Note: Descriptions are shown in the official language in which they were submitted.
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A SYSTEM AND METHOD FOR DETECTING
TAMPERING OF A UTILITY METER
FIELD OF INVENTION
[0001] The present invention relates generally to power systems, and more
particularly
to a method and apparatus for detecting possible tampering with a utility
meter.
RELEVANT BACKGROUND
[0002] Utility companies use utility meters to regulate and monitor utility
usage. Some
exemplary utility meters include electrical power meters (also referred to in
the industry
as watt-hour meters), water meters, gas meters and the like. Early utility
meters were
mechanical in nature converting the flow of the particular utility resource
through the
utility meter into mechanical movement. The mechanical movement was used to
turn a
recording device which recorded the amount of resources being used. As
technology
improved over the years, the design of the utility meter incorporated new
innovations
such as increased processing capability within the utility meter, elimination
of
mechanical parts, better accuracy and the like.
[0003] One problem utility companies continue to deal with since the advent
of the
utility meter is the tampering consumer. The tampering consumer may be an
individual
who desires to alter the monitoring capabilities of the utility meter. By
altering the
monitoring capabilities of the utility meter, the tampering consumer may
receive some or
all of the utility resources at a significantly discounted rate. This presents
a problem not
only with the theft of the utility resource but also with the potential safety
hazard that
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may be caused by the tampering consumer. The potential safety hazard may in
turn
affect other utility consumers connected to the power grid.
[0004] Previous utility meters may have had some means of detecting
tampering with
the utility meter. Commonly, a sensor may have been configured in previous
utility
meters to monitor the cover of the utility meter. Thus, when a tampering
consumer
opened the utility meter cover, an alarm condition may have been generated by
circuitry
within the utility meter. The alarm condition may then be reported in various
ways to the
utility company. Depending on the number of alarms, the frequency of the
alarms and
the like, the utility company may take any remedial action it deemed necessary
in order
to confirm and remedy the tampered condition.
[0005] Other means have been used in previous utility meters to detect
tampering.
Another example of previous ways to detect tampering with a utility meter was
to
employ a movable and conductive metal ball contained within a metal housing.
The
metal ball was positioned to move from a resting position to an alarm position
if the
utility meter was physically moved. If the utility meter moved in a certain
direction, the
ball would roll from the resting position to an alarm position which may be on
the
opposite side of the metal housing. When the ball transitioned from the
resting position
to the alarm position, the metal housing became conductive and the utility
meter then
detected the conductive change. After the utility meter detected the
conductive change,
the utility meter raised an alarm condition alerting the utility company of
the potential
tampered condition.
[0006] The previous method of detecting tampering using a mechanically
moving
conductive ball may not detect to certain types of movement of the utility
meter. The
utility meter may be moved in such a way as not to activate the mechanically
moving
conductive ball tampering detection circuitry. In addition, this type of
detection circuitry
may be costly to deploy within the utility meter. In some cases, this type of
detection
circuitry may not be mounted using surface mount technology and may have to be
hand
soldered within the utility meter. To more effectively detect possible utility
meter
tampering at a much lower cost, the present invention utilizes the
piezoelectric properties
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of a ceramic capacitor to detect movement of the meter. Circuitry associated
with the
present invention located within the utility meter monitors and detects when
the ceramic
capacitor experiences any mechanical strain, and provides a way for the
utility meter to
signal the utility company of possible meter tampering.
SUMMARY
[0007] Accordingly, there exists a need in the industry to have a utility
metering system
that can detect possible meter tampering under certain conditions by detecting
physical
movement of the meter. By detecting movement of the meter under certain
conditions,
the utility meter may be able to identify possible meter tampering and notify
the utility
company accordingly. The present disclosure recognizes this need and discloses
such a
device.
[0008] A tamper alarm circuit for detecting a tampered condition of a
utility meter is
disclosed. The tamper alarm circuit has a transducer coupled to an
amplification circuit
which is coupled to a detection circuit, the detection circuit generating an
alarm
condition when the detection circuit determines that a voltage signal
generated by the
transducer and amplified by the amplification circuit has reached a
predetermined
threshold.
