This blog post is an addition to the UAV Playground project blog. It shows you how to program a very simple UAV Playground application that provides Google Earth with some KML data it receives as NMEA data from FlightGear.
[The poor formatting of the code sections is unintended]

Download
UAVplayground-KMLPorvider.zip

Source code (ProvideKML.java)

import java.applet.Applet;import jaron.flightgear.FlightGearNMEAReceiver;
import jaron.google.GoogleEarthKMLProvider; 

public class ProvideKML extends Applet {

  FlightGearNMEAReceiver receiver;

  GoogleEarthKMLProvider provider;

  public void init() {

    receiver = new FlightGearNMEAReceiver();

    provider = new GoogleEarthKMLProvider();

    receiver.addTrackpointListener(provider);

  }

}

Google Earth KML file (Start-GoogleEarth-Tracking.kml)

<?xml version="1.0" encoding="UTF-8"?><kml xmlns="http://earth.google.com/kml/2.1">  <NetworkLink>
    <name>UAV Playground Network Link</name>

    <Link>

      <href>http://127.0.0.1:8080/</href>

      <refreshMode>onInterval</refreshMode>

      <refreshInterval>2</refreshInterval>

    </Link>

  </NetworkLink>

</kml>

FlightGear startup file (Start-FlightGear-NMEA.bat)

"%PROGRAMFILES%\FlightGear\bin\Win32\fgfs" ^  "--fg-root=%PROGRAMFILES%\FlightGear\data" ^ 
 "--nmea=socket,out,0.5,127.0.0.1,5557,tcp"

Start the application
- Start the Java application as an Applet
- Start FlightGear with the above batch file
- Start Google Earth by double-clicking on the above KML file or just open the file in Google Earth

To navigate to the track In Google Earth double-click on Places -> Temporary Places -> UAV Playground Network Link -> Tracks -> GPS Tracks.