Implement units conversion class

28 files changed, 64 insertions, 36 deletions

diff --git a/src/org/traccar/protocol/ApelProtocolDecoder.java b/src/org/traccar/protocol/ApelProtocolDecoder.java
index 6b4e43dbd..5729231a5 100644
--- a/src/org/traccar/protocol/ApelProtocolDecoder.java
+++ b/src/org/traccar/protocol/ApelProtocolDecoder.java
@@ -30,6 +30,7 @@ import org.jboss.netty.channel.ChannelHandlerContext;
 import org.traccar.BaseProtocolDecoder;
 import org.traccar.helper.Crc;
 import org.traccar.helper.Log;
+import org.traccar.helper.UnitsConverter;
 import org.traccar.model.Event;
 import org.traccar.model.Position;
 
@@ -193,12 +194,12 @@ public class ApelProtocolDecoder extends BaseProtocolDecoder {
                 if (subtype == MSG_TYPE_STATE_FULL_INFO_T104) {
                     int speed = buf.readUnsignedByte();
                     position.setValid(speed != 255);
-                    position.setSpeed(speed * 0.539957);
+                    position.setSpeed(UnitsConverter.knotsFromKph(speed));
                     position.set(Event.KEY_HDOP, buf.readByte());
                 } else {
                     int speed = buf.readShort();
                     position.setValid(speed != -1);
-                    position.setSpeed(speed / 100.0 * 0.539957);
+                    position.setSpeed(UnitsConverter.knotsFromKph(speed / 100.0));
                 }
 
                 // Course
diff --git a/src/org/traccar/protocol/AplicomProtocolDecoder.java b/src/org/traccar/protocol/AplicomProtocolDecoder.java
index 824c2af26..102c7e90d 100644
--- a/src/org/traccar/protocol/AplicomProtocolDecoder.java
+++ b/src/org/traccar/protocol/AplicomProtocolDecoder.java
@@ -26,6 +26,7 @@ import org.jboss.netty.channel.ChannelHandlerContext;
 import org.traccar.BaseProtocolDecoder;
 import org.traccar.Context;
 import org.traccar.helper.ChannelBufferTools;
+import org.traccar.helper.UnitsConverter;
 import org.traccar.model.Event;
 import org.traccar.model.Position;
 
@@ -164,7 +165,7 @@ public class AplicomProtocolDecoder extends BaseProtocolDecoder {
 
         // Speed and heading
         if ((selector & 0x0010) != 0) {
-            position.setSpeed(buf.readUnsignedByte() * 0.539957);
+            position.setSpeed(UnitsConverter.knotsFromKph(buf.readUnsignedByte()));
             buf.readUnsignedByte(); // maximum speed
             position.setCourse(buf.readUnsignedByte() * 2.0);
         }
diff --git a/src/org/traccar/protocol/Ardi01ProtocolDecoder.java b/src/org/traccar/protocol/Ardi01ProtocolDecoder.java
index fdd160bdd..3a254cf41 100644
--- a/src/org/traccar/protocol/Ardi01ProtocolDecoder.java
+++ b/src/org/traccar/protocol/Ardi01ProtocolDecoder.java
@@ -18,6 +18,7 @@ package org.traccar.protocol;
 import org.jboss.netty.channel.Channel;
 import org.jboss.netty.channel.ChannelHandlerContext;
 import org.traccar.BaseProtocolDecoder;
+import org.traccar.helper.UnitsConverter;
 import org.traccar.model.Event;
 import org.traccar.model.Position;
 
@@ -84,7 +85,7 @@ public class Ardi01ProtocolDecoder extends BaseProtocolDecoder {
         // Location data
         position.setLongitude(Double.valueOf(parser.group(index++)));
         position.setLatitude(Double.valueOf(parser.group(index++)));
-        position.setSpeed(Double.valueOf(parser.group(index++)) * 0.539957);
+        position.setSpeed(UnitsConverter.knotsFromKph(Double.valueOf(parser.group(index++))));
         position.setCourse(Double.valueOf(parser.group(index++)));
         position.setAltitude(Double.valueOf(parser.group(index++)));
         
diff --git a/src/org/traccar/protocol/AtrackProtocolDecoder.java b/src/org/traccar/protocol/AtrackProtocolDecoder.java
index e922f0cb8..b0b7ef1fc 100644
--- a/src/org/traccar/protocol/AtrackProtocolDecoder.java
+++ b/src/org/traccar/protocol/AtrackProtocolDecoder.java
@@ -27,6 +27,7 @@ import org.jboss.netty.channel.Channel;
 import org.jboss.netty.channel.ChannelHandlerContext;
 
 import org.traccar.BaseProtocolDecoder;
+import org.traccar.helper.UnitsConverter;
 import org.traccar.model.Event;
 import org.traccar.model.Position;
 
