Note: Descriptions are shown in the official language in which they were submitted.
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WIRELESS AREA NETWORK COMMUNICATIONS MODULE
FOR UTILITY METERS
FIELD OF THE INVENTION
The present invention relates in general to the field of utility meters. More
particularly, the present invention relates to automatic equipment and systems
for remote reading
of utility meters, such as electric, gas, or water meters, via a wireless area
network
communications module.
BACKGROUND OF THE INVENTION
The recent deregulation of the utility industry has created a market for
products
that provide a utility or its customers with their usage via a utility usage
meter. Utility companies
use utility usage meters to determine the utility consumption at a customer
site. A periodic
reading of the utility meter is necessary to determine the usage and to bill
the customer for the
amount used. The need to send utility company employees to customer sites to
read the meters
is costly, time consuming, and dangerous. Moreover, the frequency of meter
reading is
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increasing, e.g., daily, hourly, every 15 minutes, etc, in order to take
advantage of real time
pricing. Also, the amount of data is increasing, due to the necessity to bill
on more than just
consumption, e.g., time of use. Thus, automated means of recording and
reporting the utility
usage at customer sites is rapidly replacing the manually read utility meters.
Many companies provide automatic meter reading equipment that is capable of
reading meters on customer premises and transmitting the meter readings
automatically to a
central office of the utility company. Typical systems use telephone schemes
for transmitting the
meter readings to the central office, and must be connected to line voltage,
making it more
dangerous and time consuming to install.
In the past, there: has been on-site meter reading equipment having modem
capability which was capable of receiving telephone calls from a central off
ce through the use
of special equipment located at the telephone company, and there have also
been on-site meters
with modems which were capable of placing telephone calls to the central
office. In general,
these systems incorporate an auto-dial, auto-answer modem in each customer
site to receive
interrogation signals from the telephone line and to formulate and transmit
meter readings via the
telephone line to the utility company. Prior art systems record information on
utility usage and
periodically dial into a central office to report the utility usage for
recording and billing purposes.
These systems are used for reporting electric, gas, and water usage, and the
like.
Some prior art systems connect to a customer's existing telephone line to
communicate with the central office by sending information over the telephone
lines. The modem
shares the telephone line with the: customer's normal usage, such as incoming
and outgoing voice
communications. Such sharing requires that the system be able to recognize
when the telephone
line is in use, and to delay demanding use of the telephone line until it is
free. Steps must be
taken to prevent the data communications system from interfering with other
uses and to prevent
other uses from corrupting the transmitted data. Many locations require
extensive trenching
which is extremely costly.
Although the art of providing meter data to a central site or host is well
developed,
there remain some problems inl-~erent in this technology, particularly the use
of telephone lines
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that are shared with a customer''s normal usage. Therefore, a need exists for
systems to provide
meter data to a central office or host that overcomes the drawbacks of the
prior art.
SUMMARY OF THE INVENTION
The present invention is directed to a communications module that permits
remote
meter reading of a utility meter via a wireless modem that communicates using
data packet
networks along a communications system, such as ARDIS. 'the communications
module is a
microprocessor-based transmitter/receiver that receives data collection
requests from a system
server, initiates data collection from a utility meter, and reports the data
back to a host computer
system residing, for example, at a central office. The communications module
may also issue
requests to the meter and send tlhe data back to the host, without an
initiating request. Preferably,
session-based communication using the meter protocol is implemented between
the
communications module and the meter, and packet switching is used between the
communications server and the; communications module through the network.
An embodiment within the scope of this invention includes a communications
module for transmitting data between a meter and a host over a network. The
communications
module comprises a connector coupled to the meter for receiving meter data
from the meter and
providing the meter data to a controller; a controller for controlling the
operation of the
communications module and fir converting the meter data into a host protocol
representing the
meter data and host data and for providing the data to a radio modem; the
radio modem for
transmitting and receiving signals representing the meter data and host data
to and from the host;
and an antenna coupled to the radio modem.
According to one aspect of the invention, the communications module further
comprises a power supply coupled to the controller and the radio modem for
supplying power to
the controller and the radio modem. Preferably, the power supply is coupled to
a meter power
supply.
According to further aspects of the invention, the communications module
further
comprises an energy storage device coupled to the power supply for storing
power to be used by
the power supply. Preferably, the energy storage device comprises a capacitor
and/or a battery.
