public AppForm()
        {
            InitializeComponent();

            // get serial port connection api
            SerialPortConnectionApi connectionApi = SerialPortConnectionApi.GetInstance();

            // initialize receiver and sender objects
            this.receiver = new Receiver(connectionApi);
            this.sender   = new Sender(connectionApi);

            receiverThread            = new Thread(ReceiverThreadProcedure);
            isReceiverThreadActivated = true;
            isSenderThreadActivated   = false;
            receiverThread.Start();
        }