@@ -128,7 +129,7 @@ public class AtrackProtocolDecoder extends BaseProtocolDecoder {
             position.set(Event.KEY_INPUT, buf.readUnsignedByte());
 
             // Speed
-            position.setSpeed(buf.readUnsignedShort() * 0.539957);
+            position.setSpeed(UnitsConverter.knotsFromKph(buf.readUnsignedShort()));
 
             // Output
             position.set(Event.KEY_OUTPUT, buf.readUnsignedByte());
diff --git a/src/org/traccar/protocol/CalAmpProtocolDecoder.java b/src/org/traccar/protocol/CalAmpProtocolDecoder.java
index f5362f705..f6b06ebe7 100644
--- a/src/org/traccar/protocol/CalAmpProtocolDecoder.java
+++ b/src/org/traccar/protocol/CalAmpProtocolDecoder.java
@@ -26,6 +26,7 @@ import org.jboss.netty.channel.ChannelHandlerContext;
 import org.jboss.netty.channel.Channels;
 import org.jboss.netty.channel.MessageEvent;
 import org.traccar.BaseProtocolDecoder;
+import org.traccar.helper.UnitsConverter;
 import org.traccar.model.Event;
 import org.traccar.model.Position;
 
@@ -170,11 +171,11 @@ public class CalAmpProtocolDecoder extends BaseProtocolDecoder {
             position.setLongitude(buf.readInt() * 0.0000001);
             if (type != MSG_MINI_EVENT_REPORT) {
                 position.setAltitude(buf.readInt() * 0.01);
-                position.setSpeed(buf.readUnsignedInt() * 0.0194384449); // cm/s
+                position.setSpeed(UnitsConverter.knotsFromCps(buf.readUnsignedInt()));
             }
             position.setCourse(buf.readShort());
             if (type == MSG_MINI_EVENT_REPORT) {
-                position.setSpeed(buf.readUnsignedByte() * 0.539957); // km/h
+                position.setSpeed(UnitsConverter.knotsFromKph(buf.readUnsignedByte()));
             }
 
             // Fix status
diff --git a/src/org/traccar/protocol/CellocatorProtocolDecoder.java b/src/org/traccar/protocol/CellocatorProtocolDecoder.java
index 70d5d7c62..adb01b234 100644
--- a/src/org/traccar/protocol/CellocatorProtocolDecoder.java
+++ b/src/org/traccar/protocol/CellocatorProtocolDecoder.java
@@ -25,6 +25,7 @@ import org.jboss.netty.channel.Channel;
 import org.jboss.netty.channel.ChannelHandlerContext;
 
 import org.traccar.BaseProtocolDecoder;
+import org.traccar.helper.UnitsConverter;
 import org.traccar.model.Event;
 import org.traccar.model.Position;
 
@@ -145,7 +146,7 @@ public class CellocatorProtocolDecoder extends BaseProtocolDecoder {
             position.setLongitude(buf.readInt() / Math.PI * 180 / 100000000);
             position.setLatitude(buf.readInt() / Math.PI * 180 / 100000000.0);
             position.setAltitude(buf.readInt() * 0.01);
-            position.setSpeed(buf.readInt() * 0.01 * 1.943844);
+            position.setSpeed(UnitsConverter.knotsFromMps(buf.readInt() * 0.01));
             position.setCourse(buf.readUnsignedShort() / Math.PI * 180.0 / 1000.0);
             
             // Time
diff --git a/src/org/traccar/protocol/EelinkProtocolDecoder.java b/src/org/traccar/protocol/EelinkProtocolDecoder.java
index bbcce5cfc..6628b9c37 100644
--- a/src/org/traccar/protocol/EelinkProtocolDecoder.java
+++ b/src/org/traccar/protocol/EelinkProtocolDecoder.java
@@ -24,6 +24,7 @@ import org.jboss.netty.channel.ChannelHandlerContext;
 
 import org.traccar.BaseProtocolDecoder;
 import org.traccar.helper.ChannelBufferTools;
+import org.traccar.helper.UnitsConverter;
 import org.traccar.model.Event;
 import org.traccar.model.Position;
 
@@ -103,7 +104,7 @@ public class EelinkProtocolDecoder extends BaseProtocolDecoder {
             position.setTime(new Date(buf.readUnsignedInt() * 1000));
             position.setLatitude(buf.readInt() / 1800000.0);
             position.setLongitude(buf.readInt() / 1800000.0);
-            position.setSpeed(buf.readUnsignedByte() * 0.539957);
+            position.setSpeed(UnitsConverter.knotsFromKph(buf.readUnsignedByte()));
             position.setCourse(buf.readUnsignedShort());
             
