Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
101520253035CA 02264796 1999-03-03WO 98110394 PCT/US97/15570AUTOMATIC METER READING DATA COMMUNICATION SYSTEMBACKGROUND OF THE INVENTIONThe present invention relates to automatic meter readingdata communication systems. the inventionMore specifically,relates to an integrated device that attaches to utility meters andcommunicates commodity usage data and other information over a two-(LAN) to a remotely locatedcommunication device that transmits the data over a two-way fixed(WAN)way wireless local area networkcommon carrier wide area network to a utility serviceprovider.Commodity usage is conventionally determined by utilitycompanies using meters that monitor subscriber consumption. Theutility" service provider typically determines the subscriber'sconsumption by sending a service person to each meter location tomanually record the information displayed on the meter dial. Themanual reading is then entered into a computer which processes theinformation and outputs a billing statement for the subscriber.Often times it is very difficult for the service person to accessa meter. when access to a meter is not possible, billings aremade on the basis of estimated readings. These estimated billingsoften lead to customer complaints.Visual onâsite meter reading by utility service personnelis highly labor intensive, inefficient and very expensive.Therefore, there has been a strong interest on the part of utilitytakecosts andcompanies to advantage of modern technology to reduceoperating increase efficiency by eliminating thenecessity for visual on-site meter readings.Many attempts have been made in recent years to developan automatic meter reading system for water, gas and electricmeters which avoid the high costs of visual onâsite meter reading.However, most of these prior art systems have achieved littlesuccess.Various types of devices have been attached to utilitymeters in an effort to simplify meter reading. These devices weredeveloped to transfer commodity usage data over a communicationl0l520253035CA 02264796 1999-03-03W0 98/ 10394 PCTIUS97/15570link to a centrally located service center or utility. Thesecommunication links included telephone lines, power lines, or aradio frequency (RF) link.The use of existing telephone lines and power lines tocommunicate commodity usage data to a utility have encounteredsignificant technical difficulties. In a telephone line system,the meter data may interfere with the subscriber's normal phoneline operation, and would require cooperation between the telephonecompany and the utility company for shared use of the telephonelines. A telephone line communication link would also require ahard wire connection between the meter and the main telephone line,increasing installation costs.(PLC)require a hard wire connection between the meter and the main powerAnother disadvantage of the PLC system is the possibility oflosing data from interference on the power line.The use of a power line carriercommunication link over existing power lines would againline.Meters have been developed which can be read remotely.Such meters are configured as transponders and include a radiotransmitter for transmitting data to the utility. These prior artsystems required the meter to be polled on a regular basis by adata interrogator. The data interrogator may be mounted to amobile unit traveling around the neighborhood, incorporated withina portable hand-held unit carried by a service person, or mountedat a centrally located site. When the meter is interrogated by anRF signal from the data interrogator, the meter responds bytransmitting a signal encoded with the meter reading and any otherinformation requested. The meter does not initiate the communica-tion.However, such prior art systems have disadvantages. Thethat thegenerally has a small transceiver having a very low power outputfirst disadvantage is device mounted to the meterand thus a very short range. This would require that the interro-gation unit be in close proximity to the meters. Another disadvan-tage is that the device attached to the meter must be polled on aThe device attached to themeter is not able to initiate a communication.regular basis by the data interrogator.The mobile andhand-held data interrogators are of limited value since it is stillnecessary for utility service personnel to travel around neighbor-hoods and businesses to remotely read the meters. It only avoids-2-101520253035CA 02264796 1999-03-03WO 98/10394 PCT/US97/15570the necessity of entering a residence or other building to read themeters. The systems utilizing a data interrogator at fixedlocations still have the disadvantages of low power output from thedevices attached to the meters, and requiring polling by the datainterrogator to initiate communication.Therefore, although automatic meter reading systems areknown in the prior art, the currently available automatic meterreading systems suffer from several disadvantages, such as lowThus, it would beparticularly desirable to provide an automatic meter reading systemoperating range and communication reliability.that provides reliable communication of information from the meterto the utility,personnel to manually read the meters.thus avoiding the necessity for utility serviceSUMMARY OF THE INVENTIONAn object of the present invention is to provide areliable