Underground pipe locating system

• US 6,252,538 B1
• Filed: 11/13/1998
• Issued: 06/26/2001
• Est. Priority Date: 01/25/1996
• Status: Expired due to Term

• Current Assignee: Emrad Limited
• Original Assignee: Emrad Limited
• Inventors: Chignell, Richard J.
• Primary Examiner(s): Sotomayor, John B.
• Application Number:
  US09/117,271
• Time in Patent Office: 956 Days
• Field of Search: 342/22, 342/27, 342/191, 342/192, 342/195, 342/25, 342/196
• US Class Current: 342/22
• 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 13/885 for ground probing prospecting or detecting using electromagnetic waves G01V3/12

Abstract

A system for locating and identifying underground pipes, utilizing a ground-probing radar. The ground-probing radar system includes an antenna module and a transmit/receive sub-system. The system also includes a digital signal processing sub-system for processing the received signal to extract data corresponding to detected differences in dielectric constant and a master controller. The system still further includes a positioning sub-system, a display sub-system, a user interface and a data storage mechanism, display data and said operating parameters.

Claims

1. A ground-probing radar system, comprising:

an antenna module including at least one dipole element;

a transmit/receive sub-system electrically coupled to said antenna module, said system including structure for generating a radar signal and transferring the signal to said antenna module for radiation into the ground, and receiving a portion of the radar signal reflected therefrom;

a digital signal processing sub-system electronically connected to said transmit/receive system comprising structure for processing said received portion of said reflected radar signal to extract raw data corresponding to detected differences in dielectric constant in the ground as a function of spatial variance in three dimensions, and generating display data therefrom;

a positioning sub-system electrically connected to said master controller for maintaining the exact ground location of said radar system and generating location data therefrom;

wherein the digital signal processor sub-system is controlled to input and process raw data, in accordance with location data and display data such that underground composition may be identified and mapped,

wherein the structure for processing said received portion of said reflected radar signal uses synthetic aperture radar processing, dependent on the dielectric constant of the ground, and wherein the dielectric constant of the ground is determined by comparing the raw data with memory-stored expected responses from a buried object for a plurality of discrete depths and over a first range of dielectric constants, and wherein a second narrower range of dielectric constants is selected based on the comparison, the best matching dielectric being selected from the second range.

2. The radar system of claim 1, wherein said antenna module, said transmit/receive sub-system and said digital signal processing sub-system operate as a single-channel system.

3. The radar system of claim 1, wherein said digital signal processing sub-system structure extracts hyperbolic object data from said raw data.

4. The RADAR system of claim 3, wherein said digital signal processing sub-system structure performs cluster processing on said raw data to generate said hyperbolic object data.

5. The RADAR system of claim 4, wherein said digital signal processing sub-system structure performs a Hough transform on said object data to extract linear features of detected objects therefrom.

6. The RADAR system of claim 3, wherein said digital signal processing sub-system structure includes an AT&

T DSP 326 processor.

7. (amended) The radar system of claim 1, wherein the master controller includes an Intel 80486 processor.

8. The radar system of claim 1, wherein said display system includes a transflective display.

9. The radar system of claim 1, wherein said data storage mechanism includes a hard disc and hard disc controller.

10. The radar system of claim 1, wherein said user interface includes a set of softkeys, a softkey controller and a medium for storing a set of instructions for defining operation of said softkey controller.

11. The RADAR system of claim 1, further comprising a communications port for communicating said display data to electronic means.

12. The RADAR system of claim 11, wherein said port is connected to a CAD/CAM system.

13. The radar system of claim 1, wherein said transmit/receive sub-system includes a sampling head utilizing pulse-signal shaping.

14. The radar system of claim 1, further including mechanical means connected to said antenna module, the mechanical means being provided for rotating said at least one dipole element to define a scanning profile.

15. The radar system of claim 1, further comprising a ruggedly constructed cart including a main body housing.

16. The RADAR system of claim 15, wherein said main body housing includes a one piece rotational housing with a control panel.

17. The RADAR system of claim 15, wherein said cart includes a set of wheels and a handle for pushing said cart.

18. The RADAR system of claim 17, wherein said wheels communicate position data to said positioning sub-system.

19. The RADAR system of claim 15, wherein said antenna module is mounted on said housing with a compliant hinge.

20. The RADAR system of claim 19, wherein said antenna module includes a sacrificial wear membrane.

21. The RADAR system of claim 15, wherein said housing acts as a platform for said display sub-system.

22. The RADAR system of claim 15, wherein said housing includes system cooling means.

23. The RADAR system of claim 22, wherein said system cooling means includes at least one cooling for having at least one vent for exhausting air.

24. The radar system claim 1, wherein said transmit/receive sub-system generates a fast risetime electromagnetic pulse signal.

