detecção de velocidade para um sistema de tacógrafo

System and method for detecting and storing at least speed as an information relevant for resignation for a tachograph system. to provide a tamperproof tachograph system offering a high degree of security. An arithmetic unit detects signals for determining the speed from at least two independent sensors and compares them with each other and stores a sensor-related error message if the signals deviate significantly from each other. The signals of at least three independent sensors are compared with each other in the arithmetic unit and are checked for their plausibility by excluding any signals that significantly deviate from a plurality of signals and determining the speed of the vehicle to be stored only using one or more of those signals that deviate from each other only within defined limits.