High-Q self tuning locating transmitter

• US 8,013,610 B1
• Filed: 12/20/2007
• Issued: 09/06/2011
• Est. Priority Date: 12/21/2006
• Status: Active Grant

• Current Assignee: Seektech Inc.
• Original Assignee: Seektech Inc.
• Inventors: Denaci, Edward N., Fleming, Mark F., Levin, Ryan B., Praha, Jeffrey A., Latimer, Lisa E., Soukup, Jan, Cox, David A., Merewether, Ray, Olsson, Mark S., Turgeon, Michael E., Bench, Stephen M.
• Primary Examiner(s): LeDynh; Bot L
• Application Number:
  US11/961,858
• Time in Patent Office: 1,356 Days
• Field of Search: 324/228, 324/329
• US Class Current: 324/329
• CPC Class Codes: G01V 3/10 using induction coils
• CPC Class Codes: G01V 3/101 by measuring the impedance of the search coil; by measuring features of a resonant circuit comprising the search coil measuring impedance or characteristics derived therefrom G01R27/00, e.g. quality factor G01R27/26
• CPC Class Codes: G01V 3/15 specially adapted for use during transport, e.g. by a person, vehicle or boat
• CPC Class Codes: G01V 3/165 operating with magnetic or electric fields produced or modified by the object or by the detecting device with electromagnetic waves G01V3/17
• CPC Class Codes: Y10T 24/44376 Spring or resiliently biased about pivot

Abstract

A high-Q human-portable, battery-powered self-correcting tunable resonator in a transmitter apparatus for inducing alternating currents of high quality in buried conductors to facilitate their location. The transmitter apparatus employs an FET-driven capacitive tuning circuit and a coil design that achieves high precision, high-quality transmission signals, and which is equipped with a high-voltage booster for facilitating fault-localization applications.

Claims

1. A human-portable transmitter apparatus for generating an output signal having a frequency suitable for inducing an alternating electrical current in a buried conductor, the transmitter apparatus comprising:

a User Interface (UI) for accepting operator commands;

a controller coupled to the UI for selecting a desired output signal frequency value f_R1 responsive to an operator command;

an exciter circuit coupled to the controller for generating an excitation signal having a frequency corresponding to the desired output signal frequency value f_R1;

an electrical resonator coupled to the exciter circuit and having a primary resonant frequency to value f_R, including

a conductor assembly having an aggregate inductance value L, and

a plurality of capacitors having an aggregate capacitance value C and disposed in connection with the conductor assembly to provide the primary resonant frequency value f_R; and

and adaptive tuner coupled to the controller and the electrical resonator that adjusts the number of capacitors coupled to the conductor assembly responsive to the difference between the desired output signal frequency value f_R1 and the primary resonant frequency value f_R, thereby obtaining the capacitance value C necessary to produce a high Quality Factor (Q) output signal having the desired frequency value.

2. The transmitter apparatus of claim 1 and further comprising:

a substantially non-conductive, non-magnetic case enclosing at least the majority of the transmitter apparatus elements including the electrical resonator.

3. The transmitter apparatus of claim 2 and further comprising:

at least one conductive coil in the conductor assembly defining a low-permeability core volume, wherein at least half of the transmitter apparatus elements are disposed outside of the low-permeability core volume during operation of the transmitter apparatus.

4. The transmitter apparatus of claim 3 wherein:

the transmitter apparatus elements are disposed such that the low-permeability core volume is substantially empty during operation of the transmitter apparatus.

5. The transmitter apparatus of claim 4 wherein:

the electrical resonator Quality Factor (Q) value is at least 250 during operation of the transmitter apparatus.

6. The transmitter apparatus of claim 1 and further comprising:

at least one conductive coil in the conductor assembly defining a low-permeability core volume, wherein at least half of the transmitter apparatus elements are disposed outside of the low-permeability core volume during operation of the transmitter apparatus.

7. The transmitter apparatus of claim 1 and further comprising:

in the conductor assembly, a plurality of insulated conductors twisted together to form at least one conductor.

8. The transmitter apparatus of claim 7 and further comprising:

in the conductor assembly, a Litz wire conductor.

9. The transmitter apparatus of claim 1 and further comprising:

at least one conductive coil in the conductor assembly defining a low-permeability core volume disposed about an axis of rotation; and

at least one integral support for supporting the transmitter apparatus on a flat surface in an orientation that directs the conductive coil axis of rotation into the flat surface during operation of the transmitter apparatus.

10. The transmitter apparatus of claim 1 wherein:

at least some of the plurality of capacitors are coupled in parallel, thereby reducing the Equivalent Series Resistance (ESR) of the capacitors and increasing the Quality Factor value Q.

11. The transmitter apparatus of claim 10 wherein:

the electrical resonator has a Quality Factor (Q) value of more than 250.

12. The transmitter apparatus of claim 1 and further comprising:

a High Voltage (HV) booster circuit coupled to the electrical resonator for increasing the output signal.

13. The transmitter apparatus of claim 1 and further comprising:

an Extra-Low-Frequency (ELF) exciter circuit coupled to the electronic resonator for inducing ELF currents in the buried conductor.

