Electronic key and method for operating an electronic key

An electronic key for a vehicle comprises

• a motion sensor configured to detect a movement of a transponder unit;
• and
• a microcontroller;
• wherein
• the electronic key is configured to
• upon occurrence of a triggering event, perform a first measurement with the motion sensor resulting in a first measurement value;
• compare the first measurement value with a predefined first threshold value;
• if the first measurement value is below the predefined first threshold value,
• perform a plurality of first reference measurements, resulting in a plurality of first measurement values,
• determine a first average value over the plurality of first reference measurements, and
• store the first average value in a memory of the microcontroller;
• and
• if the first measurement value equals or is above the predefined first threshold value,
• perform a plurality of second reference measurements, resulting in a plurality of second measurement values,
• determine a second average value over the plurality of second reference measurements, and
• compare the second average value with the first average value, wherein the electronic key is considered as moving if a difference between the second average value and the first average value is greater than a third threshold.