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According to further aspects of the invention, the antenna comprises a double-
tapered dipole and a one-to-one balun. Preferably, the antenna is internal,
and the
communications module further comprises an external antenna. More preferably,
the external
antenna is a ground-plane antenma, an omni-directional antenna, a 1 /4-wave
antenna, or a'/2-wave
whip antenna.
According to a further aspect of the invention, the module is connectable to a
plurality of meters for multipoint meter reading.
According to another aspect of the invention, the communications module
comprises a power outage detector. Preferably, the power outage detector is
configured to alert
the host of a power outage after a predetermined programmable time.
According to another aspect of the invention, the controller is adapted to
detect at
least one alarm condition.
Another embodiment within the scope of this invention includes a wide area
network option board that comprises a power supply; a current limiter coupled
to the power
supply; a header coupled to the current limiter; and a serial communications
device coupled to
the header. Preferably, the power supply is an isolated step-up converter.
.Another embodiiment within the scope of this invention includes a meter that
comprises the communications module described above. According to another
aspect, the meter
further comprises the wide areas network option board described above.
According to further aspects of the present invention, the meter comprises a
display for displaying radio modem status information at predetermined
intervals. The radio
modem status information comprises at least one of signal strength, signal
quality, and module
location suitability.
The foregoing and other aspects of the present invention will become apparent
from the following detailed description of the invention when considered in
conjunction with the
accompalnying drawings.
BRIEF DESCRIPTION OF 'THE DRAWINGS
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Fig. 1 is a overview of an exemplary system in accordance with the present
invention;
Fig. 2 is a functional block diagram of an exemplary communication server,
wireless network, communications module, and meter in accordance with the
present invention;
Fig. 3 is a functional block diagram of an exemplary communications module
connected to an exemplary wide area network (WAN) option board in accordance
with the present
invention;
Fig. 4 is a functional block diagram illustrating the various components of
the
meter and WAN option board in. greater detail, and the interconnection between
the meter and the
WAN option board;
Fig. 5(a) shows an exemplary antenna for use in a preferred embodiment in
accordance with the present invention; and
Fig. 5(b) shows details of the antenna of Fig. 5(a).
DESCRIPTION OF EXEMPLARY EMBODIMENTS AND BEST MODE
The present invention is directed to a communications module that permits
remote
meter reading of a utility meter via a wireless modem that communicates using
data packet
networks along a communications system, such as ARDIS, which is a public
wireless packet
switching network operated by American Mobile Satellite Corp.
Referring to Fig;. 1, there is illustrated an overview of an exemplary network
in
which the present invention may be embodied. As illustrated, the network
includes a
communication server or host site 70, a wireless network 80, a communications
module 10 and
a meter 30.
The communications module 10 is a microprocessor-based transmitter/receiver
that
receives and/or generates data collection requests from a system server or a
host computer system,
initiates the data collection from a utility meter 30, and reports the data
back to the host site 70
residing, for example, at a central office. The communications module 10 is a
bridge between a
wireless packet-based network .and the utility meter 30. Preferably, session-
based communication
using the meter protocol is implemented between the communications module 10
and the meter
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30, and packet switching is used between the communications server and the
communications
module 10 through the wireless network.
The communications module 10 continuously monitors the connection between
the module 10 and the meter 30. Whenever communications are lost with the
meter 30 due to a
line power outage or tamper, the module waits a random length of time to allow
the line to
recover automatically. If the connection fails to recover, an alarm may be
generated and
transmitted to the communication server 70 for appropriate action. The
communications module
preferably responds to all requests and constantly monitors radio-related
information.
Additionally, the communications module 10 preferably supports ( 1 ) the meter
protocol, (2)
10 commands to get and/or set the meter/communications module configuration
request and
response, (3) commands to adjust and read the meter time, and (4) responses to
notify of a power
failure andlor power restoration.
'the meter 30 is typically read over the wireless network 80 at a
predetermined
time (e.g., after midnight). The: communications module 10 responds with the
appropriate load
profile data (e.g., for the previous 24 hours), time-of use data, as well as
any other data stored in
the meter 30.
