| 摘要 |
PURPOSE:To send a complete switching signal to a working stand-by switch by detecting the presence of a burst signal and deciding the fault of a transmission line. CONSTITUTION:Envelope signals inputted to input terminals 10, 11 are inputted to an exclusive OR circuit 14, and if both the waveforms are different from each other, an output is generated from the circuit 14 and inputted to AND circuits 17, 18. The input signals are inputted to the AND circuits 17, 18 through one- shot multivibrators 12, 13 and triggerable multivibrator circuits 15, 16 and their outputs are inputted to a flip-flop circut constituted of NAND circuits 19, 20 and sent from output terminals 21, 22 as switching signals. A switching signal selecting the input terminal 10 side in the initial status sends the switching signal from the terminal 22 at the generation of a fault in the transmission line on the input terminal 10 side to select the input terminal 11 side.
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