| 摘要 |
PURPOSE:To prevent an output of a signal having a deviated frequency even with a VCO1 stopped in the in-phase state by allowing a logical circuit to turn off a switch with an input of alarm signal and transmitting alarm at the same time. CONSTITUTION:Each output of frequency dividers 2, 4 is inputted to phase comparators 5, 6, a phase error voltage is formed and fed to a logical circuit 11. A part of an output signal of the VCO1 is fed to an output pulse detector 9 and when the detection level is less than the operating level of a frequency divider 2, an alarm signal is fed to the circuit 11. Similarly, when an output level of an output pulse detector 10 receiving an output level of a reference signal generator 3 reaches an operating level of a frequency divider 4 or below, an alarm signal is fed to the circuit 11. The circuit 11 supervises three alarm signals from the detectors 9, 10 and a comparator 5, and when a signal fault exists, a switch 12 is turned off so as to stop the transmission of the output of the VCO1 and an alarm signal is transmitted from a terminal 8. |
