TunerCh
     //Maximum number of filled buffers for the blocking queue
     private static final int BUFFER_MAX_CAPACITY = 600;
 
+    //Decimation rate where a 2048 sample fragment produces too few samples for the consumer, so the decimated samples
+    //are assembled into longer buffers.  Decoders apply additional decimation that requires a buffer length that's a
+    //multiple of their decimation.
+    private static final int ASSEMBLED_OUTPUT_DECIMATION = 1024;
+    private static final int ASSEMBLED_OUTPUT_LENGTH = 64;
+
+    //Decimation rate where sample fragments can be too short for the filter, which requires a buffer length that's a
+    //multiple of the decimation rate, so the mixed samples are assembled before decimation.
+    private static final int ASSEMBLED_INPUT_DECIMATION = 2048;
+
     private final Dispatcher<T> mBufferDispatcher;
     private final ComplexMixer mFrequencyCorrectionMixer;
     private final IRealDecimationFilter mIDecimationFilter;
@@ -59,6 +69,15 @@ public class HalfBandTunerChannelSource<T extends INativeBuffer> extends TunerCh
     private final long mFrequencyOffset;
     private volatile long mFrequencyCorrection;
     private final AtomicBoolean mPendingMixerUpdate = new AtomicBoolean();
+    private final boolean mAssembleOutput;
+    private final float[] mInputI;
+    private final float[] mInputQ;
+    private int mInputPointer;
+    private long mInputTimestamp;
+    private float[] mOutputI;
+    private float[] mOutputQ;
+    private int mOutputPointer;
+    private long mOutputTimestamp;
 
     /**
      * Constructs a frequency translating and CIC decimating channel source.
@@ -87,6 +106,9 @@ public class HalfBandTunerChannelSource<T extends INativeBuffer> extends TunerCh
 
         //The decimation filters copy the mixed samples, unless there's no decimation and the mixed samples are the output
         mReuseMixerOutput = decimation > 1;
+        mAssembleOutput = decimation >= ASSEMBLED_OUTPUT_DECIMATION;
+        mInputI = decimation >= ASSEMBLED_INPUT_DECIMATION ? new float[decimation] : null;
+        mInputQ = decimation >= ASSEMBLED_INPUT_DECIMATION ? new float[decimation] : null;
 
         //Set dispatcher to process 1/10 of estimated sample arrival rate, 20 times per second (up to 200% per interval)
         mBufferDispatcher = new Dispatcher(threadName, 50, getHeartbeatManager(), BUFFER_MAX_CAPACITY);
@@ -242,23 +264,113 @@ public class HalfBandTunerChannelSource<T extends INativeBuffer> extends TunerCh
                     }
 
                     ComplexSamples basebanded = mix(iterator.next());
-                    float[] i = mIDecimationFilter.decimateReal(basebanded.i());
-                    float[] q = mQDecimationFilter.decimateReal(basebanded.q());
 