[0009] A utility meter is disclosed. The utility meter having a utility
resource
monitoring circuit, the utility resource monitoring circuit monitoring the
amount of
resources used by a consumer. The utility resource monitoring circuit
communicates
with a tamper alarm circuit, the tamper alarm circuit having a transducer
coupled to an
amplification circuit which is coupled to a detection circuit. The detection
circuit
generating an alarm condition when the detection circuit determines that a
voltage signal
generated by the transducer and amplified by the amplification circuit has
reached a
predetermined threshold.
[0010] A method for detecting a tamper condition in a utility meter is
disclosed. The
method provides a transducer which is coupled to an amplification circuit
which is
coupled to a detection circuit. The method determines that a voltage signal
generated by
the transducer and amplified by the amplification circuit has reached a
predetermined
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threshold. The method further generates an alarm condition when the detection
circuit
determines that the amplified voltage signal has reached the predetermined
threshold.
[0011] A more complete understanding of the present invention, as well as
further
features and advantages of the invention, will be apparent from the following
detailed
description and the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Figure 1 shows a high level logic hardware block diagram of a
utility metering
device using one embodiment of the present invention.
[0013] Figure 2 shows a high level logic hardware block diagram of a power
metering
device using one embodiment of the present invention.
[0014] Figure 3 displays a tampering detection circuit in accordance with
another
embodiment of the present invention.
[0015] Figure 4 shows an alternate tampering detection circuit in
accordance with
another embodiment of the present invention.
[0016] Figure 5 displays a flow chart describing the processing of an
electrical power
meter using the detection circuitry of Figure 3 or Figure 4 in accordance with
one
embodiment of the present invention.
[0017] Figure 6 displays a flow chart describing the processing of a water
or gas utility
meter using the detection circuitry of Figure 3 or Figure 4 in accordance with
another
embodiment of the present invention.
DETAILED DESCRIPTION
[0018] The detailed description set forth below in connection with the
appended
drawings is intended as a description of various embodiments of the present
invention
and is not intended to represent the only embodiments in which the present
invention
may be practiced. The detailed description includes specific details for the
purpose of
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providing a thorough understanding of the present invention. However, it will
be
apparent to those skilled in the art that the present invention may be
practiced without
these specific details. In some instances, well-known structures and
components are
shown in block diagram form in order to avoid obscuring the concepts of the
present
invention. Acronyms and other descriptive terminology may be used merely for
convenience and clarity and are not intended to limit the scope of the
invention
[0019] Figure 1 displays a high level view of a utility metering device
100 utilizing one
embodiment of the present invention. The utility metering device 100 is
designed to
receive a utility resource at a source side 160 of the utility metering device
100. In one
embodiment, the utility resource may be electrical power provided from the
utility power
grid, typically from a transformer near the consumer site. The utility
resource received is
monitored by a utility resource monitor 120. The utility resource monitor
circuit 120
monitors the flow of utility resources through the utility metering device 100
to the
consumer.
[0020] As is displayed in Figure 1, the utility metering device 100 may
have a processor
110 which communicates with the utility resource monitor circuit 120 to
determine the
status and amount of the utility resources being used by the consumer. The
utility
resource information may be communicated to the utility company via a
communications
module 105 which is coupled to the processor 110. In one embodiment, the
communications module 105 may utilize two way radio communications to relay
the
utility usage information. In another embodiment, the communications module
105 may
utilize wireless communications to communicate within the utility monitoring
network.
In yet another alternative embodiment, the communications module 105 may use
cellular
radio communications to communicate with the utility company.
[0021] Also coupled to the processor 110 is a tamper alarm circuit 115.