             // Cell
diff --git a/src/org/traccar/protocol/GatorProtocolDecoder.java b/src/org/traccar/protocol/GatorProtocolDecoder.java
index 4078fd64f..bebba144d 100644
--- a/src/org/traccar/protocol/GatorProtocolDecoder.java
+++ b/src/org/traccar/protocol/GatorProtocolDecoder.java
@@ -24,6 +24,7 @@ import org.jboss.netty.channel.ChannelHandlerContext;
 
 import org.traccar.BaseProtocolDecoder;
 import org.traccar.helper.ChannelBufferTools;
+import org.traccar.helper.UnitsConverter;
 import org.traccar.model.Event;
 import org.traccar.model.Position;
 
@@ -91,7 +92,7 @@ public class GatorProtocolDecoder extends BaseProtocolDecoder {
             // Location
             position.setLatitude(ChannelBufferTools.readCoordinate(buf));
             position.setLongitude(ChannelBufferTools.readCoordinate(buf));
-            position.setSpeed(ChannelBufferTools.readHexInteger(buf, 4) * 0.539957);
+            position.setSpeed(UnitsConverter.knotsFromKph(ChannelBufferTools.readHexInteger(buf, 4)));
             position.setCourse(ChannelBufferTools.readHexInteger(buf, 4));
 
             // Flags
diff --git a/src/org/traccar/protocol/GlobalSatProtocolDecoder.java b/src/org/traccar/protocol/GlobalSatProtocolDecoder.java
index 512ed9da8..17cfacbb5 100644
--- a/src/org/traccar/protocol/GlobalSatProtocolDecoder.java
+++ b/src/org/traccar/protocol/GlobalSatProtocolDecoder.java
@@ -26,6 +26,7 @@ import org.jboss.netty.channel.ChannelHandlerContext;
 
 import org.traccar.BaseProtocolDecoder;
 import org.traccar.Context;
+import org.traccar.helper.UnitsConverter;
 import org.traccar.model.Event;
 import org.traccar.model.Position;
 
@@ -159,10 +160,10 @@ public class GlobalSatProtocolDecoder extends BaseProtocolDecoder {
                     position.setSpeed(Double.valueOf(value));
                     break;
                 case 'I':
-                    position.setSpeed(Double.valueOf(value) * 0.539957);
+                    position.setSpeed(UnitsConverter.knotsFromKph(Double.valueOf(value)));
                     break;
                 case 'J':
-                    position.setSpeed(Double.valueOf(value) * 0.868976);
+                    position.setSpeed(UnitsConverter.knotsFromMph(Double.valueOf(value)));
                     break;
                 case 'K':
                     position.setCourse(Double.valueOf(value));
diff --git a/src/org/traccar/protocol/GotopProtocolDecoder.java b/src/org/traccar/protocol/GotopProtocolDecoder.java
index baa54b09e..eed0b4703 100644
--- a/src/org/traccar/protocol/GotopProtocolDecoder.java
+++ b/src/org/traccar/protocol/GotopProtocolDecoder.java
@@ -24,6 +24,7 @@ import org.jboss.netty.channel.Channel;
 import org.jboss.netty.channel.ChannelHandlerContext;
 
 import org.traccar.BaseProtocolDecoder;
+import org.traccar.helper.UnitsConverter;
 import org.traccar.model.Event;
 import org.traccar.model.Position;
 
@@ -94,7 +95,7 @@ public class GotopProtocolDecoder extends BaseProtocolDecoder {
         position.setLongitude(longitude);
 
         // Speed
-        position.setSpeed(Double.valueOf(parser.group(index++)) * 0.539957);
+        position.setSpeed(UnitsConverter.knotsFromKph(Double.valueOf(parser.group(index++))));
         
         // Status
         position.set(Event.KEY_STATUS, parser.group(index++));
diff --git a/src/org/traccar/protocol/Gt06ProtocolDecoder.java b/src/org/traccar/protocol/Gt06ProtocolDecoder.java
index c4670cc2c..01ffe5490 100644
--- a/src/org/traccar/protocol/Gt06ProtocolDecoder.java
+++ b/src/org/traccar/protocol/Gt06ProtocolDecoder.java
@@ -22,6 +22,7 @@ import org.jboss.netty.channel.ChannelHandlerContext;
 import org.traccar.BaseProtocolDecoder;
 import org.traccar.Context;
 import org.traccar.helper.Crc;
+import org.traccar.helper.UnitsConverter;
 import org.traccar.model.Event;
 import org.traccar.model.Position;
 
