private async void GroupedItemsPage_Loaded(object sender, RoutedEventArgs e)
    {
        try
        {
            await SampleDataSource.CreateFile();

            Debug.WriteLine("Continue");
        }
        catch (Exception ex)
        {
            var msg = new MessageDialog(ex.StackTrace);
            await msg.ShowAsync();

            throw ex.InnerException;
        }
        GlobalVars.LastFreeSignalCheckTimer.Tick    += SampleDataSource.LastFreeSignalCheckTimer_Tick;
        GlobalVars.LastFreeSignalCheckTimer.Interval = new TimeSpan(0, 0, 0, 120);
        GlobalVars.LastFreeSignalCheckTimer.Start();
    }