#7 NXDN Decoder support. Redesigns tuner and channel frequency error management. (#2431)

Closes #7 

NXDN Decoder

* Implements: NXDN4800, NXDN9600, Type-C and Type-D decoding and trunk tracking.
* Redesigns tuner and channel frequency error management.

src/main/java/io/github/dsheirer/audio/codec/mbe/MBECallSequence.java

@@ -1,6 +1,6 @@
 /*
  * *****************************************************************************
- * Copyright (C) 2014-2022 Dennis Sheirer
+ * Copyright (C) 2014-2026 Dennis Sheirer
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -26,7 +26,6 @@ import com.fasterxml.jackson.annotation.JsonPropertyOrder;
 import com.fasterxml.jackson.annotation.JsonRootName;
 import io.github.dsheirer.identifier.Identifier;
 import io.github.dsheirer.identifier.encryption.EncryptionKey;
-import io.github.dsheirer.module.decode.p25.audio.VoiceFrame;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -288,10 +287,18 @@ public class MBECallSequence
         }
         else
         {
-            mVoiceFrames.add(new VoiceFrame(timestamp, frame));
+            add(new VoiceFrame(timestamp, frame));
         }
     }
 
+    /**
+     * Adds the voice frame to the sequence
+     */
+    public void add(VoiceFrame voiceFrame)
+    {
+        mVoiceFrames.add(voiceFrame);
+    }
+
     /**
      * Adds an encrypted audio frame to this call sequence
      *
@@ -317,6 +324,6 @@ public class MBECallSequence
      */
     public void addEncryptedVoiceFrame(long timestamp, String frame, int algorithm, int keyid, String messageIndicator)
     {
-        mVoiceFrames.add(new VoiceFrame(timestamp, frame, algorithm, keyid, messageIndicator));
+        add(new VoiceFrame(timestamp, frame, algorithm, keyid, messageIndicator));
     }
 }

src/main/java/io/github/dsheirer/audio/codec/mbe/MBECallSequenceConverter.java

@@ -1,6 +1,6 @@
 /*
  * *****************************************************************************
- * Copyright (C) 2014-2023 Dennis Sheirer
+ * Copyright (C) 2014-2026 Dennis Sheirer
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -25,7 +25,6 @@ import io.github.dsheirer.audio.AudioSegment;
 import io.github.dsheirer.identifier.IdentifierUpdateNotification;
 import io.github.dsheirer.module.decode.p25.audio.P25P1AudioModule;
 import io.github.dsheirer.module.decode.p25.audio.P25P1CallSequenceRecorder;
-import io.github.dsheirer.module.decode.p25.audio.VoiceFrame;
 import io.github.dsheirer.module.decode.p25.identifier.radio.APCO25RadioIdentifier;
 import io.github.dsheirer.module.decode.p25.identifier.talkgroup.APCO25Talkgroup;
 import io.github.dsheirer.preference.UserPreferences;

src/main/java/io/github/dsheirer/audio/codec/mbe/MBECallSequenceReader.java

@@ -1,23 +1,20 @@
 /*
+ * *****************************************************************************
+ * Copyright (C) 2014-2026 Dennis Sheirer
  *
- *  * ******************************************************************************
- *  * Copyright (C) 2014-2019 Dennis Sheirer
- *  *
- *  * This program is free software: you can redistribute it and/or modify
- *  * it under the terms of the GNU General Public License as published by
- *  * the Free Software Foundation, either version 3 of the License, or
- *  * (at your option) any later version.
- *  *
- *  * This program is distributed in the hope that it will be useful,
- *  * but WITHOUT ANY WARRANTY; without even the implied warranty of
- *  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *  * GNU General Public License for more details.
- *  *
- *  * You should have received a copy of the GNU General Public License
- *  * along with this program.  If not, see <http://www.gnu.org/licenses/>
- *  * *****************************************************************************
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
  *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
  *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ * ****************************************************************************
  */
 
 package io.github.dsheirer.audio.codec.mbe;
@@ -25,7 +22,6 @@ package io.github.dsheirer.audio.codec.mbe;
 