@@ -168,7 +169,7 @@ public class Gt06ProtocolDecoder extends BaseProtocolDecoder {
             double longitude = buf.readUnsignedInt() / (60.0 * 30000.0);
 
             // Speed
-            position.setSpeed(buf.readUnsignedByte() * 0.539957);
+            position.setSpeed(UnitsConverter.knotsFromKph(buf.readUnsignedByte()));
 
             // Course and flags
             int union = buf.readUnsignedShort();
diff --git a/src/org/traccar/protocol/KhdProtocolDecoder.java b/src/org/traccar/protocol/KhdProtocolDecoder.java
index bf1f5deea..e9d43798c 100644
--- a/src/org/traccar/protocol/KhdProtocolDecoder.java
+++ b/src/org/traccar/protocol/KhdProtocolDecoder.java
@@ -26,6 +26,7 @@ import org.jboss.netty.channel.ChannelHandlerContext;
 import org.traccar.BaseProtocolDecoder;
 import org.traccar.helper.ChannelBufferTools;
 import org.traccar.helper.Crc;
+import org.traccar.helper.UnitsConverter;
 import org.traccar.model.Event;
 import org.traccar.model.Position;
 
@@ -95,7 +96,7 @@ public class KhdProtocolDecoder extends BaseProtocolDecoder {
             // Location
             position.setLatitude(ChannelBufferTools.readCoordinate(buf));
             position.setLongitude(ChannelBufferTools.readCoordinate(buf));
-            position.setSpeed(ChannelBufferTools.readHexInteger(buf, 4) * 0.539957);
+            position.setSpeed(UnitsConverter.knotsFromKph(ChannelBufferTools.readHexInteger(buf, 4)));
             position.setCourse(ChannelBufferTools.readHexInteger(buf, 4));
 
             // Flags
diff --git a/src/org/traccar/protocol/MeitrackProtocolDecoder.java b/src/org/traccar/protocol/MeitrackProtocolDecoder.java
index 8bfd21145..3d6eb2a78 100644
--- a/src/org/traccar/protocol/MeitrackProtocolDecoder.java
+++ b/src/org/traccar/protocol/MeitrackProtocolDecoder.java
@@ -30,6 +30,7 @@ import org.jboss.netty.channel.ChannelHandlerContext;
 
 import org.traccar.BaseProtocolDecoder;
 import org.traccar.helper.ChannelBufferTools;
+import org.traccar.helper.UnitsConverter;
 import org.traccar.model.Event;
 import org.traccar.model.Position;
 
@@ -122,7 +123,7 @@ public class MeitrackProtocolDecoder extends BaseProtocolDecoder {
         position.set(Event.KEY_GSM, parser.group(index++));
 
         // Speed
-        position.setSpeed(Double.valueOf(parser.group(index++)) * 0.539957);
+        position.setSpeed(UnitsConverter.knotsFromKph(Double.valueOf(parser.group(index++))));
 
         // Course
         position.setCourse(Double.valueOf(parser.group(index++)));
@@ -215,7 +216,7 @@ public class MeitrackProtocolDecoder extends BaseProtocolDecoder {
             position.set(Event.KEY_GSM, buf.readUnsignedByte());
 
             // Speed
-            position.setSpeed(buf.readUnsignedShort() * 0.539957);
+            position.setSpeed(UnitsConverter.knotsFromKph(buf.readUnsignedShort()));
 
             // Course
             position.setCourse(buf.readUnsignedShort());
diff --git a/src/org/traccar/protocol/NavigilProtocolDecoder.java b/src/org/traccar/protocol/NavigilProtocolDecoder.java
index a51acf3fe..0a2e8ce44 100644
--- a/src/org/traccar/protocol/NavigilProtocolDecoder.java
+++ b/src/org/traccar/protocol/NavigilProtocolDecoder.java
@@ -25,6 +25,7 @@ import org.jboss.netty.channel.ChannelHandlerContext;
 
 import org.traccar.BaseProtocolDecoder;
 import org.traccar.helper.Crc;
+import org.traccar.helper.UnitsConverter;
 import org.traccar.model.Event;
 import org.traccar.model.Position;
 
@@ -161,8 +162,8 @@ public class NavigilProtocolDecoder extends BaseProtocolDecoder {
         position.setLatitude(buf.readMedium() * 0.00002);
         position.setLongitude(buf.readMedium() * 0.00002);
         
