U.S. patent application number 15/990814 was filed with the patent office on 2019-05-09 for buried object locating devices and methods.
The applicant listed for this patent is SeeScan, Inc.. Invention is credited to David A. Cox, Michael J. Martin, Ray Merewether, Mark S. Olsson, Dawn E. Shaffer.
Application Number | 20190137644 15/990814 |
Document ID | / |
Family ID | 43034821 |
Filed Date | 2019-05-09 |
View All Diagrams
United States Patent
Application |
20190137644 |
Kind Code |
A1 |
Olsson; Mark S. ; et
al. |
May 9, 2019 |
BURIED OBJECT LOCATING DEVICES AND METHODS
Abstract
A buried object locator which may include at least one antenna
array including three orthogonal antennas, each antenna sharing a
common center point, is disclosed. An electronic circuit may be
connected to the array and used to determine location information
of the buried objects by measuring signal strength and magnetic
field angular data in three dimensions.
Inventors: |
Olsson; Mark S.; (La Jolla,
CA) ; Shaffer; Dawn E.; (San Diego, CA) ;
Merewether; Ray; (La Jolla, CA) ; Martin; Michael
J.; (San Diego, CA) ; Cox; David A.; (San
Diego, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SeeScan, Inc. |
San Diego |
CA |
US |
|
|
Family ID: |
43034821 |
Appl. No.: |
15/990814 |
Filed: |
May 28, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15633682 |
Jun 26, 2017 |
9989662 |
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15990814 |
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14053401 |
Oct 14, 2013 |
9696447 |
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15633682 |
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12916886 |
Nov 1, 2010 |
8564295 |
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14053401 |
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12579539 |
Oct 15, 2009 |
7830149 |
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12916886 |
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11077947 |
Mar 11, 2005 |
7619516 |
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12579539 |
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10308752 |
Dec 3, 2002 |
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11077947 |
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10268641 |
Oct 9, 2002 |
7009399 |
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10308752 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01S 13/885 20130101;
G01V 3/15 20130101; G01S 13/88 20130101; G06F 3/016 20130101; G01S
7/03 20130101; G01V 3/08 20130101; G06F 3/0346 20130101 |
International
Class: |
G01V 3/08 20060101
G01V003/08; G01S 7/03 20060101 G01S007/03; G01S 13/88 20060101
G01S013/88; G06F 3/0346 20130101 G06F003/0346; G01V 3/15 20060101
G01V003/15; G06F 3/01 20060101 G06F003/01 |
Claims
1. A buried utility locator, comprising: a plurality of magnetic
field antenna arrays, each array including three orthogonally
oriented antenna elements; and an electronic circuit operatively
coupled to the magnetic field antenna arrays for determining
information about a buried utility based on magnetic field signals
emitted therefrom.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of and claims priority to
co-pending U.S. Utility patent application Ser. No. 15/633,682,
entitled BURIED OBJECT LOCATING DEVICE WITH A PLURALITY OF
SPHERICAL SENSOR BALLS THAT INCLUDE A PLURALITY OF ORTHOGONAL
ANTENNAE, filed Jun. 26, 2017, which is a continuation of U.S.
Utility patent application Ser. No. 14/053,401, entitled BURIED
OBJECT LOCATING DEVICES AND METHODS, filed Oct. 14, 2013, which is
a continuation of U.S. Utility patent application Ser. No.
12/916,886, now U.S. Pat. No. 8,564,295, entitled METHOD FOR
SIMULTANEOUSLY DETERMINING A PLURALITY OF DIFFERENT LOCATIONS OF
BURIED OBJECTS AND SIMULTANEOUSLY INDICATING THE DIFFERENT
LOCATIONS TO A USER, filed Nov. 1, 2010, which is a divisional
application of U.S. Utility patent application Ser. No. 12/579,539,
now U.S. Pat. No. 7,830,149, entitled AN UNDERGROUND UTILITY
LOCATOR WITH A TRANSMITTER, A PAIR OF UPWARDLY OPENING POCKETS AND
HELICAL COIL TYPE ELECTRICAL CORDS, filed Oct. 15, 2009, which is a
divisional application of U.S. Utility patent application Ser. No.
11/077,947, now U.S. Pat. No. 7,619,516, entitled SINGLE AND
MULTI-TRACE OMNIDIRECTIONAL SONDE AND LINE LOCATORS AND TRANSMITTER
USED THEREWITH, filed Mar. 11, 2005, which is a divisional
application of U.S. Utility patent application Ser. No. 10/308,752,
entitled SINGLE AND MULTI-TRACE OMNIDIRECTIONAL SONDE AND LINE
LOCATORS AND TRANSMITTER USED THEREWITH, filed Dec. 3, 2002, which
is a continuation-in-part application of U.S. Utility patent
application Ser. No. 10/268,641, now U.S. Pat. No. 7,009,399,
entitled OMNIDIRECTIONAL SONDE AND LINE LOCATOR, filed Oct. 9,
2002. This application claims priority to each of these
applications, and the content of each of these applications is
incorporated by reference herein its entirety for all purposes.
FIELD
[0002] This disclosure relates generally to electronic devices,
systems and methods for locating buried or otherwise inaccessible
pipes and other conduits, as well as cables, conductors and
inserted transmitters, by detecting an electromagnetic signal
emitted by these buried objects.
BACKGROUND
[0003] There are many situations where is it desirable to locate
buried utilities such as pipes and cables. For example, prior to
starting any new construction that involves excavation, it is
important to locate existing underground utilities such as
underground power lines, gas lines, phone lines, fiber optic cable
conduits, CATV cables, sprinkler control wiring, water pipes, sewer
pipes, etc., collectively and individually referred to herein with
the term "objects." As used herein the term "buried" refers not
only to objects below the surface of the ground, but in addition,
to objects located inside walls, between floors in multi-story
buildings or cast into concrete slabs, etc. If a back hoe or other
excavation equipment hits a high voltage line or a gas line,
serious injury and property damage can result. Severing water mains
and sewer lines leads to messy cleanups. The destruction of power
and data cables can seriously disrupt the comfort and convenience
of residents and cost businesses huge financial losses.
[0004] Buried objects can be located by sensing an electromagnetic
signal emitted by the same. Some cables such as power lines are
already energized and emit their own long cylindrical
electromagnetic field. Other conductive lines need to be energized
with an outside electrical source having a frequency typically in a
range of approximately 50 Hz to 500 kHz in order to be located.
Location of buried long conductors is often referred to as "line
tracing."
[0005] A sonde (also called a transmitter, beacon or duct probe)
typically includes a coil of wire wrapped around a ferromagnetic
core. The coil is energized with a standard electrical source at a
desired frequency, typically in a range of approximately 50 Hz to
500 kHz. The sonde can be attached to a push cable or line or it
may be self-contained so that it can be flushed. A sonde generates
a more complex electromagnetic field than that produced by an
energized line. However, a sonde can be localized to a single
point. A typical low frequency sonde does not strongly couple to
other objects and thereby produce complex interfering fields that
can occur during tracing. The term "buried objects" as used herein
also includes sondes and marker balls.
[0006] Besides locating buried objects prior to excavation, it is
further desirable to be able to determine their depth. This is
generally done by measuring the difference in field strength at two
locations.
[0007] The prior art includes many battery powered portable sonde
and line locators that employ antennas to sense an electromagnetic
signal emitted by buried objects and indicate their location via
audible tones and displays. Those that have been commercialized
have been difficult to use primarily because they are extremely
sensitive to the orientation of their antennas relative to the
buried object. With commercially available sonde and line locators
it is possible to have signal strength go up as the operator moves
farther away from the buried object. Thus these locators can
indicate a peak, then a null and then a smaller peak. This can
confuse the operator, especially if he or she interprets a smaller
peak as the buried object. Users of sonde and line locators refer
to the smaller peak as a ghost or a false peak.
[0008] FIG. 1 is a graphical vertical sectional view that
illustrates the foregoing difficulty. A sonde 10 is located inside
a plastic pipe 12 beneath a concrete slab 14. The electromagnetic
dipole field emitted by the sonde 10 is illustrated by concentric
ovals 16. A conventional locator will "see" two smaller false peaks
18 and 20 spaced from the true larger peak 22 by a pair of nulls 24
and 26.
[0009] Conventional battery powered portable sonde and line
locators have also suffered from user interfaces that are
cumbersome to use, inflexible and/or limited in their ability to
convey useful information. They typically have a small array of
labeled push buttons and a display that is primarily dedicated to
indicating numerical values in a manner that is not easy for the
operator to interpret. Only a small number of commands can be
executed in conventional sonde and line locators and the
information is not displayed in a manner that intuitively indicates
to the operator how close he or she is getting to the buried
object.
[0010] There are many instances where the land that is to be
excavated may be traversed or crisscrossed by several different
utilities such as an AC cable, a water line, a gas line, a sewer
pipe and a communications line. It would be desirable to be able to
determine their paths and their depths all at one time.
