U.S. patent application number 10/414771 was filed with the patent office on 2004-10-21 for doppler-based automated direction finding system and method for locating cable television signal leaks.
This patent application is currently assigned to Cable leakage Technologies, Inc.. Invention is credited to Eckenroth, Kenneth J., Ostteen, Michael E..
Application Number | 20040207555 10/414771 |
Document ID | / |
Family ID | 33029739 |
Filed Date | 2004-10-21 |
United States Patent
Application |
20040207555 |
Kind Code |
A1 |
Eckenroth, Kenneth J. ; et
al. |
October 21, 2004 |
DOPPLER-BASED AUTOMATED DIRECTION FINDING SYSTEM AND METHOD FOR
LOCATING CABLE TELEVISION SIGNAL LEAKS
Abstract
Provided is a Doppler based automated direction finding system
that detects radio frequency (RF) leaks in a cable television
plant. During a ride-out, the system detects leaks and stores leak
data, such as amplitude, location, and bearing. The stored data is
uploaded to a computer that performs a leak analysis. The leak
analysis isolates the leaks using Doppler-based bearing information
and separates cable leaks from other RF sources, such as power
sources and noise. Erroneous information that results from RF
reflections (multi path) may be eliminated while processing the
data using triangulation. After the leak analysis, the computer
generates work orders and maps, makes the data available to users,
and may also compile information and file reports based on the
data.
Inventors: |
Eckenroth, Kenneth J.;
(Rowlett, TX) ; Ostteen, Michael E.; (Rowlett,
TX) |
Correspondence
Address: |
HAYNES AND BOONE, LLP
901 MAIN STREET, SUITE 3100
DALLAS
TX
75202
US
|
Assignee: |
Cable leakage Technologies,
Inc.
Richardson
TX
|
Family ID: |
33029739 |
Appl. No.: |
10/414771 |
Filed: |
April 16, 2003 |
Current U.S.
Class: |
342/418 ;
324/520; 342/459; 702/59 |
Current CPC
Class: |
G01S 3/54 20130101; G01R
31/083 20130101 |
Class at
Publication: |
342/418 ;
342/459; 324/520; 702/059 |
International
Class: |
G01S 003/52; G06F
019/00; G01R 031/08 |
Claims
What is claimed is:
1. A method for identifying a radio frequency (RF) leak location in
a cable television system, wherein the method uses leak data that
includes a plurality of data sets, wherein each data set includes a
longitude, a latitude, and Doppler-based bearing information, the
method comprising: analyzing the bearing information associated
with a leak; discarding erroneous bearing information that results
from multi path; and calculating a location of the leak using a
triangulation process based on the longitude, latitude, and bearing
information of at least two of the plurality of data sets.
2. The method of claim 1 further comprising searching for at least
one pattern in the plurality of data sets, wherein the pattern
enables the location of the leak to be identified with greater
accuracy than using the triangulation process alone.
3. The method of claim 1 further comprising multiplying an
amplitude of the leak by a distance-based multiplier, wherein the
multiplier is adjusted according to a distance calculated using the
triangulation process.
4. The method of claim 1 further comprising characterizing the leak
to determine whether it is a cable television leak, wherein the
characterizing includes performing a spectral analysis.
5. The method of claim 1 wherein analyzing the bearing information
further comprises: identifying each bearing associated with the
leak; calculating a line through each identified bearing and the
leak; and calculating one or more points of intersection between
the lines.
6. The method of claim 5 further comprising using a range to
calculate the points of intersection, so that lines falling within
the range are identified as intersecting and lines falling outside
the range are identified as not intersecting.
7. The method of claim 5 further comprising averaging two or more
lines to form an average line and using the averaged line when
calculating the one or more points of intersection.
8. The method of claim 1 further comprising generating a map based
on the calculated location of the leak.
9. The method of claim 8 wherein generating the map further
comprises: creating a symbol for the leak based on a spectral
analysis, wherein the symbol indicates whether the leak is an
emission from a cable television system; creating an amplitude
indicator for the leak based on an amplitude of the leak; and
assigning an address to the leak based on the calculated location
of the leak.
10. A system for detecting a radio frequency (RF) leak in a cable
television plant, the system comprising: a processor; an antenna
unit accessible to the processor, wherein the antenna unit
comprises: a base; at least four vertical elements, wherein each
vertical element is oriented approximately perpendicular to the
base and connected thereto; and at least four horizontal elements,
wherein each horizontal element is oriented approximately parallel
to the base and connected thereto for extending a ground plane
formed by the base; a positioning unit accessible to the processor
for providing a current location; and an RF detector accessible to
the processor for detecting an amplitude of an RF emission, wherein
bearing data is generated based on a signal received from each of
the four vertical elements from the antenna unit, and wherein the
processor stores the bearing data, current location, and amplitude
in a memory.
11. The system of claim 10 further comprising a communication unit
for transferring the stored bearing data, current location, and
amplitude from the memory to an external device for processing.
12. The system of claim 11 wherein the communication unit is
operable to effect the transfer in a wireless manner.
13. The system of claim 10 wherein the base is substantially rigid
and wherein each of the vertical and horizontal elements is
flexible.