-                    try
+                    if(mInputI != null)
                     {
-                        mSamplesListener.receive(new ComplexSamples(i, q, basebanded.timestamp()));
+                        assembleInput(basebanded);
                     }
-                    catch(Throwable t)
+                    else
                     {
-                        //The listener can be made null and cause the error - only log if we have a non-null listener
-                        if(mSamplesListener != null)
-                        {
-                            mLog.error("Error dispatching complex samples to listener [" + mSamplesListener + "]");
-                        }
+                        decimate(basebanded.i(), basebanded.q(), basebanded.timestamp());
                     }
                 }
             }
         }
+
+        /**
+         * Assembles the mixed samples into buffers of the decimation rate length and decimates each full buffer.
+         * @param samples that were mixed, which are copied since the mixer output arrays can be reused.
+         */
+        private void assembleInput(ComplexSamples samples)
+        {
+            int pointer = 0;
+
+            while(pointer < samples.i().length)
+            {
+                if(mInputPointer == 0)
+                {
+                    mInputTimestamp = samples.timestamp();
+                }
+
+                int length = Math.min(samples.i().length - pointer, mInputI.length - mInputPointer);
+                System.arraycopy(samples.i(), pointer, mInputI, mInputPointer, length);
+                System.arraycopy(samples.q(), pointer, mInputQ, mInputPointer, length);
+                pointer += length;
+                mInputPointer += length;
+
+                if(mInputPointer == mInputI.length)
+                {
+                    mInputPointer = 0;
+                    decimate(mInputI, mInputQ, mInputTimestamp);
+                }
+            }
+        }
+
+        /**
+         * Decimates the samples and sends them to the listener.
+         */
+        private void decimate(float[] i, float[] q, long timestamp)
+        {
+            output(mIDecimationFilter.decimateReal(i), mQDecimationFilter.decimateReal(q), timestamp);
+        }
+
+        /**
+         * Sends the decimated samples to the listener, assembling them into larger buffers at the maximum decimation.
+         * @param i decimated samples
+         * @param q decimated samples
+         * @param timestamp of the first sample
+         */
+        private void output(float[] i, float[] q, long timestamp)
+        {
+            if(!mAssembleOutput)
+            {
+                dispatch(new ComplexSamples(i, q, timestamp));
+                return;
+            }
+
+            int pointer = 0;
+
+            while(pointer < i.length)
+            {
+                if(mOutputPointer == 0)
+                {
+                    //New arrays each time since the assembled arrays are passed to the consumer
+                    mOutputI = new float[ASSEMBLED_OUTPUT_LENGTH];
+                    mOutputQ = new float[ASSEMBLED_OUTPUT_LENGTH];
+                    mOutputTimestamp = timestamp;
+                }
+
+                int length = Math.min(i.length - pointer, ASSEMBLED_OUTPUT_LENGTH - mOutputPointer);
+                System.arraycopy(i, pointer, mOutputI, mOutputPointer, length);
+                System.arraycopy(q, pointer, mOutputQ, mOutputPointer, length);
+                pointer += length;
+                mOutputPointer += length;
+
+                if(mOutputPointer == ASSEMBLED_OUTPUT_LENGTH)
+                {
+                    mOutputPointer = 0;
+                    dispatch(new ComplexSamples(mOutputI, mOutputQ, mOutputTimestamp));
+                }
+            }
+        }
+
+        /**
+         * Sends the samples to the listener.
+         */
+        private void dispatch(ComplexSamples samples)
+        {
+            try
+            {
+                mSamplesListener.receive(samples);
+            }
+            catch(Throwable t)
+            {
+                //The listener can be made null and cause the error - only log if we have a non-null listener
+                if(mSamplesListener != null)
+                {
+                    mLog.error("Error dispatching complex samples to listener [" + mSamplesListener + "]");
+                }
+            }
+        }
     }
 }

src/test/java/io/github/dsheirer/dsp/filter/decimate/DecimationFilterFactoryTest.java

@@ -83,7 +83,25 @@ public class DecimationFilterFactoryTest
         assertEquals(2, DecimationFilterFactory.getDecimationRate(4));
         assertEquals(4, DecimationFilterFactory.getDecimationRate(5));
         assertEquals(64, DecimationFilterFactory.getDecimationRate(96));
-        assertEquals(1024, DecimationFilterFactory.getDecimationRate(4096));
+        assertEquals(1024, DecimationFilterFactory.getDecimationRate(2048));
+        assertEquals(2048, DecimationFilterFactory.getDecimationRate(4096));
+        assertEquals(4096, DecimationFilterFactory.getDecimationRate(4097));
+        assertEquals(4096, DecimationFilterFactory.getDecimationRate(100000));
+    }
+
+    /**
+     * Test: each decimation rate reduces the sample count by that rate and rejects a length that isn't a multiple.
+     */
+    @Test
+    void highestRatesDecimateAndValidateLength()
+    {
+        for(int decimation : new int[]{1024, 2048, 4096})
+        {
+            assertEquals(1, DecimationFilterFactory.getRealDecimationFilter(decimation)
+                .decimateReal(new float[decimation]).length);
+            assertThrows(IllegalArgumentException.class, () -> DecimationFilterFactory
+                .getRealDecimationFilter(decimation).decimateReal(new float[decimation / 2]));
+        }
     }
 
