U.S. patent application number 13/431782 was filed with the patent office on 2012-08-02 for remote meter reader using a network sensor system and protocol.
Invention is credited to Bar-Giora GOLDBERG, Gioia MESSINGER.
Application Number | 20120194683 13/431782 |
Document ID | / |
Family ID | 37854499 |
Filed Date | 2012-08-02 |
United States Patent
Application |
20120194683 |
Kind Code |
A1 |
GOLDBERG; Bar-Giora ; et
al. |
August 2, 2012 |
REMOTE METER READER USING A NETWORK SENSOR SYSTEM AND PROTOCOL
Abstract
A system and method is provided for automatically reading
meters, such as utility meters. A camera unit is attached to or
otherwise associated with an existing meter. From time to time,
either automatically, or upon wireless command, the camera unit
takes an image of the meter's readings, and communicates wirelessly
the image or image data, to a local area receiver. The images can
be transmitted immediately, or stored for later transmission,
depending on the network protocol. The camera unit is battery
powered, and operates communication protocols that enable extended
operational life. These protocols allow for the camera's radio and
processor to be turned on only when necessary, and then for only
brief periods of time. At most times, the camera is in a power
conserving sleep mode. Multiple camera units may be arranged to
communicate meter image data to the local area receiver, either
using asynchronous or synchronous processes.
Inventors: |
GOLDBERG; Bar-Giora; (San
Diego, CA) ; MESSINGER; Gioia; (Encinitas,
CA) |
Family ID: |
37854499 |
Appl. No.: |
13/431782 |
Filed: |
March 27, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11457098 |
Jul 12, 2006 |
8144027 |
|
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13431782 |
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60698134 |
Jul 12, 2005 |
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Current U.S.
Class: |
348/160 ;
348/E7.085 |
Current CPC
Class: |
G01D 4/008 20130101;
Y04S 20/42 20130101; H04Q 2209/50 20130101; Y02B 90/246 20130101;
G01D 4/002 20130101; Y04S 20/32 20130101; H04Q 2209/883 20130101;
H04Q 9/00 20130101; H04Q 2209/25 20130101; Y02B 90/20 20130101;
H04Q 2209/40 20130101; Y02B 90/241 20130101; Y04S 20/30 20130101;
G01D 5/39 20130101; H04Q 2209/60 20130101 |
Class at
Publication: |
348/160 ;
348/E07.085 |
International
Class: |
H04N 7/18 20060101
H04N007/18 |
Claims
1. An automated wireless meter reading system, comprising: a camera
unit adapted to be connected to a meter and with an image sensor
positioned to take an image of a meter reading area, the image
sensor normally operating in a sleep mode; a radio with the camera
unit and configured to wirelessly transmit meter data from the
camera, the radio constructed to wake up from time to time and send
a request signal; a receiver unit constructed to wirelessly receive
the meter data from the camera unit's radio and to send an
acknowledge signal to the radio only when meter data is needed; a
wide area connection with the receiver unit for communicating the
meter data to a central location; a battery providing all power to
operate the camera unit, image sensor, and the radio; and wherein
the image sensor is powered only in response to the radio receiving
the acknowledge signal and wherein the camera unit operates to
provide the wireless meter readings from time to time for a period
of more than two years prior to depletion of the battery.
Description
RELATED APPLICATIONS
[0001] This application is a continuation application of U.S.
patent application Ser. No. 11/457,098, filed Jul. 12, 2006, now
U.S. Pat. No. 8,144,027, issued Mar. 27, 2012, which claims
priority to U.S. provisional patent application No. 60/698,134,
filed Jul. 12, 2005, each of which is hereby incorporated in its
entirety including all tables, figures and claims.
FIELD OF THE INVENTION
[0002] The present invention relates to automatic meter reading and
specifically to an imager or miniature camera attached to a meter,
and to the wireless communication of meter data to a central
location. More particularly, the present invention relates to a low
power meter imager that wirelessly communicates meter image
data.
BACKGROUND
[0003] The field of remote sensing is growing rapidly. Remote
sensing has been found to be useful in security applications, as
well as for monitoring environmental, commercial and industrial
processes. Remote sensing may include capturing visible light
images, temperature, vibrations, seismic, infrared images, chemical
or acoustic data. The remote data is either stored locally for
later collection, or is transmitted via a wired or wireless
connection to a data collection point. However, the use of remote
imagers has been limited to applications where the remote camera
has a stable power source, such as connection to a utility grid, or
where the camera system can be conveniently accessed to change or
charge its battery. Accordingly, the applications for remote
imaging have been limited.
