| 摘要 |
PURPOSE:To prevent the generation of malfunction due to the disconnection of a signaling signal other than a momentary interruption fault within a prescribed time and to make it possible to replace a time slot by holding a multiplexed signaling signal under the multiplexed state for a prescribed time and then outputting the held signal. CONSTITUTION:A multiplexed signaling signal 10 is inputted to a RAM 1 in a signaling signal protecting circuit, delayed by a multiframe, and after replacing a time slot, read out from the RAM 1. A counter 5 counts up a reference clock 110 and the time slot conversion control information of the signal 10 is stored in a ROM 6. When a writing/reading signal 80 is '1', the information is read out by using the output 120 of the counter 5 as an address signal and the address signal is applied to the RAM 1. A counter 4 counts up a multiframe clock signal 90 and changes its outputs 30, 50 in accordance with a prescribed rule and an exclusive OR circuit 3 executes OR operation between the output 50 and the writing/reading signal 80 and a selecting circuit 2 selects the signal 50 or the output 60 of the circuit 3 and applied the selected signal to the RAM 1.
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