Abstract: A safety and test device for railway signalling systems comprising a calculating device or computer adapted to treat information signals, relating to prevailing speed and desired speed, and to activate a brake device if said treatment reveals that speed reduction is necessary. In order to control itself the computer is programmed to run through special test programs, suitably sections of the ordinary program with given start data, and at the end of each such test program generate a control word, specific for each test program and coming in a given sequence. A control unit connected between the computer and the brake device receives the control words generated by the computer and compares them with correct words stored in a memory and generates an output pulse, each time an incoming control word coincides with a correct control word stored in the memory.

Abstract: A transponder system with ensured synchronization for a railway signalling system, comprising an interrogating station, from which an interrogation signal is transmitted continuously, and a responder station which is energized in response to the interrogation signal and repeatedly retransmits a coded information reply signal to the interrogating station; synchronization is achieved, by starting each information transmission by means of a predetermined start signal generated in the interrogating station as a result of a predetermined bit sequence retransmitted from the responder station. In normal operation the bit sequence is generated immediately after the retransmission of a message or word and indicates the end of this message.

Abstract: A responder system in which incoming frequency f.sub.0 is converted to a harmonic frequency, e.g. 2f.sub.0, by means of a non-linear element, for example a diode, which is connected between capacitance and inductance in two parallel-connected series resonant circuits, one of which is closely tuned to the incoming frequency f.sub.0 while the other is closely tuned to the selected harmonic frequency. Incoming frequency f.sub.0 is fed to the interconnected ends of the two resonant circuits, whereby both resonant circuits are excited at their respective resonance frequencies, and the harmonic frequency 2f.sub.0 is radiated back via a common antenna connected to the interconnected ends of the two series resonant circuits. When transmitting binary information by means of pulses at the harmonic frequency 2f.sub.0 the retransmitted pulses can be marked in certain pulse intervals by eliminating the resonance condition in the second resonant circuit (2f.sub.

Abstract: A device for transmitting a coded information about an actual signal condition of a signalling system, in which a plurality of conductor pairs are energized from assigned a.c. power sources upon actuation of corresponding signal devices, separation transformers each having a plurality of secondary windings are connected to respective conductor pairs and signals from the secondary windings are rectified and fed to assigned inputs of a code unit.