The tamper
alarm circuit 115 may monitor the conditions at the utility meter 100 and when
it detects
a possible tampering condition, it notifies the processor 110 by raising a
tampering
condition alarm. After the processor 110 receives the possible tampering
condition
alarm from the tamper alarm circuit 115, the processor 110 may in turn notify
the utility
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company. After the tampering alarm condition is raised, the processor 110 may
continue
to receive information from the tamper alarm circuit 115 to determine if the
tampering
condition alarm is a one time event or is a continuous event.
[0022] Figure 2 displays an electrical watt-hour meter 200 in accordance
with another
embodiment of the present invention. The watt-hour meter 200 is designed to
monitor a
source line voltage at L1,, and L2,, at its source side 160. The source
voltage present at
the source side 160 of the watt-hour meter 200 is typically one of the common
electric
utility service voltages and generally a maximum of 480 VAC. The watt-hour
meter 200
routes the electrical energy from the source side 160 to the consumer side
contacts Li out
and L20ut of the watt-hour meter 200. Also connected to the source side 160 of
the watt-
hour meter 200 is a power failure detection circuit 230 and a display 135. The
display
135 provides a visual display of the amount of energy used at the customer
location. The
power failure detection circuit 230 monitors the voltage present at the source
side voltage
contacts L1,, and L2. In the event of a power failure, the power failure
detection circuit
230 communicates this condition to the processor 110. The watt-hour meter 200
has a
power metering circuit 220 which measures the amount of energy being used by
the
consumer.
[0023] The watt-hour meter 200 has a communications module 105 which
allows the
utility company to communicate with and gather information from the watt-hour
meter
200. In one exemplary embodiment, the communications module 105 may utilize
cellular telephone technology to communicate with the utility company service
center or
craftsperson. In this embodiment, the craftsperson may use portable computer
with a
cellular telephone to connect with the meter to retrieve status or other
useful information
from the watt-hour meter 200. In an alternative embodiment, the communications
module 105 may support other types of wireless communications. In yet another
alternative embodiment, the watt-hour metering device 100 may be connected to
a cable
modem which in turn may be attached to the consumer's cable line. In this
example, the
utility company may connect to the watt-hour meter 200 using TCP/IP or other
networking protocols.
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[0024] The watt-hour meter 200 has a tamper alarm circuit 215 which is
coupled to the
processor 110. As is explained in greater detail in the discussion of Figures
3-4, the
tamper alarm circuit 215 monitors the conditions at the watt-hour meter 200
and
determines if a tamper condition exists. If a tamper condition exists, the
tamper alarm
circuit 215 may send a tampering alarm to the processor 110 which in turn may
assess
the conditions at the watt-hour meter 200 to determine if the possible
tampering
condition wan-ants notification of the utility company. In one embodiment of
the present
invention, the tamper alarm circuit 215 may determine that a tampering alarm
should be
raised and reported to the utility company when physical movement of the watt-
hour
meter 200 is detected just prior to a power failure.
[0025] One such tampering condition may occur when the watt-hour meter 200
is
removed from service by physically pulling the watt-hour meter 200 away from
the
source side contacts Ll in and L2in and the consumer side contacts L10ut and
L20ut. In this
example, the watt-hour meter 200 may be removed by an unauthorized person in
order to
access the internal components in an attempt to either bypass the monitoring
sensors or
disable them. In one exemplary embodiment, the tamper alarm circuit 215 may
detect
this tampering condition and generate the tampering condition alarm to the
processor
110. The processor 110 in turn may receive the tampering condition alarm and
report the
tampering to the utility company via the communication module 105.
[0026] Figure 3 displays a more detailed view of an exemplary tamper alarm
circuit 215
in accordance with one embodiment of the present invention. The tamper alarm
circuit
215 is composed of an amplification stage 320 and a comparator stage 325. The
amplification stage amplifies a voltage generated by a transducer which in
this
embodiment is ceramic capacitor Ctran. Those skilled in the art appreciate
that the
transducer may include but not be limited to any piezoelectric device that
converts
mechanical movement into energy. The transducer voltage may be generated by
vibrations experienced by the transducer (capacitor Ct.). The comparator stage
325
then monitors the output of the amplification stage 320 and determines when
the voltage
from the amplification stage 320 reaches a predetermined threshold.