[0004] One application that could benefit from remote sensing is
remote meter reader. Meters, such as gas, electric, water, or other
utility meters, are attached to nearly every home or business.
These meters are often manually read every month, requiring a
utility company to send out a human meter-reader. This is an
expensive and time consuming process, and since the meters are
often located in private property areas, the meter-readers may be
subject to dog bites, human attack, or other dangers. Due to the
high cost of using human readers, some utilities use estimated
bills. With an estimated bill, the utility actually reads the meter
only a limited number of times per year, and based on historical
records, estimates bills for the months when no reading is taken.
At each reading cycle, there is a true-up, where the utility
credits for any over-charge, or a larger bill to make up for
underpayments. Either way, the estimated bills are a stop-gap so
the utility can save money, and often leads to great consumer
dissatisfaction.
[0005] Some new utility meters are being installed that have wired
or wireless communication of usage data to the utility. These
meters directly address the problem raised above, and in the long
term, may be a satisfactory solution. However, these meters are
quite expensive, and there are millions of legacy meters installed.
It will take many years, if not decades, to replace and update all
these meters. To date, there is no practical way to automatically
read these meters.
SUMMARY OF THE INVENTION
[0006] Briefly, the present invention provides a system and method
for automatically reading meters, such as utility meters by using a
low power wireless camera, sensor, or imager. The camera unit is
attached or otherwise associated with a meter. From time to time,
the camera unit takes an image of the meter's reading area, and
communicates the image or image data to a local area receiver. The
camera unit is battery powered, and operates communication
protocols that enable extended operational life. These protocols
allow for the camera's radio and processor to be turned on only
when necessary, and then for only brief periods of time. At most
times, the camera is in a power-conserving sleep mode. Multiple
camera units may be arranged to communicate meter image data to the
local area receiver, either using asynchronous or synchronous
processes. In this way, star, point-to-point, and ring topologies
are enabled. The meter image data is communicated from the receiver
to a central office using a wide area connection, where the image
data is used for determining the meter reading. In one example, the
image may be included with a utility bill as confirmed evidence of
the current meter reading.
[0007] Advantageously, the camera units of the present invention
may be attached to legacy meters, enabling very efficient and
accurate remote meter reading. Because of the low-power protocols
and structures in the camera units, in normal use the camera units
will operate autonomously for up to several years. Accordingly,
meter reading can be made more efficient and safe, and fully
automated remote meter reading is possible, even with older legacy
meters. This allows the cost, accuracy, and safety benefits of
remote meter readings to be used on existing meters. In addition,
frequent readings, even several times a day, are conveniently
possible. This enables utility companies to track hourly usage or
even charge per time of use (especially for electricity). In
addition, simple imaging DSP (digital signal processing) can be
applied to the meter image, and used to read the meter by the
utility. This information may then be used to compare to previous
readings by a computer, and create a bill without human
intervention thus improving reliability and productivity. In one
example, the bill may even include an image of the final meter
reading.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a block diagram of a meter reading system in
accordance with the present invention.
[0009] FIG. 2 is a block diagram of a meter reading system in
accordance with the present invention.
[0010] FIG. 3 is a block diagram of a meter reading system in
accordance with the present invention.
[0011] FIG. 4 is a block diagram of a meter reading system in
accordance with the present invention.
[0012] FIG. 5 is an image of meter dials taken with a meter reading
system in accordance with the present invention.
[0013] FIG. 6 is a flowchart of a method for meter reading in
accordance with the present invention.
[0014] FIG. 7 is a flowchart of a method for meter reading in
accordance with the present invention.
[0015] FIG. 8 is a flowchart of a method for synchronizing cameras
for meter reading in accordance with the present invention.