-        position.setSpeed(buf.readUnsignedByte() * 0.539957);
-        position.setCourse(buf.readUnsignedByte() * 2.0);
+        position.setSpeed(UnitsConverter.knotsFromKph(buf.readUnsignedByte()));
+        position.setCourse(buf.readUnsignedByte() * 2);
         
         short flags = buf.readUnsignedByte();
         position.setValid((flags & 0x80) == 0x80 && (flags & 0x40) == 0x40);
@@ -184,7 +185,7 @@ public class NavigilProtocolDecoder extends BaseProtocolDecoder {
         
         buf.readUnsignedByte(); // report trigger
 
-        position.setSpeed(buf.readUnsignedByte() * 0.539957);
+        position.setSpeed(UnitsConverter.knotsFromKph(buf.readUnsignedByte()));
         
         short flags = buf.readUnsignedByte();
         position.setValid((flags & 0x80) == 0x80 && (flags & 0x40) == 0x40);
@@ -251,7 +252,7 @@ public class NavigilProtocolDecoder extends BaseProtocolDecoder {
         position.setLatitude(buf.readInt() * 0.0000001);
         position.setLongitude(buf.readInt() * 0.0000001);
         
-        position.setSpeed(buf.readUnsignedByte() * 0.539957);
+        position.setSpeed(UnitsConverter.knotsFromKph(buf.readUnsignedByte()));
         position.setCourse(buf.readUnsignedByte() * 2.0);
 
         buf.readUnsignedByte(); // satellites in fix
diff --git a/src/org/traccar/protocol/RuptelaProtocolDecoder.java b/src/org/traccar/protocol/RuptelaProtocolDecoder.java
index d14fc6d15..833285ca3 100644
--- a/src/org/traccar/protocol/RuptelaProtocolDecoder.java
+++ b/src/org/traccar/protocol/RuptelaProtocolDecoder.java
@@ -25,6 +25,7 @@ import org.jboss.netty.channel.Channel;
 import org.jboss.netty.channel.ChannelHandlerContext;
 
 import org.traccar.BaseProtocolDecoder;
+import org.traccar.helper.UnitsConverter;
 import org.traccar.model.Event;
 import org.traccar.model.Position;
 
@@ -80,7 +81,7 @@ public class RuptelaProtocolDecoder extends BaseProtocolDecoder {
                 position.set(Event.KEY_SATELLITES, satellites);
                 position.setValid(satellites >= 3);
 
-                position.setSpeed(buf.readUnsignedShort() * 0.539957);
+                position.setSpeed(UnitsConverter.knotsFromKph(buf.readUnsignedShort()));
 
                 position.set(Event.KEY_HDOP, buf.readUnsignedByte() / 10.0);
 
diff --git a/src/org/traccar/protocol/SuntechProtocolDecoder.java b/src/org/traccar/protocol/SuntechProtocolDecoder.java
index dc1f2f274..f21f6e0a0 100644
--- a/src/org/traccar/protocol/SuntechProtocolDecoder.java
+++ b/src/org/traccar/protocol/SuntechProtocolDecoder.java
@@ -24,6 +24,7 @@ import org.jboss.netty.channel.Channel;
 import org.jboss.netty.channel.ChannelHandlerContext;
 
 import org.traccar.BaseProtocolDecoder;
+import org.traccar.helper.UnitsConverter;
 import org.traccar.model.Event;
 import org.traccar.model.Position;
 
@@ -95,7 +96,7 @@ public class SuntechProtocolDecoder extends BaseProtocolDecoder {
         position.setValid(true); // wrong?
 
         // Speed
-        position.setSpeed(Double.valueOf(parser.group(index++)) * 0.539957);
+        position.setSpeed(UnitsConverter.knotsFromKph(Double.valueOf(parser.group(index++))));
 
         // Course
         position.setCourse(Double.valueOf(parser.group(index++)));
diff --git a/src/org/traccar/protocol/SyrusProtocolDecoder.java b/src/org/traccar/protocol/SyrusProtocolDecoder.java
index 8a12b5e26..5959715d9 100644
--- a/src/org/traccar/protocol/SyrusProtocolDecoder.java
+++ b/src/org/traccar/protocol/SyrusProtocolDecoder.java
@@ -25,6 +25,7 @@ import org.jboss.netty.channel.Channel;
 import org.jboss.netty.channel.ChannelHandlerContext;
 
 import org.traccar.BaseProtocolDecoder;
+import org.traccar.helper.UnitsConverter;
 import org.traccar.model.Event;
 import org.traccar.model.Position;
 
@@ -154,7 +155,7 @@ public class SyrusProtocolDecoder extends BaseProtocolDecoder {
         position.setLongitude(Double.valueOf(longitude));
         
         // Speed and Course
-        position.setSpeed(Double.valueOf(parser.group(index++)) * 0.868976);
+        position.setSpeed(UnitsConverter.knotsFromMph(Double.valueOf(parser.group(index++))));
         position.setCourse(Double.valueOf(parser.group(index++)));
         
