Abstract: The invention describes a novel system for measuring short distances using the propagation time of radio signals between at least one interrogation unit and a transponder, whereby a disturbance of the transponder's response signal by its own request signal is excluded by means of a highly precise delay of the request in the transponder. The delay is realized with quartz accuracy and the necessary precision in that it takes place in a digital or analog register chain, whose register clock is kept phase synchronous with the interrogation signal, that a variable delay of the interrogation signal takes place in the interrogation unit and that this delay is adjusted by one register clock period at the synchronous time preferably by means of a binary search by means of the recognizable jump of the total running time-round trip.