[0016] FIG. 9 is a flowchart of a method for meter reading in
accordance with the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0017] Referring now to FIG. 1, an automated meter reading system
is illustrated. System 10 generally comprises an imaging camera
unit 12 attached to or otherwise coupled to a meter 30. In one
arrangement, the camera includes a lens or lens system and a CCD or
CMOS imager. From time to time, camera unit 12 takes an image of
the reading area 32 of meter 30. Reading area 32 has dials, such as
dial 34, or a digital display for presenting utility usage
information. The image is captured by camera unit 12, and
communicated back to a receiver unit 40. In one example, receiver
unit 40 is a handheld device used by a human meter reader. In this
way, a person driving in a vehicle or walking a distance away from
the meter can remotely and wirelessly read the meter. In another
example, the receiver unit is in the residential or commercial unit
for meter 30, and wirelessly receives image data. The image data
may then be communicated through a wide area connection back to the
utility company. In another example, the receiver unit may be a
centrally located receiver or hub communicating to a network of
camera units. The receiver unit may communicate with cameras in a
star network arrangement, which may operate in a generally
asynchronous manner, or may be arranged as a ring or other network
structure requiring more synchronization. It will be appreciated
that the communication processes operating between camera unit and
the receiver unit 40 may be determined by the physical, electrical,
and application requirements for each installation.
[0018] Advantageously, camera unit 12 may be configured to take
meter readings as often as required or desirable for the utility
company. For example, meter 30 may be read several times a day to
assess peak utility usage. Also, the image of reading area 32 is a
precise, accurate record of the reading, so any billing disputes
may be immediately addressed. In one example, an image of reading
area 32 may be included with a consumer bill for verification of
accurate reading. As will be described below, camera unit 12
operates as a very low power imaging system. In this way, camera
unit 12 operates particular network protocols for reducing power
consumption. By conserving power, camera unit 12 may operate on
battery 24 for several years. Since camera unit 12 may operate
autonomously for years without maintenance, and provides an
accurate, timely, and efficient way of reading legacy analog or
digital meters, meter reading system 10 may be advantageously
deployed for existing residential and commercial applications.
[0019] One example of camera unit 12 is described. Camera unit 12
has a small and compact housing for enclosing and protecting camera
components. Camera unit 12 includes an imaging sensor 14 for
capturing images of a meter dials or displays. The sensor may be,
for example, a CMOS imager sensor for reduced power consumption, or
may employ CCD imaging technology. It will be appreciated that
other evolving technologies may be used to implement the sensor.
The sensor may also be constructed to capture visible wavelength
information, or may be set to detect other wavelengths, such as
infrared. The sensor cooperates with a lens 27 to obtain the
correct size and resolution of the image to facilitate automated or
manual interpretation of the image. It will be appreciated that the
resolution should be selected high enough to support the intended
automated detection processes, if used. It will also be understood
that the resolution needed will depend on dial or digit size,
distance to the meter reading area, quality of lens, and other
application characteristics. Of course, better resolution may
support simplified and more accurate reading, but will also require
more power to take and transmit the image. One skilled in the art
will understand the tradeoffs and compromises between resolution,
automated recognition, and power consumption. Camera unit 12 also
has processor 16 for providing control and processing capability to
the camera unit. For example, processor 16 may be constructed to
configure and control sensor 14. In another example, processor 16
may apply image processing to captured images, for example, to
compress, recognize, or encrypt image data. In one specific
example, processor 16 applies a JPEG compression algorithm to
images captured by sensor 14 to reduce file size while maintaining
image quality.
[0020] Processor 16 may also implement network control settings and
processes. For example, network control settings may define how
often the camera attempts to communicate with a receiver 40, or
settings regarding encryption or compression. Further, network
control settings may include a unique ID for the camera 12. The
unique ID may be used to associate the camera with a particular
meter, and thereby be used by an accounting process to
automatically and confidently assure that the proper entity is
billed. In this way, a unique association is made between
particular meter data and the party-to-be billed. The unique ID
also enables a receiver 40 to be associated with a particular
camera, which may be a hub or another camera. Camera 12 also has
camera control settings. These camera control settings may set
integration times for sensor 14, define capture windows, or define
timing and sequential information regarding image capture.
[0021] In providing the various functions, processor 16 cooperates
with local memory 18. Local memory 18 provides storage space for
images captured by sensor 14, as well as memory space for
application and algorithmic processes performed by processor 16.
Camera 12 is intended for discrete installation, as well as
long-term operation without any required maintenance. This includes
for example remote operation relying fully on battery 24 for power.
Depending upon network and camera settings, camera 12 may operate
without battery replacement for up to three years or more. It will
be appreciated that as battery technology advances, additional
gains in battery life may be expected.