Conventional transmitters are commercially available that will
output several different signals at different frequencies that can
be applied to the same underground object or even to different
underground objects, but the line locators that have heretofore
been commercially available have not been capable of simultaneously
detecting and indicating the locations of the different objects,
their depths or their different types.
[0011] Accordingly, there is a need in the art to address the
above-described as well as other problems related to buried object
identification.
SUMMARY
[0012] In accordance with one aspect, portable sondes and line
locators are disclosed.
[0013] In another aspect, an improved method for locating one or
more buried objects by sensing electromagnetic signals emitted from
the buried objects are disclosed.
[0014] In another aspect, portable sondes and line locators with an
improved graphical user interface (GUI) are disclosed.
[0015] In another aspect, portable locators that can simultaneously
detect different buried objects and simultaneously indicate their
different locations based on electromagnetic signals are
disclosed.
[0016] In another aspect, portable locators including location
identification and/or mapping functions are disclosed.
[0017] Various additional aspects, features, and functions are
further described below in conjunction with the appended
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The present disclosure may be more fully appreciated in
connection with the following detailed description taken in
conjunction with the accompanying drawings, wherein:
[0019] FIG. 1 is a graphical vertical sectional view illustrating a
prior art technique of locating a buried sonde.
[0020] FIG. 2 is a perspective view of a portable battery powered
sonde and line locator representing a first embodiment of our
invention that is designed to sense and display the location of a
single buried object at one time.
[0021] FIG. 3 is an enlarged view of the antenna mast and two
sensor balls of the first embodiment.
[0022] FIG. 4 is an enlarged, broken away view of the lower sensor
ball of the first embodiment.
[0023] FIG. 5 is an enlarged, broken away view of the upper sensor
ball of the first embodiment.
[0024] FIG. 6 is a functional block diagram of the electronic
circuitry of the first embodiment.
[0025] FIG. 7 is an enlarged top plan view of a portion of the
housing of the first embodiment illustrating its display.
[0026] FIG. 8 is an enlarged top plan view of another portion of
the housing of the first embodiment illustrating its keypad.
[0027] FIG. 9 is a graphical vertical sectional view illustrating
the technique of locating a buried sonde with the first
embodiment.
[0028] FIG. 10 is a graphical vertical sectional view illustrating
the technique of locating a buried pipe with the first
embodiment.
[0029] FIG. 11 illustrates a SEARCH view that can be indicated on
the display of the first embodiment.
[0030] FIG. 12 illustrates a sonde mode MAP view that can be
indicated on the display of the first embodiment.
[0031] FIG. 13 illustrates a trace mode MAP view that can be
indicated on the display of the first embodiment.
[0032] FIG. 14 illustrates an alternate MAP view that can be
indicated on the display of the first embodiment.
[0033] FIG. 15 is an enlarged view of the underside of the housing
of the first embodiment.
[0034] FIG. 16 is a functional block diagram of the analog board of
the electronic circuitry of a second embodiment of our portable
battery powered sonde and line locator that is designed to
simultaneously sense and display the location of a plurality of
buried objects at the same time.
[0035] FIG. 17 is a functional block diagram of the digital board
of the electronic circuitry of the second embodiment.
[0036] FIG. 18 is an enlarged top plan view of a portion of the
housing of the second embodiment illustrating its display and
keypad and showing an exemplary trace mode MAP view in which the
locations of a plurality of different underground utilities are
simultaneously visually indicated.
[0037] FIGS. 19-22 are additional exemplary trace mode MAP views
that can be indicated on the display of the second embodiment.
[0038] FIG. 23 is a special set up screen that can be indicated on
the display of the second embodiment.
[0039] FIGS. 24-27 are additional exemplary trace mode MAP views
that can be indicated on the display of the second embodiment.
[0040] FIG. 28 is a perspective view from the top side of a
portable transmitter that can be used with either the first
embodiment or the second embodiment of our portable sonde and line
locator. The pair coil cords and their respective clips that are
normally stowed in the pockets at opposite ends of the transmitter
during transport are not illustrated in this view.
[0041] FIG. 29 is a reduced perspective view of the transmitter
illustrating the coupling of one of its clips to a ground spike and
the coupling of the other clip to a gas pipe extending from a gas
meter.
[0042] FIG. 30 is a perspective view from the bottom side of the
transmitter illustrating the removable mounting of the ground spike
to the underside thereof.
[0043] FIG. 31 is a top plan view of the transmitter without its
coil cords or clips stowed in the pockets at its opposite ends.
[0044] FIG. 32 is an enlarged vertical sectional view of the
transmitter taken along line 32-32 of FIG. 31 showing the coil
cords stowed in the pockets.
[0045] FIG. 33 is an enlarged perspective view of one of the
alligator clips of the transmitter that is used to couple a coil
cord to a pipe or other conductor.
[0046] FIG. 34 is an enlarged perspective view of a light pipe used
in the clip of FIG. 33.
[0047] FIG. 35 is a functional block diagram of the electronic
circuitry of the transmitter of FIG. 28.
[0048] FIG. 36 is an enlarged view of the display screen and keypad
of the transmitter of FIG. 28.
[0049] FIGS. 37-40 are schematic diagrams of several alternate
embodiments of the LED circuit in the one of the alligator clips of
the transmitter.
DETAILED DESCRIPTION OF EMBODIMENTS
[0050] Referring to FIG. 2, a first embodiment of the present
invention is illustrated in the form of a battery powered,
omnidirectional, manually portable system 30 that is capable of
locating a buried object by sensing an electromagnetic signal
emitted by the buried object. The system 30 includes a housing 32
and an elongate member 34 (FIG. 3) that supports spaced apart lower
and upper sensor balls 36 and 38, respectively, and connects them
to the housing 32. The housing 32 (FIG. 2) is made of openable
rigid plastic shells having a large central aperture 40 spanned by
a handle portion 42.
[0051] Circuit means illustrated in FIG. 6 are mounted partly in
the housing 32 and partly in the sensor balls 36 and 38 for sensing
an electromagnetic signal in a frequency range of approximately 50
Hz to 500 kHz emitted from a buried object and determining a
location and depth of the buried object by measuring signal
strength and field angles in three dimensions. This is accomplished
utilizing a first lower antenna array 44 (FIG. 4) and a second
upper antenna array 46 (FIG. 5) mounted inside the lower and upper
sensor balls 36 and 38, respectively. The circuit means includes a
display 48 (FIGS. 2, 6 and 7) for providing a visual indication of
the determined location and depth of the buried object. The display
48 is preferably a color or black and white LCD. The circuit means
of FIG. 6 also includes means for providing an audible indication
with increasing pitch to indicate to the operator that he or she is
getting nearer to the buried object, including a speaker (not
illustrated) mounted behind a grill 50 (FIG. 2) formed in the
housing 32.
[0052] Each of the two antenna arrays, such as the lower antenna
array 44 (FIG. 4), includes three substantially mutually orthogonal
antennas 52, 54 and 56. Each antenna is formed by a wire coil such
as 52a wrapped around a circular plastic mandrel 52b. Each wire
coil may be segmented to raise the self-resonate frequency of the
coil and thereby improve the range of useful frequencies of
electromagnetic signal that can be sensed. The wire coils and
mandrels of each array are progressively smaller so that they can
be assembled in a nested concentric arrangement. The antennas in
each array share a common center point. The elongate member 34
forms an antenna mast and is preferably made from Aluminum or GRP
(fiberglass) or other non-ferrous hollow tube. As seen in FIGS. 4
and 5, the elongate member 34 extends through the nested circular
antennas of the arrays 44 and 46. The various parts are aligned so
that a central axis of the elongate member 34 extends through the
pair of common center points of the antenna arrays 44 and 46.
[0053] The circular antennas of each of the arrays 44 and 46 are
nested and positioned such that an angle subtended between the axis
of the elongate member 34 and each of the circular antennas is
substantially identical. In the first embodiment this angle is
approximately thirty-five degrees. The mandrels, such as 52b, of
each of the innermost circular antennas have inner curved surfaces
that engage the exterior round surface of the elongate member 34.
The innermost mandrels may be keyed or otherwise secured in
predetermined vertically spaced positions along the Aluminum tube
that forms the elongate member 34. The outer two mandrels of the
antenna arrays 44 and 46 interlock with each other and with the
innermost mandrels.
[0054] The lower and upper sensor balls 36 and 38 (FIG. 3) each
include generally spherical elastomeric boots 58 and 60 (FIGS. 4
and 5) which surround and enclose the antenna arrays 44 and 46 in a
watertight manner. The lowermost portion of the lower boot 58 (FIG.
