A measuring device for detecting a humidity and temperature of a surface of a glass pane facing an interior of a vehicle. The measuring device includes at least one humidity sensor and at least one temperature sensor jointly arranged on the surface of the glass pane, an evaluation unit connected downstream of the humidity and temperature sensors, and a signal conversion and linking unit arranged between the humidity and temperature sensors and the evaluation unit. Further, the converting and linking unit generates a rectangular wave-shaped signal having at least two different impulse lengths, each impulse length being a measure of a detected humidity and temperature.