automatic meter reading data communication systemextending from a commodity meter to the utility service provider.Another object of the present invention is to provide aninterface management unit that attaches to existing commodity meterand providesregister heads commodity utilization data to aremotely located gateway node over a two-way wireless spreadspectrum local area network.A further object of the invention is to provide a gatewaynode for receiving commodity utilization data from the interfacemanagement unit and transmitting that data to a utility serviceprovider over a commercially available fixed common carrier widearea network.Yet another object of the invention is to provide thecommunication links necessary for performing data requests from theutility, preprogrammed scheduled meter readings and handlingspontaneous tamper and alarm messages from an interface managementunit attached to a commodity meter.The present invention is an automatic meter reading datacommunication system which incorporates an interface managementunit that is attachable to commodity meters such as water, gas andelectric meters for collecting, processing and transmitting datafrom the meter to a remotely located gateway node which transmitsthe data to the utility service provider. The interface management-3-101520253035CA 02264796 1999-03-03W0 98/10394 PCT/US97/15570unit replaces the register head of the commodity meter using anadapter ring to retrofit the interface management unit onto theexisting meter body for meters produced by a vdde variety ofmanufacturers. The interface management unit comprises a digitalencoder and twoâway wireless transceiver for automatically readingcommodity usage based on requests from the utility or preprogrammedscheduled readings. The interface management unit also monitorsthe status of the meters to determine tamper and alarm conditions.The encoder and transceiver of the interface managementunit are made up of four major components. These componentsinclude a supervisory microcontroller, a communication microcon-troller, a spread spectrum processor and an RF transceiver. Themicrocontroller monitors and obtainssupervisory commodityutilization data from the meter. The supervisory microcontrolleralso senses for the presence of an interrogation signal from thegateway node. The communication microcontroller is connected tothe supervisory' microcontroller and controls the internal andexternal communication functions of the interface management unit.The spread spectrunm processor is coupled to the communicationmicrocontroller for enabling the interface management unit totransmit and receive data utilizing an RF spread spectrum communi-cation technique over the local area network. The RF transceiveris coupled to the spread spectrum processor and the communicationmicrocontroller for transmitting commodity utilization data fromthe meter and for receiving interrogation signals from the gatewaynode.The gateway node is located remotely from the interfacemanagement unit to complete the local area network. The gatewaynode is also made up of four major components. These componentsinclude a wide area network interface module, an initializationmicrocontroller, a spread spectrum.processor and an RF transceiver.The gateway node is responsible for providing interrogation signalsto the interface management unit and for receiving commodityutilization data from the interface management unit for the localarea network. However, the gateway node also provides the link tothe utility service provider over a commercially available fixedtwoâway common carrier wide area network.The RFinterrogation signals from the utility or preprogrammed signals fortransceiver of the gateway node transmits-4-202530CA 02264796 2002-04-04scheduled readings to the interface management unit, and receivescommodity utilization data in return from the interface managementunit for transmission to the utility over the wide area network,The spread spectrum processor is coupled to the RP transceiver andenables the gateway node to transmit and receive data utilizing thespread spectrum communication technique. The WAN interface moduleis coupled to the spread spectrum processor and transmits data toand from the utility service provider over any commerciallyavailable wide area network that is desired. A different WANinterface module can be used for each different commerciallyavailable wide area network desired. the initialization microcon-troller is interposed between the interface module and the spreadspectrum processor for controlling operation of the spread spectrumprocessor and for controlling communication within the gatewaynode.In an alternate embodiment of the invention, a relay nodeis located between the interface management unit and the gatewaynode within the local area network to provide added communicationpower when needed. Thus, when a gateway node is located outsidethe RF communication range of the interface management unit, arelay node is required to retransmit 3? communication data to andfrom the interface management unit.Meter reading, meter information management and networkcommunications are all controlled by two-way system software thatis preprogrammed into the interface management unit duringmanufacture and installation, and preprogrammed in the gatewaynode. The software allows the interface management unit to