| 摘要 |
PURPOSE:To prevent an unnecessary alarm signal generated in an opposite station at the changeover of an active and a spare device for the purpose of maintenance, etc. by synchronizing with all test signal generating circuits of a digital sound inserting device. CONSTITUTION:The test signal generating circuits 4a-4c decide a sequence for transmitting a test signal by the counted phase of a counter counting a pulse of a clock generator generating pulses of the identical frequency. An output pulse of a synchronizing signal generating circuit 10 resets simultaneously counters in the circuits 4a-4c to bring the sequence for transmitting the test signal of the circuits 4a-4c into the identical phase. The disturbance of sequence for transmitting the test signal is not generated by the changeover of a transmission output selecting circuit 5 in this way. Accordingly, making the opposite station generate an unnecessary alarm signal is prevented. |
