Method for querying a measurement value

A method for checking a measured value, the measured value being converted to a modulation signal which influences a reflection characteristic of a sensor antenna, a signal being transmitted by a checking device, the signal being sent back with a change by the sensor antenna and the signal again being received by way of the checking device, the measured value being determined from the received changed signal, wherein a plurality of measured values are detectable by sensors and the checking device being movable past a plurality of sensor antennas, the method comprising:

• using a plurality of sensor antennas to detect a plurality of measured values of checking devices, located on a railroad line, which are part of a power supply installation of the railroad line, the checking devices each being located in a rail vehicle which moves along a track of the railroad line.