Detector for detecting a buried current carrying conductor

• US 20070290672A1
• Filed: 06/20/2006
• Published: 12/20/2007
• Est. Priority Date: 06/20/2005
• Status: Active Grant

• Current Assignee: Radiodetection Limited
• Original Assignee: Radiodetection Limited
• Inventors: Thompson, Jeff, Pearson, Richard, Worsley, Robert, Royle, John Mark
• Granted Patent: US 7,403,012 B2
• Time in Patent Office: Days
• US Class Current: 324/67
• CPC Class Codes: G01V 3/081 the magnetic field is produced by the objects or geological structures characterised by the method of magnetic field measurement G01R33/00

Abstract

A detector 1 for detecting a buried current carrying conductor comprises a digital signal processor 16 and a power supply unit 25. The power supply unit 25 is a switched mode power supply which incorporates a proportional integral differential controller feedback algorithm 33 and which is managed by the digital signal processor 16. The load 31 and source 26 voltage are monitored by the digital signal processor 16 and a look-up table. 35 is used to control a pulse width modulator 27, which drives a single ended primary induction controller 29. The self-generated noise of the power supply unit 25 does not interfere with the frequency bands of detection of the detector 1.

Claims

1. A detector for detecting a buried current carrying conductor, comprising:

two magnetic sensors, each magnetic sensor converting electromagnetic radiation into a field strength signal;

a microprocessor programmed to process the field strength signals produced by the magnetic sensors, and to isolate signals of target frequency bands; and

a power supply unit for providing regulated power rails to power the detector;

wherein the microprocessor is configured to control the power supply unit so

that the power supply unit produces electromagnetic radiation of only predetermined frequencies, those frequencies being different from the target frequency bands.

2. A detector as claimed in claim 1, wherein the power supply unit is a switched mode power supply.

3. A detector as claimed in claim 2, wherein the switched mode power supply comprises a single ended primary induction controller.

4. A detector as claimed in claim 3, comprising a pulse width modulator arranged to modulate the single ended primary induction controller.

5. A detector as claimed in claim 4, configured to control the duty cycle of the pulse width modulator so that it is a function of the load drawn from the power supply unit.

6. A detector as claimed in claim 4, configured to control the duty cycle of the pulse width modulator so that it is a function of the voltage of a power source of the power supply unit.

7. A detector as claimed in claim 4, configured to control the duty cycle of the pulse width modulator so that it is a function of a load predicted by the microprocessor to be provided by the power supply unit.

8. A detector as claimed in claim 1, wherein the power supply unit comprises a proportional integral derivative feedback loop.

9. A detector as claimed in claim 1, wherein the power supply unit comprises a power source which comprises one or more batteries.

10. A detector as claimed in claim 1, wherein the microprocessor is a digital signal processor.

11. A detector as claimed in claim 3, wherein the field strength signal produced by each antenna is sampled at a sampling rate and the single ended primary induction controller is charge pumped at four times the sampling rate.

12. A detector as claims in claim 1, wherein the regulated power rails are at +12V, +3.3V and −

3.3V.

13. A detector as claimed in claim 10, wherein the digital signal processor is programmed to process signals from each magnetic sensor in two or more frequency bands simultaneously, those bands being selected from:

(i) very low frequency band;

(ii) mains electricity frequency band; and

(iii) a predetermined frequency band produced by a dedicated signal transmitter for a detector for detecting a current carrying conductor.