INDUCTION TRANSMISSION TYPE BURIED PIPE DETECTION

摘要

PURPOSE:To enable highly accurate detection of a buried pipe by a method wherein an output of a magnetic sensor is measured moving a detector horizontally and a phase direction orthogonal to the phase direction is extracted from the output to detect buried pipe depending on a size thereof. CONSTITUTION:A phase direction is measured with respect to a transmitting magnetic field 9 of a magnetic field due to the earth, and then an output of a magnetic sensor 7 is measured moving a detector 1 horizontally in a direction assumed to be that orthogonal to the buried pipe 11 on the surface of the ground at a location where the buried pipe 11 is assumed to be buried. A signal compo nent extracted from an output of the sensor 7 is a constant multiple of the sum of a magnetic field by a current induced in the buried pipe 11 and a direct transmitting magnetic field from a transmitter 2 and is free from effect of the magnetic field due to the earth. Thus, the phase direction is set on a signal processing means 8 to process an output signal of the sensor 7 thereby obtaining such a signal component.