4) extends around the lower end of the elongate member 34. The
uppermost portion of the lower boot 58 has a lip which is seated in
the peripheral groove of a grommet 62 that surrounds the elongate
member 34. Another grommet 64 surrounds the lower end of the
elongate member 34. Additional shell-like support members 66 and 68
also surround the lower antenna array 44 and have peripheral lips
that fit within the peripheral grooves of the grommets 62 and 64. A
V-shaped pre-amplifier circuit board 70 is supported at an angle
relative to the axis of the elongate member 34 within the lower
antenna array 44 and carries pre-amplifying circuitry that is
connected to the coils of its three mutually orthogonal antennas
via suitable wires and connectors. A connector 72 on the circuit
board 70 receives a plug (not illustrated) for connecting the
pre-amplifying circuitry to wires (not illustrated) that extend
through a hole (not illustrated) in side of the hollow elongate
member 34 and through the hollow central core of the elongate
member 34. These wires are connected to additional circuit boards
hereafter described that are mounted within the housing 32 and
carry the remainder of the circuit means illustrated in FIG. 6. The
upper sensor ball 38 illustrated in FIG. 5 which has an identical
construction except that both the lowermost and the uppermost
portions of the upper boot 60 each have lips which are seated in
the peripheral grooves of additional grommets 74 and 76 that
surround the elongate member 34.
[0055] FIG. 6 is a functional block diagram of the electronic
circuitry of the first embodiment. Most of this circuitry resides
on several main circuit boards hereafter described that are mounted
within the housing 32, except for the pre-amplifying circuitry that
is mounted on separate circuit boards, such as 70 (FIG. 4), mounted
within the sensor balls 36 and 38. The pre-amplifier circuit board
70 inside the lower sensor ball 36 and the pre-amplifier circuit
board 78 mounted inside the upper sensor ball 38 are connected to
an analog circuit board 80 (FIG. 6) via multi-connector twisted
pairs, such as CAT-5 network cables. RJ style connectors are
preferably utilized for quick connection and disconnection. The
analog board 80 contains mixer circuits 82, filtering circuits 84,
gain attenuator circuits 86 and switching circuits 88.
[0056] A main digital circuit board 90 sends a single local
oscillator (LO) output signal to the analog board 80 and receives
amplified and filtered signals from the antenna coils of the lower
and upper antenna arrays 44 and 46. The digital circuit 90 board
includes a digital signal processing (DSP) module 92 and an A/D
module 94. The DSP module 92 includes digital signal processing
circuits, RAM and input/output control circuits that allow the DSP
module 92 to process information from the A/D module 94, configure
system settings and enable visible and audible indications of
location and related data to be indicated to the operator. A flash
memory and programmable logic device (PLD) portion 96 of the
digital board 90 provide system programming, input/out and control
logic and LCD driver functions.
[0057] The display 48 (FIGS. 2, 6 and 7) is a graphical LCD with a
backlight, and its contrast and backlight levels are set by
software control. An audio generation module 98 (FIG. 6) provides
tone signals to a speaker and headphone jack and communications
port assembly 100 through a power board 102. Besides allowing the
connection of a pair of headphones, the assembly 100 permits serial
communications, data download and calibration functions to be
performed. A digital volume control is also set by software
control. A numerically controlled local oscillator (LO) module 104
on the digital board 90 permits digital frequency control which is
set by software control.
[0058] A membrane-type keypad 106 (FIGS. 2, 6 and 8) with a light
sensor is connected to a keypad processor 108 (FIG. 6) on the power
board 102. The keypad processor 108 performs power enable and
keypad scanning functions. The light sensor in the keypad 106
interfaces with a backlight control circuit 110 for automatically
adjusting the level of the backlight in the display 48 to
compensate for fluctuations in the ambient light level. A
communications module 112 and sensor A/D module 114 on the power
board 102 facilitate data communications with a personal or other
computer and interfacing of sensor information to the digital board
90.
[0059] A power supply 116 on the power board 102 receives power
from four alkaline C batteries 118 and converts it to provide all
of the required voltages in the system circuitry. For batteries
other than alkaline batteries, the operator uses the keypad 106 and
display 48 to set the type of batteries using a SET UP menu under
BATTERY TYPE. This allows the system to correctly monitor battery
status and advise when power is LOW and the batteries 118 need to
be recharged or replaced. The power supply 116 also provides linear
power to the keypad processor 108 for power management when the
system is turned OFF. The system 30 can be configured to turn OFF
if no commands have been activated or no motion detected (via
optional accelerometer) after a predetermined period of time has
elapsed. It can also provide a visual and/or audible warning in
advance of this automatic shut down and allow the user to interrupt
the power down sequence. The automatic power down feature saves
battery power.
[0060] A power processor circuit 120 (FIG. 6) provides power
termination, keypad status, system control and sensor feedback
(battery voltage, temperature, illumination level, optional
accelerometer for motion/level detection, backlight control, etc.).
Finally, with regard to FIG. 6, an audio amplifier and headphone
switching module 122 supports the speaker and headphone jack and
communications port assembly 100.
[0061] The first embodiment 30 of the sonde and line locator system
of the present invention utilizes a graphic user interface (GUI) in
the form of words, numerical data, menus, symbols and icons to
indicate data and location information on the display 48 (FIG. 7).
This GUI is augmented by audible tones generated in the internal
speaker or headphones that are driven by the module 122 (FIG. 6)
through the audio jack portion of the assembly 100. The GUI allows
an operator to readily configure the system 30 and to easily locate
buried objects. The system 30 can be configured so that most of the
user menus time out if a selection is not made by the operator
within a predetermined amount of time. The system 30 can produce
two types of sounds, namely, signal sounds and event sounds. A
signal sound is related to increasing or decreasing signal
strength. It is a repeating scale that "winds" up when signal
sounds are associated with some specific occurrence.
[0062] Event sounds include:
[0063] Equator: Slot Machine
[0064] Pole: Clang
[0065] Line: Slot machine
[0066] Depth Avg. & Hold: Ding--Success
[0067] Depth Avg. & Hold: Buzz--Failure
[0068] Key Press: Click
[0069] Low Battery: Buzz
[0070] Power Down: Chime Sequence
[0071] Startup: Greeting (spoken)
[0072] A repeating scale audio tone is used to expand the
sensitivity of the system 30 to small changes in sensed and
visually indicated electromagnetic signal amplitude. The audio tone
can cycle from low to high or high to low in conjunction with
numerical values indicated on the display 48. Hysteresis is built
into the tonal switch portion of the audio amplifier and switching
module 122 (FIG. 6) so that the rising and falling switch points
are offset to prevent confusing up and down switching at the same
level of signal strength. If the sound is turned OFF, all sounds
except STARTUP and POWER DOWN are also turned off.
[0073] Referring to FIG. 7, the display 48 indicates the sonde
frequency 124, sonde level 126, active trace frequency 128, active
trace level 130, passive (AC) trace frequency 132, passive (AC)
trace level 134, audio level 136, battery level 138 and distance
(depth) 140. The display 48 also indicates the distance units 142,
overhead indicator 144, 3D field indicator 146, signal strength
148, 2D field indicator 150, horizontal field angle 152, gain level
154 and current strength 156. A few seconds after powering up, the
system 30 will allow the operator to select an operating mode from
a sonde mode at 512 Hz, an active line trace mode at 51 kHz, or a
passive AC line trace mode at 60 Hz. The default sonde mode, active
line trace mode, and passive AC passive AC line trace mode
frequencies can be set by software control elsewhere. Any of the
three modes can be selected by moving the highlight cursor and
pressing the select key 158 (FIG. 8) in the center of the keypad
106. The highlight cursor is illustrated in FIG. 7 as a small
horizontal rectangle inside the octagon in the display 48.
Alternatively, the operator can wait four seconds and the system 30
will automatically enter the highlighted mode.
[0074] Referring again to FIG. 8, the keypad 106 has a number of
other keys that can be manually depressed by the operator to select
options and execute commands. These include a menu key 160 that
opens and closes the main menu, a power ON/OFF key 162, an UP key
164 and a DOWN key 166. The UP key 164 enables the user to scroll
up through menu choices, initiate signal capture, and set the
signal and current level to 1000 ("1000 set" explained hereafter)
with a long press. The DOWN key 166 enables the user to set the
zero level reference of the system 30, scroll down through menu
choices, and execute depth average and hold. The DOWN key 166 also
zeroes the signal strength when held depressed for approximately
three seconds. The select key 158 switches the system between
SEARCH and MAP views and also selects the choice highlighted on the
display 48 when the system has a menu open. A mode select key 168
opens and closes the operating mode menu. A sound key 170 opens and
closes the sound level menu. The operator can cycle the power ON
and OFF by depressing key 162 in order to reset 1000 and "set and
zero set" to default levels.
