Method and apparatus for monitoring the relative position of a cable boring head during a boring operation

• US 5,994,904 A
• Filed: 09/29/1997
• Issued: 11/30/1999
• Est. Priority Date: 09/29/1997
• Status: Expired due to Term

• Current Assignee: AT&T Corporation (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Huffman, John Sinclair, Eslambolchi, Hossein
• Primary Examiner(s): PATIDAR, JAY M
• Application Number:
  US08/939,141
• Time in Patent Office: 792 Days
• Field of Search: 324/326, 324/66, 324/67, 324/228, 324/232, 324/327, 324/329, 324/541, 324/543, 324/544, 175/40, 175/45, 175/50, 175/62
• US Class Current: 324/326
• CPC Class Codes: E21B 47/0232 at least one of the energy sources or one of the detectors being located on or above the ground surface
• CPC Class Codes: E21B 47/024 of devices in the borehole determining slope or direction of the borehole E21B47/022
• CPC Class Codes: E21B 47/09 Locating or determining the position of objects in boreholes or wells , e.g. the position of an extending arm; Identifying the free or blocked portions of pipes
• CPC Class Codes: G01V 3/20 operating with propagation of electric current

Abstract

To more accurately detect the position of a boring head (16) relative to a utility conveyance (22) during a boring operation, the conveyance carries a low power, pulsed signal. The signal is detectable only with a limited distance from the conveyance corresponding to a minimum allowable distance between the boring head and the conveyance. The boring head (16) carries at least one detector (28) for detecting the signal radiated by the cable. If the detector (28) detects the signal, then the boring head is too close and boring operation is interrupted.

Claims

1. A method for accurately monitoring the position of a boring head relative to a buried utility conveyance during a boring operation in the vicinity of the conveyance, comprising the steps of:

impressing on the conveyance a pulsed, lower power signal whose pulse pattern is unique to an owner of the conveyance;

the signal being detectable within a limited distance from the conveyance corresponding to a minimum allowable distance between the boring head and the conveyance;

detecting, via at least one detector carried by the boring head, whether the signal is present; and

interrupting movement of the boring head upon detection of the signal.

2. The method according to claim 1 wherein the detecting step includes the steps of:

measuring how strong the pulsed signal is; and

providing an indication of the signal strength.

3. The method according to claim 2 wherein visual indication of the signal strength is provided.

4. The method according to claim 1 wherein a aural indication of the signal strength is provided.

5. The method according to claim 1 further including the step of generating a warning when the boring head becomes too close to the conveyance.

6. The method according to claim 5 wherein the warning is generated aurally.

7. The method according to claim 5 wherein the warning is generated visually.

8. Apparatus for more accurately determining the position of a boring head relative to an existing buried utility conveyance during a boring operation in the vicinity of the conveyance, comprising:

means for impressing a pulsed, low-power, low frequency signal on the buried utility conveyance whose pulse pattern is unique to an owner of the conveyance such that the signal radiates a limited distance from the conveyance corresponding to a minimum allowable distance between the boring head and the conveyance;

means carried by the boring head for detecting if the signal is present; and

means associated with the detector for determining how strong the signal is to determine whether the boring head is to close to the buried conveyance.

9. The apparatus according to claim 8 wherein the signal impressed on the utility conveyance is a 32-bit signal.

10. The apparatus according to claim 8 wherein the detecting means comprises a magnetometer.

11. The apparatus according to claim 8 wherein the signal strength determining means provides a visual indication of the signal strength.

12. The apparatus according to claim 8 wherein the signal strength determining means provides an aural indication of the signal strength.

13. The apparatus according to claim 8 further including means for generating a warning when the boring head becomes too close to the utility conveyance.

14. The apparatus according to claim 13 wherein the warning generating means provides an aural warning.

15. The apparatus according to claim 13 wherein the warning generating means provides a visual warning.