[0022] Battery 24 life is extended by having the camera normally
operate in a sleep mode, and only activating the camera for
necessary periods of time. More specifically, camera 12 normally
operates in a sleep mode where radio 20 is deactivated. Further,
except as discussed below, processor 16 is also deactivated. In
sleep mode, the processor 16 is deactivated except for a low power
timer. This low power timer draws in the range of 5 to 10 micro
amps of power. The low power timer may be set to generate an
interrupt at a set time or on a periodic basis. It will be
understood that the resolution and stability of the clock may be
selected according to application needs. For example, some
asynchronous communication processes may benefit from a relatively
inaccurate and unstable clock, while a synchronous system may need
a better resolution clock. When the low power timer generates an
interrupt signal, an interrupt activates radio 20 as well as
processor 16. The camera, now being activated, acts according to
its defined network controls and its camera controls. In one
specific example, when the camera first wakes up, it generates a
request signal through radio 20, which is transmitted by antenna
22.
[0023] After the request signal has been transmitted, the radio 20
enters a listen mode for a defined short period of time. For
example, this listen mode may be opened for 20 ms to 50 ms. During
this listen mode, the camera 12 is waiting to receive an
acknowledgment signal from a receiver, such as a hub or another
camera. If no acknowledgment signal is received during the listen
period, the camera 12 goes back to sleep, which may be for a
programmable time period. If however, the receiver 40 does respond,
then the receiver 40 may command the camera 12 to take an action.
These actions could include, to take an image, to transmit a stored
image, or to go back to sleep. Of course, the camera power
requirements increase dramatically while radio 20 and processor 16
are operating. However, the radio and processor operate for only a
short period of time, so the overall drain is not substantial.
Accordingly, it will be recognized that overall battery life is
highly dependent on how often the low power timer causes the camera
to wake up. For example, if the node camera 12 is set to wake up
and transmit its request signal once every 10 minutes, then the
battery life may extend to about three years. More frequent wake
ups will result in a shorter battery life. A more complete
description of low power cameras and low power protocols is
provided in co-pending U.S. patent application Ser. No. 11/210,411,
filed Aug. 24, 2005, and entitled "Network Sensor System and
Protocol", which is incorporated herein by reference as if set
forth in its entirety. It will be understood that the image can be
transmitted immediately after taken or stored as a data file in the
processor for later transmission, depending on the communication
protocol. Each image may have a time stamp as part of the
information field.
[0024] Both the camera unit and the Receiver unit include radio
transceivers to enable two way communications and power-conserving
networking protocols, as required by the network. Receiver unit 40
is constructed to wirelessly communicate with one or more camera
units, such as camera unit 12. The receiver unit 40 has a two-way
radio system 46 with antenna 48 constructed to cooperate with
radios in the camera units. The receiver unit also has a processor
42 and memory 44 for performing network, control, or algorithmic
processes. The receiver unit has a power source 50, which in some
cases may be a persistent source such as a connection to a utility
power grid. In other cases, power 50 may be from a battery or
rechargeable battery. For example, if receiver unit 40 is an 802.11
access point in a residential home, then the receiver unit 40 is
likely powered by connection to household power. In another
example, if receiver unit 40 is a handheld portable device, then
power 50 may be a rechargeable battery. In yet another example,
receiver unit 40 may be another camera, in which case power 50 will
be a regular battery. It will be appreciated that the type and
speed of the processor and the sophistication of applications
operating on the receiver unit, may in part be determined by the
type of power available.
[0025] Referring now to FIG. 2, a meter reading arrangement is
illustrated. Arrangement 100 has multiple camera units, such as
camera unit 12 described with reference to FIG. 1. Each camera unit
is located in a particular geography, such as at the service
entrance for a residential house, a commercial building, or an
industrial site. In FIG. 2, camera 102 is located on house 103,
camera 106 is located on house 107, and meter 110 is located on
house 111. Each camera 102, 107, and 111 is configured to
communicate wirelessly with receiver unit 115. Receiver unit 115
has a wide area connection to a utility company. In one example,
receiver unit 115 is a central hub operated by the utility company.
The receiver unit 115 operates an asynchronous network for
controlling and receiving image data from each of the cameras. From
time to time, the receiver unit 115 communicates meter reading data
to the utility company. In another example, receiver unit 115 may
be a portable receiver carried by a human meter reader or
positioned in a utility company vehicle. In this way, the portable
reader may be brought within a few hundred feet of meters, and
meters automatically and wirelessly read as the receiver unit 115
moves down the street. In this way, a meter reader does not have to
gain access to private areas of the house, but merely has to pass
by on the public sidewalk or street areas. A portable receiver unit
115 may have a wireless connection back to the utility company, or
may locally store data and then be connected to utility company
servers at a later time.