14. A network accessible computer system for processing data
associated with a plurality of radio frequency (RF) leaks in a
cable television system, wherein the data includes a plurality of
data sets, each data set containing signal information, an
amplitude, a longitude, a latitude, and Doppler-based bearing
information, the system comprising: a processor; a memory
accessible to the processor, wherein the memory is operable to
store the plurality of data sets; and a plurality of instructions
for processing by the processor, the instructions for: performing a
spectral analysis of the signal information to identify whether an
RF emission is a leak is from the cable television system;
performing a Doppler analysis using the longitude, latitude, and
bearing information to calculate a location of each leak; and
automatically generating leak information using the location
calculated by the Doppler analysis.
15. The system of claim 14 wherein the Doppler analysis further
comprises instructions for: analyzing bearing information
associated with each leak; rejecting bearing information that
results from erroneous data, wherein the erroneous data is
identified during the analyzing; and calculating a location of the
leak using a triangulation process based on the longitude,
latitude, and bearing information of at least two of the data
sets.
16. The system of claim 15 wherein the Doppler analysis further
comprises: identifying bearings associated with each leak in the
bearing information; calculating a line through each identified
bearing and the associated leak; and calculating one or more points
of intersection between the lines of each leak.
17. The system of claim 16 further comprising using a range to
calculate the points of intersection, so that lines falling within
the range are identified as intersecting and lines falling outside
the range are identified as not intersecting.
18. The system of claim 17 further comprising using an average to
calculate a line, wherein two or more lines are averaged to form an
average line.
19. The system of claim 14 wherein the leak information is made
available to a user via a web browser.
20. The system of claim 14 further comprising a wireless
communications interface, wherein data can be transferred from a
data collection device to the computer system via the wireless
communications interface in a wireless manner.
Description
BACKGROUND
[0001] The present disclosure relates generally to detecting cable
leakage and, more specifically, to a system and method for locating
and identifying cable television signal leaks.
[0002] Cable television is a system (e.g., a cable "plant") for
delivering television signals to subscribers or viewers by means of
coaxial cable. When signals above a certain power level leak from
the cable plant into the atmosphere, they may conflict with those
used by the aviation industry. Signal leakage can occur in a
variety of situations, such as when the shielding of cable cracks
or becomes weathered, when connectors become loose, or when the
cable breaks.
[0003] Rules promulgated by the Federal Communications Commission
(FCC) require cable television operators to monitor their cable
plants, including their transport media (e.g., cables). Among other
items, these rules cover monitoring and reporting on signal "leaks"
that occur in the cables. To comply with these standards, cable
companies must make power measurements of their facilities and
report data obtained during the measurements to the FCC.
[0004] Although various methods have been developed to locate cable
television leaks, each method presents one or more disadvantages.
For example, some methods lack effectiveness in locating or
identifying leaks, while others are costly or time consuming.
[0005] Accordingly, what is needed is a system and method for
accurately locating and identifying leaks, recording information
regarding each located leak, and utilizing the recorded information
to comply with regulatory requirements, schedule repairs, and
monitor cable infrastructure.
SUMMARY
[0006] Provided is a system and method for detecting cable leakage.
In one embodiment, the system is for processing data associated
with a plurality of radio frequency (RF) leaks in a cable
television system. The data includes a plurality of sets, each set
containing signal information, an amplitude, a longitude, a
latitude, and Doppler-based bearing information. The system
comprises a processor, a memory, and a plurality of instructions.
The memory is accessible to the processor and is operable to store
the plurality of data sets. The plurality of instructions are for
performing a spectral analysis using the signal information to
identify whether an RF emission is a leak from the cable television
system, performing a Doppler analysis using the longitude,
latitude, and bearing information to calculate a location of each
leak, and automatically generating repair information using the
location calculated by the Doppler analysis.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a flow chart of an exemplary method for
collecting, processing, and provisioning cable leakage data to an
end user.
[0008] FIG. 2 is a block diagram illustrating components of an
exemplary Doppler-based leak detection system that may be used in
the method of FIG. 1.
[0009] FIG. 3 is a perspective view of an antenna from the system
of FIG. 2.
[0010] FIG. 4 is an underside view of the antenna of FIG. 3.
[0011] FIG. 5 is a flow chart of an exemplary method for collecting
and storing cable leakage data using the leak detection system of
FIG. 2.
[0012] FIG. 6 is an exemplary computer system that may be used to
process and provision data collected using the method of FIG.
5.
[0013] FIG. 7 is a flow chart of a data processing method that may
be performed using the computer system of FIG. 6.
[0014] FIG. 8 is a flow chart of a leak analysis that may be
performed by the method of FIG. 7.
[0015] FIG. 9 is a flow chart of one method by which radio
frequency sources may be assigned symbols by the method of FIG.
7.
[0016] FIG. 10 is a flow chart of a Doppler routine that may be
performed by the method of FIG. 7.
[0017] FIG. 11 is an exemplary screen shot of a work order that may
be generated by the method of FIG. 7.
[0018] FIG. 12 is an exemplary screen shot of a map that may be
generated by the method of FIG. 7.
DETAILED DESCRIPTION
[0019] The present disclosure relates generally to detecting cable
leakage and, more specifically, to a system and method for locating
and identifying cable television signal leaks. It is understood,
however, that the following disclosure provides many different
embodiments or examples. Specific examples of components and
arrangements are described below to simplify the present
disclosure. These are, of course, merely examples and are not
intended to be limiting. In addition, the present disclosure may
repeat reference numerals and/or letters in the various examples.
