From b3433b7f3c6e2989ec6f5d87bb5c0f30d1006a25 Mon Sep 17 00:00:00 2001
From: Vance Vagell <vance@vagell.com>
Date: Sat, 14 Dec 2024 17:37:36 -0500
Subject: [PATCH] Add new settings to control rx and tx sampling rates, as well
 as an rx multipler (to account for varying ESP32 dev module ADC performance /
 clocks). Implements issue #138.

---
 .../KV4PHT/.idea/deploymentTargetSelector.xml |   4 +-
 .../KV4PHT/app/src/main/AndroidManifest.xml   |   4 +-
 .../vagell/kv4pht/aprs/parser/APRSPacket.java |   3 +-
 .../kv4pht/radio/RadioAudioService.java       | 229 ++++---
 .../com/vagell/kv4pht/ui/MainActivity.java    |  48 +-
 .../vagell/kv4pht/ui/SettingsActivity.java    | 159 ++++-
 .../res/layout/activity_add_edit_memory.xml   | 354 ++++++-----
 .../src/main/res/layout/activity_settings.xml | 581 +++++++++++-------
 .../kv4p_ht_esp32_wroom_32.ino                |  60 +-
 9 files changed, 937 insertions(+), 505 deletions(-)

diff --git a/android-src/KV4PHT/.idea/deploymentTargetSelector.xml b/android-src/KV4PHT/.idea/deploymentTargetSelector.xml
index 975d40c..6c7944c 100644
--- a/android-src/KV4PHT/.idea/deploymentTargetSelector.xml
+++ b/android-src/KV4PHT/.idea/deploymentTargetSelector.xml
@@ -4,10 +4,10 @@
     <selectionStates>
       <SelectionState runConfigName="app">
         <option name="selectionMode" value="DROPDOWN" />
-        <DropdownSelection timestamp="2024-12-14T00:05:55.491007900Z">
+        <DropdownSelection timestamp="2024-12-14T18:21:36.524985700Z">
           <Target type="DEFAULT_BOOT">
             <handle>
-              <DeviceId pluginId="Default" identifier="serial=192.168.1.43:45557;connection=4f3c97eb" />
+              <DeviceId pluginId="Default" identifier="serial=192.168.1.43:33629;connection=4e8a42a3" />
             </handle>
           </Target>
         </DropdownSelection>
diff --git a/android-src/KV4PHT/app/src/main/AndroidManifest.xml b/android-src/KV4PHT/app/src/main/AndroidManifest.xml
index 46c8ad8..17b7d72 100644
--- a/android-src/KV4PHT/app/src/main/AndroidManifest.xml
+++ b/android-src/KV4PHT/app/src/main/AndroidManifest.xml
@@ -35,7 +35,7 @@
             android:name=".ui.SettingsActivity"
             android:exported="true"
             android:theme="@style/Theme.KV4PHT"
-            android:windowSoftInputMode="stateVisible">
+            android:windowSoftInputMode="adjustResize">
             <intent-filter>
                 <action android:name="com.vagell.kv4pht.SETTINGS_ACTION" />
 
@@ -46,7 +46,7 @@
             android:name=".ui.AddEditMemoryActivity"
             android:exported="true"
             android:theme="@style/Theme.KV4PHT"
-            android:windowSoftInputMode="stateVisible|adjustResize"> <!-- There's an issue where fields are not scrollable, likely caused by an Android bug not honoring adjustResize on fullscreen apps, see similar bug in another project: https://github.com/dotnet/maui/issues/14281 -->
+            android:windowSoftInputMode="adjustResize">
             <intent-filter>
                 <action android:name="com.vagell.kv4pht.ADD_MEMORY_ACTION" />
                 <action android:name="com.vagell.kv4pht.EDIT_MEMORY_ACTION" />
diff --git a/android-src/KV4PHT/app/src/main/java/com/vagell/kv4pht/aprs/parser/APRSPacket.java b/android-src/KV4PHT/app/src/main/java/com/vagell/kv4pht/aprs/parser/APRSPacket.java
index 16836cd..8dd3c7a 100644
--- a/android-src/KV4PHT/app/src/main/java/com/vagell/kv4pht/aprs/parser/APRSPacket.java
+++ b/android-src/KV4PHT/app/src/main/java/com/vagell/kv4pht/aprs/parser/APRSPacket.java
@@ -58,8 +58,7 @@ public APRSPacket( String source, String destination, ArrayList<Digipeater> digi
 		this.dti = (char)body[0];
         this.aprsInformation = new InformationField(body);
     }
-    
-    
+
 	/** 
 	 * @param callsign
 	 * @return String
diff --git a/android-src/KV4PHT/app/src/main/java/com/vagell/kv4pht/radio/RadioAudioService.java b/android-src/KV4PHT/app/src/main/java/com/vagell/kv4pht/radio/RadioAudioService.java
index 12921ae..f5a3b8f 100644
--- a/android-src/KV4PHT/app/src/main/java/com/vagell/kv4pht/radio/RadioAudioService.java
+++ b/android-src/KV4PHT/app/src/main/java/com/vagell/kv4pht/radio/RadioAudioService.java
@@ -107,66 +107,18 @@ public class RadioAudioService extends Service {
     public static final int MODE_FLASHING = 4;
     private int mode = MODE_STARTUP;
     private int messageNumber = 0;
-
-    public enum ESP32Command {
-        PTT_DOWN((byte) 1),
-        PTT_UP((byte) 2),
-        TUNE_TO((byte) 3), // paramsStr contains freq, offset, tone details
-        FILTERS((byte) 4), // paramStr contains emphasis, highpass, lowpass (each 0/1)
-        STOP((byte) 5),
-        GET_FIRMWARE_VER((byte) 6);
-
-        private byte commandByte;
-        ESP32Command(byte commandByte) {
-            this.commandByte = commandByte;
-        }
-
-        public byte getByte() {
-            return commandByte;
-        }
-    }
-
-    public enum MicGainBoost {
-        NONE,
-        LOW,
-        MED,
-        HIGH;
-
-        public static MicGainBoost parseMicGainBoost(String str) {
-            if (str.equals("High")) {
-                return MicGainBoost.HIGH;
-            } else if (str.equals("Med")) {
-                return MicGainBoost.MED;
-            } else if (str.equals("Low")) {
-                return MicGainBoost.LOW;
-            }
-
-            return MicGainBoost.NONE;
-        }
-
-        public static float toFloat(MicGainBoost micGainBoost) {
-            if (micGainBoost == LOW) {
-                return 1.5f;
-            } else if (micGainBoost == MED) {
-                return 2.0f;
-            } else if (micGainBoost == HIGH) {
-                return 2.5f;
-            }
-
-            return 1.0f;
-        }
-    }
-
     public static final byte SILENT_BYTE = -128;
 
     // Callbacks to the Activity that started us
     private RadioAudioServiceCallbacks callbacks = null;
 
     // For transmitting audio to ESP32 / radio
-    public static final int AUDIO_SAMPLE_RATE = 44100;
+    public static SampleRate rxSampleRate = SampleRate.SAMPLE_RATE_44;
+    public static SampleRate txSampleRate = SampleRate.SAMPLE_RATE_44;
+    public static float rxSampleRateMult = 1.00494f;
     public static final int channelConfig = AudioFormat.CHANNEL_IN_MONO;
     public static final  int audioFormat = AudioFormat.ENCODING_PCM_8BIT;
-    public static final  int minBufferSize = AudioRecord.getMinBufferSize(AUDIO_SAMPLE_RATE, channelConfig, audioFormat) * 2;
+    public static final  int rxMinBufferSize = AudioRecord.getMinBufferSize(SampleRate.toInt(rxSampleRate), channelConfig, audioFormat) * 2;
     private UsbManager usbManager;
     private UsbDevice esp32Device;
     private static UsbSerialPort serialPort;
@@ -213,6 +165,90 @@ public static float toFloat(MicGainBoost micGainBoost) {
 
     private ThreadPoolExecutor threadPoolExecutor = null;
 
+    public enum ESP32Command {
+        PTT_DOWN((byte) 1),
+        PTT_UP((byte) 2),
+        TUNE_TO((byte) 3), // paramsStr contains freq, offset, tone details
+        FILTERS((byte) 4), // paramStr contains emphasis, highpass, lowpass (each 0/1)
+        STOP((byte) 5),
+        GET_FIRMWARE_VER((byte) 6);
+
+        private byte commandByte;
+        ESP32Command(byte commandByte) {
+            this.commandByte = commandByte;
+        }
+
+        public byte getByte() {
+            return commandByte;
+        }
+    }
+
+    public enum MicGainBoost {
+        NONE,
+        LOW,
+        MED,
+        HIGH;
+
+        public static MicGainBoost parse(String str) {
+            if (str.equals("High")) {
+                return HIGH;
+            } else if (str.equals("Med")) {
+                return MED;
+            } else if (str.equals("Low")) {
+                return LOW;
+            }
+
+            return NONE;
+        }
+
+        public static float toFloat(MicGainBoost micGainBoost) {
+            if (micGainBoost == LOW) {
+                return 1.5f;
+            } else if (micGainBoost == MED) {
+                return 2.0f;
+            } else if (micGainBoost == HIGH) {
+                return 2.5f;
+            }
+
+            return 1.0f;
+        }
+    }
+
+    public enum SampleRate {
+        SAMPLE_RATE_44,
+        SAMPLE_RATE_16;
+
+        public static SampleRate parse(String str) {
+            if (str.equals("44.1kHz")) {
+                return SAMPLE_RATE_44;
+            } else if (str.equals("16kHz")) {
+                return SAMPLE_RATE_16;
+            }
+
+            return SAMPLE_RATE_44;
+        }
+
+        public static int toInt(SampleRate sampleRate) {
+            if (sampleRate == SAMPLE_RATE_44) {
+                return 44100;
+            } else if (sampleRate == SAMPLE_RATE_16) {
+                return 16000;
+            }
+
+            return 44100;
+        }
+
+        public static String encode(SampleRate sampleRate) {
+            if (sampleRate == SAMPLE_RATE_44) {
+                return "0";
+            } else if (sampleRate == SAMPLE_RATE_16) {
+                return "1";
+            }
+
+            return "0";
+        }
+    }
+
     /**
      * Class used for the client Binder. This service always runs in the same process as its clients.
      */
@@ -244,7 +280,27 @@ public void setFilters(boolean emphasis, boolean highpass, boolean lowpass) {
     }
 