beconfigured to encode and manage input from a wide variety of water.gas and electric meters. The software enables an operator toeasily change a serial number, provide a meter reading automatical-lv or on demand, vary the units of measure being reported, andmonitor system status for reporting tamper, alarm or low batteryconditions.1U!I10l5202530CA 02264796 2002-04-04Accordingly, in one aspect, the presentinvention provides an automatic meter reading datacommunication system for obtaining commodity utilizationdata from a commodity meter, said automatic meter readingdata communication system comprising: an interfacemanagement unit removably attachable to the exterior ofthe commodity meter, the interface management unitincluding a sealed housing enclosing a digital encoderhaving an input positionable to obtain commodityutilization data from the commodity meter through thesealed housing, the interface management unit includingsoftware programmable to interpret the commodityutilization data based upon the type of commodity meter towhich the interface management unit is attached; a gatewaynode located remotely from interface management unit andcommunicating with the interface management unit over atwo-way wireless local area network; and wherein saidgateway node communicates with a utility service providerover a two-way fixed common carrier wide area network.In a further aspect, the present inventionprovides an interface management unit removably attachableto one of a pluralityâ of different types of commoditymeters, said interface management unit communicating witha remote gateway node, said interface management unitcomprising: a sealed housing positionable on the commoditymeter and enclosing a digital encoder having an inputpositioned for obtaining commodity utilization data fromthe commodity meter through the housing and for storingsaid data; an adapter ring attachable to the commoditymeter and configured to removably receive the housing ofthe interface management unit such that the input for the_5a..1015202530CA 02264796 2002-04-04digital encoder is positioned to obtain the commodityutilization data, wherein the adapter ring is configuredbased upon the type of commodity meter; and a two-waywireless transceiver coupled to said digital encoder fortransmitting commodity utilization data from the meter andfor receiving data requests from the gateway node over atwo-way wireless local are network.In a still further aspect, the present inventionprovides an interface management unit suitable for usewith a plurality of types of commodity meters, saidinterface management unit communicating with a remotegateway node, said interface management unit comprising: asealed housing removably attachable to the exterior of thecommodityâ meter; a supervisoryâ microcontroller containedwithin the housing and having an input coupled to themeter through the housing for obtaining commodityutilization data therefrom, the supervisorymicrocontroller being programmed to interpret and storethe commodity utilization data based upon the type ofcommodity meter, said supervisory microcontrollerperiodically energizing the remaining portions of saidinterface management unit to sense for the presence of aninterrogation signal; a communication microcontrollerconnected to said supervisory' microcontroller, saidcommunication microcontroller controlling the internal andexternal communication functions of said interfacemanagement unit; a spread spectrmm processor coupled tosaid communications microcontroller for enabling saidinterface management unit to transmit and receive datautilizing a spread spectrum communication technique; andan RF transceiver coupled to said spread spectrum_5b-10152025CA 02264796 2002-04-04processor and said communication microcontroller fortransmitting commodity utilization data from the interfacemanagement unit and for receiving interrogation signalsfrom the gateway node.In a further aspect, the present inventionprovides a method for automatically reading data from oneof a plurality of types of commodity meters andtransmitting that data over a twoâway wirelesscommunication line, the method comprising the steps of:selecting an adapter ring based upon the type of commoditymeter; installing the adapter ring to the exterior of thecommodity meter; removably attaching an interfacemanagement unit on the adapter ring installed on thecommodity meter, adapter ring positioning the interfacemanagement unit such that the interface management unitcan read the commodity utilization data; interrogating theinterface management unit with a gateway node locatedremotely from the interface management unit over a twoâwaywireless RF spread spectrum local area network; respondingto the interrogation signal by providing an RF messageover the local area network to the gateway note; andtransmitting the requested data from the gateway node to autility service provider over a fixedtwoâway commoncarrier wide area network.BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGSFig. 