| 摘要 |
PURPOSE:To enable the removal of a high frequency noise induced in a signal transmission cable by determining difference between signals from two search coils wound in the opposite direction. CONSTITUTION:A search coil 8 is wound in the opposite direction (in the opposite phase) to a search coil 7 and a coaxial cable 9 leading signals of the coil 7 and a coaxial cable 10 leading signals of the coil 8 are set in the same path (for example, by bundling it). If so, noise voltages the same in the potential and phase overlap signal voltages of the coaxial cables 9 and 10 while the coil 8 provides a negative signal voltage if the signal voltage of the coil 7 is positive in the potential. So, with an amplifier 11, difference is determined between input voltages from the cables 9 and 10 to obtain only a voltage indicating a high frequency magnetic field clear of a high frequency noise from an output terminal 12. |
