| 摘要 |
PROBLEM TO BE SOLVED: To provide a feeble earth-current detection method and a system therefor capable of contributing to the highly accurate detection of earthquake earth current which is a premonitory phenomenon of an earthquake by detecting a feeble earth current with high sensitivity, or to the quantitative obtainment of the electromagnetic environment. SOLUTION: Polarization fluctuation caused by a current flowing in an overhead ground wire 14 of an optical signal transmitted through an optical fiber 23 stored in the overhead ground wire 14 of a power transmission line is converted into an electrical signal by a polarization detecting part 24, and a signal showing the feeble earth-current is separated from other noise by an ultra-long wave band ELF component measuring part 26 from an output signal from the polarization detecting part 24. By this, the feeble earth-current is measured with high accuracy by utilizing the fact that the polarization fluctuation of the optical signal transmitted through the optical fiber 23 is changed by the earth current flowing in the overhead ground wire 23. COPYRIGHT: (C)2011,JPO&INPIT |
