first commit

AndroidManifest.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+      package="com.nogy.afu.soundmodem"
+      android:versionCode="1"
+      android:versionName="1.0">
+    <application android:icon="@drawable/icon" android:label="@string/app_name">
+        <activity android:name=".soundmodem"
+                  android:label="@string/app_name">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+
+    </application>
+
+
+</manifest> 

README

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+Welcome to jsoundmodem,
+
+this project was set up to enable APRSDroid to communicate via transceivers.
+Therefore it is still very limited right now.
+
+Working features:
+	- Afsk modulator
+	- APRSFrame packet builder
+	- generic Message class to store not byte-aligned messages and their
+	  length in bits. (Being unaligned is a painful property of messages
+	  after being bit stuffed
+
+Next to come:
+	- I'm thinking of an Afsk demodulator
+	- Extending the APRSFrame packet builder to a generic APRS packet
+	  handler
+
+Bastian Müller
+08/31/2010

res/layout/main.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:orientation="vertical"
+    android:layout_width="fill_parent"
+    android:layout_height="fill_parent"
+    >
+<TextView  
+    android:layout_width="fill_parent" 
+    android:layout_height="wrap_content" 
+    android:text="@string/hello"
+    />
+
+
+<Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="TX" android:id="@+id/B_TX" android:onClick="do_TX"></Button>
+</LinearLayout>

res/values/strings.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <string name="hello">Hello World, soundmodem!</string>
+    <string name="app_name">soundmodem</string>
+</resources>

src/com/nogy/afu/soundmodem/APRSFrame.java

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+/*
+ * APRS Frame generator
+ * 
+ * this class generates an AX.25 compliant UI Frame incl. bit stuffing.
+ * 
+ * 08/29/2010
+ * Bastian Müller
+ * 
+ */
+package com.nogy.afu.soundmodem;
+
+import android.test.IsolatedContext;
+
+public class APRSFrame {
+	private String srca; // Source Address
+	private String desta; // Destination Address
+	private String digia; // Digipeater Addresses
+	private byte cf; // controll field
+	private byte protoId;
+	private String data;
+	private byte flag;
+	private int framelength;
+
+	public APRSFrame (String source, String destination, String digipeaters, String data, int framelength)
+	{
+		this.cf = 0x03;
+		this.protoId = -16; // = 0xf0
+		this.flag = 0x7e;
+		this.srca = source;
+		this.desta = destination;
+		this.digia = digipeaters;
+		this.data = data;
+		this.framelength = framelength;
+	}
+
+	public static byte[] crc16(byte[] d)
+	{
+		byte[] out = new byte[2];
+		int crc = 0xFFFF;
+		int crcpoly = 0x8408;
+		int i,k=0;
+		for (i=0; i<d.length-2; i++)
+			for (k=0; k<8; k++)
+			{
+				if ((crc & 1) != ((d[i] & (1 << k))>>k))
+					crc = ((crc >> 1) ^ crcpoly) & 0xFFFF;					
+				else
+					crc >>= 1;
+			}
+		crc ^= 0xFFFF;
+		out[1] = (byte)(((crc & 0xff00) >> 8)-255-1);   // high byte
+		out[0] = (byte)((crc & 0xff)-255-1);	        // low byte
+		return out;
+	}
+
+	public static Message bitStuffAndFrame(byte[] d, int framelength)
+	{
+		byte[] out = new byte[d.length+framelength+(int)Math.ceil(d.length/5)+1];
+		int i,k=0;
+		int ones;//,bits,bytes;
+//		bits =0; 
+//		bytes =0;
+		ones = 0;
+		int temp = 0;
+		for (i=0; i<out.length; i++)
+			out[i] = 0;
+		for (i=0; i<framelength; i++)
+			out[i] = 0x7e;
+		i=0;	
+		k=framelength*8;
+		while (i<d.length*8)
+		{
+			if ((d[i/8] & (1<<(i%8))) > 0)	// current bit == 1
+			{
+
+				out[k/8] |= ((1 << (k%8))>127)? (byte)((1 << (k%8))-256): (byte)(1 << (k%8));	// insert 
+				if (ones++ == 4)			// going to stuff a 0
+				{
+					k++;
+					ones = 0;					
+				}
+			}
+			else
+			{
+				ones = 0;
+			}
+			i++;
+			k++;
+		}
+		i=0;
+		while ((i)<8)
+		{
+			if ((0x7e & (1<<(i%8))) > 0)	// current bit == 1
+			{
+				out[k/8] |= ((1 << (k%8))>127)? (byte)((1 << (k%8))-256): (byte)(1 << (k%8));	// insert 
+			}
+			k++;			
+			i++;
+		}
+		Message m = new Message();
+		m.numberOfBits = k+1;
+		m.data = out;
+		return m;
+	}
+
+	private byte[] parseCall(String call, boolean isDest)
+	{
+		byte[] out = new byte[7];	// Always 7 Byte long
+		String[] mycall;
+		mycall = call.split("-");
+		char[] c = mycall[0].toUpperCase().toCharArray();
+
+		int i=0;
+
+		for (i=0; i<6; i++)
+			out[i] = 0x40;
+
+		i=0;
+
+		while (i<c.length)
+		{
+			out[i] = (byte)(((int)(c[i])) << 1);
+			i++;
+		}
+		while (i<6)
+		{
+			out[i++] = 0x40; // Fill with Spaces			
+		}
+		if (mycall.length>1)
+		{
+			switch (Integer.parseInt(mycall[1]))
+			{
+				case 0: out[6] = 0x60; break;
+				case 1: out[6] = 0x62; break;
+				case 2: out[6] = 0x64; break;
+				case 3: out[6] = 0x66; break;
+				case 4: out[6] = 0x68; break;
+				case 5: out[6] = 0x6A; break;
+				case 6: out[6] = 0x6C; break;
+				case 7: out[6] = 0x6E; break;
+				case 8: out[6] = 0x70; break;
+				case 9: out[6] = 0x72; break;
+				case 10: out[6] = 0x74; break;
+				case 11: out[6] = 0x76; break;
+				case 12: out[6] = 0x78; break;
+				case 13: out[6] = 0x7A; break;
+				case 14: out[6] = 0x7C;  break;
+				default: out[6] = 0x60;  break;
+			}
+		}
+		else 
+			out[6] = 0x60; // SSID 0 as default;
+		if (isDest)			// set ssid-msb to 1
+		{
+			out[6] |= 0x80;
+		}
+		return out;
+	}
+
+	public Message getMessage()
+	{
+		String[] digis = this.digia.split(",");
+		byte[] out = new byte[14+digis.length*7+2+this.data.length()+2];
+		byte[] temp;
+		int k,i=0;
+		temp = parseCall(this.desta, true);
+		while(i<7)		// Fill in source
+		{
+			out[i] = temp[i];
+			i++;
+		}
+		temp = parseCall(this.srca, false);
+		while(i<14)		// Fill in dest
+		{
+			out[i] = temp[i-7];
+			i++;
+		}
+		for (k=0; k<digis.length; k++)	// Parse an fill in Digis
+		{
+			temp = parseCall(digis[k],false);
+			while(i<21+k*7)	
+			{
+				out[i] = temp[i-14];
+				i++;
+			}
+		}
+		out[i-1] |= 0x01;
+		out[i++] = this.cf;
+		out[i++] = this.protoId;
+		k=0;
+		while (k<this.data.length())
+		{
+			out[i++] = (byte)(((int)(data.charAt(k++))) -256);
+		}
+		temp = crc16(out);
+		out[i++] = temp[0];
+		out[i] = temp[1];
+		return bitStuffAndFrame(out, this.framelength);
+	}
+
+
+
+}