1 is a perspective view of an interfacemanagement unit attached to a vmter meter in accordancewith the present invention;_.5c_101520253035CA 02264796 1999-03-03W0 98/ 10394 PCT/US97ll 5570Fig. 2 is a perspective View of an adapter ring used toattach the interface management unit to the meter;Fig. 3 is an exploded perspective view of the internalstructure of an interface management unit;Fig. 4 is a front elevational view of a gateway node;Fig. 5A is a schematic view of interface management unitsfor water, gas and electric meters interfacing with a remotegateway node and the utility service provider;Fig. 5B is a schematic view of interface management unitsfor water, gas and electric meters interfacing with a proximaterelay node, a remote gateway node and the utility service provider;Fig. 6A is a flow diagram of an automatic meter readingdata communication system;Fig. 6B is a flow diagram of an alternative automaticmeter reading data communication system;Fig. 7 is a block diagram of the interface managementunit circuitry;Fig. 8 is a block diagram of the RF transceiver of theinterface management unit, the relay node and the gateway node;Fig. 9 is a block diagram of the frequency synthesizerportion of the RF transceiver of Fig. 8;Fig. 10 is a block diagram of the gateway node circuitry;Fig. 11A is a flowâ diagraut of the operation of theinterface management unit in power management and communication;Fig. 11B is a continuation of the flow diagram of Fig.11A;Fig. 11C is a continuation of the flow diagram of Fig.11B;Fig. 12 is a flow diagram of interface management unitcommissioning;Fig. 13 is a flow diagram of the interface managementunit virtual shutâoff function;Fig. 14 is a functional diagram of the automatic meterreading data communication system;Fig. 15A is a flow diagram of the WAN handler portion ofthe data communication system of Fig. 14;Fig. 15B is a flow diagram of the message dispatcherportion of the data communication system of Fig. 14;101520253035CA 02264796 1999-03-03W0 98/ 10394 PCT/US97/ 15570Fig. 15C is a flow diagram of the RF handler portion ofthe data communication system of Fig. 14;Fig. 15D is a flow diagram of the scheduler portion ofthe data communication system of Fig. 14; andFig. 15E is a flow diagram of the data stores portion ofthe data communication system of Fig. 14.DETAILED DESCRIPTION OF THE INVENTIONThe SystemAs shown in Figs. 5 and 6, the present invention providesan automatic meter reading data communication system 20 having aninterface management unit 22 which communicates with a gateway nodeLocatedin between the interface management unit 22 and the gateway node 2424 located remote from the interface management unit 22.may be a relay node 26, Figs. SB and 6B, that is located proximateto thecommunication power from the interface management unit 22 to theof theTherefore,interface management units 22 and provides additionalgateway node 24. The interfacecommunication rangemanagement unit 22 is approximately 400 ft. if agateway node 24 is farther than 400 ft. away from an interfacemanagement unit 22 then a relay node 26 is needed to retransmit themessage from the interface management unit 22 to the gateway node24. The RF communication ranges of the relay node 26 and thegateway node 24 are approximately one mile.The interface management unit 22 is primarily 51 datagathering device that may be attached to a residential utilitymeter 28 such as a water or gas meter, for transmitting gathereddata relating to consumed amounts of commodities, such as water orgas usage, to the gateway node 24. The interface management unit22 may also interface with other devices to monitor such things ashome security, environmental conditions, personal medical condi-tions, the existence of smoke or carbon monoxide, etc.The gateway node 24 interrogates interface managementunit 22 to obtain the gathered data by a radio frequency (RF)communication link and then transmits that data to a utilityservice provider 30 over a fixed wide area network (WAN) 34.In a preferred embodiment of the invention, Figs. SA and6A, a plurality of interface management units 22 attached to meters28 for different commodities,such as water, gas and electric,101520253035CA 02264796 1999-03-03W0 98/ 10394 PCT/U S97/ 15570communicate over a local area network (LAN) 32 to a gateway node 24which transmits the commodity data from interface management units22 to a utility 30 over a fixed common carrier wide area network(WAN) 34. The gateway node 24 provides end to end communicationsfrom the meter 28 to the utility 30. A first link in the datacommunication system is a twoâway 900 MHz spread spectrum LAN 32.The second link within the data communication system is designed tobe any commercially available twoâway common carrier WAN 34. Inthis embodiment, a gateway node 24 must be within the communicationrange of the interface management unit 22 which is approximately400 ft.interface management unit's communication range then a relay nodeHowever, if the gateway node 24 is outside of the26 may be provided to retransmit the data from the interfacemanagement unit 22 to the gateway node 24 as shown in Figs. SB and6B. The operating range of the relay node is approximately onemile. The relay node 26 utilizes the same RF transceiver circuitryas the interface management unit 22 and the gateway node 24. TheLAN communication links 32A and 32B shown in Fig. 6B technicallycomprise the same link as LAN 32 shown in Fig. 6A. The onlydifference is that the gateway node 24 in Fig. 6B is outside thecommunication range of interface management unit 22 thus requiringa retransmission of the data by relay node 26.The data gathered from interface management units 22 istypically provided to computers in the utility company and used togenerate billings or commodity usage data.Interface Management UnitReferring now to Fig. 1, interface management unit 22 isan integrated. unit that attaches to a water, gas or electricutility meter 28 by adapter ring 36. The interface management unit22 replaces the register head of the meter 28 using the adapterring 36 to retrofit the interface management unit 22 onto theexisting meter body 28 for the meters of a wide variety ofmanufacturers. This is accomplished by the use of a plurality ofdifferent adapter rings 36 and programmable software within theinterface management unit 22.internal structure of interfaceFig. 