| 摘要 |
Apparatus for detecting faults in buried conductors, a transmitter adapted to transmit electro-magnetic signals down the buried conductor; this signal is provided to increase an electro-magnetic path or corridor existing at the surface above the buried conductor. The invention also relates to a detecting means adapted to detect the electro-magnetic path or corridor, and to detect electro-magnetic patches formed in the path or corridor. These patches are located over the faults, and they are characterized by presence of an increased level of electro-magnetic energy caused by the faults. The transmitter means are adapted to transmit a composite signal comprising a carrier signal transmitted by a carrier signal means and a low frequency signal transmitted by a low frequency means. The carrier signal means comprise an RF carrier signal means and an audio tone signal means; the audio tone signal means are adapted to modulate signals transmitted by the RF carrier signal means. The low frequency signal means are adapted to modulate signals transmitted by the carrier signal means, and the low frequency signal is provided to increase the level of electro-magnetic energy present at faults of the buried conductor. The carrier signal means are adapted to operate in a trace mode to locate the position of the buried conductor under the ground, and this trace mode is characterized by a continuous signal transmitted by the carrier signal means.
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