| 摘要 |
PURPOSE:To change signals over rapidly by the fault-period in-use/stand-by change- over system of audio in-band signals on a time-division multiprocessing system, by providing each signal with a fault detecting circuit and by using a signal from this circuit for in-use/stand-by switching. CONSTITUTION:When leads 124 and 129 are set to ''1'' and ''0'' respectively, signals proceed to maintenance operation. With switch 130, maintenance transmission channel number is assigned and a 2,400Hz digital pattern, sent out of transmitter 117 in a 128ms period, has timing adjusted by shift register 115 or 116 and is applied to receiver 110. With switch 131, a maintenance reception channel number is assigned and a signal reception state read command for a receiving channel for maintenance is supplied at intervals of 32ms to check the reception state of the above-mentioned digital pattern. Then when not greater than two pulses or not less than five pulses are detected continuously at intervals of 32ms, for example, a decision on a signal fault is made and the in-use signal is changed over to a stand- by signal. Therefore, stand-by switching of signals can be performed rapidly without external controller. |