14. A human-portable transmitter apparatus for generating an output signal having a frequency f_R suitable for inducing an alternating electrical current in a buried conductor, the transmitter apparatus comprising:

a User Interface (UI) for accepting operator commands;

a controller coupled to the UI for selecting a desired output signal frequency value f_R1 responsive to an operator command;

an exciter circuit coupled to the controller for generating an excitation signal having a frequency corresponding to the desired output signal frequency value f_R1;

an electrical resonator coupled to the exciter circuit and having a primary resonant frequency value f_R, including

a capacitor assembly having a capacitance value C, and

a plurality of conductors having a aggregate inductance value L and disposed in connection with the capacitor assembly to provide the primary resonant frequency value f_R; and

an adaptive tuner coupled to the controller and the electrical resonator that adjusts the number of conductor turns coupled to the capacitor assembly responsive to the difference between the desired output signal frequency value f_R1 and the primary resonant frequency value f_R, thereby obtaining the inductance value L necessary to produce a high Quality Factor (Q) output signal having the desired frequency value.

15. The transmitter apparatus of claim 14 and further comprising:

a substantially non-conductive, non-magnetic case enclosing at least the majority of the transmitter apparatus elements including the electrical resonator.

16. The transmitter apparatus of claim 15 and further comprising:

at least one conductive coil in the conductor assembly defining a low-permeability core volume and having an aggregate inductance L, wherein at least half of the transmitter apparatus elements are disposed outside of the low-permeability core volume during operation of the transmitter apparatus.

17. The transmitter apparatus of claim 16 wherein:

the transmitter apparatus elements are disposed such that the low-permeability core volume is substantially empty during operation of the transmitter apparatus.

18. The transmitter apparatus of claim 17 wherein:

the electrical resonator Quality Factor (Q) value is at least 250 during operation of the transmitter apparatus.

19. The transmitter apparatus of claim 14 and further comprising:

at least one conductive coil in the conductor assembly defining a low-permeability core volume, wherein at least half of the transmitter apparatus elements are disposed outside of the low-permeability core volume during operation of the transmitter apparatus.

20. The transmitter apparatus of claim 14 and further comprising:

in the conductor assembly, a plurality of insulated conductors twisted together to form at least one conductor.

21. The transmitter apparatus of claim 20 and further comprising:

in the conductor assembly, a Litz wire conductor.

22. The transmitter apparatus of claim 14 and further comprising:

at least one conductive coil in the conductor assembly defining a low-permeability core volume disposed about an axis of rotation; and

at least one integral support for supporting the transmitter apparatus on a flat surface in an orientation that directs the conductive coil axis of rotation into the flat surface during operation of the transmitter apparatus.

23. The transmitter apparatus of claim 14 wherein:

at least some of the plurality of conductors are coupled in parallel, thereby reducing the Equivalent Series Resistance (ESR) of the conductors and increasing the Quality Factor value Q.

24. The transmitter apparatus of claim 14 and further comprising:

a High Voltage (HV) booster circuit coupled to the electrical resonator for increasing the output signal.

25. The transmitter apparatus of claim 14 and further comprising:

an Extra-Low-Frequency (ELF) exciter circuit coupled to the electronic resonator for inducing ELF currents in the buried conductor.

26. A human-portable transmitter apparatus for generating an output signal having a frequency suitable for inducing an alternating electrical current in a buried conductor, the transmitter apparatus comprising:

a User Interface (UI) for accepting operator commands;

a controller coupled to the UI for selecting a desired output signal frequency value f_R1 responsive to an operator command;

an exciter circuit coupled to the controller for generating an excitation signal having a frequency corresponding to the desired output signal frequency value f_R1;

an electrical resonator coupled to the exciter circuit and having a primary resonant frequency value f_R;

the electrical resonator including;

a conductor assembly having an aggregate inductance value L, and

a plurality of capacitors having an aggregate capacitance value C and disposed in connection with the conductor assembly to provide the primary resonant frequency value f_R,

at least one conductive coil in the conductor assembly defining a low-permeability core volume, wherein at least half of the transmitter apparatus elements are disposed outside of the low-permeability core volume during operation of the transmitter apparatus; and

a substantially non-conductive, non-magnetic case enclosing at least the majority of the transmitter apparatus elements including the electrical resonator.

27. The transmitter apparatus of claim 26 and further comprising:

an adaptive tuner coupled to the controller and the electrical resonator that adjusts the number of capacitors coupled to the conductor assembly responsive to the difference between the desired output signal frequency value f_R1 and the primary resonant frequency value f_R, thereby obtaining the capacitance value C necessary to produce a high Quality Factor (Q) signal having the desired frequency value.

28. The transmitter apparatus of claim 26 wherein:

the transmitter apparatus elements are disposed such that the low-permeability core volume is substantially empty during operation of the transmitter apparatus.

29. The transmitter apparatus of claim 26 wherein in the conductor assembly a plurality of insulated conductors twisted together to form at least one conductor.

30. The transmitter apparatus of claim 26 and further comprising:

in the conductor assembly, a Litz wire conductor.