Electrical baro transmitters are measuring the air pressure internally via electro-mechanical components. Due to the small size these sensors are quite insensitive to mechanical effects. An integrated electronics converts the measured information into electrical signals, and delivers them. The sensors are measuring the air pressure always at station level. They, partly, have the internal possibility of calculating the reduced air pressure by means of the barometric altitude formula. For this purpose, the sensor must be informed about the station level.