Pipe survey method using UWB signal

• US 8,350,570 B2
• Filed: 08/29/2008
• Issued: 01/08/2013
• Est. Priority Date: 08/31/2007
• Status: Active Grant

• Current Assignee: Louisiana Tech Research Corporation
• Original Assignee: Louisiana Tech Research Foundation; A Division Of Louisiana Tech University Foundation, Inc.
• Inventors: Allouche, Erez, Jaganathan, Arun Prakash, Simicevic, Neven
• Primary Examiner(s): LEDYNH, BOT L
• Application Number:
  US12/675,480
• Publication Number:
  US 20100237871A1
• Time in Patent Office: 1,593 Days
• Field of Search: 324/334, 324/337
• US Class Current: 324/337
• CPC Class Codes: G01S 13/0209 Systems with very large relative bandwidth, i.e. larger than 10 %, e.g. baseband, pulse, carrier-free, ultrawideband
• CPC Class Codes: G01S 13/88 Radar or analogous systems specially adapted for specific applications electromagnetic prospecting or detecting of objects, e.g. near-field detection, G01V3/00
• CPC Class Codes: G01S 13/885 for ground probing prospecting or detecting using electromagnetic waves G01V3/12
• CPC Class Codes: H01Q 13/08 Radiating ends of two-conductor microwave transmission lines, e.g. of coaxial lines, of microstrip lines
• CPC Class Codes: H01Q 13/085 Slot-line radiating ends
• CPC Class Codes: H01Q 9/28 Conical, cylindrical, cage, strip, gauze, or like elements having an extended radiating surface; Elements comprising two conical surfaces having collinear axes and adjacent apices and fed by two-conductor transmission lines waveguide horns or mouths H01Q13/00; slot antennas H01Q13/00

Abstract

A method of surveying the condition of an underground enclosure including the steps of (a) positioning at least one transmitter/receiver unit (including an antenna) within an underground, substantially nonconductive enclosure, such that a substantial air gap exists between the antenna and the inner wall of the enclosure; (b) transmitting an ultra wideband (UWB) signal toward at least a portion of the inner wall; and (c) processing the return signal in order to identify the interface between the soil and a region of conductivity different from the soil.

Claims

1. A method of surveying the condition of an underground enclosure comprising:

a. positioning at least one transmitter/receiver unit, including an antenna, within an underground, substantially nonconductive enclosure, such that a substantial air gap exists between said antenna and an inner wall of said enclosure;

b. transmitting a UWB signal toward at least a portion of an inner wall of said enclosure; and

c. processing a return signal from said transmitted signal in order to identify at least one interface between soil and a region having different electrical properties from said soil.

2. The enclosure survey method of claim 1, wherein said nonconductive enclosure comprises an underground conduit.

3. The enclosure survey method of claim 2, wherein said interface is at least one of a soil/conduit interface, a void/soil interface, a soil/boulder interface, or a soil/external pipe interface.

4. The enclosure survey method of claim 3, wherein the frequency of said UWB signal is between about 3 GHz and about 10 GHz.

5. The enclosure survey method of claim 4, further comprising transmitting a second UWB signal between about 20 GHz and about 30 GHz.

6. The enclosure survey method of claim 1, wherein said signal comprises a pulse duration of less than about 500 psec and between about 10³ and about 10⁵ pulses per second.

7. The enclosure survey method of claim 1, further comprising transmitting a first signal with a pulse duration between about 500 psec and about 100 psec and transmitting a second signal with a pulse duration of less than about 100 psec.

8. The enclosure survey method of claim 1, further comprising an antenna which rotates through an arc of at least 120°

.

9. The enclosure survey method of claim 8, wherein said antenna rotates through an arc of 360°

.

10. The enclosure survey method of claim 1, wherein said antenna is a directional antenna.

11. The enclosure survey method of claim 1, further comprising a transmitting antenna and a separate receiving antenna.

12. The enclosure survey method of claim 1, wherein a distance between a receiver antenna and at least one of a void/enclosure interface, a soil/enclosure interface or a soil/void interface is identified by a signal reflection generated by a change in conductivity of the transmission medium at said interfaces.

13. The enclosure survey method of claim 1, wherein said transmitter/receiver unit is capable of transmitting more than one signal at differing pulse durations.

14. The enclosure survey method of claim 13, wherein said transmitter/receiver unit has multiple signal generators.

15. The enclosure survey method of claim 13, wherein said transmitter/receiver unit has at least one tunable signal generator.

16. The enclosure survey method of claim 1, further comprising an antenna which is fixed against rotation.

17. The enclosure survey method of claim 1, further comprising a plurality of antennas.

18. The enclosure survey method of claim 17, wherein said plurality of antennas are discone antennas.

19. The enclosure survey method of claim 18, wherein a signal fed to each of said antennas is phase shifted from a signal fed to an adjacent antenna, thereby creating a phased array system.

20. The enclosure survey method of claim 1, wherein said signal is a time domain UWB pulsed signal.

21. The enclosure survey method of claim 20, wherein said time domain UWB pulsed signal has consecutive pulses with substantially identical wave forms.