This repetition is for the purpose of simplicity and clarity and
does not in itself dictate a relationship between the various
embodiments and/or configurations discussed.
[0020] Referring to FIG. 1, in one embodiment, a method 100
illustrates the collection, processing, and provisioning of data
that is obtained using a cable leakage detection system. As will be
described later in greater detail, the method 100 begins in step
102, where a ride-out is performed. During the ride-out, a vehicle
containing the cable leakage detection system traverses a route.
The cable leakage detection system automatically stores information
about leaks that are detected along the route, such as radio
frequency (RF) intensity (e.g., amplitude), location, etc. In step
104, the data is uploaded to a computer for processing.
[0021] In step 106, the computer performs data processing
operations, which may include performing a leak analysis and/or
using Doppler-based calculations to isolate a leak's location. In
step 108, work orders may be generated based on the processed data
and made available to a user through email, a web page, etc. In
addition, street maps may be generated based on the processed data
to indicate the locations of leaks. The map generation may include
automatically sizing and labeling the maps, and making the maps
available to the user. In steps 110 and 112, leak repair data may
be uploaded and the work orders associated with the uploaded data
may be closed.
[0022] It is understood that the method 100 is only one example and
that many of the steps may be completed in a different order, and
steps may be added or omitted. For example, the method 100 may
generate reports using the data and electronically filing the
reports with the Federal Communications Commission (FCC).
[0023] Referring to FIG. 2, one embodiment of a detection system
200, such as may be used in step 102 of FIG. 1, is illustrated. The
detection system 200 includes a control unit 202, an antenna unit
204, an automated direction finding (ADF) unit 206, and a Doppler
unit 208. The control unit 202, antenna unit 204, ADF unit 206, and
Doppler unit 208 may be mounted in a vehicle (not shown). For
example, the control unit 202 may be mounted in a docking station
210 in the passenger compartment of the vehicle, with the Doppler
unit 208 mounted to the back of the docking station 210. The
antenna unit 204 may be secured to the roof of the vehicle, and the
ADF unit 206 may be fastened to the antenna unit 204. In the
present example, the various components 202, 204, 206, 208 are
connected by cables 212, but it is understood that wireless,
optical, or other connection means may also be used.
[0024] The control unit 202 includes a processor/microcontroller
214, a memory 216, a global positioning system (GPS) unit 218, a
user interface 220, a communications interface 222, and an RF meter
224. A bus system 226 may be used to connect the various components
214, 216, 218, 220, 222, 224. The processor 214 is connected to the
memory 216, GPS unit 218 (which may be associated with an antenna),
user interface 220, communications interface 222, RF meter 224, and
Doppler unit 208 (through the docking station 210). The processor
214 receives bearing information from the Doppler unit 208,
position information from the GPS unit 218, user input information
from the user interface 220, and RF intensity information from the
RF meter 224. The processor 214 also stores data in the memory 216.
The memory 216 may include permanent memory, removable media (e.g.,
floppy disks, CD-ROMs, flash cards, etc.), and dynamic memory
(e.g., random access memory (RAM)). The communications interface
222 may provide a communications channel between the control unit
202 and the docking station 210. The communications interface 222
may also include components for use in wired or wireless
communications with other devices (not shown). Although not shown
in detail, the user interface 220 may include buttons, switches, a
keypad, a touch screen, or similar interactive controls that let a
user interact with the control unit 102, as well as a screen
display or other output portion.
[0025] The RF meter 224 may be configured to measure signals in a
broad spectrum of bandwidths, and may also be configured to display
the measured signal strength in a variety of formats. For example,
cable television operators generally monitor carrier signals in the
frequency bands 108-150 MHz. The RF meter 224 may be configured to
monitor the signal strength of carrier signals in these frequency
bands. In addition, the RF meter 224 may be configured to calculate
signal strength measurements based on the distance between the RF
meter 224 and the source of the measured signal. The RF meter 224
or the processor 214 may make adjustments to detected leak levels
based on a user defined multiplier that is entered into the control
unit 202 through the user interface 220. For example, the control
unit 202 may enable the user to indicate a distance from the RF
meter 224 to a cable. The distance may be entered or may be
selected from a range of distances. The multiplier accounts for the
distance, so that selecting a distance of 20 feet results in a
multiplier of 2 (e.g., 2.times. detected leak level). Accordingly,
a leak recorded as a 20 would become a leak of 40. Similarly,
selecting a distance of 160 would result in the leak being recorded
as a 320. This enables the control unit 202 to account for
variations in distance between the RF meter 224 and the source of
the leak.
[0026] It is understood that certain components that are
illustrated as being contained in the control unit 202 may be
separate components. For example, the GPS unit 218 and the RF meter
224 may both be separate from the control unit 202 and may
communicate with the processor 214 via an interface, such as the
communications interface 222.
[0027] Power to the control unit 202 may be provided from a variety
of sources, such as an external direct current source (e.g., a
vehicle battery). When the control unit 110 is powered on, a
software program is executed by the processor 216, as will be
described in greater detail below with reference to FIG. 5.