     public void setMicGainBoost(String micGainBoost) {
-        this.micGainBoost = MicGainBoost.parseMicGainBoost(micGainBoost);
+        this.micGainBoost = MicGainBoost.parse(micGainBoost);
+    }
+
+    public void setRxSampleRate(String rxSampleRate) {
+        this.rxSampleRate = SampleRate.parse(rxSampleRate);
+        initAudioTrack();
+        initAFSKModem();
+    }
+
+    public void setTxSampleRate(String txSampleRate) {
+        this.txSampleRate = SampleRate.parse(txSampleRate);
+        initAFSKModem();
+        // Recording sample rate is set in MainActivity (which owns the recording object).
+    }
+
+    public void setRxSampleRateMult(String rxSampleRateMult) {
+        try {
+            this.rxSampleRateMult = Float.parseFloat(rxSampleRateMult);
+        } catch (Exception e) {
+            this.rxSampleRateMult = 1.00494f; // Use default if some bad data in the setting.
+        }
     }
 
     public static void setMaxFreq(int newMaxFreq) {
@@ -444,7 +500,10 @@ public void tuneToFreq(String frequencyStr, int squelchLevel, boolean forceTune)
         squelch = squelchLevel;
 
         if (serialPort != null) {
-            sendCommandToESP32(ESP32Command.TUNE_TO, makeSafe2MFreq(activeFrequencyStr) + makeSafe2MFreq(activeFrequencyStr) + "00" + squelchLevel);
+            sendCommandToESP32(ESP32Command.TUNE_TO, makeSafe2MFreq(activeFrequencyStr) +
+                    makeSafe2MFreq(activeFrequencyStr) + "00" + squelchLevel +
+                    String.format("%05d", (int) (SampleRate.toInt(rxSampleRate) * rxSampleRateMult)) + // e.g. "44100"
+                    String.format("%05d", SampleRate.toInt(txSampleRate))); // e.g. "44100"
         }
 
         // Reset audio prebuffer
@@ -531,7 +590,11 @@ public void tuneToMemory(ChannelMemory memory, int squelchLevel, boolean forceTu
 
         if (serialPort != null) {
             sendCommandToESP32(ESP32Command.TUNE_TO,
-                    getTxFreq(memory.frequency, memory.offset) + makeSafe2MFreq(memory.frequency) + getToneIdxStr(memory.tone) + squelchLevel);
+                    getTxFreq(memory.frequency, memory.offset) +
+                            makeSafe2MFreq(memory.frequency) +
+                            getToneIdxStr(memory.tone) + squelchLevel +
+                            String.format("%05d", (int) (SampleRate.toInt(rxSampleRate) * rxSampleRateMult)) + // e.g. "44100"
+                            String.format("%05d", SampleRate.toInt(txSampleRate))); // e.g. "44100"
         }
 
         // Reset audio prebuffer
@@ -578,17 +641,19 @@ private void checkScanDueToSilence() {
         // means there is no signal detected on the given frequency) even when there is. I did
         // extensive debugging and even rewrote large portions of the DRA818v library to determine
         // that this was the case. So in lieu of that, we scan using a timing/silence-based system.
-        if (consecutiveSilenceBytes >= (AUDIO_SAMPLE_RATE * SEC_BETWEEN_SCANS)) {
+        if (consecutiveSilenceBytes >= (SampleRate.toInt(rxSampleRate) * SEC_BETWEEN_SCANS)) {
             consecutiveSilenceBytes = 0;
             nextScan();
         }
     }
 
     private void initAudioTrack() {
-        if (audioTrack != null) {
+        if (null != audioTrack) {
+            audioTrack.stop();
             audioTrack.release();
             audioTrack = null;
         }
+
         audioTrack = new AudioTrack.Builder()
                 .setAudioAttributes(new AudioAttributes.Builder()
                         .setUsage(AudioAttributes.USAGE_MEDIA)
@@ -596,11 +661,11 @@ private void initAudioTrack() {
                         .build())
                 .setAudioFormat(new AudioFormat.Builder()
                         .setEncoding(audioFormat)
-                        .setSampleRate(AUDIO_SAMPLE_RATE)
+                        .setSampleRate(SampleRate.toInt(rxSampleRate))
                         .setChannelMask(AudioFormat.CHANNEL_OUT_MONO)
                         .build())
                 .setTransferMode(AudioTrack.MODE_STREAM)
-                .setBufferSizeInBytes(minBufferSize)
+                .setBufferSizeInBytes(rxMinBufferSize)
                 .setSessionId(AudioManager.AUDIO_SESSION_ID_GENERATE)
                 .build();
         audioTrack.setAuxEffectSendLevel(0.0f);
@@ -935,7 +1000,7 @@ public void sendAudioToESP32(byte[] audioBuffer, boolean dataMode) {
             // as audio sampling. Otherwise, we'll overwhelm its DAC buffer and some audio will
             // be lost.
             final Handler handler = new Handler(Looper.getMainLooper());
-            final float msToSendOneChunk = (float) TX_AUDIO_CHUNK_SIZE / (float) AUDIO_SAMPLE_RATE * 1000f;
+            final float msToSendOneChunk = (float) TX_AUDIO_CHUNK_SIZE / (float) SampleRate.toInt(txSampleRate) * 1000f;
             float nextSendDelay = 0f;
             byte[] finalAudioBuffer = audioBuffer;
             for (int i = 0; i < audioBuffer.length; i += TX_AUDIO_CHUNK_SIZE) {
@@ -1093,17 +1158,22 @@ private void handleESP32Data(byte[] data) {
         if (mode == MODE_RX || mode == MODE_SCAN) {
             if (prebufferComplete && audioTrack != null) {
                 synchronized (audioTrack) {
-                    if (afskDemodulator != null) { // Avoid race condition at app start.
+                    try {
+                        if (afskDemodulator != null) { // Avoid race condition at app start.
+                            // Add the audio samples to the AFSK demodulator.
+                            float[] audioAsFloats = convertPCM8ToFloatArray(data);
+                            afskDemodulator.addSamples(audioAsFloats, audioAsFloats.length);
+                        }
+
                         // Play the audio.
                         audioTrack.write(data, 0, data.length);
 
-                        // Add the audio samples to the AFSK demodulator.
-                        float[] audioAsFloats = convertPCM8ToFloatArray(data);
-                        afskDemodulator.addSamples(audioAsFloats, audioAsFloats.length);
-                    }
-
-                    if (audioTrack != null && audioTrack.getPlayState() != AudioTrack.PLAYSTATE_PLAYING) {
-                        audioTrack.play();
+                        if (audioTrack != null && audioTrack.getPlayState() != AudioTrack.PLAYSTATE_PLAYING) {
+                            audioTrack.play();
+                        }
+                    } catch (Exception e) {
+                        // Objects may cease to exist when user changes rx sample rate
+                        return;
                     }
                 }
             } else {
@@ -1115,11 +1185,16 @@ private void handleESP32Data(byte[] data) {
                         prebufferComplete = true;
                         // Log.d("DEBUG", "Rx prebuffer full, writing to audioTrack.");
                         if (audioTrack != null) {
-                            if (audioTrack.getPlayState() != AudioTrack.PLAYSTATE_PLAYING) {
-                                audioTrack.play();
-                            }
-                            synchronized (audioTrack) {
-                                audioTrack.write(rxBytesPrebuffer, 0, PRE_BUFFER_SIZE);
+                            try {
+                                if (audioTrack.getPlayState() != AudioTrack.PLAYSTATE_PLAYING) {
+                                    audioTrack.play();
+                                }
+                                synchronized (audioTrack) {
+                                    audioTrack.write(rxBytesPrebuffer, 0, PRE_BUFFER_SIZE);
+                                }
+                            } catch (Exception e) {
+                                // audioTrack may cease to exist when user changes rx sample rate
+                                return;
                             }
                         }
 
@@ -1221,8 +1296,8 @@ public void handlePacket(byte[] data) {
         };
 
         try {
-            afskDemodulator = new Afsk1200MultiDemodulator(AUDIO_SAMPLE_RATE, packetHandler);
-            afskModulator = new Afsk1200Modulator(AUDIO_SAMPLE_RATE);
+            afskDemodulator = new Afsk1200MultiDemodulator(SampleRate.toInt(rxSampleRate), packetHandler);
+            afskModulator = new Afsk1200Modulator(SampleRate.toInt(txSampleRate));
         } catch (Exception e) {
             Log.d("DEBUG", "Unable to create AFSK modem objects.");
         }
@@ -1298,8 +1373,8 @@ private void txAX25Packet(Packet ax25Packet) {
             @Override
             public void run() {
                 // Add some silence before and after the data.
-                int bytesOfLeadInDelay = (AUDIO_SAMPLE_RATE / 1000 * MS_SILENCE_BEFORE_DATA);
-                int bytesOfTailDelay = (AUDIO_SAMPLE_RATE / 1000 * MS_SILENCE_AFTER_DATA);
+                int bytesOfLeadInDelay = (SampleRate.toInt(txSampleRate) / 1000 * MS_SILENCE_BEFORE_DATA);
+                int bytesOfTailDelay = (SampleRate.toInt(txSampleRate) / 1000 * MS_SILENCE_AFTER_DATA);
                 byte[] combinedAudio = new byte[bytesOfLeadInDelay + simpleAudioBytes.length + bytesOfTailDelay];
                 for (int i = 0; i < bytesOfLeadInDelay; i++) {
                     combinedAudio[i] = SILENT_BYTE;
diff --git a/android-src/KV4PHT/app/src/main/java/com/vagell/kv4pht/ui/MainActivity.java b/android-src/KV4PHT/app/src/main/java/com/vagell/kv4pht/ui/MainActivity.java
index 974c60c..887cc9d 100644
--- a/android-src/KV4PHT/app/src/main/java/com/vagell/kv4pht/ui/MainActivity.java
+++ b/android-src/KV4PHT/app/src/main/java/com/vagell/kv4pht/ui/MainActivity.java
@@ -90,7 +90,6 @@ kv4p HT (see http://kv4p.com)
 import com.vagell.kv4pht.radio.RadioAudioService;
 