3 shows themanagement unit 22. Interface management unit 22 comprises topcover 40, bottom cover 46, and two printed circuit boards 42 and-3-101520253035CA 02264796 1999-03-03W0 98/10394 PCT/US97ll557044. Printed circuit board 42 is preferably an RF antenna with acut out 48 for the liquid crystal display 38 on printed circuitboard 44. The liquid crystal display 38 displays meter reading,unit of measure, tamper and status conditions. Printed circuitboard 44 includes various components and connectors as detailed inthe block diagram of Fig. 7. Interface management unit 22 ispowered by" a battery 50. The compact integrated design andadaptability with various meters and meter brands presents a costsavings from prior art systems.The interface management unit 22 is an integrated,digital encoder and two-way wireless transceiver that monitors theactivity of a utility meter 28, such as a water, gas or electricmeter, ascertaining commodity usage by counting pulses produced bya rotating vane in the water, and communicates commodity usagedata, via a RF local area network (LAN) to a relay node 26 or agateway node 24. The events counted by interface management unit22 are usually pulses generated by a turbine or other transducerAdditionalfeatures, such as valve actuation outputs and tamper inputs, mayelement responsive to commodity flow through the meter.also be provided in interface management unit 22.As hereinafter described in detail, communication betweenthe interface management unit 22 and the relay node 26 or gatewaynode 24 is preferably established using a two-way 900 MHz directsequence, spread spectrum data transmission technique having aplurality of channels in the employed frequency band. Theinterface management unit 22 performs its automatic meter readingfunctions in response to requests from the utility, from prepro-grammed scheduled readings, or from spontaneous alarm messages.These automatic meter reading functions include monthly usagereadings, remote first and final meter readings, realâtime tamperdetection and notification, virtual shutâoff function, and alarmsystem functions. In addition, the interface management unit 22attached to a water meter is capable of leak detection and low flowreporting, and is submersible in pit applications without a fixedantenna attachment. An interface management unit 22 attached to agas meter is capable of runaway meter detection. The interfacemanagement unit 22 also performs security and information manage-ment tasks.101520253035CA 02264796 1999-03-03WO 98/10394 PCT/US97/15570The interface management unit 22 is installed using aportable computer to program utility identification numbers, metersettings and readings, units of measure, and alarm set points.Once the interface management unit is installed, it is linked to agateway node over two-way wireless LAN 32. As mentioned above, theinterface management unit 22 does not need to be awakened in orderto send data. The interface management unit can either initiate acommunication on its own, perform previously programmed scheduledreadings or respond to requests from the utility through thegateway node 24.Communication NodesThe gateway node 24 is shown in Fig. 4. The gateway node24 is typically located on top of a power pole so that it may actIt thusThe gateway node 24includes an antenna 52 for receiving and transmitting data over theas a communication node between LAN 32 and WAN 34.functions as the LAN to WAN connection.communication links, and a power line carrier connector 54 forconnecting a power line to power the gateway node 24. The gatewaynode 24 may also be solar powered. The compact design allows foreasy placement on any existing utility pole or similarly situatedelevated location. The gateway node 24 provides end to endcommunications from the meter to the utility. The wireless gatewaynode 24 interfaces with the interface management unit 22 over atwo-way 900 MHz spread spectrum LAN 32. Also, the gateway node 24will interface and be compatible with any WAN 34 for communicatingwith the utility.meet a variety of data reporting needs.The gateway node 24 is field programmable toThe gateway node 24 receives data requests for water, gasand electric meter data, interrogates the meter and forwards usageinformation, as well as condition status data, over the WAN 34 tothe utility 30.safety,It also provides communication links with othersecurity and information nodes. The gatewayâ node 24exchanges data with certain, predetermined, interface managementunits for which it is responsible, and "listens" for signals fromthose interface management units. The gateway node 24 does notstore data for extended periods, thus minimizing security risks.The gateway node's RF communication range is typically one mile.