[0028] Referring now to FIG. 3, one embodiment of the antenna unit
204 is illustrated in greater detail. In the present example, the
antenna unit 204 comprises a relatively rigid square base 300 that
is sixteen and a half inches on each side. The base 300 forms a
planar surface with an upper surface 302 and a lower surface 304.
Four vertical elements 306, 308, 310, 312 are positioned on the
upper surface 302 so that one vertical element is at each corner
and oriented perpendicular to the planar surface of the base 300.
Each vertical element 306, 308, 310, 312 is the same length, which
may be generally between eighteen and twenty-four inches long. The
actual length selected for the vertical elements depends on the
wavelength of the signals to be detected. For example, each
vertical element may be approximately 1/4 wavelength of the target
signal. Cable RF signals used for signal leakage are generally in
the range of 108-150 MHz. As is known in the art, the 1/4
wavelength for the 150 MHz signal may be calculated as 11811
inches/150/4=19.685 inches. Accordingly, a length may be selected
for the vertical elements 306, 308, 310, 312 that maximizes
performance over the desired range of frequencies. Furthermore, the
vertical elements 306, 308, 310, 312 may be spaced to avoid
undesirable intercoupling, which may occur with a spacing of 1/8
wavelength.
[0029] The base 300 includes four corners 314, 316, 318, 320. One
of four horizontal elements 322, 324, 326, 328 is attached to each
corner and oriented parallel with the planar surface of the base
300. In some embodiments, each comer may be bent upwards or
downwards so as to present a small surface that is approximately
perpendicular to the planar surface of the base 300. The horizontal
elements 322, 324, 326, 328 may then be attached to the small
perpendicular surfaces. The horizontal elements 322, 324, 326, 328
serve to extend the size of the base 300 while providing
flexibility. For example, if the horizontal elements 322, 324, 326,
328 are each twenty-four inches long, an additional two feet may be
added to each side of the base 300, depending on the orientation of
the horizontal members. Although more than four horizontal elements
may be used, it has been discovered that four horizontal elements
are generally sufficient to gather the wavelength and the resulting
amplitude.
[0030] Because the horizontal members 322, 324, 326, 328 are
flexible, they can return to their original position after being
displaced. For example, the base 300 may be mounted to the roof of
a truck that has a ladder rack on each side. The base 300 may be
mounted on one or more "legs" (not shown) that raise the base 300
above the ladder racks. Due to the relatively small footprint of
the base 300, not much room is needed. However, the horizontal
elements 322, 324, 326, 328 make the base 300 functionally larger
and, because they are flexible, they can be displaced by ladders,
etc., and return to their original position.
[0031] Referring also to FIG. 4, the ADF unit 206 may be attached
to the lower surface 304 of the antenna unit 104. The ADF unit 106
includes an ADF antenna board 408 that is contained in a housing
410. The ADF antenna board 408 includes four pin diodes that are
connected to the four vertical elements 306, 308, 310, 312 (FIG. 3)
via connections 412. The ADF antenna board is also connected to the
Doppler unit 208 via a coaxial cable 414 and a multiple conductor
wire 416. In operation, the pin diodes may be switched on and off
relatively quickly by the Doppler unit 208, enabling the coaxial
cable 414 to sequence through the vertical elements 306, 308, 310,
312. In the present example, sixteen points of resolution are
provided, with each point representing a direction. It is
understood that more points of resolution (e.g., thirty-two or
sixty-four) may be used to provide additional directional
detail.
[0032] Referring now to FIG. 5, a method 500 (representing a
software program) may be used by the cable leakage detection system
200 of FIG. 2 to detect and store leakage data. In general, the
method 500 "reads" signal bearing information from the Doppler unit
208 (as detected by the antenna unit 204 and ADF unit 206),
geographic location information (e.g., longitude and latitude) from
the GPS unit 218, and signal strength information (e.g., power)
from the RF meter 224. The method 500 then extracts the read
information and stores it in a file in the memory 216. In the
present example, the information is stored in one of four comma
delimited text files. The four files pertain to a range of signal
strengths. For example, the four files may pertain to signal
strength ranges: (1) 0-19 .mu.V/m; (2) 20-49 .mu.V/m; (3) 50-149
.mu.V/m; and (4) 150 .mu.V/m and up.
[0033] After the control unit 202 is powered on, the method 500
controls the reading and storing of information received from the
Doppler unit 208, GPS unit 218, user interface 220, and RF meter
224, as well as the display of information through the user
interface 220. The storing of information is performed by writing
information to the memory 216.
[0034] At step 502, the processor 214 of the control unit 202 reads
the memory 216 to determine whether a configuration file (not
shown) exists on a removable memory device (assuming such a device
is present). The configuration file is an editable file that may be
used to initialize various parameters of the cable leakage
detection system 200. One such parameter may include the default
distance between the RF meter 224 and the source of the measured
signal. Another such parameter may include a distance at which
measurements from the RF meter 224 may be appended with one or more
symbols (e.g., a `*`, ` `(a space), `<`, or `>`) within one
of the four comma delimited text files. Each of these symbols is
designated as a "DMARK." The DMARK is used to annotate measurements
that are being taken by the RF meter 224, when the meter is set at
a high sensitivity threshold. For example, measurements made at
distances greater than 100 feet, may read 25 .mu.V/m while the same
reading taken at 20 feet may read 5 .mu.V/m. This DMARK can then be
imported along with the measured signal into a mapping program for
display. If a configuration file exists on the removable memory
device, the method 500 proceeds to step 504.