[0075] The first embodiment 30 of the sonde and line locator system
of the present invention uses the multi-directional antenna arrays
44 and 46 (FIGS. 4 and 5) along with circuit means (FIG. 6) that
includes advanced software programming to make pinpointing sondes
and tracing buried lines fast, accurate and easy. The GUI
implemented via the display 48 (FIGS. 2 and 7) allows the operator
to "see" the fields and to quickly resolve complex locating
problems. The first embodiment 30 measures and displays
electromagnetic fields emitted by long conductors such as energized
wires, video inspection camera push cables, conduits or pipes when
in its tracing mode. The passive AC tracing mode is a specialized
case of the tracing mode where the line is already energized with
50 or 60 Hz electrical power. Active transmitters such as sondes
are located in the sonde mode. Unlike conventional paddle or stick
locators, which can only measure signal strength in the direction
of the individual antenna(s), the first embodiment 30 measures both
signal strength and field angles in three dimensions (3D). This
enhanced capability makes it possible for the first embodiment 30
to indicate a mapping display on the LCD 48.
[0076] FIG. 9 is a graphical vertical sectional view illustrating
the technique of locating a buried sonde 10 with the first
embodiment 30. The sonde 10 is "seen" only as a single peak 130 and
there are no confusing nulls or false peaks. Compare this technique
to the prior art approach illustrated in FIG. 1.
[0077] FIG. 10 is a graphical vertical sectional view illustrating
the technique of locating a metal pipe 132 buried in a concrete
slab 134 with the first embodiment 30. The pipe 132 has a signal
applied thereto which generates a long cylindrical electromagnetic
field illustrated by concentric circles 136. The pipe 132 is "seen"
by the first embodiment 30 as a single peak 138 directly above the
pipe 132, without any nulls or false peaks.
[0078] The first embodiment 30 offers the following advantages over
conventional sonde and line locators. First, the sensed
electromagnetic signal always gets stronger as the operator
carrying the first embodiment 30 gets closer to the buried object.
Second, nulls and false ("ghost") peaks are eliminated. With
conventional locators, it is possible to have signal strength go up
as the operator moves away from the buried object. A conventional
locator "sees" a larger peak, then a null, and then a smaller peak.
This can confuse the operator especially if he or she interprets a
smaller peak (known as a ghost or false peak) as the buried object.
Third, the orientation of the first embodiment 30 relative to the
buried object does not have any effect on sensed signal strength.
The operator can approach from any angle with the first embodiment
30 held in any orientation and he or she need not know the lie of
the pipe or wire. Conventional sonde and line locators must be
orientated in a specific manner to locate a sonde or trace a line
once the initial signal has been picked up. Fourth, the first
embodiment 30 facilitates the solution of difficult location tasks
by indicating graphical map views and angle indicators on the
display 48 to help interpret electromagnetic signal
characteristics.
[0079] Each of the three modes of operation of the first embodiment
(sonde mode, line trace mode and AC line trace mode) has two views
that can be indicated on the display 48, namely, a SEARCH view and
a MAP view. The SEARCH view emphasizes locating based on signal
strength and it is the default view for the sonde mode. The MAP
view emphasizes locating based on field angles and is the default
view for the line trace and AC line trace modes.
[0080] Referring to FIG. 11, in the SEARCH view a numeric (digital)
signal strength is indicated at 172 on the display 48. This number
gets larger as the system 30 gets closer to the buried object and
the sensed electromagnetic signal gets stronger. This number gets
smaller as the system 30 gets further away from the buried object
and the sensed electromagnetic signal gets weaker. An octagonal
"track" pattern 174 has a rectangular signal strength indicator 176
with an internal chevron symbol that continuously moves in a
non-linear manner around the pattern 174 to indicate the change in
sensed electromagnetic signal strength. Clockwise movement of the
indicator 176 represents increased signal strength whereas
counter-clockwise movement of the indicator 176 represents
decreased signal strength. Thus, the moving signal strength
indicator 176 provides a convenient analog representation of the
variation in sensed signal strength. Each revolution of the
indicator 176 around the octagonal pattern 174 is matched by a
corresponding audible tone or sound that indicates larger or
smaller sensed signal strength. A naked chevron maximum signal
marker 178 marks the point of maximum signal strength and appears
when the sensed signal begins to decrease. In the SEARCH VIEW, each
revolution of the signal strength indicator 176 is accompanied by a
tonal amp, which can repeat for each revolution. This provides an
audible indication that represents both the direction and amount of
signal sensed and mirrors the same information shown on the display
48 by the indicator 176.
[0081] The octagonal pattern 174 (FIG. 11) and the indicator 176
that travels around the same in a generally circular fashion
provide a visual analog indication to an operator that represents
the variation in sensed signal strength. The pattern 174 need not
be octagonal in shape, but could be square, circular, oval, etc.
The pattern 174 yields an important advantage in that it provides
an interior space inside the "track" where the digital signal
strength 172 and a mini-map 180 can be displayed. The mini-map 180
represents a condensed version of the MAP view hereafter described.
The MAP view shows visual cues that guide the operator toward the
source of the signal in the different modes as explained.
[0082] Referring to FIG. 12, when the sonde mode MAP view is shown
on the display 48 of the system 30 a sonde axis is indicated at
182. This axis represents the approximate direction of the pipe
when the system 30 is positioned above the pipe and between the
poles. A zoom ring 184 magnifies the area when the first embodiment
30 is close to a pole for more accurate pole location. The zoom
ring 184 represents a zoomed out search area adjacent to the pole.
The equator is indicated by a dotted line 186 and a pole
symbol/icon is indicated at 188. The equator is the point where the
field lines are flat or horizontal. As in the earth model, the
equator is the line at zero degrees latitude. At the point when the
field lines are straight up and down, or vertical, this is called a
"pole." Poles are distinct points, not lines like the equator. The
GUI of the system 30 displays the equator 186 (FIG. 12) where the
field angle above the sonde is zero degrees. Event sounds can also
be generated in conjunction with this display. These include
specific sounds when the system 30 is positioned over the pole, or
over the equator, or when other states occur, like low battery.
[0083] Referring to FIG. 13, when the trace mode MAP view is shown
on the display 48 of the system 30 a solid graphic line 190
represents a position of an energized line as measured by the lower
antenna array 44. The dotted line 192 presents the position of an
energized line as measured by the upper antenna array 46. The solid
graphic line 190 indicates the location of the system 30 and moves
side-to-side on the display with respect to a buried object
emitting an electromagnetic field that is approximately cylindrical
using the measured angle of the field with respect to the system
30. If the measured field angle is zero degrees (orthogonal to the
longitudinal axis of the antenna mast 34) the GUI of the system 30
will display the line 190 centered on the display 48. The solid
graphic line 190 is also displayed offset from the center of the
display 48 in an amount proportional to the measured tilt of the
field. The direction of the offset is set by the direction of tilt
of the measured field. The field angle does not have to be
explicitly calculated in order to accomplish the foregoing.
However, something equivalent thereto must be calculated. This
could be done with ratios, but they would be reducible to their
field angle equivalents. The presence of any distortion or
interference in the field of interest will cause the solid graphic
line 190 and the dotted line 192 to move out of alignment. A sound
event, such as increasing pitch, can also be generated to indicate
nearness and/or to indicate which side of the solid graphic line
190 the system 30 is located on. Such a sound event could be a
synthesized voice saying LEFT or RIGHT.
[0084] The GUI of the system 30 can also display lines as described
above in different colors or labeled in a different way for each of
the two antenna arrays 44 and 46. The GUI of the system 30 can also
display poles 188 and the equator 186 when locating a buried object
with a dipole field, e.g. a sonde. The graphical display can be
configured as a radar scope type display screen where a "pole" is
displayed in the center of the screen if the field is vertical
(ninety degrees) and then proportionally offset from the center of
the display screen depending upon the direction and the degree of
tilt of the field, either with respect to the system 30 itself or
with respect to a vertically corrected orientation if a gravity
sensor is incorporated into the system.
[0085] Referring to FIG. 14, an alternate sonde mode MAP view can
be shown on the display 48 of the system 30 in which the
orientation of the pipe is represented by a pair of parallel lines
196 which are broken in their intermediate region, which
corresponds to the equator, to indicate positional uncertainty when
the operator is standing on the equator. Clearly, a pipe or other
conduit must exist in order for a sonde to be inserted into the
same so the parallel lines 196 indicate the sonde axis. The lines
196 move or rotate as the operator walks around above the sonde.
The dotted line 198 represents the equator and the icon 200
indicates that the system 30 is in its sonde mode. The sonde icon
200 alternates from one end of the equator to the other. The dashed
cross-hair 202 represents the center point of the display 48. The
small triangular symbols or brackets 204 on either side of the
digital signal strength number 206 are displayed whenever the
current signal strength shown is equal to the largest value stored
in memory for the current locating session (since POWER UP). This
allows the operator to move along the equator and then stop as soon
as the peak (strongest sensed signal) is passed. As soon as the
signal strength begins to decrease, the brackets 204 and the sonde
sound event turn OFF. When the operator reverses direction and
returns to a point of equal or greater signal strength the brackets
204 reappear and the sound event returns.