 
-import java.io.UnsupportedEncodingException;
 import java.util.Arrays;
 import java.util.List;
 import java.util.concurrent.LinkedBlockingQueue;
@@ -103,7 +102,7 @@ public class MainActivity extends AppCompatActivity {
     private boolean isRecording = false;
     private int channelConfig = AudioFormat.CHANNEL_IN_MONO;
     private int audioFormat = AudioFormat.ENCODING_PCM_8BIT;
-    private int minBufferSize = AudioRecord.getMinBufferSize(RadioAudioService.AUDIO_SAMPLE_RATE, channelConfig, audioFormat) * 2;
+    private int txMinBufferSize = AudioRecord.getMinBufferSize(RadioAudioService.SampleRate.toInt(RadioAudioService.txSampleRate), channelConfig, audioFormat) * 2;
     private Thread recordingThread;
 
     // Active screen type (e.g. voice or chat)
@@ -604,8 +603,8 @@ private void handleChatPacket(APRSPacket aprsPacket) {
             }
         }
 
-        // If the message type is unknown, we at least display the raw contents as a comment.
-        if (aprsMessage.type == APRSMessage.UNKNOWN_TYPE && (null == comment || comment.trim().length() == 0)) {
+        // If there is a fault in the packet, or the message type is unknown, we at least display the raw contents as a comment.
+        if (aprsPacket.hasFault() || (aprsMessage.type == APRSMessage.UNKNOWN_TYPE && (null == comment || comment.trim().length() == 0))) {
             if (null != infoField) {
                 try {
                     comment = "Raw: " + new String(infoField.getRawBytes(), "UTF-8");
@@ -847,6 +846,9 @@ public void run() {
                 AppSetting disableAnimationsSetting = viewModel.appDb.appSettingDao().getByName("disableAnimations");
                 AppSetting maxFreqSetting = viewModel.appDb.appSettingDao().getByName("maxFreq");
                 AppSetting micGainBoostSetting = viewModel.appDb.appSettingDao().getByName("micGainBoost");
+                AppSetting rxSampleRateSetting = viewModel.appDb.appSettingDao().getByName("rxSampleRate");
+                AppSetting txSampleRateSetting = viewModel.appDb.appSettingDao().getByName("txSampleRate");
+                AppSetting rxSampleRateMultSetting = viewModel.appDb.appSettingDao().getByName("rxSampleRateMult");
                 AppSetting lastMemoryId = viewModel.appDb.appSettingDao().getByName("lastMemoryId");
                 AppSetting lastFreq = viewModel.appDb.appSettingDao().getByName("lastFreq");
                 AppSetting lastGroupSetting = viewModel.appDb.appSettingDao().getByName("lastGroup");
@@ -907,6 +909,28 @@ public void run() {
                             }
                         }
 
+                        if (rxSampleRateSetting != null) {
+                            String rxSampleRate = rxSampleRateSetting.value;
+                            if (radioAudioService != null) {
+                                radioAudioService.setRxSampleRate(rxSampleRate);
+                            }
+                        }
+
+                        if (txSampleRateSetting != null) {
+                            String txSampleRate = txSampleRateSetting.value;
+                            if (radioAudioService != null) {
+                                radioAudioService.setTxSampleRate(txSampleRate);
+                                initAudioRecorder();
+                            }
+                        }
+
+                        if (rxSampleRateMultSetting != null) {
+                            String rxSampleRateMult = rxSampleRateMultSetting.value;
+                            if (radioAudioService != null) {
+                                radioAudioService.setRxSampleRateMult(rxSampleRateMult);
+                            }
+                        }
+
                         if (squelchSetting != null) {
                             squelch = Integer.parseInt(squelchSetting.value); // The tuneTo() calls below pass squelch to RadioAudioService.
                         }
@@ -1363,8 +1387,14 @@ private void initAudioRecorder() {
             return;
         }
 
-        audioRecord = new AudioRecord(MediaRecorder.AudioSource.VOICE_COMMUNICATION, RadioAudioService.AUDIO_SAMPLE_RATE, channelConfig,
-                audioFormat, minBufferSize);
+        if (null != audioRecord) {
+            audioRecord.stop();
+            audioRecord.release();
+            audioRecord = null;
+        }
+
+        audioRecord = new AudioRecord(MediaRecorder.AudioSource.VOICE_COMMUNICATION, RadioAudioService.SampleRate.toInt(RadioAudioService.txSampleRate), channelConfig,
+                audioFormat, txMinBufferSize);
 
         if (audioRecord.getState() != AudioRecord.STATE_INITIALIZED) {
             Log.d("DEBUG", "Audio init error");
@@ -1393,15 +1423,15 @@ public void run() {
 
     private void processAudioStream() {
         while (isRecording) {
-            byte[] audioBuffer = new byte[minBufferSize];
+            byte[] audioBuffer = new byte[txMinBufferSize];
             int bytesRead;
-            bytesRead = audioRecord.read(audioBuffer, 0, minBufferSize);
+            bytesRead = audioRecord.read(audioBuffer, 0, txMinBufferSize);
 
             if (bytesRead > 0) {
                 if (radioAudioService != null) {
                     radioAudioService.sendAudioToESP32(Arrays.copyOfRange(audioBuffer, 0, bytesRead), false);
 
-                    int bytesPerAnimFrame = RadioAudioService.AUDIO_SAMPLE_RATE / RECORD_ANIM_FPS;
+                    int bytesPerAnimFrame = RadioAudioService.SampleRate.toInt(RadioAudioService.txSampleRate) / RECORD_ANIM_FPS;
                     long audioChunkByteTotal = 0;
                     int waitMs = 0;
                     for (int i = 0; i < bytesRead; i++) {
diff --git a/android-src/KV4PHT/app/src/main/java/com/vagell/kv4pht/ui/SettingsActivity.java b/android-src/KV4PHT/app/src/main/java/com/vagell/kv4pht/ui/SettingsActivity.java
index 93fff0c..6322bdb 100644
--- a/android-src/KV4PHT/app/src/main/java/com/vagell/kv4pht/ui/SettingsActivity.java
+++ b/android-src/KV4PHT/app/src/main/java/com/vagell/kv4pht/ui/SettingsActivity.java
@@ -44,6 +44,7 @@ kv4p HT (see http://kv4p.com)
 import com.google.android.material.textfield.TextInputEditText;
 import com.vagell.kv4pht.R;
 import com.vagell.kv4pht.data.AppSetting;
+import com.vagell.kv4pht.radio.RadioAudioService;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -67,6 +68,7 @@ protected void onCreate(Bundle savedInstanceState) {
         populateOriginalValues();
         populateMaxFrequencies();
         populateMicGainOptions();
+        populateSampleRateOptions();
         attachListeners();
     }
 
@@ -108,6 +110,19 @@ private void populateMicGainOptions() {
         micGainBoostTextView.setAdapter(arrayAdapter);
     }
 
+    private void populateSampleRateOptions() {
+        AutoCompleteTextView rxSampleRateTextView = findViewById(R.id.rxSampleRateTextView);
+        AutoCompleteTextView txSampleRateTextView = findViewById(R.id.txSampleRateTextView);
+
+        List<String> sampleRateOptions = new ArrayList<String>();
+        sampleRateOptions.add("44.1kHz");
+        sampleRateOptions.add("16kHz");
+
+        ArrayAdapter arrayAdapter = new ArrayAdapter(this, R.layout.dropdown_item, sampleRateOptions);
+        rxSampleRateTextView.setAdapter(arrayAdapter);
+        txSampleRateTextView.setAdapter(arrayAdapter);
+    }
+
     private void populateOriginalValues() {
         if (threadPoolExecutor == null) {
             return;
@@ -125,7 +140,9 @@ public void run() {
                 AppSetting disableAnimationsSetting = MainViewModel.appDb.appSettingDao().getByName("disableAnimations");
                 AppSetting maxFreqSetting = MainViewModel.appDb.appSettingDao().getByName("maxFreq");
                 AppSetting micGainBoostSetting = MainViewModel.appDb.appSettingDao().getByName("micGainBoost");
-
+                AppSetting rxSampleRateSetting = MainViewModel.appDb.appSettingDao().getByName("rxSampleRate");
+                AppSetting txSampleRateSetting = MainViewModel.appDb.appSettingDao().getByName("txSampleRate");
+                AppSetting rxSampleRateMultSetting = MainViewModel.appDb.appSettingDao().getByName("rxSampleRateMult");
 