A typical communications exchange over the network proceeds as follows. The
communication server or host site 70 sends a request over the wireless network
80 to the
communications module I 0. The communications module 10 receives the request,
and retrieves
the requested data from within the module 10 itself and/or the utility usage
meter 30 (via
transmit/receive cable 15). The; data is the transmitted back to the
communication server 70 via
the wireless network 80 for further processing.
Although the communications module 10 is shown and described as being separate
from the meter 30, it is contemplated that the communications module 10 can be
implemented
within the meter 30, in addition to providing the flexibility to be remotely
located outside of the
meter 30. The utility usage meter 30 preferably comprises an Alpha Power+
Meter or Alpha
Meter manufactured by ABB Power T&D Company. Other meters may be used as
utility usage
meter 30. It is noted that the preferred Alpha Meter or Alpha Power+ Meter
utilize a standard
ABB protocol as a meter protocol. 'Che communications module 10 enables
communications over
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a wireless network 80, such as the ARDIS network in the United States and the
BeIIARDIS
network in Canada. Other packet switched wireless networks may be utilized as
the present
invention is particularly suitable for packet-based wireless transmission.
Preferably, the
communications server 70 comprises a CSM system or AMR server, available from
ABB Power
T&D Information Systems, Raleigh, North Carolina.
Referring to Fi.g. 2, there is illustrated a functional block diagram of the
communication server 70, wireless network 80, communications module 10, and
meter 30. As
illustrated, the communication server 70 may be functionally divided into
three main platforms.
The Applications are services and processes that in some way manipulate data
in the real time
database. For example, the Applications may comprise an historical database
70A, a user
interface 70B, and an export and import system 70C. Applications are not a
part of the
communication server 70 itself , and use a public subscriber interface to
communicate with the
remote communication server 7UD and its real time database (not shown). The
public subscriber
interface is provided such that the remote communications server 70D does not
need to be
specifically programmed for each subscriber application, but rather can make
all information
collected therein publicly available. The subscribing application then selects
the information
needed to fulfill its particular task.
The Remote C<nnmunication Server (RCS) 70D is the main application in the
communication server 70 that serves other applications. The RCS 70D is built
around the real
time database. The real time database stores configuration and other data
without any time stamp
(i.e., using last reported values). Time stamped data acre sent to the
subscriber and stored in a
relational database 70A for long term storage.
Line Interface Modules (LIM) are real-time interfaces that are used to
communicate
with remote devices (e.g., comununications module 10 and meter 30). The LIMB
are essentially
protocol converters and are responsible for converting between the Remote
Server Protocol (RSP)
and the protocol used at the remote device (e.g., the ABB meter protocol). In
the preferred
embodiment utilizing the ABB Alpha Meter as utility meter 30, only two LIMB
communicate with
the ABB Alpha Meter. The AlphaLIM 70G communicates with the meter either using
the public
switched telephone network or a leased line {direct connection). The ArdisLIM
70E
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communicates with the Alpha Meter through the ARDIS radio network. The
ArdisLIM 70E
communicates with the ARDIS network 80 using an Internet connection, a leased
line, or a dial-up
line, and an X.25 card, available from Eicon Technology, Montreal, Quebec.
RFGate software,
available from Nettech Systems. lnc., Princeton, NJ, is used as low-level
access software to reach
the X.25 line.
On the remote side, the meter 30 is cormected to communications module 10. An
exemplary communications module 10 is the AlphaStar, manufactured by A13B
Power T&D
Company. The communication's module 10 comprises software that converts from
the ARDI S RF
protocol to the ABB Protocol used by the meter 30. Using the communications
module 10 in
combination with the ArdisLIM 70E, the meter 30 functions similarly as if it
was connected to a
telephone modem.
In addition, the meter 30 has a datalink feature, which facilitates
communication
with the communications module 10 and supports session-based, wireline
transmission, thereby
reducing the airlink protocol and minimizing airtime. The communication server
70 issues
datalink requests. It is noted that the request from the communication server
70 to the meter 30
should be as small as possible i:or a maximum of 1 packet (240 bytes or 480
bytes, for example,
depending on the protocol supported by the network at the install location).
The response back
from the meter 30 to the communication server 70 should minimize the data and
put it into as few
packets as possible (e.g., two or fewer for 2 channels of load profile data
every 15 minutes for 24
hours).