-10-101520253035WO 98/10394CA 02264796 1999-03-03PCT/U S97/ 15570The relay node 26 acts as an intermediate transceiver toprovide additional power boost to get the RF signal from theinterface management unit 22 to the gateway node 24. The relaynode 26 can be either solar powered or powered through a power linecarrier connection. The same RF transceiver circuitry found in theinterface management unit 22 and the gateway node 24 is utilized inthe relay node 26.A wide variety of fixed wide area network (WAN) communi-cation systems such as those employed with two-way pagers, cellulartelephones, conventional telephones, personal communicationservices (PCS), cellular digital packet data (CDPD) systems, andsatellites may be used to communicate data between the gatewaynodes and the utility. The data communication system utilizeschannelized direct sequence spread spectrum transmissions forcommunicating between the interface management units, relay nodesand gateway nodes.Circuitry of Interface Management UnitFig. 7 shows a block diagram of a half duplex channel-ized, direct sequence, spread spectrum circuit board 44 withininterface management unit 22. The circuit board is composed offour major functional components; supervisory microcontroller 56,communication microcontroller 58, spread spectrun1processor 60, andradio frequency (RF) transceiver 62.supervisory microcontroller 56 carries out the primaryinterface function between interface management unit 22 and meter28. This includes detecting and accumulating pulses from utilitymeter transducer 64. The accumulated pulse totalization may beconverted to corresponding units of commodity âvolume and theresults displayed on liquid crystal display (LCD) 38 to provide avisual indication of commodity consumption. The supervisorymicrocontroller also monitors inputs from tamper switch 66 forunauthorized use or status reporting. The microcontroller 56 iscoupled to a low battery detector 68 for monitoring battery power.This microcontroller 56 also includes the data systemssupervisory timer which controls power management functions.During normal operation supervisory microcontroller 56 is runningat a predetermined clock speed, for example 32.768 KHz, which isprovided by an external crystal oscillator 70. All other compo--11..101520253035CA 02264796 1999-03-03WO 98/10394 PCT/US97/15570nents in the interface management unit 22 are either in a low power"sleep" mode or have power completely removed from them. Periodi-cally, supervisory microcontroller 56 applies power to the othercomponents and "wakes" them "up" to ascertain whether an interro-The wakeup power application may occur every 2-8 seconds, typically.gating RF signal from gateway node 24 is present or not.If aninterrogatory signal is not present, power is removed from theother components or they are returned to the low power sleep mode.This technique is used to conserve battery power, and thus extendbattery life. If a valid interrogatory signal is present, inter-face management unit 22 will transmit data to relay node 26 orgateway node 24.Supervisory microcontroller 56 may comprise the micropro-cessor component sold by Toshiba of Japan under the designationTMP47P422VN.Communication microcontroller 58 is responsible for allaspects of radio frequency (RF) communication management ininterface management unit 22 including determining whether or notany given RF signal is a valid interrogating signal and performingthe actual data interchange with gateway node 24. Microcontroller58 provides control information to spread spectrum processor 60 andRF transceiver 62 to control spread spectrunm protocol and RFchannelization.As noted above, when communication microcontroller 58 isnot performing communication activities it is in a "sleep" mode.Communication microcontroller 58 may comprise themicroprocessor component sold by Microchip of Chandler, Arizonaunder the designation PICl6LC74â04/L.As noted above, data communication systent 20 of thepresent invention.preferably employs spread spectrum communicationsbetween interface management unit 22 and gateway node 24, or relaynode 26.The spread spectrum communication technique makes use ofa sequential noise-like signal structure, for example, pseudo-noise(PN) codes to spread a normally narrowband information signal overa relatively wide band of frequencies. The receiver correlatesthese signals to retrieve the original information signal. Thetechnique may be further understood by reference to U.S. Patent5,166,952 and the numerous publications cited therein.