                 runOnUiThread(new Runnable() {
                     @Override
@@ -174,6 +191,21 @@ public void run() {
                             AutoCompleteTextView micGainBoostTextView = (AutoCompleteTextView) findViewById(R.id.micGainBoostTextView);
                             micGainBoostTextView.setText(micGainBoostSetting.value, false);
                         }
+
+                        if (rxSampleRateSetting != null) {
+                            AutoCompleteTextView rxSampleRateTextView = (AutoCompleteTextView) findViewById(R.id.rxSampleRateTextView);
+                            rxSampleRateTextView.setText(rxSampleRateSetting.value, false);
+                        }
+
+                        if (txSampleRateSetting != null) {
+                            AutoCompleteTextView txSampleRateTextView = (AutoCompleteTextView) findViewById(R.id.txSampleRateTextView);
+                            txSampleRateTextView.setText(txSampleRateSetting.value, false);
+                        }
+
+                        if (rxSampleRateMultSetting != null) {
+                            TextView rxSampleRateMultTextView = (TextView) findViewById(R.id.rxSampleRateMultTextView);
+                            rxSampleRateMultTextView.setText(rxSampleRateMultSetting.value);
+                        }
                     }
                 });
             }});
@@ -302,6 +334,57 @@ public void afterTextChanged(Editable s) {
                 setMicGainBoost(newText);
             }
         });
+
+        TextView rxSampleRateTextView = findViewById(R.id.rxSampleRateTextView);
+        rxSampleRateTextView.addTextChangedListener(new TextWatcher() {
+            @Override
+            public void beforeTextChanged(CharSequence s, int start, int count, int after) {
+            }
+
+            @Override
+            public void onTextChanged(CharSequence s, int start, int before, int count) {
+            }
+
+            @Override
+            public void afterTextChanged(Editable s) {
+                String newText = ((TextView) findViewById(R.id.rxSampleRateTextView)).getText().toString().trim();
+                setRxSampleRate(newText);
+            }
+        });
+
+        TextView txSampleRateTextView = findViewById(R.id.txSampleRateTextView);
+        txSampleRateTextView.addTextChangedListener(new TextWatcher() {
+            @Override
+            public void beforeTextChanged(CharSequence s, int start, int count, int after) {
+            }
+
+            @Override
+            public void onTextChanged(CharSequence s, int start, int before, int count) {
+            }
+
+            @Override
+            public void afterTextChanged(Editable s) {
+                String newText = ((TextView) findViewById(R.id.txSampleRateTextView)).getText().toString().trim();
+                setTxSampleRate(newText);
+            }
+        });
+
+        TextView rxSampleRateMultTextView = findViewById(R.id.rxSampleRateMultTextView);
+        rxSampleRateMultTextView.addTextChangedListener(new TextWatcher() {
+            @Override
+            public void beforeTextChanged(CharSequence s, int start, int count, int after) {
+            }
+
+            @Override
+            public void onTextChanged(CharSequence s, int start, int before, int count) {
+            }
+
+            @Override
+            public void afterTextChanged(Editable s) {
+                String newText = ((TextView) findViewById(R.id.rxSampleRateMultTextView)).getText().toString().trim();
+                setRxSampleRateMult(newText);
+            }
+        });
     }
 
     /**
@@ -353,6 +436,80 @@ public void run() {
         });
     }
 
+    /**
+     * @param rxSampleRate The rate at which rx audio should be sampled by the ESP32 firmware, e.g. "44.1kHz", "16kHz"
+     */
+    private void setRxSampleRate(String rxSampleRate) {
+        if (threadPoolExecutor == null) {
+            return;
+        }
+
+        threadPoolExecutor.execute(new Runnable() {
+            @Override
+            public void run() {
+                AppSetting setting = MainViewModel.appDb.appSettingDao().getByName("rxSampleRate");
+
+                if (setting == null) {
+                    setting = new AppSetting("rxSampleRate", rxSampleRate);
+                    MainViewModel.appDb.appSettingDao().insertAll(setting);
+                } else {
+                    setting.value = rxSampleRate;
+                    MainViewModel.appDb.appSettingDao().update(setting);
+                }
+            }
+        });
+    }
+
+    /**
+     * @param txSampleRate The rate at which tx audio should be sampled by the ESP32 firmware, e.g. "44.1kHz", "16kHz"
+     */
+    private void setTxSampleRate(String txSampleRate) {
+        if (threadPoolExecutor == null) {
+            return;
+        }
+
+        threadPoolExecutor.execute(new Runnable() {
+            @Override
+            public void run() {
+                AppSetting setting = MainViewModel.appDb.appSettingDao().getByName("txSampleRate");
+
+                if (setting == null) {
+                    setting = new AppSetting("txSampleRate", txSampleRate);
+                    MainViewModel.appDb.appSettingDao().insertAll(setting);
+                } else {
+                    setting.value = txSampleRate;
+                    MainViewModel.appDb.appSettingDao().update(setting);
+                }
+            }
+        });
+    }
+
+    /**
+     * @param rxSampleRateMult A multipler (with baseline of 1.0) to apply to the rx sample rate.
+     *                         This can be used to adjust for ESP32 dev boards that aren't sampling
+     *                         at exactly the right rate.
+     */
+    private void setRxSampleRateMult(String rxSampleRateMult) {
+        if (threadPoolExecutor == null) {
+            return;
+        }
+
+        threadPoolExecutor.execute(new Runnable() {
+            @Override
+            public void run() {
+                AppSetting setting = MainViewModel.appDb.appSettingDao().getByName("rxSampleRateMult");
+
+                if (setting == null) {
+                    setting = new AppSetting("rxSampleRateMult", rxSampleRateMult);
+                    MainViewModel.appDb.appSettingDao().insertAll(setting);
+                } else {
+                    setting.value = rxSampleRateMult;
+                    MainViewModel.appDb.appSettingDao().update(setting);
+                }
+            }
+        });
+    }
+
     private void setCallsign(String callsign) {
         if (callsign == null) {
             return;
diff --git a/android-src/KV4PHT/app/src/main/res/layout/activity_add_edit_memory.xml b/android-src/KV4PHT/app/src/main/res/layout/activity_add_edit_memory.xml
index 960932f..a3a6c9e 100644
--- a/android-src/KV4PHT/app/src/main/res/layout/activity_add_edit_memory.xml
+++ b/android-src/KV4PHT/app/src/main/res/layout/activity_add_edit_memory.xml
@@ -7,189 +7,211 @@
     android:orientation="vertical"
     tools:context=".ui.AddEditMemoryActivity"
     android:background="@drawable/bg"
-    android:paddingTop="96dp"
-    android:paddingRight="24dp"
-    android:paddingBottom="24dp"
-    android:paddingLeft="24dp">
-
-    <TextView
-        android:id="@+id/addEditToolbarTitle"
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
-        android:text="Add memory"
-        android:textSize="32sp"
-        app:fontWeight="500"
-        android:textColor="@color/primary"
-        android:layout_marginBottom="16dp"
-        android:layout_gravity="center"
-        android:layout_weight="0"/>
-
-    <ScrollView
-        android:layout_width="match_parent"
-        android:layout_height="wrap_content"
-        android:layout_weight="0"
-        android:orientation="vertical">
+    android:fitsSystemWindows="true">
 
-        <LinearLayout
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="0dp"
+        android:layout_weight="1"
+        android:orientation="vertical"
+        android:padding="24dp">
+
+        <TextView
+            android:id="@+id/addEditToolbarTitle"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="Add memory"
+            android:textSize="32sp"
+            app:fontWeight="500"
+            android:textColor="@color/primary"
+            android:layout_marginBottom="16dp"
+            android:layout_gravity="center"
+            android:layout_weight="0"/>
+
+        <ScrollView
             android:layout_width="match_parent"
             android:layout_height="wrap_content"
-            android:orientation="vertical">
+            android:layout_weight="0"
+            android:orientation="vertical"
+            android:scrollbars="none">
 
             <LinearLayout
                 android:layout_width="match_parent"
                 android:layout_height="wrap_content"
                 android:orientation="vertical">
 