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[0027] Within the amplification stage 320 is an inverting amplifier Ul .
The negative
terminal of the amplifier Ul is connected to R5 which is in turn connected to
the
capacitor C. The other side of the capacitor Ct. is connected to ground. The
gain of
the amplifier Ul with respect to the piezoelectric voltage Vt. developed by
the capacitor
Ct. is determined by the resistance of R6 and the reactance of Ct. (also
referred to as
Xt. in the formula below) as given by:
Vo R6
Xtran
Van
[0028] Since Xt. decreases with increasing frequency, the circuit gain
correspondingly
increases with frequency. A maximum is achieved at the frequency where the
value of
the gain expression and the amplifiers open loop gain are equal. At higher
frequencies
the circuit gain decreases with the amplifier's open loop characteristics. In
one
exemplary embodiment, the value for R6 is 1.0 MS2 and Ct. is 220nF. With these
values, and a typical low cost operational amplifier gain-bandwidth product of
100,000,
the maximum gain is approximately 1000 at about 85 Hz. Therefore, a 1 mVAC
voltage
signal generated by the capacitor Ct. will result in about a 1.0 VAC output
signal at 85
Hz from the output of the amplifier Ul
[0029] Within the amplification stage 320 are resistors R1, R2 and R3
which form a
voltage divider that provides a DC bias to the voltage generated by the
capacitor Ct. as
well as provides a threshold voltage used by the comparator stage 325. More
specifically
the total voltage drop across resistors R2 and R3 is used to determine the
threshold of the
comparator U2 within the comparator stage 325 and the voltage drop across
resistor R3
provides the DC bias for the amplifier Ul . Adding the DC bias for amplifier
Ul
improves the transducer gain of the capacitor C. In one embodiment, resistors
R1, R2
and R3 may be 232 kn, 20 kn, and 200 1cS2 respectively. Using these resistive
values,
and assuming a voltage source Vs of 5 volts DC, the bias applied to the input
side of the
amplified Ul is about 2.2 VDC. In this configuration, the amplified signal
generated
from the capacitor Ct. will be an AC component on top of the 2.0 VDC bias.
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Correspondingly, the sum of the voltage drops across resistors R2 and R3 is
about 2.4
VDC and is used for the threshold to determine if the voltage signal produced
by the
amplifier Ui is at or above a predetermined threshold. The predetermined
threshold may
correspond to a tampering alarm condition. Additionally, capacitors Ci and C2
provide
filtering for noise components, while resistors R4 and R5 provide a buffer to
limit the
amount of current that may flow through the amplifier Ui. In one embodiment
the
capacitors C1 and C2 may be 100 nF capacitors and resistors R4 and R5 may be
4.7 ki2
resistors.
[0030] In an exemplary embodiment, Capacitor Ctran may use barium titanate
as a
principal dielectric constituent. In this embodiment, the capacitor Ct. may
range from
0.2 piF up to 1.0 piF and may have dielectric characteristics of Y5V or Z5U.
Those
skilled in the art appreciate that capacitors with dielectric characteristics
similar to those
previously mentioned typically exhibit the most prominent piezoelectric
characteristics
within the family of ceramic capacitors and are among the least expensive
types. The
piezoelectric properties (also may be referred to as micro-phonic properties)
of capacitor
Ctran allow the capacitor Ct. to function as a transducer converting
mechanical strain
into electrical signals. Embodiments of the present invention take advantage
of the
piezoelectric capabilities of ceramic capacitors having barium titanate as a
principal
dielectric constituent. However, those skilled in the art appreciate that
capacitors using a
different dielectric constituent other than barium titanate may exhibit
similar
piezoelectric properties and may therefore function as a suitable transducer.
