System clock supplying device and frequency shift determining method of master oscillator

摘要

A system clock supplying device having a duplex structure formed by an own system and another system configured to generate a system clock based on output of a master oscillator in an own device, the system clock supplying device includes a frequency shift measuring determining part configured to measure frequency shift between a reference clock for system synchronization supplied from an outside and a clock output from a master oscillator of the own system and configured to send a frequency shift determining result based on the measuring result to a system clock supplying device of another system; and an abnormality portion determining part configured to determine whether the frequency shift is generated in an output clock of the master oscillator of the own system, an output clock of the master oscillator of the other system or the reference clock, on the basis of a frequency shift determining result of the master oscillator of the own system obtained from the frequency shift measuring determining part of the own system and frequency shift determining result of the master oscillator of the other system obtained from the frequency shift measuring determining part of the other system.