-                <com.google.android.material.textfield.TextInputLayout
+                <LinearLayout
                     android:layout_width="match_parent"
                     android:layout_height="wrap_content"
-                    android:layout_weight="0"
-                    style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox"
-                    android:hint="Memory name"
-                    app:hintTextColor="@color/primary_deselected"
-                    app:boxStrokeColor="@color/primary"
-                    android:textColorHint="@color/primary_deselected"
-                    android:paddingBottom="16dp">
-
-                    <com.google.android.material.textfield.TextInputEditText
-                        android:id="@+id/editNameTextInputEditText"
+                    android:orientation="vertical">
+
+                    <com.google.android.material.textfield.TextInputLayout
                         android:layout_width="match_parent"
-                        android:layout_height="match_parent"
-                        android:layout_weight="1"
-                        android:textSize="20dp"
-                        android:textColor="@color/primary"
-                        android:inputType="text">
-                    </com.google.android.material.textfield.TextInputEditText>
-                </com.google.android.material.textfield.TextInputLayout>
-
-                <com.google.android.material.textfield.TextInputLayout
-                    android:layout_width="match_parent"
-                    android:layout_height="wrap_content"
-                    android:layout_weight="0"
-                    android:layout_marginTop="8dp"
-                    style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox.ExposedDropdownMenu"
-                    android:hint="Memory group (optional)"
-                    app:hintTextColor="@color/primary_deselected"
-                    app:boxStrokeColor="@color/primary"
-                    android:textColorHint="@color/primary_deselected"
-                    android:paddingBottom="16dp">
-
-                    <AutoCompleteTextView
-                        android:id="@+id/editMemoryGroupTextInputEditText"
+                        android:layout_height="wrap_content"
+                        android:layout_weight="0"
+                        style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox"
+                        android:hint="Memory name"
+                        app:hintTextColor="@color/primary_deselected"
+                        app:boxStrokeColor="@color/primary"
+                        android:textColorHint="@color/primary_deselected"
+                        android:paddingBottom="16dp">
+
+                        <com.google.android.material.textfield.TextInputEditText
+                            android:id="@+id/editNameTextInputEditText"
+                            android:layout_width="match_parent"
+                            android:layout_height="match_parent"
+                            android:layout_weight="1"
+                            android:textSize="20dp"
+                            android:textColor="@color/primary"
+                            android:inputType="text">
+                        </com.google.android.material.textfield.TextInputEditText>
+                    </com.google.android.material.textfield.TextInputLayout>
+
+                    <com.google.android.material.textfield.TextInputLayout
                         android:layout_width="match_parent"
-                        android:layout_height="match_parent"
-                        android:layout_weight="1"
-                        android:textSize="20dp"
-                        android:textColor="@color/primary"
-                        android:inputType="text"/>
-                </com.google.android.material.textfield.TextInputLayout>
-
-                <com.google.android.material.textfield.TextInputLayout
-                    android:layout_width="match_parent"
-                    android:layout_height="wrap_content"
-                    android:layout_weight="0"
-                    android:layout_marginTop="8dp"
-                    style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox"
-                    android:hint="Frequency"
-                    app:hintTextColor="@color/primary_deselected"
-                    app:boxStrokeColor="@color/primary"
-                    android:textColorHint="@color/primary_deselected"
-                    android:paddingBottom="16dp">
-
-                    <com.google.android.material.textfield.TextInputEditText
-                        android:id="@+id/editFrequencyTextInputEditText"
+                        android:layout_height="wrap_content"
+                        android:layout_weight="0"
+                        android:layout_marginTop="8dp"
+                        style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox.ExposedDropdownMenu"
+                        android:hint="Memory group (optional)"
+                        app:hintTextColor="@color/primary_deselected"
+                        app:boxStrokeColor="@color/primary"
+                        android:textColorHint="@color/primary_deselected"
+                        android:paddingBottom="16dp">
+
+                        <AutoCompleteTextView
+                            android:id="@+id/editMemoryGroupTextInputEditText"
+                            android:layout_width="match_parent"
+                            android:layout_height="match_parent"
+                            android:layout_weight="1"
+                            android:textSize="20dp"
+                            android:textColor="@color/primary"
+                            android:inputType="text"/>
+                    </com.google.android.material.textfield.TextInputLayout>
+
+                    <com.google.android.material.textfield.TextInputLayout
                         android:layout_width="match_parent"
-                        android:layout_height="match_parent"
-                        android:layout_weight="1"
-                        android:textSize="20dp"
-                        android:inputType="numberDecimal"
-                        android:textColor="@color/primary">
-                    </com.google.android.material.textfield.TextInputEditText>
-                </com.google.android.material.textfield.TextInputLayout>
-
-                <com.google.android.material.textfield.TextInputLayout
-                    android:layout_width="match_parent"
-                    android:layout_height="wrap_content"
-                    android:layout_weight="0"
-                    android:layout_marginTop="8dp"
-                    style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox.ExposedDropdownMenu"
-                    android:hint="Offset"
-                    app:hintTextColor="@color/primary_deselected"
-                    app:boxStrokeColor="@color/primary"
-                    android:textColorHint="@color/primary_deselected"
-                    android:paddingBottom="16dp">
-
-                    <AutoCompleteTextView
-                        android:id="@+id/editOffsetTextView"
+                        android:layout_height="wrap_content"
+                        android:layout_weight="0"
+                        android:layout_marginTop="8dp"
+                        style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox"
+                        android:hint="Frequency"
+                        app:hintTextColor="@color/primary_deselected"
+                        app:boxStrokeColor="@color/primary"
+                        android:textColorHint="@color/primary_deselected"
+                        android:paddingBottom="16dp">
+
+                        <com.google.android.material.textfield.TextInputEditText
+                            android:id="@+id/editFrequencyTextInputEditText"
+                            android:layout_width="match_parent"
+                            android:layout_height="match_parent"
+                            android:layout_weight="1"
+                            android:textSize="20dp"
+                            android:inputType="numberDecimal"
+                            android:textColor="@color/primary">
+                        </com.google.android.material.textfield.TextInputEditText>
+                    </com.google.android.material.textfield.TextInputLayout>
+
+                    <com.google.android.material.textfield.TextInputLayout
                         android:layout_width="match_parent"
-                        android:layout_height="match_parent"
-                        android:layout_weight="1"
-                        android:inputType="none"
-                        android:text="None"
-                        android:textSize="20dp"
-                        android:textColor="@color/primary"/>
-                </com.google.android.material.textfield.TextInputLayout>
-
-                <com.google.android.material.textfield.TextInputLayout
-                    android:layout_width="match_parent"
-                    android:layout_height="wrap_content"
-                    android:layout_weight="0"
-                    android:layout_marginTop="8dp"
-                    style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox.ExposedDropdownMenu"
-                    android:hint="Tone"
-                    app:hintTextColor="@color/primary_deselected"
-                    app:boxStrokeColor="@color/primary"
-                    android:textColorHint="@color/primary_deselected"
-                    android:paddingBottom="16dp">
-
-                    <AutoCompleteTextView
-                        android:id="@+id/editToneTextView"
+                        android:layout_height="wrap_content"
+                        android:layout_weight="0"
+                        android:layout_marginTop="8dp"
+                        style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox.ExposedDropdownMenu"
+                        android:hint="Offset"
+                        app:hintTextColor="@color/primary_deselected"
+                        app:boxStrokeColor="@color/primary"
+                        android:textColorHint="@color/primary_deselected"
+                        android:paddingBottom="16dp">
+
+                        <AutoCompleteTextView
+                            android:id="@+id/editOffsetTextView"
+                            android:layout_width="match_parent"
+                            android:layout_height="match_parent"
+                            android:layout_weight="1"
+                            android:inputType="none"
+                            android:text="None"
+                            android:textSize="20dp"
+                            android:textColor="@color/primary"/>
+                    </com.google.android.material.textfield.TextInputLayout>
+
+                    <com.google.android.material.textfield.TextInputLayout
                         android:layout_width="match_parent"
-                        android:layout_height="match_parent"
-                        android:layout_weight="1"
-                        android:inputType="none"
-                        android:text="None"
-                        android:textSize="20dp"
-                        android:textColor="@color/primary"/>
-                </com.google.android.material.textfield.TextInputLayout>
-
+                        android:layout_height="wrap_content"
+                        android:layout_weight="0"
+                        android:layout_marginTop="8dp"
+                        style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox.ExposedDropdownMenu"
+                        android:hint="Tone"
+                        app:hintTextColor="@color/primary_deselected"
+                        app:boxStrokeColor="@color/primary"
+                        android:textColorHint="@color/primary_deselected"
+                        android:paddingBottom="16dp">
+
+                        <AutoCompleteTextView
+                            android:id="@+id/editToneTextView"
+                            android:layout_width="match_parent"
+                            android:layout_height="match_parent"
+                            android:layout_weight="1"
+                            android:inputType="none"
+                            android:text="None"
+                            android:textSize="20dp"
+                            android:textColor="@color/primary"/>
+                    </com.google.android.material.textfield.TextInputLayout>
+                </LinearLayout>
             </LinearLayout>
+        </ScrollView>
+    </LinearLayout>
 
-            <LinearLayout
-                android:layout_width="match_parent"
-                android:layout_height="wrap_content"
-                android:orientation="horizontal"
-                android:layout_marginTop="12dp"
-                android:gravity="right"
-                android:layout_weight="0">
-
-                <Button
-                    android:id="@+id/cancelButton"
-                    android:layout_width="wrap_content"
-                    android:layout_height="56dp"
-                    android:layout_weight="0"
-                    android:background="?android:attr/selectableItemBackground"
-                    android:text="Cancel"
-                    android:textSize="20dp"
-                    android:textFontWeight="500"
-                    android:textColor="@color/primary"
-                    android:textAllCaps="false"
-                    android:enabled="true"
-                    android:onClick="cancelButtonClicked" />
-
-                <Button
-                    android:id="@+id/saveButton"
-                    android:layout_width="wrap_content"
-                    android:layout_height="56dp"
-                    android:layout_weight="0"
-                    android:text="Save"
-                    android:textSize="20dp"
-                    android:textFontWeight="500"
-                    android:textColor="@color/black"
-                    android:textAllCaps="false"
-                    android:enabled="true"
-                    android:onClick="saveButtonClicked"/>
-            </LinearLayout>
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:orientation="vertical"
+        android:layout_weight="0">
+
+        <View
+            android:layout_width="fill_parent"
+            android:layout_height="1dp"
+            android:layout_weight="1"
+            android:background="@color/primary"
+            android:gravity="center_vertical" />
+
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:orientation="horizontal"
+            android:layout_marginTop="16dp"
+            android:gravity="right"
+            android:layout_weight="0"
+            android:layout_alignParentBottom="true">
+
+            <Button
+                android:id="@+id/cancelButton"
+                android:layout_width="wrap_content"
+                android:layout_height="56dp"
+                android:layout_weight="0"
+                android:background="?android:attr/selectableItemBackground"
+                android:text="Cancel"
+                android:textSize="20dp"
+                android:textFontWeight="500"
+                android:textColor="@color/primary"
+                android:textAllCaps="false"
+                android:enabled="true"
+                android:onClick="cancelButtonClicked" />
+
+            <Button
+                android:id="@+id/saveButton"
+                android:layout_width="wrap_content"
+                android:layout_height="56dp"
+                android:layout_weight="0"
+                android:layout_marginBottom="16dp"
+                android:text="Save"
+                android:textSize="20dp"
+                android:textFontWeight="500"
+                android:textColor="@color/black"
+                android:textAllCaps="false"
+                android:enabled="true"
+                android:onClick="saveButtonClicked"/>
         </LinearLayout>
-    </ScrollView>
+    </LinearLayout>
+
 </LinearLayout>
\ No newline at end of file
diff --git a/android-src/KV4PHT/app/src/main/res/layout/activity_settings.xml b/android-src/KV4PHT/app/src/main/res/layout/activity_settings.xml
index 6281cf3..e25534a 100644
--- a/android-src/KV4PHT/app/src/main/res/layout/activity_settings.xml
+++ b/android-src/KV4PHT/app/src/main/res/layout/activity_settings.xml
@@ -7,280 +7,423 @@
     android:orientation="vertical"
     tools:context=".ui.SettingsActivity"
     android:background="@drawable/bg"
-    android:paddingTop="96dp"
-    android:paddingRight="24dp"
-    android:paddingBottom="24dp"
-    android:paddingLeft="24dp"
-    android:id="@+id/settingsTopLevelView">
-
-    <TextView
-        android:id="@+id/settingsToolbarTitle"
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
-        android:text="Settings"
-        android:textSize="32sp"
-        app:fontWeight="500"
-        android:textColor="@color/primary"
-        android:layout_marginBottom="16dp"
-        android:layout_gravity="center"/>
-
-    <ScrollView
+    android:id="@+id/settingsTopLevelView"
+    android:fitsSystemWindows="true">
+
+    <LinearLayout
         android:layout_width="match_parent"
         android:layout_height="match_parent"
-        android:layout_weight="1"
-        android:orientation="vertical">
+        android:orientation="vertical"
+        android:padding="24dp">
 
