System for detecting the location and orientation of a temporarily inaccessible object
First Claim
1. A system for detecting the location and orientation of a temporarily inaccessible object, such as a boring mole or a locator unit in an underground pipeline, comprising providing that object with first means (1) for generating a rotating electromagnetic field, and detecting the presence of the object from the electromagnetic radiation by coil aerial means (6) at a receiver, characterised in that the object is further provided with second means (7) for generating a further electromagnetic field of frequency and phase related to the rotary field, and in that the receiver is further provided with means (9) for deriving from the further field a reference frequency and with means (13) for relating to that reference frequency the signal from the rotating field as received by an aerial (6) of the coil aerial means having a set orientation, the phase difference being indicative of the departure (α
- ) of the first generating means, and hence of said object, from a base orientation.
1 Assignment
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Accused Products
Abstract
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 centered 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 γ. The position and orientation of the object may be determined in all six degrees of freedom using a portable detector/receiver.
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Citations
10 Claims
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1. A system for detecting the location and orientation of a temporarily inaccessible object, such as a boring mole or a locator unit in an underground pipeline, comprising providing that object with first means (1) for generating a rotating electromagnetic field, and detecting the presence of the object from the electromagnetic radiation by coil aerial means (6) at a receiver, characterised in that the object is further provided with second means (7) for generating a further electromagnetic field of frequency and phase related to the rotary field, and in that the receiver is further provided with means (9) for deriving from the further field a reference frequency and with means (13) for relating to that reference frequency the signal from the rotating field as received by an aerial (6) of the coil aerial means having a set orientation, the phase difference being indicative of the departure (α
- ) of the first generating means, and hence of said object, from a base orientation.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
Specification