[0035] At step 504, the configuration file is read into the memory
(RAM) of the control unit 202. The designated parameters associated
with the configuration file are then transferred by the processor
214 to the RF meter 224. Upon receipt of the parameters, the RF
meter 224 begins measuring the designated frequency, and calculates
the power of the designated frequency according to the distance
parameter provided. If, at step 502, a configuration file does not
reside in the removable memory device, a default configuration file
is read, at step 506, from the memory 216 and transferred to the RF
meter 224, as above. The method 500 then proceeds to step 508.
[0036] At step 508, the processor 214 of the control unit 202 reads
the power measurement from the RF meter 224. Typically, this power
measurement is in numerical units such as 50 .mu.V/m. The power
measurement is based on the distance between the RF meter 224 and
the source of the measured signal, and relates to the designated
frequency band. The method 500 then proceeds to step 510.
[0037] At step 510, a spectral analysis is performed to identify
spectral indicators based on the power measurements obtained in
step 508. The spectral analysis is designed to determine whether a
detected RF signal is from a cable leak (CABLE), a power source
(POWER), or noise (INTERFERENCE), such as erroneous RF
transmissions. In the present example, the following default values
(which may be changed by a user) are in use:
1 Leak levels (.mu.V/m) 1:200 2:150 3:100 4:50 Search radii (m)
1:200 2:150 3:100 4:50
[0038] The spectral analysis may model the physics of a leak
because leaks with larger values radiate further than leaks with
smaller values. For example, it would be difficult to find a 50
.mu.V/m leak that is close to a 200 .mu.V/m leak, because the 200
.mu.V/m leak would mask the 50 .mu.V/m leak. This relationship is
reflected in the spectral analysis. During the spectral analysis,
an initial leak parameter is used to identify level 1 leaks (e.g.,
leaks of 200 .mu.V/m and higher). A 200 meter leak circle (based on
the search radii) is drawn with its origin at the source of the
highest leak level. It is understood that a leak circle may not
actually be drawn, but that a drawn circle is useful for purposes
of illustration. Within the leak circle, the data may be analyzed
to identify attributes from which spectral indicators may be
derived. For example, spectral indicators may be used to identity
whether a detected RF signal is from a cable leak, a power source,
or noise. For purposes of illustration, the following spectral
indicators are used: `-`=INTERFERENCE; `#`=POWER; `+`=CABLE
[0039] In the case of power, the data may be analyzed to identify
spikes that rise from a noise floor. If a spike is high enough
(when compared to a predetermined level), it is assigned the `#`
spectral indicator, indicating that the signal is coming from a
power source. Similarly, the data may be analyzed to identify video
signatures, in which case the source is assigned a `+` spectral
indicator. If the data has no identifiable characteristics, it may
be assigned a default symbol, such as the `-` spectral indicator.
After the spectral analysis is complete, the method 500 continues
to step 512.
[0040] At step 512, the processor 214 may display the read power
measurement via the user interface 220. At this point, a user of
the cable leakage detection system 200 can examine a display
associated with the user interface 220 to determine the measured
signal strength of the designated frequency band. The method 500
then proceeds to step 514, where the processor 214 reads
geographical position information from the GPS unit 218. The
geographical position information may include such information as
longitude, latitude, altitude, and time. The method 500 then
proceeds to step 516.
[0041] In step 516, the processor 214 receives bearing information
from the Doppler unit 208. The Doppler unit 208 may obtain and
process bearing information from the antenna unit 204 and ADF unit
206 as follows. In the present example, the Doppler unit 208
rapidly sequences through the pin diodes of the ADF unit 206 and
sequentially reads data from each vertical element 306, 308, 310,
and 312 of the antenna unit 304. This provides sets of four
readings (e.g., data points) that may then be processed by the
Doppler unit 208 to provide bearing information based on the
strength of the reading from each vertical element 306, 308, 310,
and 312. As the antenna unit 204 moves relative to a leak,
additional bearing information may be obtained that provides
additional information regarding the leak's location through, for
example, triangulation.
[0042] The method 500 then proceeds to step 518, where the
processor 214 stores the power measurement read at step 508, the
longitude and latitude geographic information read at step 514, and
the bearing information read at step 516, into the memory 216
within the control unit 202. In the present example, the
information is stored as a comma delimited text file (e.g., power,
longitude, latitude, bearing). The processor 214 then forms a
continuous processing loop by proceeding back to step 508. The
processing loop, which may include steps 508 through 518, may
execute at predetermined intervals, such as once per second. Thus,
every second the control unit 202 reads a power measurement from
the RF meter 224, geographic information from the GPS unit 218,
bearing information from the Doppler unit 208, and stores the power
measurement, the longitude and the latitude, and the bearing into a
comma delimited text file. This process continues until the control
unit 202 is turned off, paused, or until an end command is entered,
as discussed below.