-        <LinearLayout
-            android:layout_width="match_parent"
+        <TextView
+            android:id="@+id/settingsToolbarTitle"
+            android:layout_width="wrap_content"
             android:layout_height="wrap_content"
-            android:orientation="vertical">
+            android:layout_weight="0"
+            android:text="Settings"
+            android:textSize="32sp"
+            app:fontWeight="500"
+            android:textColor="@color/primary"
+            android:layout_marginBottom="16dp"
+            android:layout_gravity="center"/>
+
+        <ScrollView
+            android:layout_width="match_parent"
+            android:layout_height="0dp"
+            android:layout_weight="1"
+            android:orientation="vertical"
+            android:fillViewport="true"
+            android:scrollbars="none">
 
-            <com.google.android.material.textfield.TextInputLayout
+            <LinearLayout
                 android:layout_width="match_parent"
                 android:layout_height="wrap_content"
-                android:layout_weight="0"
-                style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox"
-                android:hint="Your callsign"
-                app:hintTextColor="@color/primary_deselected"
-                app:boxStrokeColor="@color/primary"
-                android:textColorHint="@color/primary_deselected">
-
-                <com.google.android.material.textfield.TextInputEditText
-                    android:id="@+id/callsignTextInputEditText"
+                android:orientation="vertical">
+
+                <com.google.android.material.textfield.TextInputLayout
                     android:layout_width="match_parent"
-                    android:layout_height="match_parent"
-                    android:layout_weight="1"
-                    android:textSize="20dp"
-                    android:maxLength="10"
-                    android:maxLines="1"
-                    android:singleLine="true"
-                    android:textColor="@color/primary">
-                </com.google.android.material.textfield.TextInputEditText>
-            </com.google.android.material.textfield.TextInputLayout>
-
-            <TextView
-                android:layout_width="wrap_content"
-                android:layout_height="wrap_content"
-                android:fontFamily="@font/jost"
-                android:text="Squelch"
-                android:textColor="@color/primary_deselected"
-                android:textSize="16dp"
-                android:labelFor="@id/squelchSlider"
-                android:layout_marginTop="16dp"/>
-
-            <com.google.android.material.slider.Slider
-                android:id="@+id/squelchSlider"
-                android:layout_width="match_parent"
-                android:layout_height="wrap_content"
-                android:valueFrom="0.0"
-                android:valueTo="8.0"
-                android:stepSize="1.0"
-                app:labelBehavior="gone" /> <!-- Would like to keep the label, but the color is illegible and can't figure out how to set it. -->
+                    android:layout_height="72dp"
+                    android:layout_weight="0"
+                    style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox"
+                    android:hint="Your callsign"
+                    app:hintTextColor="@color/primary_deselected"
+                    app:boxStrokeColor="@color/primary"
+                    android:textColorHint="@color/primary_deselected">
 
-            <TextView
-                android:layout_width="wrap_content"
-                android:layout_height="wrap_content"
-                android:fontFamily="@font/jost"
-                android:text="Filters"
-                android:textColor="@color/primary_deselected"
-                android:textSize="16dp"
-                android:layout_marginTop="16dp"/>
-
-            <Switch
-                android:id="@+id/emphasisSwitch"
-                android:layout_width="match_parent"
-                android:layout_height="wrap_content"
-                android:text="Pre- &amp; De-emphasis"
-                android:textSize="18dp"
-                android:textColor="@color/primary"
-                android:layout_marginTop="8dp"
-                android:trackTintMode="add"/>
-
-            <Switch
-                android:id="@+id/highpassSwitch"
-                android:layout_width="match_parent"
-                android:layout_height="wrap_content"
-                android:text="Highpass"
-                android:textSize="18dp"
-                android:textColor="@color/primary"
-                android:layout_marginTop="8dp"
-                android:trackTintMode="add"/>
-
-            <Switch
-                android:id="@+id/lowpassSwitch"
-                android:layout_width="match_parent"
-                android:layout_height="wrap_content"
-                android:text="Lowpass"
-                android:textSize="18dp"
-                android:textColor="@color/primary"
-                android:layout_marginTop="8dp"
-                android:trackTintMode="add"/>
-
-            <TextView
-                android:layout_width="wrap_content"
-                android:layout_height="wrap_content"
-                android:fontFamily="@font/jost"
-                android:text="Accessibility"
-                android:textColor="@color/primary_deselected"
-                android:textSize="16dp"
-                android:layout_marginTop="24dp"/>
-
-            <Switch
-                android:id="@+id/stickyPTTSwitch"
-                android:layout_width="match_parent"
-                android:layout_height="wrap_content"
-                android:text="Sticky PTT"
-                android:textSize="18dp"
-                android:textColor="@color/primary"
-                android:layout_marginTop="8dp"
-                android:trackTintMode="add"/>
-
-            <Switch
-                android:id="@+id/noAnimationsSwitch"
-                android:layout_width="match_parent"
-                android:layout_height="wrap_content"
-                android:text="Disable animations"
-                android:textSize="18dp"
-                android:textColor="@color/primary"
-                android:layout_marginTop="8dp"
-                android:trackTintMode="add"/>
+                    <com.google.android.material.textfield.TextInputEditText
+                        android:id="@+id/callsignTextInputEditText"
+                        android:layout_width="match_parent"
+                        android:layout_height="match_parent"
+                        android:layout_weight="1"
+                        android:textSize="20dp"
+                        android:maxLength="10"
+                        android:maxLines="1"
+                        android:singleLine="true"
+                        android:textColor="@color/primary">
+                    </com.google.android.material.textfield.TextInputEditText>
+                </com.google.android.material.textfield.TextInputLayout>
 
-            <LinearLayout
-                android:layout_width="match_parent"
-                android:layout_height="wrap_content"
-                android:orientation="horizontal"
-                android:layout_marginTop="8dp">
+                <TextView
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:fontFamily="@font/jost"
+                    android:text="Squelch"
+                    android:textColor="@color/primary_deselected"
+                    android:textSize="16dp"
+                    android:labelFor="@id/squelchSlider"
+                    android:layout_marginTop="16dp"/>
+
+                <com.google.android.material.slider.Slider
+                    android:id="@+id/squelchSlider"
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:valueFrom="0.0"
+                    android:valueTo="8.0"
+                    android:stepSize="1.0"
+                    app:labelBehavior="gone" /> <!-- Would like to keep the label, but the color is illegible and can't figure out how to set it. -->
 
                 <TextView
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
                     android:fontFamily="@font/jost"
-                    android:text="Closed captions"
+                    android:text="Audio"
+                    android:textColor="@color/primary_deselected"
+                    android:textSize="16dp"
+                    android:layout_marginTop="16dp"/>
+
+                <Switch
+                    android:id="@+id/emphasisSwitch"
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:text="Pre- &amp; De-emphasis"
+                    android:textSize="18dp"
                     android:textColor="@color/primary"
+                    android:layout_marginTop="8dp"
+                    android:trackTintMode="add"/>
+
+                <Switch
+                    android:id="@+id/highpassSwitch"
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:text="Highpass"
                     android:textSize="18dp"
-                    android:layout_gravity="center_vertical"
-                    android:layout_weight="1"
-                    android:labelFor="@id/closedCaptionsButton"/>
+                    android:textColor="@color/primary"
+                    android:layout_marginTop="8dp"
+                    android:trackTintMode="add"/>
 
-                <Button
-                    android:id="@+id/closedCaptionsButton"
-                    android:layout_width="wrap_content"
-                    android:layout_height="32dp"
-                    android:layout_weight="0"
-                    android:background="?android:attr/selectableItemBackground"
-                    android:text="System setting"
-                    android:textSize="16dp"
-                    android:textFontWeight="500"
+                <Switch
+                    android:id="@+id/lowpassSwitch"
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:text="Lowpass"
+                    android:textSize="18dp"
                     android:textColor="@color/primary"
-                    android:textAllCaps="true"
-                    android:enabled="true"
-                    android:onClick="closedCaptionsButtonClicked"
-                    android:layout_gravity="end"
-                    android:textAlignment="viewEnd"
-                    android:padding="0dp" />
+                    android:layout_marginTop="8dp"
+                    android:trackTintMode="add"/>
 
-            </LinearLayout>
+                <LinearLayout
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:orientation="horizontal">
 
-            <TextView
-                android:layout_width="wrap_content"
-                android:layout_height="wrap_content"
-                android:fontFamily="@font/jost"
-                android:text="Advanced"
-                android:textColor="@color/primary_deselected"
-                android:textSize="16dp"
-                android:layout_marginTop="24dp"/>
+                    <TextView
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:fontFamily="@font/jost"
+                        android:text="Mic gain boost"
+                        android:textColor="@color/primary"
+                        android:textSize="18dp"
+                        android:layout_gravity="center_vertical"
+                        android:layout_weight="1"
+                        android:labelFor="@id/micGainBoostTextView"/>
 
-            <LinearLayout
-                android:layout_width="match_parent"
-                android:layout_height="wrap_content"
-                android:orientation="horizontal">
+                    <com.google.android.material.textfield.TextInputLayout
+                        android:layout_width="wrap_content"
+                        android:layout_height="40dp"
+                        android:padding="0dp"
+                        android:layout_weight="0"
+                        style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox.ExposedDropdownMenu"
+                        app:hintTextColor="@color/primary_deselected"
+                        app:boxStrokeColor="@color/primary"
+                        android:textColorHint="@color/primary_deselected">
+
+                        <AutoCompleteTextView
+                            android:id="@+id/micGainBoostTextView"
+                            android:layout_width="160dp"
+                            android:layout_height="wrap_content"
+                            android:padding="0dp"
+                            android:layout_weight="1"
+                            android:inputType="none"
+                            android:text="None"
+                            android:textSize="20dp"
+                            android:textColor="@color/primary"/>
+                    </com.google.android.material.textfield.TextInputLayout>
+                </LinearLayout>
 
