Electromagnetic prospecting device and electromagnetic prospecting method

摘要

An electromagnetic prospecting apparatus (1) comprising: a transmission unit (46, 48) for generating a periodically changing magnetic field to a prospecting target; a detection unit (2, 2A) including a SQUID (20) for detecting a magnetic field generated according to the Prospecting goal is generated; anda data processing unit (3, 3A) for collecting detection results obtained by the detection unit, the detection unit comprising a feedback coil (21) for generating a magnetic field for canceling a magnetic field entering the SQUID and a feedback circuit (221, 222, 223, 224) for supplying a current corresponding to a voltage generated by the SQUID to the feedback coil, and the data processing unit is operable to generate a plurality of time-dependent data units each having a length of at least one period of the variable magnetic field; magnetic field detection data entering over a certain period of time, to determine whether or not a deviation from a reference value by an amount equal to or greater than a threshold occurs in the respective extracted time-dependent data units, a time-dependent data unit in whichthe deviation from the reference value by the amount equal to or greater than the threshold value occurs from the plurality of time-dependent data units, and output a prospecting result showing the prospecting destination based on remaining time-dependent data units, wherein a time-dependent waveform of the variable magnetic field is a pulse waveform wherein a positive direction pulse and a negative direction pulse are repeated periodically with a zero crossing therebetween, and the data processing unit determines whether or not the deviation by the amount equal to or greater than the threshold occurs based on a value before a first one Time period is obtained from a first time point at which the pulse of the positive direction starts to return to zero, and a value obtained before the first time period from a second time point at which the pulse of the negative direction starts to zero z urückzukehren.