[0026] Referring now to FIG. 3, another arrangement 150 is
illustrated. Arrangement 150 has camera unit 152 located at house
154, camera unit 157 located at house 159, and camera unit 168
located at house 166. Each house has a receiver unit associated
with it. For example, house 154 has receiver unit 156, house 159
has receiver unit 161, and house 166 has receiver unit 164. It will
be appreciated that although the geographic areas of FIG. 3 are
illustrated with reference to residential homes, the geographic
areas may be residential apartments, commercial establishments, or
industrial facilities. It will also be understood that the
geographic areas may be meter areas within a single manufacturing
facility. For example, the geographic areas may represent an array
of meters supporting manufacturing equipment, or may be an array of
meters in a utility room. The receiver units 156, 161, and 164 may
be, for example, constructed to operate according to 802.11
protocols. In such a case, the associated cameras would also
operate according this protocol, and enable simple communication
between cameras and receiver units. In one specific example, the
receiver units are also configured as Internet access points. In
this way, each receiver unit has wide area connection to the
utility company through an Internet connection. In this
arrangement, each receiver unit obtains image information from its
associated camera through an 802.11 communication, and then
communicates meter data via the Internet to the utility company.
This has the advantage of using existing communication modes and
equipment for communication, but uses equipment not under the
control of the utility company. Accordingly, receiver units may
alternatively be constructed as proprietary equipment under the
control of the utility company.
[0027] Referring now to FIG. 4, another arrangement 200 is
illustrated. In arrangement 200, a camera 215 is located in house
217, camera unit 208 is in house 211, and camera 204 is in house
206. Due to the geographic arrangement, a centralized hub
configuration is not available. Instead, the receiver unit 225
operates at the end of a set of point-to-point connections between
cameras. Receiver unit 225 again may operate according to existing
protocols, or may be proprietary to the utility company. As before,
receiver unit 225 is responsible for communicating meter data to
the utility company through a wide area connection.
[0028] Arrangement 200 requires more synchronization then required
for previous arrangements. For example, it is desirable that camera
204, 208, and 215 all wake up at about the same time. In this way,
upon waking up and receiving instruction for taking an image,
images taken by camera 204 may be communicated to receiver unit 225
through camera 208 and 215 respectively. Accordingly, the low-power
timer in cameras in arrangement 200 is selected to operate with
sufficient stability and resolution to provide the needed
synchronization. It will be understood that the stability and
resolution of the low power clock may be adjusted according to the
synchronization processes used. For example, the cameras may be set
to resynchronize from time to time, and depending upon the period
between resynchronization, the stability and accuracy of the clock
may be adjusted. For example, if the cameras are set to
resynchronize quite often, then the low-power clocks can still be
selected with relatively low resolution and stability. However, if
the resynchronization period is lengthy, then the clocks will need
additional stability and resolution. The trade-off between a more
stable clock and resynchronization time may need to be made for
each specific application. It will be understood that higher
stability clocks require more power consumption during sleep mode,
but that the resynchronization period consumes considerably more
power than sleep mode. Therefore, a compromise can be made between
the selection of clock stability and accuracy, and the
resynchronization period among cameras. A specific topology for a
more synchronous and cooperating network is the mesh network. It
will be understood the meter-reading system may also be arranged as
a mesh, and that one skilled in the art would understand the
tradeoffs and compromised required to implement and operate such a
mesh network.
[0029] Referring now to FIG. 5, meter images are illustrated. Image
250 shows a typical analog electric meter having rotational dials.
These are home meter images taken by an Avaak miniature camera as
described with reference to FIG. 1. A camera unit takes image 250,
and the image may be automatically processed through recognition
software to determine current meter readings. The automated
recognition processes may be operated locally at the camera, at the
central hub, or at the central utility office. The determination of
where to do the automated recognition will be dependent upon
available power, and the particular image environment. A copy of
image 250 may also be included with a utility bill, thereby
providing accurate information for consumer or commercial
reference. FIG. 275 shows an analog meter reading for a typical gas
meter.
