| 摘要 |
PURPOSE:To stop the transmission of an ineffective burst signal by allowing a digital circuit terminator at calling to decide the transmission period of a subscriber burst and a station and a digital subscriber circuit at incoming to decide it independently respectively. CONSTITUTION:A synchronizing mode switching signal MX is set to an independen synchronizing mode at calling of a subscriber's equipment and a transmission start signal is transmitted to a burst timing circuit BT of a digital line terminator DSU, then the circuit BT decides independently the transmission period of a subscriber burst signal Bs at each burst period independently and transmits it to a transmission circuit SD and a switch circuit SW. The circuit SD transmits the signal Bs to a digital subscriber circuit DLC via subscriber line SL. When a station burst signal Bo from the circuit DLC is received by the terminator DSU at incoming, a frame synchronizing circuit FS detects the arrival period of the signal Bo and transmits the signal to the circuit BT. Thus, the circuit BT decides the transmission period of the signal Bs and transmits the signal to the circuit DLC via the circuit SD. The circuit DLC decides the transmission period of the signal Bo independently at incoming and depending on the signal Bs at calling. |
