ANORDNING FOR ATT HOJA SEKERHETEN MOT FEL VID INFORMATIONSOVERFORING

摘要

A device is provided for protection against the presence of transmission errors in an information transmission system used in railroading. An interrogation apparatus emits a periodically variable interrogation signal within a specified frequency band consisting of successive frequency ranges. A reply apparatus selectively dampens the interrogation signal in sub-ranges of each frequency range so as to provide a frequency-selectively reflected interrogation signal which has power penetrations in the respective sub-ranges. The first switching member is provided to produce a first impulse sequence whose impulses lie centrally at the border of the sub-ranges. A comparator then determines whether the center of the power penetration lies within one of the sub-range border impulses. If such is the case, an interference signal is activated. Similarly a second switching member is provided which produces a second impulse sequence having impulses wider than those of the first impulse sequence. When the center of a power penetration lies within one of the impulses of the second impulse sequence, an alert signal is activated.