[0030] Referring now to FIG. 6, a system 300 for reading a meter is
illustrated. In system 300 a remote camera sensor is attached to a
meter as shown in block 302. For example, the meter may be attached
or strapped to the outside of the meter housing, or may be
positioned within the meter case itself. It will be appreciated
that the attachment of a camera to a meter can use any of several
know attachment devices or adhesives. The camera is configured to
take an image of the meter as shown in block 304. For example, the
camera may have one or more lenses in front of its sensor that
enable the meter dials or digits to be captured with sufficient
resolution to be automatically or manually deciphered. Also, the
camera may have an associated lamp or lighting system for
illuminating a dark meter. This lamp system may be augmented with
an ambient light detection system, which illuminates the lamp only
when ambient light is not sufficient. In one example, the imager
itself is used to detect the level of ambient light, and responsive
to unacceptably low contrast, will illuminate a lamp. In this way,
the power cost of operating a lamp is only expended when
necessary.
[0031] The camera then takes an image of the meter dial or digits
as shown in block 306. This image may be taken periodically
according to an internal clock in the camera system, or may be set
or adjusted by a central controller such as a hub. In another
example, the timing of the images may be defined by the utility,
and communicated to the camera through a hub or other receiver. In
this way, a utility may require faster rates of images during peak
usage times, while allowing fewer images during off usage periods.
Optionally, the image may be processed locally for image character
recognition as shown in block 307. The image data is then
wirelessly communicated to a local radio system as shown in block
308. This local receiver may be for example, a local 802.11 access
point, a proprietary receiver or hub, a mobile radio, or a portable
reader. It will be appreciated that several configurations of the
radio system may be used. Since the local radio system may have
additional power and processing capability, it may optionally be
able to do character recognition as shown in block 309. The meter
data, whether raw image or processed data, is then communicated to
the utility through a wide area connection as shown in block 311.
This wide area connection may be another wide area wireless system,
or may be through a connected network such as the Internet.
[0032] The central office then may perform central image
recognition as shown in block 314, and may also put the image on
the bill for reference. The utility is then able to advantageously
use the meter data for preparing timely and accurate bills. It will
also be understood that the camera system may send only change
information in its images. In this regard, the imager may from time
to time take a reference frame of the meter dial, and thereafter
send only the differences between the reference frame and the
current frame. Although this requires some additional processing at
the camera, such processing is relatively simple, and may reduce
substantially the amount of time necessary to operate the radio.
Since the radio is a relatively high power device, performing such
comparison on the local radio may net cause usage of less
power.
[0033] Referring now to FIG. 7, a meter reading system 350 is
illustrated. System 350 has multiple camera systems, with each
camera attached to a meter and positioned to take an image of that
meter's dials or digits as shown in block 353. Each camera is
physically and electronically configured to take an image of the
meter reading area as shown in block 355. From time to time, each
camera takes an image, and may apply local image recognition or
other image processing as shown in block 351. Each camera
communicates its image or other meter data to a central receiver
hub as shown in block 364, which again may apply image recognition
or other image processing algorithms. The central receiving hub
then communicates the data to the utility company agent as shown in
block 368. This communication may be wireless, or in a typical
example, will be through a wired Internet connection. The utility
agent is then able to apply additional image processing or image
recognition as shown in block 371, and then put the image on the
bill as shown in 373.
[0034] The multiple cameras of system 350 may operate in an
asynchronous mode where each camera generates a pilot signal from
time to time. The pilot signal is generated responsive to an
unstable and relatively inaccurate low power clock. After
generating its pilot, each camera waits a short period of time for
the receiver to respond. If the receiver responds, the camera may
act to take a picture or transmit data. However, if the transmitter
does not respond, then the camera may go back into a sleep mode and
try again a predetermined length of time later. In this way, a
highly efficient and low-power asynchronous network system is
enabled. In another example, the cameras may have a higher degree
of synchronization due to physical, timing, or application
requirements. However, when possible, such a low-power asynchronous
star configuration provides desirable power savings.
[0035] Referring now to FIG. 8, a system for reading meters is
illustrated. System 400 has multiple cameras attached to meters,
and positioned to take an image from each meter as shown in blocks
403 and 405. Due to geographic or application requirements, the
cameras are arranged in a ring or point-to-point network
construction. In this arrangement, additional synchronization is
typically required between the cameras. Again, it will be assumed
that the receiver or hub has sufficient power to remain on at all
times, although in some situations, the hub may also be a lower
power device. As shown in block 408, the cameras are sufficiently
synchronized so they generally power on at about the same time, and
are then able to establish a communication path with a receiver or
hub. The accuracy of this synchronization may be selected according
to application needs, and involves trade-offs between the quality
and power of each camera's low power clock circuit, and according
to the resynchronization cycle between cameras. Further, additional
synchronization may be required for high-speed or critical
applications.
