| 摘要 |
<p>A transmission channel (1) has modems (11,12) and each end and operates in duplex mode. Access in the respective direction is made via couplers (5,6) which are connected to interfaces (7,8). One interface (8) contains decision circuits comprising two JK bistables whose Q outputs are applied to an exclusive OR gate (14). Input signals (OB1,2) from a fault detector are applied through the interfaces to the bistable clock inputs and by feeding back the gate output (X) and its inverse to the JK inputs a valid or invalid command signal is issued. This command signal controls operation of one of the couplers to allow transmission of signals through one or other of the interfaces (3,4).</p> |