         // Validity
diff --git a/src/org/traccar/protocol/TeltonikaProtocolDecoder.java b/src/org/traccar/protocol/TeltonikaProtocolDecoder.java
index d2f77549c..d3e946f69 100644
--- a/src/org/traccar/protocol/TeltonikaProtocolDecoder.java
+++ b/src/org/traccar/protocol/TeltonikaProtocolDecoder.java
@@ -26,6 +26,7 @@ import org.jboss.netty.channel.Channel;
 import org.jboss.netty.channel.ChannelHandlerContext;
 
 import org.traccar.BaseProtocolDecoder;
+import org.traccar.helper.UnitsConverter;
 import org.traccar.model.Event;
 import org.traccar.model.Position;
 
@@ -106,7 +107,7 @@ public class TeltonikaProtocolDecoder extends BaseProtocolDecoder {
                 }
                 
                 if (checkBit(locationMask, 3)) {
-                    position.setSpeed(buf.readUnsignedByte() * 0.539957);
+                    position.setSpeed(UnitsConverter.knotsFromKph(buf.readUnsignedByte()));
                 }
                 
                 if (checkBit(locationMask, 4)) {
@@ -144,7 +145,7 @@ public class TeltonikaProtocolDecoder extends BaseProtocolDecoder {
 
                 position.setValid(satellites != 0);
 
-                position.setSpeed(buf.readUnsignedShort() * 0.539957);
+                position.setSpeed(UnitsConverter.knotsFromKph(buf.readUnsignedShort()));
 
                 position.set(Event.KEY_EVENT, buf.readUnsignedByte());
 
diff --git a/src/org/traccar/protocol/Tk103ProtocolDecoder.java b/src/org/traccar/protocol/Tk103ProtocolDecoder.java
index 81481ced8..e51f8dea5 100644
--- a/src/org/traccar/protocol/Tk103ProtocolDecoder.java
+++ b/src/org/traccar/protocol/Tk103ProtocolDecoder.java
@@ -24,6 +24,7 @@ import org.jboss.netty.channel.Channel;
 import org.jboss.netty.channel.ChannelHandlerContext;
 
 import org.traccar.BaseProtocolDecoder;
+import org.traccar.helper.UnitsConverter;
 import org.traccar.model.Event;
 import org.traccar.model.Position;
 
@@ -120,7 +121,7 @@ public class Tk103ProtocolDecoder extends BaseProtocolDecoder {
         position.setLongitude(longitude);
 
         // Speed
-        position.setSpeed(Double.valueOf(parser.group(index++)) * 0.539957);
+        position.setSpeed(UnitsConverter.knotsFromKph(Double.valueOf(parser.group(index++))));
 
         // Time
         time.set(Calendar.HOUR_OF_DAY, Integer.valueOf(parser.group(index++)));
diff --git a/src/org/traccar/protocol/Tr20ProtocolDecoder.java b/src/org/traccar/protocol/Tr20ProtocolDecoder.java
index cd0bde746..048f510b4 100644
--- a/src/org/traccar/protocol/Tr20ProtocolDecoder.java
+++ b/src/org/traccar/protocol/Tr20ProtocolDecoder.java
@@ -24,6 +24,7 @@ import org.jboss.netty.channel.Channel;
 import org.jboss.netty.channel.ChannelHandlerContext;
 
 import org.traccar.BaseProtocolDecoder;
+import org.traccar.helper.UnitsConverter;
 import org.traccar.model.Event;
 import org.traccar.model.Position;
 
@@ -116,7 +117,7 @@ public class Tr20ProtocolDecoder extends BaseProtocolDecoder {
             position.setLongitude(longitude * hemisphere);
 
             // Speed
-            position.setSpeed(Double.valueOf(parser.group(index++)) * 0.539957);
+            position.setSpeed(UnitsConverter.knotsFromKph(Double.valueOf(parser.group(index++))));
 
             // Course
             position.setCourse(Double.valueOf(parser.group(index++)));
diff --git a/src/org/traccar/protocol/TramigoProtocolDecoder.java b/src/org/traccar/protocol/TramigoProtocolDecoder.java
index b578efb4a..38b343ad9 100644
--- a/src/org/traccar/protocol/TramigoProtocolDecoder.java
+++ b/src/org/traccar/protocol/TramigoProtocolDecoder.java
@@ -20,6 +20,7 @@ import org.jboss.netty.buffer.ChannelBuffers;
 import org.jboss.netty.channel.Channel;
 import org.jboss.netty.channel.ChannelHandlerContext;
 import org.traccar.BaseProtocolDecoder;
+import org.traccar.helper.UnitsConverter;
 import org.traccar.model.Event;
 import org.traccar.model.Position;
 