[0036] At a predefined time, all the cameras wake up as shown in
block 411. Typically, it will be understood that synchronization is
sufficient if all the cameras wake up within a few milliseconds of
each other. Of course, the tighter the synchronization, the less
time the radios and processors need to be on. Again, trade-offs can
be made between the quality of the low-power clock and the level of
desired synchronization. Once the cameras wake up, they establish
communication between each other and with the hub. Upon command,
each camera takes an image as shown in block 414. The command may
be generated locally, from the hub, or from the utility. Each
camera has an established relationship in the network, and knows if
it communicates with a camera or with a hub. If the camera is next
to the hub, then that camera can communicate its data directly to
the central hub as shown in block 418. However, if the camera is
not next to the hub then that camera passes its data through one or
more other cameras as shown in block 421. In this way, either
directly, or via other cameras, the central hub obtains all the
image data or other meter data, which can then be communicated to
the utility company agent as shown in block 423. As described
before, the utility company agent may use the information for image
recognition, billing, or placing an image on the consumer's
bill.
[0037] Referring now to FIG. 9, a system for synchronizing image
cameras is illustrated. System 450 has a low-power timer in a
camera unit as shown in block 452. The accuracy and resolution of
the low-power timer is set according to the synchronization
processes used in the overall network. For example, faster
synchronization requirements would require a better low-power
timer. In a similar manner, longer resynchronization periods would
again require a better and thereby more power consuming low-power
timer. Those skilled in the art will appreciate the trade-offs
between timer quality and power usage and overall system
resynchronization and synchronization requirements. This low-power
timer is configured to generate a periodic interrupt as shown in
block 454. Typically, this periodic interrupt is set according to
the resynchronization cycle required by the overall network
structure. In this way, the camera is configured 451 for
resynchronization and operation within a synchronous data transfer
environment.
[0038] The system 450 has a low-power synchronization process 480.
Although the process is referred to as low-power, the process does
consume power as the radio and processor is active for at least a
short period of time. However, the synchronization process is
considerably more power efficient than the full power imaging
process 490 discussed below. In the low-power synchronization
process, the camera operates in sleep mode 461 until the low-power
timer generates an interrupt as shown in block 463. In sleep mode,
the radio is off, as well as the processor. Typically, only minimal
circuitry is operating, such as the low-power timer. Upon receiving
the low-power interrupt, the radio and processor power up as shown
in block 465. The radio and processor of other cameras also power
up, and thereby enable each camera to establish communication with
the next camera, and the last camera to establish communication
with the receiver hub as shown in block 368. Upon establishing
communication, the cameras synchronize clocks as shown in block
471. It will be appreciated that numerous processes may be applied
for synchronizing clocks between networked devices. The cameras
also inquire as to whether it is time to take an image as shown in
block 473. Typically, the resynchronization interrupt will have
been received many times without the need to take an image.
Therefore, the camera generally goes back to sleep and waits for
the next resynchronization interrupt. In one example,
resynchronization may be done every few seconds. At such a
resynchronization rate, a relatively inaccurate and low-power
timing circuit may still be used, and the battery for the camera
unit may still last years depending upon the number of images taken
and communicated in process 490. Of course, it will be appreciated
that other resynchronization cycles may be selected based upon
application needs, quality of the low-power timer circuit, and
resynchronization schedule.
[0039] From time to time, during a resynchronization process, a
command will be received to take an image as shown in block 473. In
such a case, each camera goes into its full-power image process as
shown in block 490. In this process, each camera takes an image as
shown in block 475, and then may store or process that image data
locally as shown in block 477. Such storage and processing is
optional, but may facilitate improved network efficiencies and
collision avoidance during communications. Whether stored or not,
the camera then communicates the data to the next camera or to the
hub as shown in block 479. In this way, the image data from every
camera is transmitted to the hub, where it is then communicated via
wide area network to the utility.
[0040] While particular preferred and alternative embodiments of
the present intention have been disclosed, it will be appreciated
that many various modifications and extensions of the above
described technology may be implemented using the teaching of this
invention. All such modifications and extensions are intended to be
included within the true spirit and scope of the appended
claims.
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