Greisinger gtd 1100 precision digital altimeter barometer and thermometer greisinger gtd 1100 p the greisinger gtd 1100 is a precision digital altimeter barometer and thermometer that measures the absolute pressure of the ambient atmosphere with a resolution of 0 1mbar the gtd 1100 can be used as a reference for calibration the precision altimeter is ideal for professional use in metrology and in leisure sports it can also be used for determining the height of buildings and structures h