COMMUNICATIONS MODL1LE
Referring to Fi~;. 3, the communications module 10 includes a radio or
wireless
modem 12, a microprocessor 14, an internal antenna 16, a memory 20 that is
preferably non-
volatile, an optional power supply 24, and an optional energy storage device
22. Also included
is a header 25, preferably having 4 pins: Tx, Rx, Power, and Ground. An
optional external
antenna 18, such as a standard. ground-plane antenna, an omni-directional
antenna, a 1 /4-wave
antenna, or a'/~-wave whip antenna, for example, can be used to improve radio
coverage in fringe
areas. The communications module 10 is connected to an option board 50
residing in the meter
30, which is described in further detail below. The communications module 1 U
further includes
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an outage or power failure (PF) detector 26. The communications module 10
preferably
communicates at a rate between about 9600 and about 19200 bps, but any
communication rate can
be used. Moreover, the communications module 10 preferably has a programmable
delay that is
adjustable between about zero seconds and about 65535 seconds before reporting
an outage.
The communication module contains a wireless modem 12 that communicates over
various data-packet networks including, but not limited to, ARDIS, BellSouth
Wireless Data,
Reflex, GSM, satellite, and other packet wireless data networks. The type of
modem that is used
is dependent on the network that is used. The ARDIS network uses the Motorola
DataTAC
technology. A preferred modem is the Motorola ARDIS modem, model number SOSsd.
Another
exemplary modem is an ARI>I S modem from Research In Motion (RIM).
Preferably, the A12DIS modem from RIM has a 14-pin lmm pitch flat flex cable
that it uses for signal pins only. The power for the modem is supplied via a
two-wire Molex
connector with a secured lock-fit. The 14-pin signal connector is a Low
Insertion Force (LIF) type
connector. The connector contacts are tin plated, which are preferably gold
plated. The main
advantage to using the RIM modem is that it has a simpler protocol (RAP) and
can be used to
communicate with an ARDIS modem or a RAM Mobile Data modem. This allows one
protocol
to be implemented in the processor that can talk to two networks, depending on
which modem is
attached. The RIM modem can be attached using very high bond tape, for
example, manufactured
by 3M, or by any other mechanical means.
The modem 12 uses a significant amount of power (e.g., about 1 A at 7.SV or
about
7.SW) to transmit data. Preferably, the communications module 10 is powered
from the DC
voltage in the meter 30 instead of from AC power or an external source.
Therefore, it is desirable
to have some means of storing enough charge in the communications module 10 to
be able to
handle the transmission. There are a number of approaches to storing energy.
One energy storage
device 22 is a battery or series of batteries that are used to power the modem
32 and allow the
electronics to draw power off the meter supply. However, few batteries are
currently available that
handle instantaneous current draws of 1 A and then return to zero current (OA)
draw. Modem
manufacturers recommend using nickel cadmium (NiCad) batteries because this
technology
handles this type of load very well.
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Another approac;h is to use capacitors as an energy storage device 22.
Capacitors
are less expensive than batteries and use less complicated charging circuits
than those used for
batteries. The capacitors also typically have a longer lifetime than
batteries. Moreover, capacitors
can be selected that have a high temperature rating and can last approximately
8 to 10 years in an
outdoor environment. Measurement devices, including an analog-to-digital
converter (ADC), can
be used to measure the voltage on the capacitors while the modem is
transmitting. This gives a
digital representation of the derivative of the voltage on the capacitors with
respect to time
(dV/dT). As the capacitors age or begin to wear out, the capacitors are not
able to store as much
energy as they did when they ware new. As the capacitors begin to wear out,
the dV/dT curve will
increase. Calculations are made to determine when the capacitors have aged
such that they are no
longer able to store enough energy to ensure the reliability of the product
and can send an alarm
notification to the host 70 indiicating the unit should be replaced. It should
be noted that the
communications module can be supplied with power from any type of power
source, and is not
limited to the batteries or capacitors described above.
The energy storage capacity should be enough to support the transmitter for
normal
data transmission and alarm conditions, especially when a primary power outage
occurs and
should also accommodate retries. Alarm conditions include, but are not limited
to, "no contact
with the meter (possible cable cut}", "poor power quality", and "loss of
power, possible theft
condition" .
