public double AntennaHeight {get; set;}

{
    var newSrc = new SerialPortDeviceLocationSource();
    //Specify the COM port the device is connected to
    newSrc.ComPort = "Com3";
    newSrc.BaudRate = 4800;
    newSrc.AntennaHeight = 3;  // meters
                               //fill in other properties as needed

    var props = new DeviceLocationProperties();
    props.AccuracyThreshold = 10;   // meters

    // jump to the background thread
    //Note: Run within a QueuedTask
    //open the device
    DeviceLocationService.Instance.Open(newSrc, props);
}