@@ -120,7 +121,7 @@ public class TramigoProtocolDecoder extends BaseProtocolDecoder {
             pattern = Pattern.compile("([NSWE]{1,2}) with speed (\\d+) km/h");
             matcher = pattern.matcher(sentence);
             if (matcher.find()) {
-                position.setSpeed(Double.valueOf(matcher.group(2)) * 0.539957);
+                position.setSpeed(UnitsConverter.knotsFromKph(Double.valueOf(matcher.group(2))));
                 position.setCourse(0); // matcher.group(1) for course
             }
 
diff --git a/src/org/traccar/protocol/TytanProtocolDecoder.java b/src/org/traccar/protocol/TytanProtocolDecoder.java
index 5e48c2813..3ef0e11b7 100644
--- a/src/org/traccar/protocol/TytanProtocolDecoder.java
+++ b/src/org/traccar/protocol/TytanProtocolDecoder.java
@@ -25,6 +25,7 @@ import org.jboss.netty.channel.Channel;
 import org.jboss.netty.channel.ChannelHandlerContext;
 import org.traccar.BaseProtocolDecoder;
 import org.traccar.helper.ChannelBufferTools;
+import org.traccar.helper.UnitsConverter;
 import org.traccar.model.Event;
 import org.traccar.model.Position;
 
@@ -92,7 +93,7 @@ public class TytanProtocolDecoder extends BaseProtocolDecoder {
             // Speed
             int speed = buf.readUnsignedByte();
             if (speed < 250) {
-                position.setSpeed(speed * 0.539957);
+                position.setSpeed(UnitsConverter.knotsFromKph(speed));
             }
             
             while (buf.readerIndex() < end) {
diff --git a/src/org/traccar/protocol/UlbotechProtocolDecoder.java b/src/org/traccar/protocol/UlbotechProtocolDecoder.java
index af61b0b6e..3ec50b3fc 100644
--- a/src/org/traccar/protocol/UlbotechProtocolDecoder.java
+++ b/src/org/traccar/protocol/UlbotechProtocolDecoder.java
@@ -20,6 +20,7 @@ import org.jboss.netty.channel.Channel;
 import org.jboss.netty.channel.ChannelHandlerContext;
 import org.traccar.BaseProtocolDecoder;
 import org.traccar.helper.ChannelBufferTools;
+import org.traccar.helper.UnitsConverter;
 import org.traccar.model.Event;
 import org.traccar.model.Position;
 
@@ -84,7 +85,7 @@ public class UlbotechProtocolDecoder extends BaseProtocolDecoder {
                     position.setValid(true);
                     position.setLatitude(buf.readInt() / 1000000.0);
                     position.setLongitude(buf.readInt() / 1000000.0);
-                    position.setSpeed(buf.readUnsignedShort() * 0.539957);
+                    position.setSpeed(UnitsConverter.knotsFromKph(buf.readUnsignedShort()));
                     position.setCourse(buf.readUnsignedShort());
                     position.set(Event.KEY_HDOP, buf.readUnsignedShort());
                     break;
diff --git a/src/org/traccar/protocol/VisiontekProtocolDecoder.java b/src/org/traccar/protocol/VisiontekProtocolDecoder.java
index aeabed039..2fe58e5be 100644
--- a/src/org/traccar/protocol/VisiontekProtocolDecoder.java
+++ b/src/org/traccar/protocol/VisiontekProtocolDecoder.java
@@ -24,6 +24,7 @@ import org.jboss.netty.channel.Channel;
 import org.jboss.netty.channel.ChannelHandlerContext;
 
 import org.traccar.BaseProtocolDecoder;
+import org.traccar.helper.UnitsConverter;
 import org.traccar.model.Event;
 import org.traccar.model.Position;
 
@@ -107,7 +108,7 @@ public class VisiontekProtocolDecoder extends BaseProtocolDecoder {
         position.setLongitude(longitude);
 
         // Speed
-        position.setSpeed(Double.valueOf(parser.group(index++)) * 0.539957);
+        position.setSpeed(UnitsConverter.knotsFromKph(Double.valueOf(parser.group(index++))));
 
         // Course
         position.setCourse(Double.valueOf(parser.group(index++)));
diff --git a/src/org/traccar/protocol/WialonProtocolDecoder.java b/src/org/traccar/protocol/WialonProtocolDecoder.java
index 5638c2dbe..423f614bc 100644
--- a/src/org/traccar/protocol/WialonProtocolDecoder.java
+++ b/src/org/traccar/protocol/WialonProtocolDecoder.java
@@ -26,6 +26,7 @@ import org.jboss.netty.channel.Channel;
 import org.jboss.netty.channel.ChannelHandlerContext;
 
 import org.traccar.BaseProtocolDecoder;
+import org.traccar.helper.UnitsConverter;
 import org.traccar.model.Event;
 import org.traccar.model.Position;
 
