Detector for Calculating the Depth of a Buried Conductor

• US 20100001714A1
• Filed: 03/02/2009
• Published: 01/07/2010
• Est. Priority Date: 03/03/2008
• Status: Active Grant

• Current Assignee: Radiodetection Limited
• Original Assignee: Radiodetection Limited
• Inventors: Royle, John Mark
• Granted Patent: US 8,125,210 B2
• Time in Patent Office: Days
• US Class Current: 324/67
• CPC Class Codes: G01V 3/08 operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices with electromagnetic waves G01V3/12

Abstract

A detector for calculating a depth of a buried conductor comprises a plurality of antennas B, M T for detecting an electromagnetic field radiated by the conductor and means for calculating the depth of said conductor based on the field detected by the antennas B, M, T. The calculated depth of the conductor is displayed when one or more predetermined criteria are satisfied.

Claims

1. A detector for calculating a depth of a buried conductor, the detector comprising:

a plurality of antennas for detecting an electromagnetic field radiated by said conductor;

means for calculating the depth of said conductor based on the field detected by the antennas; and

means for displaying the calculated depth of said conductor,

wherein the detector is configured such that the calculated depth is displayed on means for displaying the calculated depth when one or more predetermined criteria are satisfied.

2. A detector as claimed in claim 1, further comprising means for calculating an angle φ

between the vertical and a line joining said conductor to the detector, wherein a predetermined criterion is the angle φ

is within ±

10°

.

3. A detector as claimed in claim 1, further comprising means for calculating an angle φ

between an axis of said conductor and a plane perpendicular to an axis of the antennas, wherein a predetermined criterion is the angle φ

is within ±

10′

.

4. A detector as claimed in claim 1, further comprising means for calculating the second derivative of the phase of the electromagnetic fields detected at the antennas, wherein a predetermined criterion is the second derivative of the phase is less than 0.5°

/s².

5. A detector as claimed in claim 1, further comprising means for calculating the standard deviation of the depth calculation referred to a 10 Hz bandwidth, wherein a predetermined criterion is the standard deviation of the depth calculation should be less than 5%.

6. A detector as claimed in claim 1, further comprising an analogue to digital converter, ADC, having a dynamic range for digitising signals output from the antennas, wherein a predetermined criterion is the signals input to the ADC are within the dynamic range of the ADC.

7. A detector as claimed in claim 1, further comprising means for calculating a first derivative of a magnitude of the field detected at the antennas, wherein a predetermined criterion is the first derivative of the magnitude of the field detected at the antennas is less than 5% of the signal/s.

8. A detector as claimed in claim 1, further comprising means for calculating phase correlation across the antennas, wherein a predetermined criterion is the phase difference between the antennas is less than 5°

.

9. A method of calculating a depth of a buried conductor, the method comprising:

providing a plurality of antennas for detecting an electromagnetic field radiated by said conductor;

calculating the depth of said conductor based on the field detected by the antennas; and

providing a display device for displaying the calculated depth of said conductor,

wherein the calculated depth is displayed on the display device when one or more predetermined criteria are satisfied.

10. A method as claimed in claim 9, further comprising calculating an angle θ

between the vertical and a line joining said conductor to the detector, wherein a predetermined criterion is the angle θ

is within ±

10°

.

11. A method as claimed in claim 9, further comprising calculating an angle φ

between an axis of said conductor and a plane perpendicular to an axis of the antennas, wherein a predetermined criterion is the angle φ

is within ±

10°

.

12. A method as claimed in claim 9, further comprising calculating the second derivative of the phase of the electromagnetic fields detected at the antennas, wherein a predetermined criterion is the second derivative of the phase is less than 0.5°

/s².

13. A method as claimed in claim 9, further comprising calculating the standard deviation of the depth calculation referred to a 10 Hz bandwidth, wherein a predetermined criterion is the standard deviation of the depth calculation should be less than 5%.

14. A method as claimed in claim 9, further comprising providing an analogue to digital converter, ADC, having a dynamic range for digitising signals output from the antennas, wherein a predetermined criterion is the signals input to the ADC are within the dynamic range of the ADC.

15. A method as claimed in claim 9, further comprising calculating a first derivative of a magnitude of the field detected at the antennas, wherein a predetermined criterion is the first derivative of the magnitude of the field detected at the antennas is less than 5% of the signal/s.

16. A method as claimed in claim 9, further comprising calculating phase correlation across the antennas, wherein a predetermined criterion is the phase difference between the antennas is less than 5°

.

17. A detector for calculating a depth of a buried conductor, the detector comprising:

a plurality of antennas for detecting an electromagnetic field radiated by said conductor;

a microprocessor configured to calculate the depth of said conductor based on the field detected by the antennas; and

a display device for displaying the calculated depth of said conductor,

wherein the detector is configured such that the calculated depth is displayed on the display device when one or more predetermined criteria are satisfied.

18. A detector as claimed in claim 17, wherein the microprocessor is further configured to calculate an angle θ

between the vertical and a line joining said conductor to the detector, wherein a predetermined criterion is the angle θ

is within ±

10°

, preferably within ±

5° and

preferably within ±

2°

.

19. A detector as claimed in claim 17, wherein the microprocessor is further configured to calculate an angle φ

between an axis of said conductor and a plane perpendicular to an axis of the antennas, wherein a predetermined criterion is the angle φ

is within ±

100, preferably within ±

5° and

preferably within ±

20.

20. A detector as claimed in claim 17, wherein the microprocessor is further configured to calculate the second derivative of the phase of the electromagnetic fields detected at the antennas, wherein a predetermined criterion is the second derivative of the phase is less than 0.5/s², preferably less than 0.2/s² and preferably less than 0.1°

/s².

21. A detector as claimed in claim 17, wherein the microprocessor is further configured to calculate the standard deviation of the depth calculation referred to a 10 Hz bandwidth, wherein a predetermined criterion is the standard deviation of the depth calculation should be less than 5%, preferably less than 2% and preferably less than 1%.

22. A detector as claimed in claim 17, further comprising providing an analogue to digital converter, ADC, having a dynamic range for digitising signals output from the antennas, wherein a predetermined criterion is the signals input to the ADC are within the dynamic range of the ADC.

23. A detector as claimed in claim 17, wherein the microprocessor is further configured to calculate a first derivative of a magnitude of the field detected at the antennas, wherein a predetermined criterion is the first derivative of the magnitude of the field detected at the antennas is less than 5% of the signal/s, preferably less than 2% of the signal/s and preferably less than 1% of the signal/s.

24. A detector as claimed in claim 17, wherein the microprocessor is further configured to calculate phase correlation across the antennas, wherein a predetermined criterion is the phase difference between the antennas is less than 5°

, preferably less than 2° and

preferably less than 1°

.