Method for Monitoring the State of a Distance Sensor Operating Based on Propagation Time Determination of Electromagnetic Waves

A method for monitoring the state of a distance sensor operating based on a propagation time determination of electromagnetic waves, wherein during a measurement process a transmission signal is generated by a control and evaluation unit of the distance sensor, and the transmission signal is partially emitted as an emission signal into a detection space of the distance sensor, wherein the transmission signal returns partially as a parasitic ringing signal to the control and evaluation unit through interaction with components of the distance sensor and is detected, the method comprising:

• during operation, in an actual state of the distance sensor, detecting an operating temperature of the distance sensor and determining an operating frequency spectrum of a ringing signal generated and detected at the operating temperature, wherein a reference frequency spectrum of a ringing signal generated and detected at a reference temperature in a good state of the distance sensor is stored in the distance sensor,
• determining an expected reference frequency spectrum from the operating temperature and the operating frequency spectrum determined at the operating temperature,
• comparing the reference frequency spectrum stored in the distance sensor with the expected reference frequency spectrum in a comparison step,
• determining a reference frequency spectrum deviation based on the comparing,
• determining a state deviation of the distance sensor from the reference frequency spectrum deviation, and
• signaling, at least indirectly, the state deviation.