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.google.common.base.Joiner;
-import io.github.dsheirer.module.decode.p25.audio.VoiceFrame;
 
 import java.io.IOException;
 import java.nio.file.Files;

src/main/java/io/github/dsheirer/audio/codec/mbe/VoiceFrame.java

@@ -0,0 +1,194 @@
+/*
+ * *****************************************************************************
+ * Copyright (C) 2014-2026 Dennis Sheirer
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ * ****************************************************************************
+ */
+
+package io.github.dsheirer.audio.codec.mbe;
+
+import com.fasterxml.jackson.annotation.JsonIgnore;
+import com.fasterxml.jackson.annotation.JsonInclude;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.annotation.JsonPropertyOrder;
+import com.fasterxml.jackson.annotation.JsonRootName;
+
+/**
+ * Voice frame using hexadecimal representation of the transmitted voice and ecc bits
+ */
+@JsonRootName(value = "frame")
+@JsonInclude(JsonInclude.Include.NON_NULL)
+@JsonPropertyOrder({"tag", "encryption_algorithm", "encryption_key_id", "encryption_mi", "time", "hex"})
+public class VoiceFrame
+{
+    private long mTimestamp;
+    private String mFrame;
+    private Integer mAlgorithm;
+    private Integer mKeyId;
+    private String mMessageIndicator;
+    private String mTag;
+
+    public VoiceFrame()
+    {
+        //no-arg constructor for faster jackson deserialization
+    }
+
+    /**
+     * Constructs an unencrypted voice frame
+     *
+     * @param timestamp the frame was transmitted
+     * @param frame with voice and ecc bits
+     */
+    public VoiceFrame(long timestamp, String frame)
+    {
+        mTimestamp = timestamp;
+        mFrame = frame;
+    }
+
+    /**
+     * Constructs an encrypted voice frame
+     *
+     * @param timestamp the message was transmitted
+     * @param frame of hexadecimal values
+     * @param algorithm used to encrypt the voice frame
+     * @param keyid used to encrypt the voice frame
+     * @param messageIndicator for the key generator fill
+     */
+    public VoiceFrame(long timestamp, String frame, int algorithm, int keyid, String messageIndicator)
+    {
+        this(timestamp, frame);
+        mAlgorithm = algorithm;
+        mKeyId = keyid;
+        mMessageIndicator = messageIndicator;
+    }
+
+    /**
+     * Tag value for the voice frame
+     */
+    @JsonProperty("tag")
+    public String getTag()
+    {
+        return mTag;
+    }
+
+    /**
+     * Sets the optional tag value for the frame
+     * @param tag to set
+     */
+    public void setTag(String tag)
+    {
+        mTag = tag;
+    }
+
+    /**
+     * Timestamp the frame was transmitted
+     *
+     * @return timestamp in milliseconds since epoch (1970)
+     */
+    @JsonProperty("time")
+    public long getTimestamp()
+    {
+        return mTimestamp;
+    }
+
+    public void setTimestamp(long timestamp)
+    {
+        mTimestamp = timestamp;
+    }
+
+    /**
+     * Transmitted voice frame and ecc bits in hexadecimal
+     */
+    @JsonProperty("hex")
+    public String getFrame()
+    {
+        return mFrame;
+    }
+
+    public void setFrame(String frame)
+    {
+        mFrame = frame;
+    }
+
+    /**
+     * Audio frame bytes
+     * @return frame bytes or null
+     */
+    @JsonIgnore
+    public byte[] getFrameBytes()
+    {
+        if(mFrame != null)
+        {
+            byte[] bytes = new byte[mFrame.length() / 2];
+            for(int x = 0; x < mFrame.length(); x += 2)
+            {
+                String hex = mFrame.substring(x, x + 2);
+                bytes[x / 2] = (byte) (0xFF & Integer.parseInt(hex, 16));
+            }
+
+            return bytes;
+        }
+
+        return null;
+    }
+
+    /**
+     * Algorithm identifier numeric value
+     *
+     * @return algorithm id
+     */
+    @JsonProperty("encryption_algorithm")
+    public Integer getAlgorithm()
+    {
+        return mAlgorithm;
+    }
+
+    public void setAlgorithm(int algorithm)
+    {
+        mAlgorithm = algorithm;
+    }
+
+    /**
+     * Key identifier
+     *
+     * @return key id
+     */
+    @JsonProperty("encryption_key_id")
+    public Integer getKeyId()
+    {
+        return mKeyId;
+    }
+
+    public void setKeyId(int keyId)
+    {
+        mKeyId = keyId;
+    }
+
+    /**
+     * Key generator fill values
+     *
+     * @return message indicator
+     */
+    @JsonProperty("encryption_mi")
+    public String getMessageIndicator()
+    {
+        return mMessageIndicator;
+    }
+
+    public void setMessageIndicator(String messageIndicator)
+    {
+        mMessageIndicator = messageIndicator;
+    }
+}