| 摘要 |
PURPOSE:To surely execute hitless switching even at transient time by inhibiting the output of an asynchronous detection circuit when the judged result of a phase comparator circuit shows the coincidence of phases. CONSTITUTION:An asynchronous detection circuit 103 judges whether a signal 13 switched by a hitless switching circuit 101 and a clock 14 outputted from a PLL circuit 102 are synchronized or not and while the judged result of a phase comparator circuit 104 shows the coincidence of phases, an equipment fault signal 15 is not outputted. Therefore, since no equipment fault signal 15 is outputted even when there is phase difference between a living signal 11 and an auxiliary signal 10 or even when the living signal 11 and the auxiliary signal 10 are hourly deviated, hitless line switching can be executed by the hitless switching circuit 101 without performing switching at a receiving terminal switching circuit 105. |