[0031] Any vibration imparting strain to the capacitor Ct. may result in
an AC signal
being generated by the capacitor Ct.. The generated signal is directed into
the input of
the amplifier Ui. The generated signal is amplified as previously described
and the
output of the amplifier Ui is directed to the positive input of comparator U2.
Comparator
U2 receives the amplified signal (the output of U1) and compares the amplified
signal to
a predetermined voltage threshold present at the negative input. When the
amplified
voltage exceeds the predetermined threshold, the output of the comparator U2
is driven
high and reaches the supply voltage V. As displayed in Figure 3, the output of
the
comparator U2 may be directed to latching logic 315. In one embodiment, the
latching
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logic 315 may be a single flip-flop designed to clock in a logic "1" when the
output of
the comparator U2 is driven high. In this embodiment, the flip-flop is reset
after being
read by the processor 110. In an alternative embodiment, the latching logic
315 may be
a series of flip-flops or possibly a counter that records the number of times
the
comparator U2 output is driven high. The processor 110 may read the flip-flops
or
counter in order to determine how many times the predetermined threshold was
met or
exceeded over a certain period of time. In this embodiment, the flip-flops or
counter
may also be reset after the processor 110 has read them.
[0032] Figure 4 displays another exemplary tamper alarm circuit 215' in
accordance
with an alternative embodiment of the present invention. The tamper alarm
circuit 215'
has an amplification stage 420 connected to an analog to digital (A/D)
converter 450.
The output of the A/D converter is then sent to the processor 110. Similar to
the
amplifier Ul in Figure 3, amplifier U10 amplifies the voltage signal generated
by the
capacitive transducer C. The gain associated with the amplification of the
generated
AC signal with respect to the piezoelectric voltage Vt. developed by Ct. is
determined
by the resistor R14 , the reactance of Ct. and the open loop characteristics
of amplifier
U10, similar to amplifier Ul in Figure 3. In one exemplary embodiment, the
resistor R14
may be a 11\4S2 resistor. Similar to the voltage divider of Figure 3, the
voltage divider
consisting of resistors R10 and R11 provide a DC bias for the output of the
amplifier U10.
In one embodiment, the values for resistors R10 and RI I may both be 2331d2 .
Capacitor
C4 provides noise filtering while resistors R12 and R13 limit the amount of
current that
may flow through the amplifier U10 when the voltage supply Vs is removed and
capacitor C4 discharges. In yet other alternative embodiments, the A/D
converter 450 as
well as amplification stage 420 may be performed by circuitry already
contained within
the processor 110.
[0033] Figure 5 displays a process flow 500 outlining steps the processor
110 may take
in order to determine if a tamper alarm condition has occurred in the watt-
hour meter 200
in accordance with one embodiment of the present invention. The process flow
500
begins at start block and proceeds to block 504. At block 504, the processor
110
monitors the conditions at the watt-hour meter 200. As displayed in Figure 2,
the
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processor 110 may utilize the power failure detection circuit 230 to monitor
the power
conditions at the source side 160 of the watt-hour meter 200.
[0034] The process flow 500 continues on from block 504 to decision block
506. At
decision block 506, the processor 110 determines if a power failure has
occurred. If a
power failure has not occurred, the process flow 500 continues back to block
504. If at
decision block 506 a power failure has occurred, the process flow 500
continues on to
decision block 507. In the event of a power failure, the processor 110 may
receive a
power failure indication from the power failure detection circuit 230. Even
though a
power failure may have occurred, the processor 110 may continue to operate if
it
receives power from an alternate power supply such as a battery, large
discharging
capacitor or the like. In this embodiment, the processor 110 may continue to
operate and
process the conditions at the watt-hour meter 200.
[0035] At decision block 507, the processor 110 determines if the tamper
alarm circuit
215 has detected a tamper alarm condition. As discussed previously, the tamper
alarm
circuit 215 may generate a tamper alarm condition due to vibrations sensed by
the
capacitive transducer Ctran. If at decision block 507 the processor 110 has
determined
that a tamper alarm condition exists, the process flow 500 proceeds to
decision block
508. If no tamper alarm condition is detected, the process flow continues on
to block
512. The tamper alarm circuit 215 may generate the tamper alarm condition if
the
conditions previously mentioned occurred either prior to or shortly after the
power
failure. This is described in further detail in the discussions of block 508.