[0086] The system 30 measures depth by comparing the strength of
the signal detected by the lower antenna array 44 to that detected
by the upper antenna array 46. The system 30 need not have upper
and lower arrays to accomplish depth measurement, and indeed depth
could be measured using only a single one of the arrays 44 or 46
that includes three mutually orthogonal antennas with a fourth
antenna spaced above or below the array. In order to accurately
measure the depth of the buried object the elongate member 34 which
functions as the antenna mast should be pointed at the source of
the electromagnetic signal. The actual depth is measured when the
lower sensor ball 36 is touching the ground directly above the
buried object. Alternatively, the distance to the buried object can
be measured when the lower sensor ball 36 is not touching the
ground. It will be understood by those skilled in the art that the
system 30 need not have depth measuring capability, in which case a
single antenna array such as 44 would suffice, but as a practical
matter, a commercially viable sonde and line locator needs to
include a depth measuring capability. It may be possible to mount
the upper antenna or antenna array 46 inside the housing 32 instead
of on the elongate member, but this may subject the antenna or
array to excessive noise from the microelectronic circuitry on the
circuit boards 80, 90 and 102 (FIG. 6).
[0087] There are two ways that the system 30 can measure and
indicate the depth of the buried object. It can indicate real time
depth continuously in the bottom left corner of the display 48 at
140 (FIG. 7). Alternatively, by pressing and releasing the DOWN key
166 (FIG. 8) the display 48 will indicate in large numbers in the
center thereof a "count down" from four seconds, second by second.
During this count down the system 30 will measure the depth and
average the measurements, and filially display the average depth in
the lower left hand corner of the display 48 at 140.
[0088] The system 30 displays the overhead indicator 144 (FIG. 7)
on the LCD 48 if the upper antenna array 46 receives more signal
than the lower antenna array 44. Typically this tells the operator
that an overhead source of electromagnetic signal is present, such
as an overhead AC power line. Negative depths can be indicated by
illuminating the overhead indicator rather than a single negative
number.
[0089] Pressing the UP key 164 (FIG. 8) when the system 30 is in
the SEARCH or MAP view will save the current signal strength to
temporary memory and hold the same until the system 30 is turned
OFF. This value is displayed at location 148 (FIG. 7) on the
display 48 when in the SEARCH view. If the operator saves the
current signal strength while in the MAP view he or she will need
to switch to the SEARCH view in order to see the same. This feature
can be used to compare the signal strength of the two poles when
locating a sonde. A level sonde under level ground will have the
same signal strength at each pole. If the sonde is inclined, the
upward tilting end will be read as a higher signal strength. If the
sonde is near a transition in a pipe type, e.g. going from ABS
plastic to cast iron, the cast iron end of the pipe may be read as
a lower signal strength.
[0090] The system 30 indicates the relative current strength 156
(FIG. 7) on the display 48. This helps the operator see any drop in
signal strength that may indicate a junction in the line or if the
line splits. The current signal strength also verifies that the
correct line is being traced as signal strength may bleed over to
shallower lines. These shallower lines may be read as having
similar signal strength but the current strength may be lower.
[0091] At the beginning of the effort to locate a buried object
with the system 30 it is helpful to have the system 30 read "0.0"
for the starting point. Due to other interference signals this may
not be the case. The temporary zero set command is a valuable tool
that can be used for single locate environments where there is some
interference present. This helps the system 30 sense only that
signal that is emitted by the sonde or line since it zeroes out the
other signals before the sonde or line transmitter is turned ON.
When the sonde or line transmitter signal is turned ON then the
apparent sensitivity will be set to read only that signal.
[0092] The system 30 can also be set to read 1000 when directly
over the buried object. This gives the operator a maximum signal
strength value that can simplify tracing. The 1000 set feature
references the current signal level to the displayed value of 1000
and re-maps the sensitivity of the circuit to represent the range
of signals between the reference level stored at the zero set, and
the reference at the 1000 set to the numerically displayed range of
0 to 1000. During a line trace the 1000 set feature makes it easier
for the operator to stay on the line and also see changes in signal
level. Signal strength varies as the line depth changes. If the
line splits the signal strength drops since a portion of the signal
then travels along one leg of the split and the remaining portion
travels along the other leg. For example if the displayed signal
strength has dropped to 500 the measured signal has dropped by
fifty percent.
[0093] The system 30 permits the signal strength value for the
frequency of interest in different modes to be temporarily set to
zero or permanently set to zero. The permanent zero set feature
allows the operator to adjust the minimum level of electromagnetic
signal that will be shown on the display 48. This allows the system
30 to effectively disregard signals smaller than the consistent
ambient noise level. It is useful to have the system read "0.0"
when no signal is present as a starting out point or base line.
Some operators will prefer maximum sensitivity while others prefer
to only show signal when it is strong and well above any
interfering noise signals. Environmental noise may be very high in
industrial areas and very low in rural areas. The permanent zero
set feature allows the operator to effectively tune the system 30
to work in optimal fashion in a given environment and to meet the
operator's personal preferences. Typically the user would take the
system 30 to a "quiet spot" on the site, with no signal present,
and then adjust the signal strength to "0.0". Then any signals
larger than this will be read and indicated as some larger
value.
[0094] The system 30 also indicates an icon in the form of a globe
194 (FIGS. 7, 11, 12 and 13) in which the measured field angle is
indicated as being located on the pole if it is at ninety degrees
and indicated as being on the equator if it is at zero degrees.
[0095] A plurality of brightly colored plastic marker chips 210
(FIG. 15) are removeably mounted on a post 212 that extends from
the elongate member 34, directly beneath the housing 32. These
marker chips 210 can be removed and placed on the ground to
facilitate the process of locating a sonde or tracing a line with
the system 30. The marker chips 210 have starred apertures with
deflectable fingers that allow them to snap fit over a flared outer
end of the post 212. The inner end of the post 212 can be secured
to the elongate member 34 in any suitable fashion, such as with a
molded plastic U-shaped clamp (not shown). The clamp snaps on the
elongate member 34 and can slide and rotate. Preferably, there are
two orange triangular shaped marker chips 210 that can be placed on
the ground to mark the poles, and a single yellow octagonal marker
chip 210 that can be placed on the ground to mark the location of
the sonde. A knob 214 can be rotated counter clockwise to remove a
door 216 that covers the compartment for the batteries 118. A
synthetic rubber bumper 218 surrounds the housing 32. A helpful
icon reference label 220 is affixed to the underside of the housing
32. A serial number label 222 also affixed to the underside of the
housing 32 which bears a unique number and bar code that identifies
the specific system 30 from all similar systems that have been
manufactured.
[0096] From the foregoing detailed description it will also be
appreciated that the present invention also provides a method of
locating a buried object by sensing an electromagnetic signal
emitted by the buried object. Broadly, the method includes an
initial step of traversing a topside area beneath which an object
emitting the electromagnetic signal is buried with at least one
antenna array 44 including three substantially mutually orthogonal
antennas. The method further includes the step of sensing the
electromagnetic signal emitted by the buried object with the array
44. The method also includes the step of determining a location of
the buried object based on the sensed electromagnetic signal
without having to align the antenna array 44 relative to the buried
object while eliminating nulls 24 and 26 (FIG. 1) and false peaks
18 and 20. In order to measure depth, while avoiding a null
detection, the topside area is simultaneously traversed with the
second antenna array 46 that includes at least a pair of
antennas.
[0097] In order for the system 30 to correctly sense the total
field vector, the response of each coil within each of the arrays
44 and 46 needs to be calibrated with respect to the response of
the other two coils within the same array. The geometry of the
antenna arrays 44 and 46 and the manner in which they are mounted
to the elongate member 34 greatly facilitates the calibration of
the system 30. Conventional sonde and line locators typically have
at least one antenna in their array that has an axis that is
substantially in alignment with part of the supporting structure.
If any one of the antennas in the array has its axis orthogonal to
the axis of the calibrating field, then it is not possible to
calibrate that antenna as its response will be nominally zero. The
system 30 has a preferable geometry where each antenna has
substantially the same offset angle relative to the axis of the
elongate member or antenna mast 34. This makes it possible to
calibrate each of the three antennas in each array relative to the
other two antennas in the same array. This can be done by placing
the system 30 within a tubular solenoid field. The two antenna
arrays 44 and 46 need to be very accurately aligned and centered
within the solenoid calibration field. The solenoid field must be
substantially cylindrical so that a uniform, rotationally symmetric
calibration field is generated. Making the antenna arrays 44 and 46
spherical and enclosing them in the sensor balls 36 and 38 allows a
fixture to be constructed for readily centering the calibration
field relative to the elongate member or antenna mast 34.
Furthermore, making the antenna arrays 44 and 46 relatively small
and round, and precisely centering these antenna arrays on the
elongate member 34 minimizes the mass of the shielding required on
the calibration chamber.
