| 摘要 |
PROBLEM TO BE SOLVED: To provide a PDS transmission system which eliminates the need for wiring between subscriber devices and can transfer an alarm to an in-office device even if a signal cannot be received normally in a subscriber device. SOLUTION: A timer part is provided and made to operate based on normal up-directional signal output timing reported from an in-office device to respective subscriber devices and even if a subscriber device becomes unable to receive the up-directional signal output timing normally from the in-office device, an alarm is transferred according to the timing clocked by the timer part.
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