A preferred microprocessor 14 is the H8S/2350, manufactured by Hitachi. The
microprocessor 14 preferably has a 16-bit or 32-bit architecture, with a
preferred operating
frequency of about 3.6864 MHZ and operating voltage of 3.3V. It should be
noted the invention
is not limited to this microprocc;ssor and that any microprocessor can be
used. The microprocessor
14 also preferably has an on-chiip RAM and at least 2 universal asynchronous
receiver transmitters
(UARTs). One DART may be used for the connection to the meter 30, and the
other for a
connection to the radio modem 12.
The microproccasor 14 preferably interfaces to the radio modem 12 in "RAP" or
"NCL" mode (or other appropriate protocol) depending upon the radio supplier
chosen. The
microprocessor 14 in the communications module 10 responds to requests from a
server such as
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an Energy AxisT"', CSM, C&I server, an AMR server, or RCS 250 communications
server and
converts these requests to meter 30 protocol requests. The microprocessor 14
listens to the radio
modem 12, interprets requests, responds, preferably immediately, and/or passes
those requests
onto the meter 30, extracts the data, and converts it to a minimized packet
response to the server
request on a near-real time basis. A protocol is defined that is used to
communicate between the
communications module 10 and the host system 70. The communications module 10
passes data
requests to the meter 30, retrieves the data from the meter 30, and returns it
to the host system.
The host system is responsible for re-assembling the data packets in their
correct order,
interpreting the data, and loading it into a database for evaluation.
The communications module 10 offers in-field upgradeability. This is
accomplished through the use of flash memory 23. One of the major factors in
choosing flash
memory is the availability of the flash in single-supply programming voltage
which eliminates the
need to generate special supplies for programming purposes. The memory 23
operates at a
minimum of about 3.3V, but memory operable at other voltages can also be used.
Because the
bus width of the microprocessor 14 is preferably 16 bits, a 16-bit wide memory
part is desired,
although not required. The memory 23 is preferably at least 1 megabit in
density and can be
organized either as 128kb x 8 or as 64kb x 16, although 128kb x 8 is
preferred. The access time
is preferably between about 80ns and 200ns. If an 8-bit part is used, the
access time becomes
more critical because two acceases are required for each instruction fetch.
'This affects the
operating speed directly so care must be taken in finding the right balance
between total memory
access times and operating frequencies. The communications module 10 can store
host data in any
optional storage means such as a RAM or EEPROM 21.
'the communications module 10 is preferably mounted in a water-resistant
enclosure (not shown), and positioned near a utility usage meter 30, but can
be located anywhere.
The enclosure houses the components of the communications module 10 including
the internal
antenna 16, the radio modem 12, an optional external antenna connector. The
communications
module enclosure is preferably weather resistant and has a connector for
accepting the cable
coming from the meter 30.
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A watertight RF .connection is also desirable so that an external antenna 18
can be
connected. The external Rf connector should have the ability to be directly
coupled to the
wireless modem 12 with a connector, preferably an MMCX or SMA connector. The
external
antenna 18 is preferably isolated from the meter to prevent a possible shock
hazard. The
communications module 10 preferably withstands the same environmental
constraints placed on
the utility meter.
A holeplug can be punched out of the bottom of the communications module 10
and a connector, such as an MMCX to type N coaxial adapter, can be inserted to
accommodate
the external antenna 18 to improve radio coverage in fringe areas.
When the communications module 10 is first installed, the energy storage
device
22, if so equipped, is charged, and the module 10 initiates communications
with the meter 30. The
communications module 10 sends the meter ID back to the host 70 the first time
it is connected
to a meter. The communications module 10 does not send the meter ID back to
the host 70 unless
the meter ID stored in non-volatile RAM differs from that of the current meter
ID (e.g., if it is
attached to another meter).
The meter 30 preferably transmits an alarm notification when the meter 30 is
tampered with, damaged, or power is removed due to an outage. The meter 30
also preferably
transmits a notification when power is restored to the meter 30. The tamper
and damage alarms
are preferably approximately immediate. The outage notification and the power
restored
notification can be delayed by a randomly generated amount of time to avoid
overloading the
network.