src/com/nogy/afu/soundmodem/Afsk.java

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+/*
+ * AFSK modulator
+ * 
+ * This class helps sending out AFSK modulated data packets for e.g. hamradio use
+ * 
+ * 08/27/2010
+ * Bastian Müller
+ * 
+ */
+
+package com.nogy.afu.soundmodem;
+
+import android.media.AudioFormat;
+import android.media.AudioManager;
+import android.media.AudioTrack;
+
+public class Afsk {
+	public static int f_low = 1200;
+	public static int f_high = 2200;
+	public static int bps = 1200;
+	public static int samplerate = 12000;
+	public static int pcmBits = 16;
+
+	public short[] pcmData;
+
+	private AudioTrack a;
+
+	private float volume;
+
+	public Afsk()
+	{
+		volume = AudioTrack.getMaxVolume()/2;		
+	}
+
+	public void setVolume(float vol)	
+	{
+		this.volume = vol;
+	}
+
+	public void sendMessage(Message m)
+	{
+		int i,k=0;
+		int t=0;
+		int datapoint=0;
+		double cospos=0;
+		int lasttone=f_low;
+		pcmData = new short[(m.numberOfBits*samplerate)/bps];
+		for (i=0; i<m.numberOfBits; i++)
+		{
+
+
+				t=0;
+				if ((m.data[i/8] & (1<<(i%8)))==0) // bit to transmit is 0
+				{
+					lasttone = (lasttone==f_low)?f_high:f_low;
+				}
+				while(t++<samplerate/bps)
+				{
+					pcmData[datapoint++]=(short) Math.round(Math.cos(cospos)*((1 << (pcmBits-1))-1));
+
+					cospos += 2*Math.PI*lasttone/samplerate;
+					if (cospos > 2*Math.PI)
+						cospos -= 2*Math.PI;					
+				}
+
+		}
+		sendPCM();
+
+	}
+
+	private void sendPCM()
+	{
+		a = new AudioTrack(
+				AudioManager.STREAM_MUSIC,
+				samplerate,
+				AudioFormat.CHANNEL_CONFIGURATION_MONO,
+				AudioFormat.ENCODING_PCM_16BIT,
+				pcmData.length*2,
+				AudioTrack.MODE_STATIC
+				);
+		a.setPlaybackRate(samplerate);
+		a.write(pcmData, 0, pcmData.length);
+		a.setStereoVolume(this.volume, this.volume);
+		a.play();
+		//a.g
+
+	}	
+
+
+}

src/com/nogy/afu/soundmodem/Message.java

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+/*
+ * Simple struct type of class 'cause I needed it
+ * Contains a bit stuffed AX.25 UI Frame
+ * 
+ * 08/29/2010
+ * Bastian Müller
+ * 
+ */
+
+package com.nogy.afu.soundmodem;
+
+public class Message {
+	public int numberOfBits;
+	public byte[] data;
+}