| 摘要 |
PROBLEM TO BE SOLVED: To prevent a misdetection during surveying an embedded pipe position from the ground surface by sending a current of transmission signal to the embedded pipe and detecting the magnetic field generated by the current flowing in the embedded pipe with a receiver on the ground. SOLUTION: An embedded pipe surveying device surveys embedded pipe position by detecting a magnetic field generated by a transmission current f0 sent in the embedded pipe 1 and flowing in the embedded pipe 1 with a receiver (1). By overlapping signals fHz and 2fHz, consisting of two different frequencies from the transmission signal f0 on the transmission signal f0 sent in the embedded pipe, whether in-phase or reversed phase from the transmission signal f0 is determined from the waveform of the magnetic field of the two different frequencies detected with the receiver (2). By differentiating combined wave of the signals fHz and 2fHz of two frequencies which differ from the transmission signal detected with the receiver, whether in-phase or reversed phase from the transmission signal f0 is determined. |
