| 摘要 |
PROBLEM TO BE SOLVED: To immediately detect a frequency deviation and to realize a rapid alarm detection by inputting a signal having the frequency deflection and carrying out a serial/parallel conversion. SOLUTION: When a clock signal having a frequency deviation is inputted to a circuit, the signal is branched to monitor it and the signal is inputted to a serial/parallel conversion circuit 1. In the serial/parallel conversion circuit 1, a signal of a frequency divider 3 is inputted for sampling of the signal. Then, the signal is converted into a digital signal of N bit matching to the frequency of the clock signal monitored. A parallel signal value of N bit is previously confirmed when a permissible defined value of the frequency deviation is inputted to the serial/parallel conversion circuit 1. If a circuit is designed so as to output an alarm signal when the signal of N bit is inputted to the circuit, for example, the alarm signal is outputted in the case where the clock signal is varied by a center frequency±100 Hz.
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