     /**
@@ -138,7 +156,7 @@ public class DecimationFilterFactoryTest
     @Test
     void aliasRejection()
     {
-        for(int decimation = 2; decimation <= 512; decimation *= 2)
+        for(int decimation = 2; decimation <= DecimationFilterFactory.MAXIMUM_DECIMATION_RATE; decimation *= 2)
         {
             double sampleRate = DECIMATED_SAMPLE_RATE * decimation;
 

src/test/java/io/github/dsheirer/source/tuner/bladerf/BladeRfTunerTest.java

@@ -20,11 +20,16 @@ package io.github.dsheirer.source.tuner.bladerf;
 
 import static org.junit.jupiter.api.Assertions.assertArrayEquals;
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertInstanceOf;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import com.fasterxml.jackson.databind.DeserializationFeature;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import io.github.dsheirer.bladerf.GainMode;
+import io.github.dsheirer.bladerf.Version;
+import io.github.dsheirer.buffer.SignedByteNativeBuffer;
+import io.github.dsheirer.dsp.filter.channelizer.ComplexPolyphaseChannelizerM2;
 import io.github.dsheirer.source.tuner.TunerClass;
 import io.github.dsheirer.source.tuner.TunerType;
 import io.github.dsheirer.source.tuner.configuration.TunerConfiguration;
@@ -64,15 +69,85 @@ class BladeRfTunerTest
         assertEquals(BladeRfSampleRate.RATE_1_25, BladeRfSampleRate.getClosest(rates, 1));
     }
 
+    @Test
+    void sampleRatesFollowTheDeviceMaximum()
+    {
+        //bladeRF 2.0 on USB 3.0 with FPGA version 0.15.0 or later
+        assertEquals(List.of(BladeRfSampleRate.values()), BladeRfSampleRate.getRates(122_880_000));
+        //bladeRF 2.0 on USB 3.0 with an older FPGA version
+        assertEquals(BladeRfSampleRate.RATE_61_44, BladeRfSampleRate.getRates(61_440_000).getLast());
+        //bladeRF 1.0 on USB 3.0
+        assertEquals(BladeRfSampleRate.RATE_40_0, BladeRfSampleRate.getRates(40_000_000).getLast());
+        //USB 2.0
+        assertEquals(BladeRfSampleRate.RATE_7_5, BladeRfSampleRate.getRates(8_000_000).getLast());
+    }
+
+    @Test
+    void savedRateAboveTheDeviceMaximumIsReduced()
+    {
+        List<BladeRfSampleRate> rates = BladeRfSampleRate.getRates(40_000_000);
+
+        assertEquals(BladeRfSampleRate.RATE_40_0, BladeRfSampleRate.getClosest(rates,
+                BladeRfSampleRate.RATE_122_88.getRate()));
+    }
+
+    @Test
+    void onlyRatesAbove61MhzAreOversampled()
+    {
+        assertFalse(BladeRfSampleRate.RATE_61_44.isOversampled());
+        assertTrue(BladeRfSampleRate.RATE_70_0.isOversampled());
+        assertTrue(BladeRfSampleRate.RATE_122_88.isOversampled());
+    }
+
+    @Test
+    void oversampledUsableBandwidthIsLimitedByTheAnalogFilter()
+    {
+        assertEquals(0.90, BladeRfTunerController.getOversampleUsableBandwidthPercentage(BladeRfSampleRate.RATE_70_0));
+        assertEquals(66_000_000, BladeRfTunerController.getOversampleUsableBandwidthPercentage(
+                BladeRfSampleRate.RATE_122_88) * BladeRfSampleRate.RATE_122_88.getRate(), 1.0);
+    }
+
+    @Test
+    void oversampleRequiresFpga15()
+    {
+        assertFalse(BladeRfTunerController.isOversampleSupported(new Version(0, 14, 0, "0.14.0")));
+        assertTrue(BladeRfTunerController.isOversampleSupported(new Version(0, 15, 0, "0.15.0")));
+        assertTrue(BladeRfTunerController.isOversampleSupported(new Version(0, 16, 3, "0.16.3")));
+        assertTrue(BladeRfTunerController.isOversampleSupported(new Version(1, 0, 0, "1.0.0")));
+    }
+
+    @Test
+    void streamBufferFitsTheEightBitNativeBuffer()
+    {
+        int sampleCount = 65536;
+
+        assertEquals(sampleCount, new SignedByteNativeBuffer(new byte[sampleCount * 2], 0, 0, 0, 1).sampleCount());
+    }
+
     @Test
     void sampleRatesDivideIntoPolyphaseChannels()
     {
         for(BladeRfSampleRate rate : BladeRfSampleRate.values())
         {
-            assertEquals(0, rate.getRate() % 50_000, rate.toString());
+            if(rate != BladeRfSampleRate.RATE_61_44 && rate != BladeRfSampleRate.RATE_122_88)
+            {
+                assertEquals(0, rate.getRate() % 50_000, rate.toString());
+            }
+
+            int channelCount = ComplexPolyphaseChannelizerM2.getChannelCount(rate.getRate());
+            assertEquals(0, channelCount % 2, rate.toString());
+            assertTrue((double)rate.getRate() / channelCount >= 25_000.0, rate.toString());
         }
     }
 
