| 摘要 |
<p>A temporarily inaccessible object such as a locator in a buried pipe has a first transmitter (1) which produces an electromagnetic field rotating about a horizontal axis (A-A) and a second transmitter (7) which produces a solenoidal field centred on that axis. The rotating field is remotely detected at a receiver using a vertical axis coil (6) which locates the object and a reference signal is obtained by a horizontal coil (9) at the receiver. The roll α of the object may be determined by detecting the phase difference between the detected signal and the reference signal. The yaw or angle β of departure from a desired horizontal direction is obtained from a maximum output of the horizontal receiver coil (9). With a third transmitter (15) producing another phase related field rotating about a horizontal axis transverse to the first one (A-A) a similar technique at the receiver gives the pitch angle η. The position and orientation of the object may be determined in all six degrees of freedom using a portable detector/receiver.</p> |