                 <TextView
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
                     android:fontFamily="@font/jost"
-                    android:text="Max tx frequency"
+                    android:text="Accessibility"
+                    android:textColor="@color/primary_deselected"
+                    android:textSize="16dp"
+                    android:layout_marginTop="24dp"/>
+
+                <Switch
+                    android:id="@+id/stickyPTTSwitch"
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:text="Sticky PTT"
+                    android:textSize="18dp"
                     android:textColor="@color/primary"
+                    android:layout_marginTop="8dp"
+                    android:trackTintMode="add"/>
+
+                <Switch
+                    android:id="@+id/noAnimationsSwitch"
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:text="Disable animations"
                     android:textSize="18dp"
-                    android:layout_gravity="center_vertical"
-                    android:layout_weight="1"
-                    android:labelFor="@id/maxFreqTextView"/>
+                    android:textColor="@color/primary"
+                    android:layout_marginTop="8dp"
+                    android:trackTintMode="add"/>
 
-                <com.google.android.material.textfield.TextInputLayout
-                    android:layout_width="wrap_content"
-                    android:layout_height="40dp"
-                    android:padding="0dp"
-                    android:layout_weight="0"
-                    style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox.ExposedDropdownMenu"
-                    app:hintTextColor="@color/primary_deselected"
-                    app:boxStrokeColor="@color/primary"
-                    android:textColorHint="@color/primary_deselected">
+                <LinearLayout
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:orientation="horizontal"
+                    android:layout_marginTop="8dp">
 
-                    <AutoCompleteTextView
-                        android:id="@+id/maxFreqTextView"
-                        android:layout_width="160dp"
+                    <TextView
+                        android:layout_width="wrap_content"
                         android:layout_height="wrap_content"
-                        android:padding="0dp"
+                        android:fontFamily="@font/jost"
+                        android:text="Closed captions"
+                        android:textColor="@color/primary"
+                        android:textSize="18dp"
+                        android:layout_gravity="center_vertical"
                         android:layout_weight="1"
-                        android:inputType="none"
-                        android:text="148MHz"
-                        android:textSize="20dp"
-                        android:textColor="@color/primary"/>
-                </com.google.android.material.textfield.TextInputLayout>
-            </LinearLayout>
+                        android:labelFor="@id/closedCaptionsButton"/>
 
-            <LinearLayout
-                android:layout_width="match_parent"
-                android:layout_height="wrap_content"
-                android:orientation="horizontal">
+                    <Button
+                        android:id="@+id/closedCaptionsButton"
+                        android:layout_width="wrap_content"
+                        android:layout_height="32dp"
+                        android:layout_weight="0"
+                        android:background="?android:attr/selectableItemBackground"
+                        android:text="System setting"
+                        android:textSize="16dp"
+                        android:textFontWeight="500"
+                        android:textColor="@color/primary"
+                        android:textAllCaps="true"
+                        android:enabled="true"
+                        android:onClick="closedCaptionsButtonClicked"
+                        android:layout_gravity="end"
+                        android:textAlignment="viewEnd"
+                        android:padding="0dp" />
+
+                </LinearLayout>
 
                 <TextView
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
                     android:fontFamily="@font/jost"
-                    android:text="Mic gain boost"
-                    android:textColor="@color/primary"
-                    android:textSize="18dp"
-                    android:layout_gravity="center_vertical"
-                    android:layout_weight="1"
-                    android:labelFor="@id/micGainBoostTextView"/>
+                    android:text="Advanced"
+                    android:textColor="@color/primary_deselected"
+                    android:textSize="16dp"
+                    android:layout_marginTop="24dp"/>
 
-                <com.google.android.material.textfield.TextInputLayout
-                    android:layout_width="wrap_content"
-                    android:layout_height="40dp"
-                    android:padding="0dp"
-                    android:layout_weight="0"
-                    style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox.ExposedDropdownMenu"
-                    app:hintTextColor="@color/primary_deselected"
-                    app:boxStrokeColor="@color/primary"
-                    android:textColorHint="@color/primary_deselected">
+                <LinearLayout
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:orientation="horizontal">
 
-                    <AutoCompleteTextView
-                        android:id="@+id/micGainBoostTextView"
-                        android:layout_width="160dp"
+                    <TextView
+                        android:layout_width="wrap_content"
                         android:layout_height="wrap_content"
+                        android:fontFamily="@font/jost"
+                        android:text="Max tx frequency"
+                        android:textColor="@color/primary"
+                        android:textSize="18dp"
+                        android:layout_gravity="center_vertical"
+                        android:layout_weight="1"
+                        android:labelFor="@id/maxFreqTextView"/>
+
+                    <com.google.android.material.textfield.TextInputLayout
+                        android:layout_width="wrap_content"
+                        android:layout_height="40dp"
                         android:padding="0dp"
+                        android:layout_weight="0"
+                        style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox.ExposedDropdownMenu"
+                        app:hintTextColor="@color/primary_deselected"
+                        app:boxStrokeColor="@color/primary"
+                        android:textColorHint="@color/primary_deselected">
+
+                        <AutoCompleteTextView
+                            android:id="@+id/maxFreqTextView"
+                            android:layout_width="160dp"
+                            android:layout_height="wrap_content"
+                            android:padding="0dp"
+                            android:layout_weight="1"
+                            android:inputType="none"
+                            android:text="148MHz"
+                            android:textSize="20dp"
+                            android:textColor="@color/primary"/>
+                    </com.google.android.material.textfield.TextInputLayout>
+                </LinearLayout>
+
+                <LinearLayout
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:orientation="horizontal">
+
+                    <TextView
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:fontFamily="@font/jost"
+                        android:text="Rx sample rate"
+                        android:textColor="@color/primary"
+                        android:textSize="18dp"
+                        android:layout_gravity="center_vertical"
                         android:layout_weight="1"
-                        android:inputType="none"
-                        android:text="None"
-                        android:textSize="20dp"
-                        android:textColor="@color/primary"/>
-                </com.google.android.material.textfield.TextInputLayout>
+                        android:labelFor="@id/rxSampleRateTextView"/>
+
+                    <com.google.android.material.textfield.TextInputLayout
+                        android:layout_width="wrap_content"
+                        android:layout_height="40dp"
+                        android:padding="0dp"
+                        android:layout_weight="0"
+                        style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox.ExposedDropdownMenu"
+                        app:hintTextColor="@color/primary_deselected"
+                        app:boxStrokeColor="@color/primary"
+                        android:textColorHint="@color/primary_deselected">
+
+                        <AutoCompleteTextView
+                            android:id="@+id/rxSampleRateTextView"
+                            android:layout_width="160dp"
+                            android:layout_height="wrap_content"
+                            android:padding="0dp"
+                            android:layout_weight="1"
+                            android:inputType="none"
+                            android:text="44.1kHz"
+                            android:textSize="20dp"
+                            android:textColor="@color/primary"/>
+                    </com.google.android.material.textfield.TextInputLayout>
+                </LinearLayout>
+
+                <LinearLayout
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:orientation="horizontal">
+
+                    <TextView
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:fontFamily="@font/jost"
+                        android:text="Tx sample rate"
+                        android:textColor="@color/primary"
+                        android:textSize="18dp"
+                        android:layout_gravity="center_vertical"
+                        android:layout_weight="1"
+                        android:labelFor="@id/txSampleRateTextView"/>
+
+                    <com.google.android.material.textfield.TextInputLayout
+                        android:layout_width="wrap_content"
+                        android:layout_height="40dp"
+                        android:padding="0dp"
+                        android:layout_weight="0"
+                        style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox.ExposedDropdownMenu"
+                        app:hintTextColor="@color/primary_deselected"
+                        app:boxStrokeColor="@color/primary"
+                        android:textColorHint="@color/primary_deselected">
+
+                        <AutoCompleteTextView
+                            android:id="@+id/txSampleRateTextView"
+                            android:layout_width="160dp"
+                            android:layout_height="wrap_content"
+                            android:padding="0dp"
+                            android:layout_weight="1"
+                            android:inputType="none"
+                            android:text="44.1kHz"
+                            android:textSize="20dp"
+                            android:textColor="@color/primary"/>
+                    </com.google.android.material.textfield.TextInputLayout>
+                </LinearLayout>
+
+                <LinearLayout
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:orientation="horizontal"
+                    android:layout_marginBottom="32dp">
+
+                    <TextView
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:fontFamily="@font/jost"
+                        android:text="Rx sample rate mult"
+                        android:textColor="@color/primary"
+                        android:textSize="18dp"
+                        android:layout_gravity="center_vertical"
+                        android:layout_weight="1"
+                        android:labelFor="@id/rxSampleRateMultTextView"/>
+
+                    <com.google.android.material.textfield.TextInputLayout
+                        android:layout_width="wrap_content"
+                        android:layout_height="40dp"
+                        android:layout_weight="0"
+                        style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox"
+                        app:hintTextColor="@color/primary_deselected"
+                        app:boxStrokeColor="@color/primary"
+                        android:textColorHint="@color/primary_deselected">
+
+                        <com.google.android.material.textfield.TextInputEditText
+                            android:id="@+id/rxSampleRateMultTextView"
+                            android:layout_width="160dp"
+                            android:layout_height="match_parent"
+                            android:layout_weight="1"
+                            android:textSize="20dp"
+                            android:maxLength="7"
+                            android:maxLines="1"
+                            android:text="1.00494"
+                            android:inputType="numberDecimal"
+                            android:singleLine="true"
+                            android:textColor="@color/primary"
+                            android:padding="0dp">
+                        </com.google.android.material.textfield.TextInputEditText>
+                    </com.google.android.material.textfield.TextInputLayout>
+                </LinearLayout>
             </LinearLayout>
+        </ScrollView>
+
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:orientation="vertical"
+            android:layout_weight="0">
+
+            <View
+                android:layout_width="fill_parent"
+                android:layout_height="1dp"
+                android:layout_weight="1"
+                android:background="@color/primary"
+                android:gravity="center_vertical" />
 
             <LinearLayout
                 android:layout_width="match_parent"
                 android:layout_height="wrap_content"
                 android:orientation="horizontal"
-                android:layout_marginTop="32dp"
-                android:gravity="right">
+                android:layout_marginTop="16dp"
+                android:gravity="right"
+                android:layout_alignParentBottom="true">
 