[0043] The software program embodying the method 500 may include
several interrupt routines that are designated as steps 520 through
530. The first, step 520, may be used if the comma delimited text
file is stored in temporary memory (e.g., RAM) in step 518 or if a
backup copy is to be made. For example, the routine may interrupt
the continuous loop of steps 508 through 518 at predetermined
intervals (e.g., every two minutes) for the purpose of storing the
comma delimited text file into the memory 216 (from RAM) or writing
the file to a backup disk, such as a floppy disk. This step
provides data backup to the control unit 202 such that if power is
lost, no more than two minutes (or another predetermined time
interval) of data will be lost.
[0044] In some embodiments, the processor 214 may perform
processing on the comma delimited text file before storing it. For
example, the processing may begin when the processor 214 examines
the text file to determine the value of the measured power signal
for each second of time. The processor 214 extracts the comma
delimited text file into one of the four different text files
discussed above according to predefined signal strength criteria.
For example, one text file may contain power, longitude and
latitude, and bearing for power measurements between 0 and 19
.mu.V/m, a second text file may contain power measurements between
20 and 49 .mu.V/m, a third text file may contain power measurements
between 50 and 149 .mu.V/m, and a fourth text file may contain
power measurements above 149 .mu.V/m. After extracting the
delimited text file into four different text files, the processor
214 may store the files as described. The method 500 then continues
the execution loop of steps 508 and 518.
[0045] When the processor 214, at step 520, stores the text files,
it may first read the memory 216 to determine whether any comma
delimited text files already exist. If text files do exist in the
memory 216 pertaining to the four signal strength designations, the
processor 214 appends the new files onto the preexisting files.
Thus, no preexisting files are written over by the processor 214.
If no text files exist in the memory 216 during the execution of
step 520, the processor 214 creates the files and stores the comma
delimited text within them.
[0046] A second interrupt, step 522, may occur when a user wishes
to change the distance between the RF meter 224 and the measured
signal. As described previously, a user may wish to change the
distance measurement to provide more accurate power readings
depending on the distance to the source of the measured signal. The
user enters the desired distance or selects a distance from a
predetermined range using the interface 222. Upon receipt, the RF
meter 224 calculates the measured power according to the new
distance.
[0047] A third interrupt, step 524, provides a user with the
ability to create other comma delimited text files according to his
own criteria. The other text files are termed "flag files" and
contain a flag letter (e.g., A, B, or C) as well as longitude,
latitude, and bearing. This capability allows a user to log to the
memory 216 location information of particular observable
information such as a broken cable (flag A), a damaged pedestal
(flag B), etc. The files may be created using the user interface
220. The processor 214 stores the flag, along with the most
recently read longitude and latitude into a comma delimited text
file in the memory 216. The processor 214 may append subsequent
flag entries into existing text files in the manner described
above.
[0048] A fourth interrupt is provided at step 526 which allows a
user to end the method 500, and thus end the logging of power
measurements to the memory 216. The user can end the method 500,
for example, by pressing a key associated with the user interface
220. The key press is transmitted to the processor 214. Upon
receipt, the processor 214 stores the existing text files into the
memory 216, discontinues reading information from the Doppler unit
208, GPS unit 218, and RF meter 224, and halts program execution.
In some embodiments, the control unit 202 may not be able to
restart execution until power is turned off and then back on.
[0049] A fifth interrupt is provided at step 528 that allows a user
to start, pause, or restart the method 500 from the user interface
220. For example, the user may toggle between program execution and
program pause by pressing one or more keys associated with the user
interface 220. If the method 500 is already being executed,
pressing the key may cause the method to pause or suspend
execution.
[0050] A sixth interrupt may provided at step 530 that allows a
user to set the speed at which power, position, and bearing
information are read from the RF meter 224, GPS unit 218, and
Doppler unit 208, and stored in the memory 216. The speed may be
entered via the user interface 220 by entering a desired time
interval or by selecting a time interval from a predetermined
range. The processor 214 then logs data at a rate corresponding to
the entered speed.
[0051] In addition to the above interrupts, a supervisory interrupt
(not shown) may be provided that produces an error log of
particular error conditions that may occur within the control unit
202. For example, an error condition may result from the failure of
any one of the RF meter 224, GPS unit 218, Doppler unit 208, or
user interface 220 to communicate with the processor 214 within the
control unit 202. The error log may be a text file that details the
nature of the error and is stored in the memory 216.
[0052] Referring now to FIG. 6, in another embodiment, an exemplary
computer 600, such as may utilize leakage data collected using the
method 500 of FIG. 5, is illustrated. The computer 600 may include
a central processing unit ("CPU") 602, a memory unit 604, an
input/output ("I/O") device 606, and a network interface 608. The
components 602, 604, 606, and 608 are interconnected by a bus
system 610. It is understood that the computer may be differently
configured and that each of the listed components may actually
represent several different components. For example, the CPU 602
may actually represent a multi-processor or a distributed
processing system; the memory unit 604 may include different levels
of cache memory, main memory, hard disks, and remote storage
locations; and the I/O device 606 may include monitors, keyboards,
and the like.
[0053] The computer 600 may be connected to a network 612. Because
the computer 600 may be connected to the network 612, certain
components may, at times, be shared with other computers and
digital devices 614. Therefore, a wide range of flexibility is
anticipated in the configuration of the computer. Furthermore, it
is understood that, in some implementations, the computer 600 may
act as a server to other computers 614.