WAN BOARD
'The meter 30 preferably contains a removable wide area network (WAN) option
board 50 that connects to the communications module 10, as shown in Fig. 3,
and provides KYZ
relays 52 (preferably two), a power supply 54, a current limiter 56, a pin
header 58 (preferably
having 4 pins: Tx, Rx, Power, and Ground), and a serial communications device
60. The current
limiter 56 prevents anything in the communication module external enclosure
from consuming
too much current, which would cause the meter 30 to reset. Preferably, the
transmit (Tx) and
receive (Rx) pins on the header S8 are optically isolated from the meter 30.
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'the two KYZ relays 52 are preferably substantially identical. The power
supply
54 is preferably an isolated step-~up converter operating at maximum possible
efficiency. It should
be noted that the meter power supply is buffered by the communications module
10 to increase
the short time duration energy capability. Preferably, the DC voltage is
isolated by a transformer.
Referring to Fig. 4, there is shown a functional block diagram of the
interconnection of the option board 50 and the meter 30. As illustrated, the
transmit/receive cable
connects to the pin header 58. T'he transmit (Tx) and receive (Rx) leads are
input to the serial
communication device 60. The power and ground lines are input to the power
supply 54. The
option board 50 is connected t:o an option connector 30C provided within the
meter 30. The
10 option connector 30C is connected to a serial communications line 30D,
which is connected to the
DART (not shown) within the rnicrocontroller 30B. The DART preferably operates
in a session-
based fashion with the option board 50 to receive and transmit data and
commands from the option
board 50 and the communications module 10. Information and commands may be
passed from
the communications module 1 (1 to the microcontroller 30B or Meter IC 30A via
the option
15 connector 30C to affect the operation of the microcontroller 30B or Meter
IC 30A and other
functions controlled by the microcontroller 30B or Meter IC 30A.
It is noted that the connection between option board 50 and the option
connector
30C is illustrated in the exemplary configuration as having certain signals or
leads. The
connection between option bo~crd 50 and the option connector 30C is not
limited to such signals,
nor is the option board 50 limited to having the disclosed elements and
functions, as other
functionalities may be provided.
ANTENNA
An internal antc;nna 16 is mounted within the communications module enclosure.
In areas where transmission interference is prevalent or network/host signal
levels are irregular
or insufficient, an external antenna 18 can be used. The external antenna
connector can use the
same jumper as the internal antenna.
Preferably, a double-tapered dipole antenna, as shown in Fig. 5(a), is used as
the
internal antenna 16. An exemplary antenna is a double-tapered, printed circuit
dipole for about
806 to about 870 MHZ, and preferably comprises a copper plate 90 shaped in the
desired antenna
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pattern. The dipole length is adjusted to compensate for the dielectric
loading effects of both the
antenna printed circuit board 91 and the enclosure in which the communications
module IO is
mounted. Thus, the antenna 16 is preferably shortened from its free-space
resonant length, and
tuned to match its environment. The antenna has extended dipoles and enhances
broad bandwidth.
The additional taper of the dipolf;s in the vicinity of the feed-point gap in
the center of the antenna
I6 center provides a match to a transmission line, preferably 50 ohm. The
double taper provides
more bandwidth than a single bowtie antenna or an antenna with no taper. Also
in the center of
the antenna is a one-to-one balun 19, preferably 50 ohm and a printed circuit
balun, shown in
detail in Fig. 5(b). The baiun 19 converts unbalanced coaxial cable to
balanced termination for
a balanced dipole antenna. T'he: balun 19 prevents currents induced in the
coaxial cable shield
from flowing into the antenna as unbalanced and disturbing the feed-point
impedance and antenna
radiation pattern. A jack 27, preferably an MMCX female jack, is included to
terminate the cable
from the modem 12. Although Figs. 5(a) and 5(b) show exemplary measurement
specifications,
it is contemplated that the specifications can be changed in accordance with
the desired antenna
characteristics.
OUTAGE DETECTION
The communications module 10 continuously monitors the connection between the
module 10 and the meter 30. Whenever communications are lost with the meter 30
due to a line
power outage or tamper, the module waits a programmable, predetermined length
of time, such
as two minutes, to allow the line to recover automatically. Then the module 10
waits a random
amount of time, for example, between about zero and about 65535 seconds, to
transmit an outage
notification message to the host 70. When power is restored, the
communications module 10
waits a random amount of time, for example, between about zero and about 6553
S seconds before
waking up the modem 12, thereby enabling the transmitter so that it can log on
the network. After
power is restored, the modem 12 waits a random amount of time, for example,
between about five
and ten minutes, to send a "back in service" notification or message to the
host 70 indicating that
power has been restored.