                 <Button
                     android:id="@+id/doneButton"
                     android:layout_width="wrap_content"
                     android:layout_height="56dp"
                     android:layout_weight="0"
-                    android:layout_marginBottom="64dp"
+                    android:layout_marginBottom="16dp"
                     android:text="Done"
                     android:textSize="20dp"
                     android:textFontWeight="500"
@@ -290,5 +433,5 @@
                     android:onClick="doneButtonClicked"/>
             </LinearLayout>
         </LinearLayout>
-    </ScrollView>
+    </LinearLayout>
 </LinearLayout>
\ No newline at end of file
diff --git a/microcontroller-src/kv4p_ht_esp32_wroom_32/kv4p_ht_esp32_wroom_32.ino b/microcontroller-src/kv4p_ht_esp32_wroom_32/kv4p_ht_esp32_wroom_32.ino
index e33f662..841faee 100644
--- a/microcontroller-src/kv4p_ht_esp32_wroom_32/kv4p_ht_esp32_wroom_32.ino
+++ b/microcontroller-src/kv4p_ht_esp32_wroom_32/kv4p_ht_esp32_wroom_32.ino
@@ -46,12 +46,10 @@ int matchedDelimiterTokens = 0;
 #define MODE_STOPPED 2
 int mode = MODE_STOPPED;
 
-// Audio sampling rate, must match what Android app expects (and sends).
-#define AUDIO_SAMPLE_RATE 44100
-
-// Offset to make up for fact that sampling is slightly slower than requested, and we don't want underruns.
-// But if this is set too high, then we get audio skips instead of underruns. So there's a sweet spot.
-#define SAMPLING_RATE_OFFSET 218
+// Audio sampling rate and baud rates must match what Android app expects.
+int rxAudioSampleRate = 44100; // May be changed by TUNE_TO
+int txAudioSampleRate = 44100; // Ditto
+int baudRate = 921600; // Variable because may be dynamic / configurable in the future.
 
 // Buffer for outgoing audio bytes to send to radio module
 #define TX_TEMP_AUDIO_BUFFER_SIZE 4096 // Holds data we already got off of USB serial from Android app
@@ -102,22 +100,19 @@ int fadeDirection = 0; // 0: no fade, 1: fade in, -1: fade out
 int attenuation = ATTENUATION_MAX; // Full volume
 bool lastSquelched = false;
 
-
 ////////////////////////////////////////////////////////////////////////////////
 /// Forward Declarations
 ////////////////////////////////////////////////////////////////////////////////
 
 void initI2SRx();
 void initI2STx();
-void tuneTo(float freqTx, float freqRx, int tone, int squelch);
+void tuneTo(float freqTx, float freqRx, int tone, int squelch, int newRxSampleRate, int newTxSampleRate);
 void setMode(int newMode);
 void processTxAudio(uint8_t tempBuffer[], int bytesRead);
 
-
-
 void setup() {
   // Communication with Android via USB cable
-  Serial.begin(921600);
+  Serial.begin(baudRate);
   Serial.setRxBufferSize(USB_BUFFER_SIZE);
   Serial.setTxBufferSize(USB_BUFFER_SIZE);
 
@@ -144,7 +139,6 @@ void setup() {
     result = dra->handshake(); // Wait for module to start up
   }
   // Serial.println("handshake: " + String(result));
-  // tuneTo(146.700, 146.700, 0, 0);
   result = dra->volume(8);
   // Serial.println("volume: " + String(result));
   result = dra->filters(false, false, false);
@@ -165,9 +159,9 @@ void initI2SRx() {
   adc1_config_width(ADC_WIDTH_BIT_12);
   adc1_config_channel_atten(ADC1_CHANNEL_6, ADC_ATTEN_DB_0);
 
-  static const i2s_config_t i2sRxConfig = {
+  i2s_config_t i2sRxConfig = {
       .mode = (i2s_mode_t) (I2S_MODE_MASTER | I2S_MODE_RX | I2S_MODE_ADC_BUILT_IN),
-      .sample_rate = AUDIO_SAMPLE_RATE + SAMPLING_RATE_OFFSET,
+      .sample_rate = rxAudioSampleRate,
       .bits_per_sample = I2S_BITS_PER_SAMPLE_32BIT,
       .channel_format = I2S_CHANNEL_FMT_ONLY_LEFT,
       .communication_format = i2s_comm_format_t(I2S_COMM_FORMAT_I2S | I2S_COMM_FORMAT_I2S_MSB),
@@ -190,9 +184,9 @@ void initI2STx() {
   }
   i2sStarted = true;
 
-  static const i2s_config_t i2sTxConfig = {
+  i2s_config_t i2sTxConfig = {
       .mode = (i2s_mode_t) (I2S_MODE_MASTER | I2S_MODE_TX | I2S_MODE_DAC_BUILT_IN),
-      .sample_rate = AUDIO_SAMPLE_RATE,
+      .sample_rate = txAudioSampleRate,
       .bits_per_sample = I2S_BITS_PER_SAMPLE_16BIT,
       .channel_format = I2S_CHANNEL_FMT_ONLY_RIGHT,
       .intr_alloc_flags = 0,
@@ -237,15 +231,12 @@ void loop() {
         // commands appropriately. Or at least extract the business logic from them to avoid that duplication.
         case COMMAND_TUNE_TO:
         {
-          // Example:
-          // 145.4500144.8500061
-          // 8 chars for tx, 8 chars for rx, 2 chars for tone, 1 char for squelch (19 bytes total for params)
           setMode(MODE_RX);
 
           // If we haven't received all the parameters needed for COMMAND_TUNE_TO, wait for them before continuing.
           // This can happen if ESP32 has pulled part of the command+params from the buffer before Android has completed
           // putting them in there. If so, we take byte-by-byte until we get the full params.
-          int paramBytesMissing = 19;
+          int paramBytesMissing = 29;
           String paramsStr = "";
           if (paramBytesMissing > 0) {
             uint8_t paramPartsBuffer[paramBytesMissing];
@@ -264,14 +255,19 @@ void loop() {
             paramBytesMissing--;
           }
 
+          // Example:
+          // 145.4500144.85000614410044100
+          // 8 chars for tx, 8 chars for rx, 2 chars for tone, 1 char for squelch, 5 char for rx sample rate, 5 char for tx sample rate (29 bytes total for params)
           float freqTxFloat = paramsStr.substring(0, 8).toFloat();
           float freqRxFloat = paramsStr.substring(8, 16).toFloat();
           int toneInt = paramsStr.substring(16, 18).toInt();
           int squelchInt = paramsStr.substring(18, 19).toInt();
+          int newRxSampleRate = paramsStr.substring(19, 24).toInt();
+          int newTxSampleRate = paramsStr.substring(24, 29).toInt();
 
           // Serial.println("PARAMS: " + paramsStr.substring(0, 16) + " freqTxFloat: " + String(freqTxFloat) + " freqRxFloat: " + String(freqRxFloat) + " toneInt: " + String(toneInt));
 
-          tuneTo(freqTxFloat, freqRxFloat, toneInt, squelchInt);
+          tuneTo(freqTxFloat, freqRxFloat, toneInt, squelchInt, newRxSampleRate, newTxSampleRate);
         }
           break;
         case COMMAND_FILTERS:
@@ -332,15 +328,12 @@ void loop() {
             break;
           case COMMAND_TUNE_TO:
           {
-            // Example:
-            // 145.4500144.8500061
-            // 8 chars for tx, 8 chars for rx, 2 chars for tone, 1 char for squelch (19 bytes total for params)
             setMode(MODE_RX);
 
             // If we haven't received all the parameters needed for COMMAND_TUNE_TO, wait for them before continuing.
             // This can happen if ESP32 has pulled part of the command+params from the buffer before Android has completed
             // putting them in there. If so, we take byte-by-byte until we get the full params.
-            int paramBytesMissing = 19;
+            int paramBytesMissing = 29;
             String paramsStr = "";
             if (paramBytesMissing > 0) {
               uint8_t paramPartsBuffer[paramBytesMissing];
@@ -359,12 +352,19 @@ void loop() {
               paramBytesMissing--;
             }
 
+            // Example:
+            // 145.4500144.85000614410044100
+            // 8 chars for tx, 8 chars for rx, 2 chars for tone, 1 char for squelch, 1 char for rx sample rate, 1 char for tx sample rate (29 bytes total for params)
             float freqTxFloat = paramsStr.substring(0, 8).toFloat();
             float freqRxFloat = paramsStr.substring(8, 16).toFloat();
             int toneInt = paramsStr.substring(16, 18).toInt();
             int squelchInt = paramsStr.substring(18, 19).toInt();
+            int newRxSampleRate = paramsStr.substring(19, 24).toInt();
+            int newTxSampleRate = paramsStr.substring(24, 29).toInt();
+
+            // Serial.println("PARAMS: " + paramsStr.substring(0, 16) + " freqTxFloat: " + String(freqTxFloat) + " freqRxFloat: " + String(freqRxFloat) + " toneInt: " + String(toneInt));
 
-            tuneTo(freqTxFloat, freqRxFloat, toneInt, squelchInt);
+            tuneTo(freqTxFloat, freqRxFloat, toneInt, squelchInt, newRxSampleRate, newTxSampleRate);
           }
             break;
           case COMMAND_FILTERS:
@@ -524,7 +524,13 @@ void loop() {
   }
 }
 
-void tuneTo(float freqTx, float freqRx, int tone, int squelch) {
+void tuneTo(float freqTx, float freqRx, int tone, int squelch, int newRxSampleRate, int newTxSampleRate) {
+  rxAudioSampleRate = newRxSampleRate;
+  txAudioSampleRate = newTxSampleRate;
+
+  initI2SRx();
+
+  // Tell radio module to tune
   int result = dra->group(DRA818_25K, freqTx, freqRx, tone, squelch, 0);
   // Serial.println("tuneTo: " + String(result));
 }