+    @Test
+    void maximumUsbRateDoesNotOverflow()
+    {
+        assertEquals(1_966_080_000L, BladeRfSampleRate.RATE_61_44.getRate() * 32L);
+        assertTrue(BladeRfSampleRate.RATE_61_44.getRate() * 32L <= Integer.MAX_VALUE);
+        assertEquals(1_966_080_000L, BladeRfSampleRate.RATE_122_88.getRate() * 16L);
+    }
+
     @Test
     void configurationSurvivesSerialization() throws Exception
     {

src/test/java/io/github/dsheirer/source/tuner/channel/HalfBandTunerChannelSourceTest.java

@@ -20,9 +20,18 @@ package io.github.dsheirer.source.tuner.channel;
 
 import io.github.dsheirer.buffer.FloatNativeBuffer;
 import io.github.dsheirer.buffer.INativeBuffer;
+import io.github.dsheirer.buffer.SignedByteNativeBuffer;
+import io.github.dsheirer.dsp.filter.decimate.DecimationFilterFactory;
+import io.github.dsheirer.dsp.filter.decimate.IRealDecimationFilter;
+import io.github.dsheirer.sample.complex.ComplexSamples;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.concurrent.atomic.AtomicInteger;
 import org.junit.jupiter.api.Test;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
  * Verifies that the heterodyne channel source applies frequency updates on the sample processing thread.
@@ -76,6 +85,137 @@ public class HalfBandTunerChannelSourceTest
         assertEquals(50000.0, source.getSampleRate());
     }
 
