protected virtual void OnVTGModeChanged(MTK3339 sender, VTGModes e)
 {
     if (VTGModeChanged != null)
         VTGModeChanged(sender, e);
 }
        private void ParseVTGData(string[] Data)
        {
            double dTmp;

            // Course (in degrees)
            if (Data[1] != string.Empty)
            {
                dTmp = double.Parse(Data[1]);
                if (_course != dTmp)
                {
                    _course = dTmp;
                    OnCourseChanged(this, _course);
                }
            }

            // Ignore next field (reference, always T)

            // Ignore next 2 fields (needs GlobalTop Customization Service)

            // Speed (in Knots)
            if (Data[5] != string.Empty)
            {
                dTmp = double.Parse(Data[5]);
                if (_speed != dTmp)
                {
                    _speed = dTmp;
                    OnSpeedChanged(this, _speed, _speed * 1.151);
                }
            }

            // Ignore Next field (reference, always N)

            // Ignore next 2 fields (same speed but in km/hr)

            // VTG Mode
            switch (Data[9])
            {
                case "D":   // Differential
                    if (_vtgMode != VTGModes.Differential)
                    {
                        _vtgMode = VTGModes.Differential;
                        OnVTGModeChanged(this, _vtgMode);
                    }
                    break;
                case "E":   // Estimated
                    if (_vtgMode != VTGModes.Estimated)
                    {
                        _vtgMode = VTGModes.Estimated;
                        OnVTGModeChanged(this, _vtgMode);
                    }
                    break;
                default:    // Autonomous
                    if (_vtgMode != VTGModes.Autonomous)
                    {
                        _vtgMode = VTGModes.Autonomous;
                        OnVTGModeChanged(this, _vtgMode);
                    }
                    break;
            }

        }