@@ -107,7 +108,7 @@ public class WialonProtocolDecoder extends BaseProtocolDecoder {
         // Speed
         String speed = parser.group(index++);
         if (speed != null) {
-            position.setSpeed(Double.valueOf(speed) * 0.539957);
+            position.setSpeed(UnitsConverter.knotsFromKph(Double.valueOf(speed)));
         }
 
         // Course
diff --git a/src/org/traccar/protocol/WondexProtocolDecoder.java b/src/org/traccar/protocol/WondexProtocolDecoder.java
index 556e1b2ad..0c627b07c 100644
--- a/src/org/traccar/protocol/WondexProtocolDecoder.java
+++ b/src/org/traccar/protocol/WondexProtocolDecoder.java
@@ -24,6 +24,7 @@ import org.jboss.netty.channel.Channel;
 import org.jboss.netty.channel.ChannelHandlerContext;
 
 import org.traccar.BaseProtocolDecoder;
+import org.traccar.helper.UnitsConverter;
 import org.traccar.model.Event;
 import org.traccar.model.Position;
 
@@ -88,7 +89,7 @@ public class WondexProtocolDecoder extends BaseProtocolDecoder {
         // Position data
         position.setLongitude(Double.valueOf(parser.group(index++)));
         position.setLatitude(Double.valueOf(parser.group(index++)));
-        position.setSpeed(Double.valueOf(parser.group(index++)) * 0.539957);
+        position.setSpeed(UnitsConverter.knotsFromKph(Double.valueOf(parser.group(index++))));
         position.setCourse(Double.valueOf(parser.group(index++)));
         position.setAltitude(Double.valueOf(parser.group(index++)));
 
diff --git a/src/org/traccar/protocol/XirgoProtocolDecoder.java b/src/org/traccar/protocol/XirgoProtocolDecoder.java
index 74b1bd077..7ff82a5aa 100644
--- a/src/org/traccar/protocol/XirgoProtocolDecoder.java
+++ b/src/org/traccar/protocol/XirgoProtocolDecoder.java
@@ -25,6 +25,7 @@ import org.jboss.netty.channel.Channel;
 import org.jboss.netty.channel.ChannelHandlerContext;
 
 import org.traccar.BaseProtocolDecoder;
+import org.traccar.helper.UnitsConverter;
 import org.traccar.model.Event;
 import org.traccar.model.Position;
 
@@ -95,7 +96,7 @@ public class XirgoProtocolDecoder extends BaseProtocolDecoder {
         position.setLatitude(Double.valueOf(parser.group(index++)));
         position.setLongitude(Double.valueOf(parser.group(index++)));
         position.setAltitude(Double.valueOf(parser.group(index++)));
-        position.setSpeed(Double.valueOf(parser.group(index++)) * 0.868976);
+        position.setSpeed(UnitsConverter.knotsFromMph(Double.valueOf(parser.group(index++))));
         position.setCourse(Double.valueOf(parser.group(index++)));
 
         // Additional data
diff --git a/src/org/traccar/protocol/Xt013ProtocolDecoder.java b/src/org/traccar/protocol/Xt013ProtocolDecoder.java
index 62deed0ea..37f204bb3 100644
--- a/src/org/traccar/protocol/Xt013ProtocolDecoder.java
+++ b/src/org/traccar/protocol/Xt013ProtocolDecoder.java
@@ -18,6 +18,7 @@ package org.traccar.protocol;
 import org.jboss.netty.channel.Channel;
 import org.jboss.netty.channel.ChannelHandlerContext;
 import org.traccar.BaseProtocolDecoder;
+import org.traccar.helper.UnitsConverter;
 import org.traccar.model.Event;
 import org.traccar.model.Position;
 
@@ -94,7 +95,7 @@ public class Xt013ProtocolDecoder extends BaseProtocolDecoder {
         // Location
         position.setLatitude(Double.valueOf(parser.group(index++)));
         position.setLongitude(Double.valueOf(parser.group(index++)));
-        position.setSpeed(Double.valueOf(parser.group(index++)) * 0.539957);
+        position.setSpeed(UnitsConverter.knotsFromKph(Double.valueOf(parser.group(index++))));
         position.setCourse(Double.valueOf(parser.group(index++)));
         position.setAltitude(Double.valueOf(parser.group(index++)));
         position.setValid(parser.group(index++).equals("F"));