[0036] At decision block 508, the processor 110 determines if the tamper
condition
alarm has been generated within a predetermined period of time either
preceding or
following a power failure indication. As discussed previously, the tamper
condition
alarm may be the latched output of the latching logic 315 as shown in Figure
3. In an
alternate embodiment the tamper condition alarm may be the digital output of
the A/D
converter 450 as shown in Figure 4. If the tamper condition alarm is within
the
predetermined period of time, the processor 110 proceeds on to block 510. If
the
transducer signal is not within the predetermined period of time, the process
flow
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continues on to block 512. At block 512, the processor 110 continues with
shutting the
watt-hour meter 200 down as per a predetermined power failure process. After
the
processor 110 finishes processing the normal power failure at block 512, the
process
flow 500 ends at block 514.
[0037] If at block 508, the processor 110 determines that the tamper
condition alarm has
occurred with the predetermined period of time, the processor 110 may take the
appropriate steps of notifying the utility company of the possible tampering
condition as
shown at block 510. In one embodiment, the processor 110 may communicate this
information directly to the utility company via the communication module 105
(Figure
2). This communication may be performed over cellular communications, two way
radio
communications or the like. Alternatively, the processor 110 may activate a
colored
LED on the watt-hour meter 200. For example, the processor 110 may illuminate
a red
LED on the faceplate of the watt-hour meter 200 allowing the utility
craftsperson an easy
way of identifying any meter that may have been tampered with. In this
embodiment,
the processor 110 may continue to illuminate the colored LED until the utility
company
instructs the processor 110 to reset its tamper condition alarm. In an
alternative
embodiment, an alert icon and a code number may be displayed on the LCD
display of
the watt-hour meter 200. In yet another alternate embodiment, the processor
110 may
activate an auditory response such as an audible alarm.
[0038] After the processor 110 has conveyed the tampering condition alarm
to the utility
company, the tamper condition alarm may be reset several different ways. In
one
embodiment, the processor 110 may require the crafts person to physically
depress a
particular switch on the watt-hour meter 200. Alternatively, the processor may
keep the
tampering condition active until instructed via commands sent by the utility
company to
reset the condition. In yet another alternate embodiment, the processor 110
may reset
itself after another predetermined amount of time. After the processor has
processed the
tamper condition alarm at block 510, the process flow 500 ends at block 514.
[0039] Figure 6 displays a process flow 600 in accordance with another
embodiment of
the present invention. The process flow 600 may apply to other types of
utility meters
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such as water meters or gas meters which may utilize a tamper alarm circuit
215 as
shown in Figure 3. The first step in the process flow 600 begins at block 602.
The
process flow 600 proceeds to block 604. At block 604, the processor 110 may
monitor
the utility usage. As the processor 110 monitors the utility usage, the
processor 110
typically monitors the conditions for any type of abnormality. Any condition
that the
utility company deems to be uncommon or unexpected may be considered abnormal
for
purposes of this example. From block 604, the process flow 600 continues to
decision
block 606.
[0040] At decision block 606, the processor 110 may make the determination
that an
abnormal condition has occurred. If an abnormal condition has occurred, the
process
flow 600 continues to block 608. At block 608, the processor 110 may enable
the tamper
alarm circuit 215. In one exemplary embodiment, the utility meter 100 may not
have a
constant and almost unlimited power source as is available in a power meter.
In order to
conserve power, the tamper alarm circuit 215 may only be turned on when an
abnormal
condition has been detected. Turning the tamper alarm circuit 215 on only when
needed,
the processor 110 may conserve operating power.
[0041] The process flow 600 proceeds from block 608 to decision block 610.