[0098] FIG. 16 is a functional block diagram of the analog board
80' of the electronic circuitry of a second embodiment of our
portable battery powered sonde and line locator that is designed to
simultaneously sense and display the location of a plurality of
buried objects at the same time. It is similar to the analog board
80 of the first embodiment 30 except that the former includes more
mixers 224 for processing the various signals in different
frequency bands that are received by all of the antennas. FIG. 17
is a functional block diagram of the digital board 90' of the
electronic circuitry of the second embodiment. It is similar to the
digital board 90 of the first embodiment 30 except that the former
includes a plurality of numerically controlled local oscillator
(LO) modules 226 that send a plurality of output signals to the
analog board 80'. The modified digital board 90' receives amplified
and filtered signals from the antenna coils of the lower and upper
antenna arrays 44 and 46 in a fashion similar to that of the
digital board 90, except that the former is simultaneously
processing signals generated in different frequency bands.
[0099] The second embodiment allows the user to seek and locate
electromagnetic signals emitted by different buried objects at
different frequencies. Preferably the second embodiment allows the
user to select between different frequency bands separated by
orders of magnitude, e.g. frequency bands centered on 100 Hz, 1
kHz, 10 kHz and 100 kHz, and within different channels within the
bands. Preferably, the channels within each band are separated by
some uniform amount, e.g. 10 Hz or 100 Hz.
[0100] The mechanical and electro-mechanical aspects of the second
embodiment are similar to those of the first embodiment illustrated
in FIG. 2 except as otherwise indicated hereafter. Throughout this
description like reference numerals refer to like parts. The
software of the second embodiment is designed to enable a plurality
of different buried objects to be simultaneously detected and their
locations and depths simultaneously indicated visually and/or
audibly.
[0101] FIG. 18 is an enlarged top plan view of a portion of the
housing 32 of the second embodiment illustrating its display 48 and
keypad 106 and showing an exemplary trace mode MAP view in which
the locations of a plurality of different underground utilities are
simultaneously visually indicated. A phone utility icon 228 is
indicated on the display 48 without the line orientation feature
selected. An electric utility icon 230 is indicated on the display
48 with the line orientation feature selected and indicated by a
solid bold diagonal line 232. A 60 Hz icon 234 is indicated on the
display 48 without the line orientation feature selected. A gas
utility icon 236 is indicated on the display 48 without the line
orientation feature selected.
[0102] Continuing with FIG. 18, if a sonde is being used, the sonde
frequency and level are indicated at a location 238 in the upper
left corner of the display 48. No values for the sonde frequency
and level are illustrated in FIG. 18. High, medium and low
frequencies are indicated by unique corresponding wave form
patterns 240. The icon of the currently selected utility, in this
case the electric utility, is shown at 230' in the upper left
corner of the display 48. An AC trace level can be indicated at
location 242. In FIG. 18, no AC trace level is illustrated. The
audio level currently selected on the second embodiment is
illustrated by the bar graph 244 on the display 48. The level of
the currently selected battery type used in the second embodiment
is illustrated by the bar graph 246 on the display 48. The depth or
distance of the currently selected utility is indicated on the
display at 248 which in the example of FIG. 18 is ten inches. A 3D
field indicator is indicated by the octagon 250 and a signal
strength for the selected utility is indicated at 252, which in the
example of FIG. 18 is 1182. A 2D horizontal field indicator is
indicated at 254. The horizontal angle is digitally indicated on
the display 48 at 256 which in the example of FIG. 18 is two
degrees. A small graphic tab or notch 258 moves clockwise along a
large octagonal race track 260 in a clockwise direction to indicate
increasing field strength and in a counter-clockwise direction to
indicate decreasing field strength. An auto-gain step is digitally
indicated at a location 262 which in the example of FIG. 18 is a 3.
Finally, a source current level is indicated on the display 48 of
the second embodiment at a location 264 which in the example of
FIG. 18 is 976. All highlighted information indicated around the
periphery of the display 48 of the second embodiment that pertains
to a specific selected utility will change when the selected
utility is changed. Different utilities can be selected by pressing
the select key 158 in the center of the keypad 106.
[0103] FIGS. 19-27 are additional exemplary trace mode MAP views
that can be indicated on the display of the second embodiment.
FIGS. 19-22 correspond to, and demonstrate how the screen on the
display 48 changes as the display "focus" is switched from one
utility to the next by actuation of, for example, the select key
158. In the case of FIGS. 19-22 there are a total of four utilities
active, one of which is a passive 60 Hz source. The selected
utility in each case is shown with a bold line through its icon
while the others only show short "tails." The bold line 232
indicates the orientation of the selected utility. The short tails
on the non-selected utilities show the approximate orientation of
the electromagnetic fields associated with each corresponding
sensed frequency. Grey scale or other methods could be used to
indicate the unselected utilities. All of the field or signal
specific data changes each time a different utility is selected.
The indicated field strength, field angles, current and depth are
specific to each selected utility. The signal from the upper
antenna ball 38 (dashed line 266) also changes in the screens
illustrated in FIGS. 20-22. The corresponding one of the icons 228,
230, 234 and 236 is indicated in the upper left corner of the
display 48 which changes to indicate the currently selected
utility.
[0104] Besides visual indications of the different locations of the
different utilities, the second embodiment can give audible
indications such as tones, synthesized human voices, or musical
voices. For example, the second embodiment could tell the user
"sewer two feet left" then "sewer one foot left" then "above sewer"
as the user moves the line locator to the left. The second
embodiment could also say "turn right" or "turn left" if the angle
between the traced line and the locator is greater than some
pre-programmed value. The audible turn indicators could also give
the magnitude, e.g. "turn, right, two." Musical voices could
include a tuba for sewer, a claxon for electric, etc.
[0105] FIG. 23 illustrates a special set up screen that can be
indicated on the display 48 of the second embodiment. It allows the
user to adjust the amount of signal discrimination. If the
electromagnetic signal is less than some specified value the signal
strength for that utility is indicated as zero. This allows the
user to have the display 48 only indicate strong, valid signals.
This helps the user in many situations in sorting out "noise" from
the target signals of interest. This feature of the second
embodiment is similar to the "zero set" feature of the first
embodiment except that the former allows the "strength" of the zero
set to be varied as needed. Preferably, the second embodiment
allows the user to individually set a zero threshold (and also 1000
magnitude set) for each utility separately and individually, and to
save this information. It also preferably allows the user to reset
each zero at any time during the location process to manage or
minimize cross-talk or coupling between different lines. The zero
threshold can be used as a criteria or trigger to display or not
display any of a plurality of utilities. For example, if the signal
strength of the target utility is less than a reference level, and
the locus of the locator is set to another utility subchannel, then
the second embodiment will not display (or alter the display) of
that utility.
[0106] FIG. 24 illustrates the manner in which the display 48 of
the second embodiment indicates the location of a marker ball
illustrated by the unique icon 268. Preferably the configuration of
the icon 268 can be varied to indicate different types of buried
utility makers, also sometimes referred to as marker balls, locator
pegs and marker discs.
[0107] FIG. 25 illustrates an alternate way of indicating different
types of utilities on the display 48 of the second embodiment. In
this example, the user is tracing multiple gas lines G1, G2, etc.
However, the display could also indicate W, G, E, etc. for water,
gas, electric, and so forth. Simple numerals like 1, 2, 3, etc.
could also be used.
[0108] FIG. 26 illustrates the manner in which the second
embodiment can change the selected utility trace line from bold to
dashed if the measured depth is negative. If the measured depth is
negative, the signal source is either above the locator (user) or
the signal is highly distorted or perhaps mostly attributable to
noise. In any event, the second embodiment preferably has the
capability of indicating a measure of uncertainty in how
information is displayed to the user.
[0109] FIG. 27 illustrates the manner in which the second
embodiment can indicate information encoded on trace signals placed
on utilities. In this example an 800 phone number has been detected
and indicated on the display 48.
[0110] FIG. 28 is a perspective view from the top side of a
portable transmitter 270 that can be used with either the first
embodiment or the second embodiment of our portable sonde and line
locator. It will be understood that a user will need several
transmitters of this type to energize each different utility with
the appropriate electric signal. The transmitter 270 includes a
hollow molded plastic portable housing 272 preferably having a pair
of outwardly and upwardly opening receptacles or pockets 274 and
276 at opposite ends thereof. A horizontal control panel 278 is
mounted on the top side of the housing 272 for receiving manually
inputted commands. The control panel 278 includes a membrane type
keypad 280 with a plurality of individual pushbutton keys 280'. The
control panel 278 further includes a plurality of individual
colored LEDs 281, many of which are associated with a particular
one of the keys 280'. Additional LEDs 281 on the control panel 278
are not associated with a particular key 280 but will indicate a
warning or status condition such as the presence of high voltage at
the output coupling. An LCD display 282 also forms a part of the
control panel 278. On the control panel 278 of the transmitter 270,
the manual selection of different frequencies for activating and
tracing various utility lines follows the colors normally
associated with particular types of utilities. Electricity is
indicated by an illuminated red LED, gas is indicated by an
illuminated yellow LED, sewer is indicated by an illuminated green
LED, water is indicated by an illuminated blue LED and
communications is indicated by an illuminated orange LED.
