EXFO FTB-1 - Manual (Page 64)

Setting Up Your Unit
54 FTB-1
Recalibrating the Touchscreen
Recalibrating the Touchscreen
If you notice the touchscreen does not behave in the way it used to
(for example, it is now difficult to select items) it probably needs a
recalibration.
The default calibration method is performed using nine points, but you can
also perform a 4-point, or even a 25-point calibration (linearization) if you
need more accuracy.
You can stop the calibration process at any time, but the touchscreen will
still need calibration. The parameters are taken into account only when the
process is complete.
To recalibrate the touchscreen:
1. From the Main Menu, tap System Settings.
2. If necessary, from System Settings, tap Display & Sound.