| 摘要 |
PCT No. PCT/GB95/01723 Sec. 371 Date Jan. 16, 1997 Sec. 102(e) Date Jan. 16, 1997 PCT Filed Jul. 21, 1995 PCT Pub. No. WO96/03664 PCT Pub. Date Feb. 8, 1996In order to identify a cable buried underground, a very low frequency voltage signal is applied to the cable and an electric field sensor is brought into proximity with the cable. The sensor thus detects the voltage signal on the cable and so identifies the cable. The sensor is unaffected by one or more additional cables carrying voltage signals, which are proximate the cable of interest, as the electric filters from such additional cables do not pass to the cable of interest. The sensor is mounted on a probe which is mounted into a bore in the soil around the cable of interest. The probes may also carry a magnetometer for detecting magnetic fields generated by low frequency alternating current signals on the cable of interest. |