[0054] Referring now to FIG. 7, in another embodiment, a method 700
illustrates using the computer 600 of FIG. 6 to process data that
was collected using the method 500 of FIG. 5. In the present
example, the computer 600 is a server and may be accessed by other
computers 614. In step 702, data is uploaded to the server 600 for
processing. The data may be uploaded to the computer server in a
variety of ways. For example, the data may be transferred from the
control unit 202 to a computer (e.g., the computer 614) using
removable media (e.g., a floppy disk or flash card), by wireless
transfer (e.g., Nextel, CDPD, or GSM/GPRS), by a cable (e.g., a
serial cable), or by interfacing the control unit 202 with a
docking station connected to the computer 614. The computer 614 may
then transfer the data to the server 600. In some embodiments, each
detection system 200 may be associated with a unique identifier
that may be used by the server 600 to identify the source of the
uploaded data. Accordingly, a user may initiate an upload procedure
by pressing a key associated with the user interface 220 of the
control unit 202, at which time a client program residing on the
computer 614 will retrieve the data from the memory 216, transfer
the data to the server 600, store a backup of the data in the
computer 614's memory, and delete the files from the memory
216.
[0055] In step 704, the uploaded data is processed. Exemplary
processing may include leak analysis (FIGS. 8 and 9) and the
execution of Doppler routines on the data (FIG. 10).
[0056] Referring also to FIG. 8, a method 800 illustrates the leak
analysis of step 704 in greater detail. Once the data is uploaded
to the server 600, a leak analysis may be initiated that performs a
logical search through the data. In the present example, the
following default values (which may be changed by a user) are in
use:
2 Leak levels (.mu.V/m) 1:200 2:150 3:100 4:50 Search radii (m)
1:200 2:150 3:100 4:50
[0057] The leak analysis may model the physics of a leak because
leaks with larger values radiate further than leaks with smaller
values. For example, it would be difficult to find a 50 .mu.V/m
leak that is close to a 200 .mu.V/m leak, because the 200 .mu.V/m
leak would mask the 50 .mu.V/m leak. This relationship is reflected
in the leak analysis.
[0058] In steps 802 and 804, the method 800 begins with an initial
leak parameter and identifies level 1 leaks (e.g., leaks of 200
.mu.V/m and higher). In step 806, a 200 meter leak circle (based on
the search radii) is drawn with its origin at the source of the
highest leak level. It is understood that a leak circle may not
actually be drawn, but that a drawn circle is useful for purposes
of illustration. The method 800 then proceeds to step 808, where
symbols are derived based on spectral indicators (such as those
assigned in step 510 of FIG. 5), as is illustrated in greater
detail in FIG. 9.
[0059] Referring also to FIG. 9, a method 900 assigns symbols based
on a previous spectral analysis. It is understood that the spectral
analysis may be performed as part of the present step if desired.
The symbols are designed to indicate whether a detected RF signal
is from a cable leak (CABLE), a power source (POWER), or noise
(INTERFERENCE), such as erroneous RF transmissions. The leak
analysis, using the results of the method 900 and the previously
determined amplitudes and spectral indicators, produces a point
file (e.g., a data set) that includes an amplitude, a symbol type,
and a spectral indicator for each leak. In the present example, the
following indicators and symbols are used:
[0060] Spectral indicators: `-`=INTERFERENCE; `#`=POWER;
`+`=CABLE
[0061] Symbols: circle=INTERFERENCE; triangle=POWER;
square=CABLE
[0062] The symbol (circle, triangle, or square) is selected as
follows. In step 902, a determination is made as to whether all the
spectral indicators inside the leak circle are `-`. If yes, the
method 900 proceeds to step 904, where the INTERFERENCE symbol
(circle) is selected. This is the only time the INTERFERENCE symbol
is created. If no, the method 900 continues to step 906, where a
determination is made as to whether there are more `+` or `#`
spectral indicators in the leak circle. The symbol is selected
based on a majority, so the POWER symbol (triangle) will be
selected if the majority of the spectral indicators are `#`(step
908), and the CABLE symbol (square) will be selected if the
majority of the spectral indicators are `+`(step 910). No majority
(e.g., a tie) results in the selection of the CABLE symbol (step
910).
[0063] Referring again to FIG. 8, after assigning the symbols based
on the spectral indicators, the method 800 continues to step 810,
where the street address that is nearest to the highest identified
leak level is selected. In step 812, all the data points in the
leak circle are removed except the highest identified leak level.
In step 814, a determination is made as to whether all of the
iterations have been performed (e.g., whether leaks have been
identified using the predefined parameters). If not, the method 800
proceeds to step 816, where the next leak parameter is selected.
The method 800 then returns to step 804 and identifies leaks,
performs spectral analysis, etc., as previously described with
respect to steps 804-814. This enables the method 800 to identify
and label smaller leaks that were covered by the highest identified
leak level. After the leak analysis is completed, the method 800
ends and the method 700 of FIG. 7 may execute a Doppler routine, as
is described in greater in detail with reference to FIG. 10.