25. The RADAR system of claim 24, wherein said signal has a peak amplitude of around fifty (50) volts and a time constant of around one nanosecond (10-9 sec.).

26. The RADAR system of claim 15, wherein said housing includes an electronics module, rear panel module, battery module, reset panel, cooling fan module and wheel sensor module.

27. The radar system of claim 1, wherein said antenna module includes at least one delay coil.

28. The radar system of claim 1, wherein said antenna module includes at least two dipole elements.

29. The RADAR system of claim 28, wherein said transmit/receive sub-system and said digital signal processing sub-system operate in conjunction with said antenna module and said microcontroller for two-channel operation.

30. The RADAR system of claim 29, wherein said digital signal processing sub-system structure utilizes a synthetic aperture RADAR processing which isolates and uses the dielectric constant of the medium of operation and focuses hyperbolic object data to a single port based thereon.

31. The RADAR system of claim 28, wherein said two-channel system operates four data channels to allow co-channel data processing.

32. The RADAR system of claim 31, further comprising two antenna modules and wherein said transmit/receive sub-system includes two transmitters and two receivers.

33. The RADAR system of claim 32, wherein said two antenna modules are mounted on a single rotating shaft for rotation of areas of interest.

34. The radar system of claim 1, wherein the system is housed in a hand-held mechanical structure.

35. The radar system of claim 34, wherein said system includes mechanical structure to house and support said system in a form of a moving vehicle.

36. The Radar system of claim 28, wherein said antenna module includes a resistively loaded antenna element, comprising an elongate strip of sheet material, which sheet has, over its area, a uniform electrical resistance, the width of said strip being varied along its length in order to provide a desired resistive loading of the antenna element.

37. The radar system of claim 36, wherein said sheet material of said antenna element comprises a synthetic plastics substrate having deposited thereon a coating of electrically resistive material.

38. The RADAR system of claim 37, wherein the surface electrical resistance of said coating of said antenna element is from 10-20 ohms per square.

39. The radar system of claim 36, wherein said elongate strip of said antenna element is at least partly of triangular form and has an electrically conductive contact area provided across the wider end of the strip.

40. The radar system of claim 39, wherein said strip of said antenna element comprises a section of rectangular configuration located between said contact area and the wider end of the triangular part of the strip.

41. The radar system of claim 39, wherein said contact area of said antenna element is of V-shaped configuration.

42. The radar system of claim 36, wherein said antenna module comprises at least one pair of resistively loaded antenna elements connected to form a dipole.

43. The RADAR system of claim 42, comprising two pairs of said elements arranged as a crossed dipole.

44. The radar system of claim 42, wherein each of said elements is folded upon itself.

45. The radar system of claim 44, wherein each of said elements has an upper portion terminating in said contact areas and housed in one limb of a support of cruciform section the center portion of which support accommodates electrical conductors coupled to the contact areas of elements extending within respective limbs of said support, and further has a lower portion extending below the corresponding limb and being resiliently deformable to conform to a surface in contact therewith.

46. The RADAR system of claim 28, wherein said antenna module includes elements which are disposed on a circumferential surface of a body of generally circular cross-section, said body being mounted for rotation to enable it to be rolled over a surface.

47. The RADAR system of claim 46, wherein said antenna elements of said array are coupled to an input and/or output via a commutating means associated with the rotary mounting of said body, whereby only antenna elements or elements having a predetermined orientation relatively to said mounting are coupled to said input and/or output.

48. The radar system of claim 46, wherein said body is provided with a replaceable ablative layer.

49. The radar system of claim 46, wherein said body comprises a hollow drum having a peripheral surface of dielectric material which is transparent to, or presents a relatively low loss to, a radar signal, and said antenna elements are disposed on the internal surface of said drum.

50. The RADAR system of claim 49, wherein said drum contains electronic apparatus coupled to said antenna elements, and wherein said drum incorporates anechoic cavities between the antennae and said apparatus to provide for absorption of radiation transmitted or reflected in a direction from the periphery of the drum towards said apparatus.

51. The Radar system of claim 13, wherein said sampling head includes a GaAs sampling bridge and fast step recovery diodes such that sampling may be accomplished in a range of from about 1.8 to 3 Ghz.

52. The radar system of claim 1, wherein the system further comprises:

a master controller electrically connected to said digital signal processor sub-system for controlling operation of said radar system, including system data flow control;

a display sub-system electrically connected to said master controller for displaying said display data;

a user interface comprising structure enabling a user to communicate with said master controller thereby affecting system processing operating parameters; and

a data storage mechanism electrically connected to said master controller for storing raw data, display data and said operating parameters.

53. A RADAR antenna system comprises an array of antenna elements disposed over an endless surface, said endless surface being mounted for movement over another surface by circulation whereby each antenna element is brought in its turn into close proximity with said other surface.