+    private static HalfBandTunerChannelSource<INativeBuffer> source(double sampleRate) throws Exception
+    {
+        return new HalfBandTunerChannelSource<>(sourceEvent -> {}, new TunerChannel(CHANNEL_FREQUENCY, 12500), sampleRate,
+            new ChannelSpecification(25000.0, 12500, 6000.0, 7000.0), "test", null);
+    }
+
+    /**
+     * Test: a decoder can apply more decimation at the highest source decimation rates, where a 2048 sample fragment
+     * produces 2 samples or less, since these are assembled into larger buffers for the decoder.
+     */
+    @Test
+    void highDecimationProvidesBuffersThatDecodersCanDecimate() throws Exception
+    {
+        //Tuner sample rates that select a decimation of 1024, 2048 and 4096
+        for(int[] rates : new int[][]{{30_000_000, 1024}, {60_000_000, 2048}, {120_000_000, 4096}})
+        {
+            for(int decoderDecimation : new int[]{2, 4, 8, 16, 32, 64})
+            {
+                HalfBandTunerChannelSource<INativeBuffer> source = source(rates[0]);
+                IRealDecimationFilter filter = DecimationFilterFactory.getRealDecimationFilter(decoderDecimation);
+                List<Throwable> errors = new ArrayList<>();
+                AtomicInteger sampleCount = new AtomicInteger();
+
+                source.setListener(samples ->
+                {
+                    try
+                    {
+                        sampleCount.addAndGet(samples.i().length);
+                        filter.decimateReal(samples.i());
+                    }
+                    catch(Throwable t)
+                    {
+                        errors.add(t);
+                    }
+                });
+
+                //Each native buffer has 65536 samples in 2048 sample fragments
+                int nativeBuffers = 64 * rates[1] / 65536;
+
+                for(int x = 0; x < nativeBuffers; x++)
+                {
+                    source.new NativeBufferProcessor().receive(new SignedByteNativeBuffer(new byte[131072], 0L, 0, 0, 1));
+                }
+
+                assertEquals(List.of(), errors);
+                assertEquals((double)rates[0] / rates[1], source.getSampleRate());
+                assertEquals(64 * (nativeBuffers * 65536 / rates[1] / 64), sampleCount.get());
+            }
+        }
+    }
+
+    /**
+     * Test: assembled buffers preserve the timestamp of the first sample in each buffer.
+     */
+    @Test
+    void assembledBuffersPreserveTimestamps() throws Exception
+    {
+        HalfBandTunerChannelSource<INativeBuffer> source = source(120_000_000.0);
+        List<ComplexSamples> buffers = new ArrayList<>();
+        source.setListener(buffers::add);
+
+        //Each native buffer has 32768 samples that produce 8 decimated samples, so 12 native buffers provide 96 samples
+        for(long timestamp = 1000; timestamp <= 12000; timestamp += 1000)
+        {
+            source.new NativeBufferProcessor().receive(new FloatNativeBuffer(new float[65536], timestamp, 0.0f));
+        }
+
+        assertEquals(1, buffers.size());
+        assertEquals(64, buffers.getFirst().i().length);
+        assertEquals(64, buffers.getFirst().q().length);
+        assertEquals(1000L, buffers.getFirst().timestamp());
+    }
+
+    /**
+     * Test: assembling sample fragments doesn't change the samples, so the output matches decimating complete blocks,
+     * including when sample buffers end with a short fragment.
+     */
+    @Test
+    void assembledInputMatchesContinuousDecimation() throws Exception
+    {
+        int decimation = 4096;
+        //Native buffers provide a 2048 sample fragment and a 1024 sample fragment, which straddle the filter blocks
+        int fragment = 3072;
+        int fragments = 800;
+        float[] interleaved = new float[fragment * fragments * 2];
+
+        for(int x = 0; x < fragment * fragments; x++)
+        {
+            double phase = 2.0 * Math.PI * 3000.0 * x / 120_000_000.0;
+            interleaved[x * 2] = (float)Math.cos(phase);
+            interleaved[x * 2 + 1] = (float)Math.sin(phase);
+        }
+
+        HalfBandTunerChannelSource<INativeBuffer> source = source(120_000_000.0);
+        List<ComplexSamples> buffers = new ArrayList<>();
+        source.setListener(buffers::add);
+
+        for(int x = 0; x < fragments; x++)
+        {
+            float[] samples = Arrays.copyOfRange(interleaved, x * fragment * 2, (x + 1) * fragment * 2);
+            source.new NativeBufferProcessor().receive(new FloatNativeBuffer(samples, 0L, 0.0f));
+        }
+
+        IRealDecimationFilter expectedI = DecimationFilterFactory.getRealDecimationFilter(decimation);
+        float[] blockI = new float[decimation];
+        List<Float> expected = new ArrayList<>();
+
+        for(int x = 0; x + decimation <= fragment * fragments; x += decimation)
+        {
+            for(int y = 0; y < decimation; y++)
+            {
+                blockI[y] = interleaved[(x + y) * 2];
+            }
+
+            expected.add(expectedI.decimateReal(blockI)[0]);
+        }
+
+        int pointer = 0;
+
+        for(ComplexSamples buffer : buffers)
+        {
+            for(float sample : buffer.i())
+            {
+                assertEquals(expected.get(pointer++), sample, 1e-4f);
+            }
+        }
+
+        assertEquals(expected.size() / 64 * 64, pointer);
+        assertTrue(pointer > 0);
+    }
+
     /**
      * Test: concurrent tuner frequency and channel correction updates are both reflected in the mixer.
      */