The communications module 10 desirably has a configurable outage detection.
The
communications module 10 determines whether or not to do outage reporting
based on remotely
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controllable configuration settings. If this field is set in the
communications module 10, then the
communications module 10 will alert the host system 70 of an outage. Thus, the
communications
module 10 preferably supports the outage reporting feature of the meter 30,
whether the meter 30
supports it or not. The communications module 10 will transmit an outage
message within a
S programmable time of, for example, between about zero and about 6SS3S
seconds following the
initiation of the power failure. A message will also be transmitted to report
power restoration
following the return of power to the meter 30. There will be a random delay in
sending the
restoration message of, for exannple, between about one and fifteen minutes.
This delay facilitates
restoration reporting without overloading the system with an instantaneous
receipt of multiple
incoming messages.
After the power fails, the communications module 10 reduces current draw on
the
system by turning off all unneeded peripherals and putting the microprocessor
14 in the lowest
power mode available. The communications module 10 also controls the modem
power usage
mode to further reduce power. As described above, the communications module 10
then waits a
1 S random amount of time between the minimum and maximum values it has been
programmed with
before waking back up. Upon wake-up, the microprocessor 14 verifies that power
is still out and
if it is, proceeds to transmit the outage notification to the host 70. If the
power has been restored,
the communications module 10 proceeds as normal, without transmitting the
outage notification.
If power is restored while the microprocessor 14 is asleep, the communications
module 10 aborts
the outage sequence.
If the meter 30 is read over the network 80 at a predetermined time (e.g.,
after
midnight), the communications module 10 responds with the appropriate load
profile data (e.g.,
for the previous 24 hours). T'irne-of use data, and preferably any other data
stored in the meter 30,
can be retrieved by the host. The communications module 10 preferably responds
to all requests
2S and constantly monitors radio coverage, and signal strength. A summary of
the minimum,
maximum, and average Receive Signal Strength Indicator (RSSI) along with the
number of times
the modem 12 has gone out of coverage, along with other status information,
can be returned with
a predefined host command.
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The communications module 10 preferably supports the meter protocol, and
commands to get and/or set the meter/communications module configuration
request, and to adjust
the meter time, and responses to notify of a power failure and/or power
restoration, to provide the
get and/or set the meter/communications module configuration response, and to
provide the meter
time.
STATUS DISPLAY
'Che communications module 10 further provides the ability to display the
status
of the wireless modem 12 on the meter 30. The display on the meter 30 can be
interrupted (not
lost) at predetermined intervals. to show such radio status information as
signal strength (e.g.,
Receive Signal Strength Indicator or RSSI), signal quality, and whether it is
recommended that
the module 10 be placed elsewhere (e.g., "yes" means the module is functioning
properly and does
not need to be moved, "no" means that the location is not suitable and the
module should be
located elsewhere). The determination of "yes" or "no" is made responsive to
the RSSI values.
The meter display is also used to alert personnel when the meter is being
queried by the host (by
displaying "busy").
'the information to be transmitted is encapsulated in a protocol. A listening
module
is preferably implemented in the network 80 to transfer information packets
and perform any
needed protocol conversion.
Preferably, the rneter 30 has a clock and transmits its time and date
information
back to the communications module 10 and host 70 along with additional data
obtained from a
meter reading. Moreover, the clock is preferably synchronized with a national
time standard prior
to making data collections. The communications module 10, after performing all
meter functions
for a transmission, reads the rrieter clock and builds a time and date
information message and
sends it to the host 70. The host 70 determines whether or not the meter time
is within the limit
by comparing the transmission delay to the differences between meter time and
host time. If the
host determines that the meter Mime is off, the host 70 sends the
communications module 10 the
difference to adjust the meter time. The difference can be positive or
negative. The
communications module 10 then adjusts the meter's clock. If the host 70 cannot
determine the
meter time accuracy, it tries again during the next clock cycle and generates
an alarm if
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unsuccessful.
Although illustrated and described herein with reference to certain specific
embodiments, the present invention is nevertheless not intended to be limited
to the details shown.
Rather, various modifications may be made in the details within the scope and
range of
equivalents of the claims and without departing from the invention.