[0064] Referring now to FIG. 10, a method 1000 uses bearing
information collected via the Doppler unit 208 to more accurately
characterize a leak. Although the method 1000 is illustrated for
purposes of clarity as a method separate from the leak analysis
method 700 of FIG. 7, it is understood that the method 1000 may be
integrated into the method 700.
[0065] Doppler based data may be used to overcome problems
associated with determining a source of the leak. For example, when
a vehicle is on a ride-out, it is difficult to calculate the actual
distance from the vehicle to the cable. One way to do this is to
use an estimated range, as was described above with respect to FIG.
5. Another way is to incorporate Doppler data, as this allows such
benefits as a triangulation. However, one problem with Doppler
based data stems from reflected signals (e.g., multi path). These
reflected signals may be detected, even though they are erroneous.
Multi path may affect both the amplitude of RF leakage levels and
the calculated location of the leaks. As will be described below,
the negative effect of multi path may be overcome while processing
the bearing data.
[0066] In step 1002, all bearings for each measured leak are
identified. In step 1004, lines are "drawn" (e.g., calculated) out
from each measured leak using the bearing information. For example,
if bearing information is taken on a single leak once a second for
three seconds, there would be three lines drawn from the leak. In
steps 1006 and 1008, points of intersection are determined for the
lines associated with each leak and, if a line does not match, it
is rejected as being the result of multi path. In some embodiments,
a range of intersecting lines may be averaged during the
processing. For example, one line that is twenty feet from a point
may be averaged with another line that is forty feet from the point
to produce a single line that is thirty feet from the point.
[0067] In step 1010, the distance to the leak can be calculated
using triangulation. The calculated distance may then be used to
alter the multiplier for that leak to more accurately identify the
amplitude of the leak. For example, a leak detected at 4 .mu.V/m
with a calculated distance of 80 feet would be identified as a 32
.mu.V/m leak.
[0068] The bearing information may also be examined to identify
patterns that provide additional details regarding a leak. For
example, a leak may be in a cable located at the back of a house,
rather than on a pole. During a ride-out, RF signals from the leak
may be detected when the detection system 200 is positioned on the
road between the house where the leak occurs and a neighboring
house, but may be blocked when a house is between the detection
system 200 and the leak. Accordingly, data representing the leak
will exist for the time the leak is detected (from between the
houses), but there will be no data for the positions on either side
of the leak (where a house is blocking the leak from being
detected). Therefore, by examining the data for a general pattern
(such as NULL, leak data, NULL), it may be determined that the leak
is at the back of a house, rather than on a pole. Other patterns
may be used to identify similar information.
[0069] It is understood that the bearing information may be used in
addition to the distance information gathered with respect to FIG.
5 (e.g., as a check) or may replace the distance data entirely.
After the leaks are processed using the Doppler routine, the method
1000 ends and the method 700 of FIG. 7 continues to step 706.
[0070] Referring again to FIG. 7 and also to FIG. 11, work orders
may be generated in step 706 based on the processing of step 704.
Referring specifically to FIG. 1, a work order 1100 may include
location information 1102, amplitude of the leak 1104 (which may be
corrected using Doppler data as described with respect to FIG. 10),
and additional information. In some embodiments, the work order may
be emailed to a technician and/or may be viewed as a web page
provided by the server 600.
[0071] Referring again to FIG. 7 and also to FIG. 12, maps and
associated information may be generated in step 708. Referring
specifically to FIG. 12, a map screen 1200 illustrates a map 1202
of a leakage area may be generated by superimposing the processed
data onto a digital map by latitude and longitude. For example, the
latitude and longitude of the work order of FIG. 11 may be used to
place the leak onto the map of FIG. 12, along with an associated
symbol 1206 as described above (e.g., a square for a cable leak). A
circle 1208 may be drawn around each leak to indicate the amplitude
of the leak or other information. Flag information (e.g., to
indicate a broken wire or a damaged pedestal) may also be indicated
on the map or in a comments section. Another map 1204 may reproduce
the general area of which the map 1202 is a part. It is understood
that the view of the map may be adjustable (e.g., zoomed in or
out), and that other known map techniques may be used to alter the
map as desired.
[0072] Other functionality may be incorporated into the method 700
as desired. For example, a user may access a map or list of
ride-outs, along with leaks that were detected during each
ride-out. A user may also define leak parameters that are used for
processing the data, as well as flags and other information. In
addition, the method 700 may be used to generate summaries,
reports, or other compilations of data to enable users to more
accurately estimate repair costs, equipment upgrades, personnel
needs, and perform other planning tasks. Furthermore, the method
700 may incorporate the data into a report, such as is required by
the FCC, and automatically file the report.
[0073] While the preceding description shows and describes one or
more embodiments, it will be understood by those skilled in the art
that various changes in form and detail may be made therein without
departing from the spirit and scope of the present disclosure. For
example, although a server is used to describe various embodiments
of the present disclosure, another computer or other digital device
could also be used. In addition, LORAN or other positioning
techniques may be used. Also, other mapping approaches may be
utilized as disclosed in detail in U.S. Pat. No. 5,294,937,
entitled "CABLE LEAKAGE MONITORING SYSTEM" and assigned to the same
assignee as the present disclosure, and hereby incorporated by
reference as if reproduced in its entirety. Therefore, the claims
should be interpreted in a broad manner, consistent with the
present disclosure.
* * * * *