[0111] An electronic circuit 284 illustrated in block diagram form
in FIG. 35 is physically supported on one or more printed circuit
boards (not illustrated) mounted inside the housing 272 (FIG. 28).
The electronic circuit 284 receives commands from the control panel
278 and generates a predetermined electrical output signal in
response to the commands. More particularly the electronic circuit
284 of the transmitter 270 allows the user to select from a
plurality of frequency bands each separated by an order of
magnitude, and then from a plurality or cluster of signals within
those bands. By way of example, the frequency bands may be centered
on 100 Hz, 1 kHz, 10 kHz and 100 kHz. The channels within each band
are stepped or spaced at suitable equal intervals apart, such as 10
Hz, to allow them to be readily discriminated, as is well known in
the art. Preferably the electronic circuit 284 is also able to
generate a very high frequency signal, such as 480 kHz, for
specialized tracing activities. The second embodiment of the
locator can be programmed to seek this frequency. The transmitter
270 can also generate single frequencies not spaced apart by orders
of magnitude.
[0112] Referring to FIG. 35, the electronic circuit 284 of the
transmitter 270 includes a central processor circuit 286 including
A/D converter 288, EEPROM 290 and a pulse width modulator (PWM) 292
for generating the audio drive signal for a buzzer type annunciator
294. The central processor circuit 286 drives the LCD display 282
and the backlight drive 296 for the display 282. The electronic
circuit 284 also includes a contrast adjust circuit 298.
[0113] The electronic circuit 284 of the transmitter 270 further
includes a power supply 300 having a plurality of replaceable
batteries 302, such as eight C type alkaline cells. The central
processor circuit 286 receives power from the power supply 300 via
a linear regulator circuit 306. The central processor circuit 286
controls power to the rest of the system by switching a system
power circuit 304. The central processor circuit 286 also controls
a boost switching power supply (SPS) 308 to set a variable output
voltage (Vboost) which is fed to a power drive circuit 330. The
voltage at the batteries 302 and optionally the output of the boost
SPS 308 are fed to the A/D converter 288 to measure battery voltage
in order to estimate remaining battery power and boost voltage. A
frequency synthesis circuit 310 is connected between the central
processor circuit 286 and a drive and feedback circuit 312. The
frequency synthesis circuit includes a first numerically controlled
oscillator (NCO) circuit 314 that generates a base frequency and a
second numerically controlled oscillator (NCO) circuit 316 that
generates a so-called "sniff" frequency to facilitate location. By
way of example, the sniff frequency may be a very high frequency,
such as 480 kHz. The outputs of the first NCO circuit 314 and the
second NCO circuit 316 may be adjusted through variable amplifiers
318 and 320, respectively. The central processor circuit 286
controls the NCO circuits 314 and 316 via F select lines 322 and
324, respectively. The central processor circuit 286 controls the
variable amplifier 318 via base level line 326 and controls the
variable amplifier 320 via trace level line 328.
[0114] The drive and feedback circuit 312 includes the power drive
circuit 330 that receives an electric signal with a preselected
voltage directly from the boost SPS circuit 308 and the amplified
signals from the NCO circuits 314 and 316 and the variable
amplifiers 318 and 320. The output signal of the power drive
circuit 330 is fed through a current sense circuit 332 that
provides an output sense voltage proportional to the drive current.
This sense voltage is fed to the A/D converter 288 to measure the
current. The power drive signal is then fed to an output voltage
sense circuit 334 which provides an output sense voltage
proportional to the drive voltage. This sense voltage is fed to the
A/D converter 288 to measure the output voltage. The current sense
and voltage sense signals are used to determine the power being
delivered to the load. The power drive signal is then fed through
an output drive protection circuit 336 which protects the drive and
feedback circuits 312 from being damaged by connection to an
external power source such as a live high voltage wire. The output
drive protection circuit 336 contains a fuse as well as filtering
and clamping circuits. The power drive signal is then fed from the
output drive protection circuit 336 into a drive routing circuit
338 that includes manually actuated drive and inductive clamp
switches 340 and 342 that allow the final output signal of the
electronic circuit 284 of the transmitter 270 to be coupled to a
selected utility via coupling means such as an inductive antenna
344, an inductive clamp 346 or a coil cord connector 348.
[0115] Referring to FIG. 29, in one configuration of the
transmitter 270 a pair of electrical cords 350 and 352 are each
stowable in a corresponding one of the pockets 274 and 276. The
electrical cords each have a conductor with an inner end that is
electrically connected to the electronic circuit 284. Preferably
the electrical cords 350 and 352 are of the springy helical coil
type that readily stretch and contract. The cords 350 and 352
should be as small and lightweight as possible so that their
lengths can be maximized and they will still fit within their
respective pockets 274 and 276. We have found that the inner
conductors of the coil cords 350 and 352 which are covered with
plastic insulation can be made of steel instead of the usual Copper
found in such cords. Steel is much stronger than Copper and
therefore the conductors can be made smaller. The higher electrical
resistance is acceptable in a transmitter application as the
resistance of the types of circuits (utilities) to which the
transmitter 270 will typically be connected is high.
[0116] Referring still to FIG. 29, alligator style clips 354 and
356 with spring biased opposing electrically conductive jaws are
electrically connected to the outer ends of the conductors in each
of the electrical cords 350 and 352 for coupling the predetermined
electrical signal across a selected utility line which, in FIG. 29,
is a gas line 358. The gas line 358 joins with an above-ground gas
meter 360 and a majority of its length extends underground. The
alligator clip 356 is connected to the conductor of the coil cord
352 which is in turn connected to the positive electrical output
signal of the electronic circuit 284 via the drive routing circuit
338. The alligator clip 356 is clamped around the gas line 358 to
energize the same so that it emits electromagnetic radiation at the
desired frequency for optimum tracing. The other alligator clip 354
is connected to the outer end of the conductor of the coil cord 350
which is in turn connected to the ground side of the electronic
circuit 284. The alligator clip 354 is clamped around the upper
portion of a T-shaped steel ground spike 362 that is driven into
the soil to complete the circuit across the gas line 358.
[0117] FIG. 29 also illustrates a pivotal handle 364 of the
transmitter in its raised position. The handle 364 is generally
U-shaped and the lower ends of its legs are pivotally connected to
opposite sides of the housing 272 near the control panel 278. The
intermediate segment of the handle 364 can be grasped by a user to
lift and carry the transmitter 270 to the location of the
above-ground portion of the utility that is to be energized.
[0118] FIG. 30 is a perspective view from the bottom side of the
transmitter 270 illustrating the removable mounting of the ground
spike 362 thereto. A removable bottom wall 366 of the housing 272
has a pair of spaced apart sleeves 368 and 370 formed therein which
slidingly receive the pointed round shaft portion 362a of the
ground spike 362. A pair of shoulders 372 and 374 are also formed
on the bottom wall 366 adjacent the sleeves 368 and 370,
respectively. The shaft portion 362a rides over the shoulders 372
and 374 to provide a snug fit. Curved pairs of opposing guide walls
376 and 378 are connected to the bottom wall 366 before the first
sleeve 368 and after the second sleeve 370 so that the ground spike
362 can be inserted from either end of the housing 272 and the
handle portion 362b thereof will be received in one of the
conformably shaped handle receiving slots such as 380 formed at
either end of the housing 272. The pointed shaft portion 362a of
the ground spike 362 is preferably made of steel while the handle
portion 362b is preferably molded from plastic and rigidly secured
to the blunt end of the shaft portion 362a. The bottom wall 366 of
the housing 272 of the transmitter 270 is formed with a pair of
diagonally located key-hole shaped apertures 382 and 384 that allow
a bicycle or other locking cable to be passed through one of the
pockets 274 and 276 to lock the transmitter 270 to a gas pipe or
other fixture to prevent the transmitter from being stolen. A
gasket or boot 386 made of a suitable elastomer such as synthetic
rubber surrounds the base of the housing 272 and provides a water
tight seal between the removable bottom wall 366 and the remainder
of the housing 272. The boot 386 deforms to allow the handle
portion 362b of the ground spike 362 to move past the same upon
insertion thereof into the sleeves 368 and 370 and helps retain the
ground spike 362 in its loaded and stored position illustrated in
FIG. 30.
[0119] Referring still to FIG. 30, access to the eight C cell
alkaline batteries 302 (FIG. 32) is accomplished by unscrewing a
knob 388 to permit removal of a battery compartment cover 390. A
removable fuse 392 may be unscrewed and replaced. The fuse is part
of the output drive protection circuit 336. A female headphone type
jack 394 is provided for the connection of an inductive clamp (not
illustrated). A power type jack 396 permits an auxiliary power
source to be connected to the electronic circuit 284.