At
decision block 610, the processor 110 makes the determination if the tamper
alarm
circuit 215 has detected a tamper condition alarm. If a tamper condition alarm
has been
detected, the processor 110 notifies the utility company of the tamper
condition alarm at
block 612 and the process flow 600 ends at block 614. If the tamper alarm
circuit 115
has not detected any tampering, the process flow 600 returns to block 604, and
the
processor 110 continues to monitor the utility usage.
[0042] At block 612, the processor 110 may communicate the possible
tampering
condition directly to the utility company via the communication module 105
(Figure 1).
This may be done over cellular communications, two way radio communications or
the
like. Alternatively, the processor 110 may activate a colored LED on the
utility meter
100. For example, the processor 110 may illuminate a red LED on the faceplate
of the
utility meter 100 allowing the utility craftsperson an easy way of identifying
any meter
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that may have been tampered with. In an alternative embodiment, an alert icon
and a
code number may be displayed on the LCD display of the watt-hour meter 200. In
yet
another alternate embodiment, the processor 110 may activate an auditory
response such
as an alarm.
[0043] In another exemplary embodiment, the tamper alarm circuit 215 or
215' may be
installed in a gas meter or a water meter that may have enough power to allow
the tamper
alarm circuit 215 or 215' to receive continuous power. In this embodiment, the
tamper
alarm circuit 215 or 215' may be used to determine the abnormal condition as
described
at block 606 of Figure 6. Receiving power continuously allows the processor to
use the
tamper alarm circuit 215 or 215' to continuously monitor the conditions at the
utility
meter for tampering.
[0044] It should be noted that upon the report of a possible tamper
condition alarm, the
utility company may perform one of several different responses. For example,
if a large
truck should pass near a water meter, the tamper alarm circuit 215 may
determine a
possible tampering condition has occurred due to the vibrations induced by the
truck. In
this instance, the utility company may continue to monitor the particular
utility meter
100 to see if the meter is still operating normally. If the utility meter is
still operating
normally, the utility company may simply reset the tamper condition alarm at
the water
meter. Alternatively, if the utility company receives tamper condition alarms
from
several utility meters 100 within a close proximity of each other, the utility
company
may continue monitoring the meters in question to determine if there has been
an event
that does not correspond to tampering such as a thunderstorm, hail storm,
sonic boom or
other type of event not corresponding to a possible tampering condition.
[0045] Additionally, the tamper alarm circuit 215 may be designed to be
more or less
sensitive to vibrations by adjusting the gain of the amplifier Ul (Figure 3).
Thus, if a
water meter is always installed underground it may be more susceptible to
vibrations
from sources other than tampering and the gain may be reduced. Reducing the
gain
makes the tampering detection circuit 300 less sensitive to vibrations.
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CA 02710919 2010-06-28
WO 2009/086432 PCT/US2008/088253
[0046] The various illustrative logical blocks, modules, circuits,
elements, and/or
components described in connection with the embodiments disclosed herein may
be
implemented or performed with a general purpose processor, a digital signal
processor
(DSP), an application specific integrated circuit (ASIC), a field programmable
gate array
(FPGA) or other programmable logic component, discrete gate or transistor
logic,
discrete hardware components, or any combination thereof designed to perform
the
functions described herein. A general-purpose processor may be a
microprocessor, but
in the alternative, the processor may be any conventional processor,
controller,
microcontroller, or state machine. A processor may also be implemented as a
combination of computing components, e.g., a combination of a DSP and a
microprocessor, a plurality of microprocessors, one or more microprocessors in
conjunction with a DSP core, or any other such configuration.
[0047] Although specific embodiments have been illustrated and described
herein, those
of ordinary skill in the art appreciate that any arrangement, which is
calculated to achieve
the same purpose, may be substituted for the specific embodiments shown and
that the
invention has other applications in other environments. This application is
intended to
cover any adaptations or variations of the present invention. The following
claims are in
no way intended to limit the scope of the invention to the specific
embodiments
described herein.
