| 摘要 |
PURPOSE:To obtain the results of measurement free from difference with individuals, by determining a phase of a vertical component of a magnetic field generated from a buried cable with synchronous detection of the vertical component by a horizontal component thereof to enhance changes in the signal output with respect to changes in the position of a detection coil. CONSTITUTION:Coils 1 and 2 are arranged at an interval of distance l with a straight line 12 paralleling the ground surface 11 as axis and a detection signal is outputted to tuning circuits 3 and 4 interlinking an alternating line of magnetic force 14 with a cable 13. Outputs of the circuits 3 and 4 are outputted to a differential amplification circuit 8 through an inversion amplifier 5 on one hand and to the circuit 8 and a synchronous signal transmitting circuit 7 through an amplifier 6 on the other. An output of the circuit 7 is inputted into a synchronous detection circuit 9, which synchronously detects inversion and non-inversion signals from the circuit 8 as DC signal to be outputted to an indicator 10. |
