| 摘要 |
PROBLEM TO BE SOLVED: To provide a phase alarm circuit capable of preventing malfunction according to noise, and notifying abnormality in phase difference generated at high speed between transmitted waves by two sets of mutually switched transmitters of redundancy configuration, and to provide its alarm generating method. SOLUTION: A phase alarm circuit 8 monitors a beat signal and outputs an alarm if the signal becomes over a fixed level. The circuit comprises comparators 63 and 73 for comparing an inputted beat signal with a predetermined alarm level, and generating and outputting an alarm signal; an alarm mask 74 for conducting alarm output for the alarm signal after 1 second, for example, is past, in order to prevent malfunction due to noise etc.; a monostable multivibrator 75 inputted with the output of the comparator 73; and an OR circuit 76 for outputting a logical sum of the output of the monostable multivibrator 75 and the output of the comparator 63 to the alarm mask 74. COPYRIGHT: (C)2006,JPO&NCIPI
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