| 摘要 |
PURPOSE:To prevent the clock step out of a low-order station, carrier reproduction step-out and frame step out by continuously changing the difference of a clock frequency accompanied by the switching of a clock from a switch circuit until the clock frequency switched by means of prescribed responsibility. CONSTITUTION:A clock continuous change circuit 116 is provided between the switching circuit 115 and a frame synchronizing signal generation circuit 113. When the reproduction of clock CLKi and a master clock CLKM are switched and the difference of the frequency between the clocks exists, the clock continuous change circuit 116 continuously changes from a side to be switched to a side to switch. The continuous change is executed within a range that step out does not occur and in such a way that it becomes shortest time. Thus, clock reproduction step out and carrier reproduction step out can be prevented and the phase of a frame synchronizing signal coincide, whereby frame step out in the low-order station can be prevented. |
