Claims
- 1. An article for supplying an underground utility which may be electronically detected from above ground, comprising:
- a plurality of passive electronic markers, each having a coil of wire connected in parallel with a capacitor, forming a resonant circuit; and
- a hollow conduit member having a wall, an outer surface, and an inner surface, said markers being attached to said conduit member at predetermined intervals, said predetermined intervals forming a pattern which encodes information about the underground utility.
- 2. The article of claim 1 wherein said electronic markers are attached to said outer surface of said conduit member.
- 3. The article of claim 1 wherein said electronic markers are attached to said inner surface of said conduit member.
- 4. The article of claim 1 wherein said electronic markers are imbedded in said wall of said conduit member.
- 5. The article of claim 1 wherein said markers have longitudinal axes, said axes being oriented in a predetermined pattern.
- 6. The article of claim 1 wherein said plurality of electronic markers includes a set of first markers having a first resonant frequency, and a set of second markers having a second resonant frequency which is different from said first resonant frequency, said first and second markers being arranged along said conduit member in a predetermined order.
- 7. The article of claim 1 wherein said conduit member is constructed of a nonmetallic material.
- 8. An article for supplying natural gas underground, which may be electronically detected from above ground, comprising:
- a plurality of passive electronic markers; and
- a tubular pipe formed of polyethylene, having a wall, an outer surface, and an inner surface, said markers being imbedded in said wall at predetermined intervals, said predetermined intervals forming a pattern which encodes information about the underground utility.
- 9. The article of claim 8 wherein said electronic markers are attached to said outer surface of said pipe.
- 10. The article of claim 9 wherein said passive electronic markers include a coil of wire connected in parallel with a capacitor, forming a resonant circuit.
- 11. The article of claim 9 wherein said markers have longitudinal axes, said axes being oriented in a predetermined pattern.
- 12. The article of claim 9 wherein said plurality of passive electronic markers includes a set of first markers having a first resonant frequency, and a set of second markers having a second resonant frequency which is different from said first resonant frequency, said first and second markers being arranged along said pipe in a predetermined order.
- 13. A method of manufacturing an article for supplying an underground utility, the article being electronically locatable from above ground, comprising the steps of:
- obtaining a plurality of electronic markers;
- constructing a hollow conduit, having a wall, an inner surface, and an outer surface; and
- attaching said electronic markers to said inner surface of said conduit at predetermined intervals, said predetermined intervals forming a pattern which encodes information about the underground utility.
- 14. The method of claim 13 wherein said electronic markers are attached to said outer surface of said conduit.
- 15. The method of claim 13 wherein said electronic markers have longitudinal axes, said axes being oriented in a predetermined pattern as they are attached to said conduit.
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of U.S. patent application Ser. No. 409,523 filed Sept. 18, 1989.
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
4119908 |
Cosman et al. |
Oct 1978 |
|
4449098 |
Nakamura et al. |
May 1984 |
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4767237 |
Cosman et al. |
Aug 1988 |
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Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
409523 |
Sep 1989 |
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