[0120] FIG. 31 is a top plan view of the transmitter 270 without
its coil cords 350 and 352 or alligator clips stowed in the pockets
274 and 276 at its opposite ends. A pair of drain holes 398 and 400
formed in the bottom wall 366 are visible in this figure.
[0121] FIG. 32 is an enlarged sectional view of the transmitter
taken along line 32-32 of FIG. 31 showing the coil cords 350 and
352 stowed in the pockets 274 and 276, respectively. Four of the C
cell batteries 302 are also visible in this figure.
[0122] FIG. 33 is an enlarged perspective view of one of the
alligator clips 356 of the transmitter 270 that is used to couple
the coil cord 352 to the gas pipe 358. One of the jaw handles 402
is provided with a cylindrical over-molding 404 that houses and
protects one or more LEDs and supporting circuitry hereafter
described. The illumination from these LEDs is made visible by
means of light pipe 406. Illumination from these LEDs provides
visual feedback to the user that the line or cable to which the
jaws 408 and 410 have been clamped is receiving the output signal
of the transmitter 270. FIG. 34 is an enlarged perspective view of
one configuration for the light pipe 406 used in the alligator clip
356 illustrated in FIG. 33 that enables three hundred sixty degree
viewing. This configuration can only accept one LED at a time but
the light pipe could be modified to receive and transmit the light
from a plurality of LEDs simultaneously.
[0123] FIG. 36 is an enlarged view of the control panel 278 of the
transmitter 270 illustrating details of its display screen 282 and
its keypad 280 of the transmitter 270. The keypad 280 has a number
of keys or pushbuttons that can be manually depressed by the user
to select options and execute various commands. The keypad 280
includes UP, DOWN and SELECT pushbuttons 412, 414 and 416,
respectively. There are six different pushbuttons with graphics for
six different types of utilities, each having an associated LED 281
of the appropriate color which is illuminated when that pushbutton
is depressed. The reference numeral 280' and its lead line point to
the pushbutton for selection of the communications utility. A menu
key 418 opens and closes the main menu, selections from which are
indicated on the display 282 and may be scrolled through and
selected via actuation of pushbuttons 412, 414 and 416. A power
ON/OFF pushbutton 420 allows the transmitter 270 to be turned ON
and OFF. A sound pushbutton 422 opens and closes the sound level
menu. The control panel 278 also has three frequency mode selection
pushbuttons 424, 426 and 428 situated in a vertical row to the
right of the UP, DOWN and SELECT pushbuttons 412, 414 and 416.
Finally the control panel has a separate warning LED 430 that is
illuminated to warn the user that a hazardous voltage is present.
The central processor circuit 286 has all the intelligence and
programming for providing a user friendly graphical user interface
(GUI) on the LCD display 282, one example of which is illustrated
in FIG. 36.
[0124] FIGS. 37-40 are schematic diagrams of several alternate
embodiments of the LED circuit in the alligator clip 356 of the
transmitter 270. In the circuit of FIG. 37 two LEDs 432 and 434 are
oppositely oriented and connected in parallel. The LED 432 is
connected in series with the output cable 352. While this circuit
provides the brightest illumination, special LEDs are required. In
the circuit of FIG. 38 a SIDAC or DIAC 436 is connected in series
with the cable 352. Two oppositely oriented LEDs 438 and 440 are
connected in parallel with the SIDAC or DIAC 436 through a resistor
442. The circuit of FIG. 39 is similar to the circuit of FIG. 38
except that the SIDAC or DIAC 436 is replaced with a second
resistor 444. This is a very low cost option. The circuit of FIG.
40 is similar to that of FIG. 39 except that the second resistor
444 is replaced with a bidirectional zener diode 446. This circuit
offers a good compromise between cost and brightness.
[0125] While we have described preferred embodiments of an improved
sonde and line locator and improved methods of locating buried
objects that emit an electromagnetic signal, they can be varied and
modified in many ways. For example, the antenna arrays 44 and 46
could each have a ferrite core instead of an air core. Each coil in
an array could be split into multiple coils offset from the center
line (axis of the elongate member 34). Wiring these multiple coils
in series would produce a signal similar to that of a single coil
centered about the center line. For example, the multiple coils
could be positioned on the flat surfaces of a polyhedron such as an
octahedron. Depth measuring capability is not essential so a second
antenna array need not be used, or depth could be sensed with only
the lower array 44 with three mutually orthogonal antennas and a
fourth antenna mounted on the elongate member 34 spaced from the
array or within the housing 32. The features and attributes of the
GUI including the selectable modes and the SEARCH and MAP views
could be widely varied. Audible tones are not absolutely necessary.
Conversely, audible tones could be used without any visual
display.
[0126] Continuing with the description of various modifications to
our invention, the physical shape of the housing 32 could be
altered as needed. The elongate member 34 that provides the antenna
mast need not be a hollow Aluminum or fiberglass tube but could be
a solid member with any cross-section molded around the twisted
pairs that connect the pre-amps 70 and 78 in the sensor balls 36
and 38 to the analog circuit board 82 mounted in the housing 32 The
arrangement and designation of keys on the keypad 106 could be
widely varied. The signal from the upper antenna array 46 could be
used when the system 30 is at or near one of the sonde poles to
indicate the direction to the sonde. Either the first embodiment or
the second embodiment of our sonde and line locator could
incorporate a GPS receiver for downloading locating data and
comparing the same to stored municipal map data to ensure that well
known utilities are accounted for before commencing to locate a
buried object. The housing 32 can incorporate a bubble level
indicating device and an internal two-axis (or more) accelerometer.
The bubble level would help the operator locate buried pipes. The
output of the accelerometer would help the system 30 correct the
presented display information if the operator did not hold the
system 30 truly vertical. Further electronics, including the A/D,
processors and gain and filtering blocks could be contained in or
near the lower and upper sensor balls 36 and 38. The marker chips
210 could be directly mounted to the housing 32.
[0127] The second embodiment of our sonde and line locator uses
frequency division multiplexing (FDM) to simultaneously sense the
different electromagnetic signals emitted by different utilities
and to determine their different locations. However those skilled
in the art will appreciate that a portable sonde and line locator
incorporating the basic concepts of our second embodiment could be
designed to operate with other well-known multiplexing schemes such
as time division multiple access (TDMA) or code division multiple
access (CDMA).
[0128] The use of three coils represents a minimal solution for
measuring the magnitude and direction of the magnetic field
emanating from the buried object. There is no requirement that the
coils be mutually orthogonal. Mathematically, the coils only need
to be linearly independent. That is, the coils need to span the
vector space of interest. By way of example, the first embodiment
and the second embodiment of our sonde and line locator could
incorporate one antenna array that includes four or more
non-coplanar and non-co-axial antennas. In vector notation, three
orthogonal coils for a particularly simple basis set: {(1,0,0),
(0,1,0), (0,0,1)}. An example of a non-orthogonal basis set would
be {(1,0,0), (1,1,0), (1,1,1)}. A non-orthogonal basis set might be
useful to satisfy some packaging constraint. A person skilled in
the art would recognize that orthogonality is not essential and it
may be relaxed to meet physical limitations on the configuration of
the locator. The use of four or more coils in the first and second
embodiments of our sonde and line locator provides a number of
advantages. First, this configuration is robust against failures.
It is generally easy to design the circuitry to recognize that one
of the coils has failed and to drop back to an (n-1) mathematical
solution. Second, the use of four or more coils makes the locator
less susceptible to very small scale perturbations in the field. A
least squares reduction to three mutually orthogonal components of
the field is possible by Gaussian elimination, Singular Value
Decomposition or other standard methods. Third, the use of four or
more coils allows measurement of local gradients in the field. To
do this, a total of eight coils are needed. This is best
illustrated by considering the first embodiment which uses a total
of six coil, three coils in each antenna array. More information
would be desirable, namely, whether the vertical gradient is
increased to the left or to the front. The use of three additional
coils to the front and three additional coils to the right yields a
total of twelve coils to measure these gradients, which results in
an over-determined system. The over-determined system can be solved
in the least squares sense by the standard methods to yield nine
components:
[0129] *Bx/*x *By/*xa *Bz/*x [0134] *Bx/*y *By/*y *Bz/*y [0135]
*Bx/*z *By/*z *Bz/*z
[0130] These nine components are not linearly independent because
Maxwell's equations require that the magnetic field has no
divergence (del dot B=0) and there are only eight independent
components and therefore a minimum of eight coils is required to
fully resolve the local curvature and magnitude of the magnetic
field. Again, the positions and orientations of these coils do not
have to be on a rectilinear set of axes but may be placed on the
surface of a sphere, for example. More than eight coils may be
reduced to the minimal set of components in a least squares
sense.
[0131] These and other modifications will be readily apparent to
those skilled in the art. Therefore the protection afforded the
present invention should only be limited in accordance with the
scope of the following claims and their equivalents.
* * * * *