| 摘要 |
PROBLEM TO BE SOLVED: To detect the approach of a train surely for safety's sake in maintenance operations of a railroad line by installing an alarm system, adopting malfunction preventing relay circuit, in a rail. SOLUTION: Some troubles in a wave transmitter and both first and second train detection circuits are al outputted to the safety side. In a wave receiver circuit, L, C filters and a mechanical filter are inputted into an input part, and RA, Schmitt, PA, detection circuits or the like used with an active element are made into two circuits apposed, and all the troubles are outputted to the safety side as well. A pinpoint train detection circuit is one that aims at an improvement in safety by means of a high frequency generator, a magnetic sensor and respective two sets of OR circuits, and it stops the generation by an overhead approach of the train, outputting a pulse. A rail is aλ/2 cable and coarsely connected to a generator circuit of 12.5MHz, and the distributed constant is varied by the train approach, receiving the frequency modulation.
|
