US4085360A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for determining the presence of or absence of an underground body
Assignee: Individual
•
Filing: 1976-06-14
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Granted: 1978-04-18
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Expires: 1996-06-14
Abstract
Abstract An instrument for detecting the presence or absence of a buried pipe or cable employs three or more generally vertical coil aerials which define a triangular or polygonal area on the ground. The natural or induced electromagnetic radiation from any underground pipe or cable cutting that area gives rise to phase differences at the aerials which can be discriminated. The aerial array may be adjustable, and the discrimination may be direct or involve mixing the received signals. Facility for listening to various frequencies, perhaps simultaneously, can be provided.
Inventors
- 👤 Mark Ian Howell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 04:12
CPC Classifications
G; G01; G01V; G01V3/00; G01V3/08; G01V3/10; G01V3/104
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
117 words
An instrument for determining the presence or absence of an underground body capable of radiating an electromagnetic field, such as a buried pipe or cable, comprising an array of at least three generally similarly oriented receiver antenna coils, means for mounting such coils so that their extended axes define the corners of a polygonal area on the ground, a receiver including means coupled to said coils for comparing the phases of signals produced in all the coils, and means coupled to said comparing means for giving a warning signal only when any two of the first-mentioned signals are in antiphase thereby to indicate that at least one pair of said extended axes are straddling an underground body.
Claim 2
Dependent Claim
117 words
An instrument for determining the presence or absence of an underground body capable of radiating an electromagnetic field, such as a buried pipe or cable, comprising an array of at least three generally similarly oriented receiver antenna coils, means for mounting such coils so that their extended axes define the corners of a polygonal area on the ground, a receiver including means coupled to said coils for comparing the phases of signals produced in all the coils, and means coupled to said comparing means for giving a warning signal only when any two of the first-mentioned signals are in antiphase thereby to indicate that at least one pair of said extended axes are straddling an underground body.
Claim 3
Dependent Claim
15 words
An instrument according to claim 1, wherein there are three coils defining a triangular area.
Claim 4
Dependent Claim
13 words
An instrument according to claim 1, wherein the coils have mutually parallel axes.
Claim 5
Dependent Claim
27 words
An instrument according to claim 1, wherein the coils are pivotally mounted so that they may be splayed outwardly relative to each other, in the downward direction.
Claim 6
Dependent Claim
21 words
An instrument according to claim 1, wherein the receiver includes a phase discriminator for comparing the outputs from all the coils.
Claim 7
Dependent Claim
34 words
An instrument according to claim 1 wherein the receiver is adapted to use one coil output as a reference signal, and to make phase comparisons between this reference signal and the other coil signals.
Claim 8
Dependent Claim
37 words
An instrument according to claim 1, wherein the receiver is adapted to combine the outputs of a plurality of coils and compare the combined output with the output from one of the coils in a phase detector.
Claim 9
Dependent Claim
17 words
An instrument according to claim 7, wherein the coil outputs are first directed through respective hi-pass/lo-pass amplifiers.
Claim 10
Dependent Claim
21 words
An instrument according to claim 1 wherein the receiver is adapted to monitor the signals from the coils at differing frequencies.
Claim 11
Dependent Claim
23 words
An instrument according to claim 9, wherein the receiver is adapted to monitor the signals from the coils at two different frequencies simultaneously.
Claim 12
Dependent Claim
16 words
An instrument as claimed in claim 1, wherein the coil signals are integrated to increase sensitivity.
Claim 13
Independent Claim
101 words
A method of determining the presence or absence of an underground body capable of radiating an electromagnetic field, such as a buried pipe or cable, comprising arranging at least three generally similarly oriented receiver antenna coils so that their extended axes define the corners of a polygonal area on the ground, comparing the phases of signals produced in all the coils, thereby to determine whether any two of said signals are in antiphase, and providing a warning signal only when any two first-mentioned said signals are in antiphase, representative of the presence of a said body directly below said polygonal area.
Claim 14
Independent Claim
101 words
A method of determining the presence or absence of an underground body capable of radiating an electromagnetic field, such as a buried pipe or cable, comprising arranging at least three generally similarly oriented receiver antenna coils so that their extended axes define the corners of a polygonal area on the ground, comparing the phases of signals produced in all the coils, thereby to determine whether any two of said signals are in antiphase, and providing a warning signal only when any two first-mentioned said signals are in antiphase, representative of the presence of a said body directly below said polygonal area.
Claim 15
Dependent Claim
28 words
A method as claimed in claim 12, wherein a generator is used in the vicinity of said site to induce AC energy in any buried pipes or cables.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-04-17 | 1981-10-17 | 1982-04-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-04-17 | 1985-10-17 | 1986-04-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-04-17 | 1989-10-17 | 1990-04-18 | $7700.00 | Window Closed / Lapsed |