-12..101520253035W0 98/10394CA 02264796 1999-03-03PCT/US97/15570The use of the spread spectrum communication technique,when used in conjunction with the direct sequence modulationtechnique, hereinafter described, gives data communications system20 a measure of security, increased immunity from interference andthe potential for operating more than one interface management unitwithin a given environment. The improved signal to noise ratioallows the system to operate with increased range. These communi~cation techniques also avoid the need to obtain licensure fromgovernmental authorities controlling radio communication.Spread spectrum processor 60 functions to perform spreadspectrum encoding of the data from communication microcontroller 58provided to RF transceiver 62 and decoding of the spread spectrumdata from the RF transceiver. The spread spectrum processor alsogenerates the 2.4576 MHz clock signal for communication microconâtroller 58 and the frequency synthesizer 72 of RF transceiver 62.The spread spectrum processor 60 may comprise an applicationspecific integrated circuit (ASIC) gate array made and sold byCylink Corporation of Sunnyvale, California, under the designationSST32ADL which contains a 9.8304 MHz crystal oscillator 74, dataregisters, and encoding/decoding logic.The encoding/decoding logic of spread spectrum processor60 samples the incoming serial data from the communicationmicrocontroller and converts it into a 32 bit pseudo-noise (PN)encoded data streanx at a rate which is divided from crystaloscillator 74 by a factor of 192. The PN sequence represents twodata input samples. Each pair of the serial data bits or "dibits"is represented by a unique 32 bit PN sequence.Fig. 8 shows a block diagram of RF transceiver 62 ofinterface management unit 22.Communication to and from interface management unit 22may be carried out in one of a preselected number, for example 24channels in a preselected frequency band, for example 902-928 MHz.Interface management unit 22 receives data and transmits a responseon a single RF channel which is the same for both transmit andreceive operation. As hereinafter described, the specific RFchannel used for communication is chosen during commissioning andThe RF channel ischosen to be different fronl the operating channels of other,installation of the unit and loaded into memory.adjacent interface management units, thereby to prevent two or more-13-101520253035CA 02264796 1999-03-03W0 98/10394 PCT/US97/15570interface management units from responding to the same interroga-tion signal.Frequency synthesizer' 72 performs the modulation anddemodulation of the spread spectrum data provided by spreadspectrum processor 60 onto a carrier signal and demodulation ofsuch data from the carrier signal. The RF transceiver has separatetransmitter 76 and receiver 78 sections fed from frequencysynthesizer 72 which is shared by the two sections.Antenna 80 is coupled through band pass filter 82 to aswitch 84,microcontroller 58, which connects the desired one of transmittertransmit-receive antenna operated by communication76 or receiver 78 to antenna 80.The output of spread spectrum processor 60 to frequencysynthesizer 72 comprises a 2.4576 MHz reference frequency signal inconductor 86 and a PN encoded base band signal in conductor 88.Frequency synthesizer 72 may comprise a National SemiconductorLMX2332A Dual Frequency Synthesizer.The direct sequence modulation technique employed. byfrequency synthesizer 72 uses a high rate binary code (PN code) tomodulate the base band signal. The resulting spread signal is usedto modulate the transmitterâs RF carrier signal. The spreadingcode is a fixed length PN sequence of bits, called chips, which isof theand the fixedsequence allows the code to be replicated in the receiver forconstantly being recycled. The pseudo-random naturesequence achieves the desired signal spreading,recovery of the signal. Therefore, in direct sequence, the baseband signal is modulated with the PN code spreading function, andthe carrier is modulated to produce the wide band signal.Minimum shift keying (MSK) modulation is used in order toallow reliable communications, efficient use of the radio spectrum,and to keep the component count and power consumption low. Themodulation performed by frequency synthesizer 72 is minimum shiftkeying (MSK) at a chip rate of 819.2 Kchips per second, yielding atransmission with a 6 dB instantaneous bandwidth of 670.5 KHz.The receiver bandwidth of interface management unit 22 isnominally 1 MHz, with a minimum bandwidth of 900 KHz. Frequencyresolution of the synthesizer is 0.2048 MHz, which will be used tochannelize the band into 24 channels spaced a minimum of 1.024 MHZapart. This frequency channelization is used to minimize interfer--14-101520CA 02264796 1999-03-03W0 98/10394 PCT/US97/15570ence between interface management units within a common communi-cation range as well as providing growth for future, advancedfeatures associated with the data communication system.Frequency control of the RF related oscillators in thesystem is provided by dual phase locked loop (PLL) circuitry withinfrequency synthesizer 72. The phase locked loops are controlledand programmed by communication microcontroller 58 via a serialprogramming control bus 100, Fig. 7. As shown in Fig. 9, frequencysynthesizer 72 produces two RF signals which are mixed together invarious combinations to produce a transmission carrier and todemodulate incoming RF signals. The transmission carrier is basedon frequencies in the 782-807 MHz range provided in conductor 102and the demodulation signal is based on frequencies in the 792-817MHz range provided in conductor 104. These signals may be referredto as RF transmit and RF receive local oscillation signals.Table I below is a summary of the transmission channelfrequencies and associated frequency synthesizer transmit/receiveoutputs in conductors 102 and 104. The signals in the table areprovided by the two PLL sections in the dual frequency synthesizer72.-15-101520253035CA 02264796 1999-03-03WO 98/10394 PCT/US97/15570Table IChannel Channel Transmit Local Receive LocalNumber Frequency (MHZ) Oscillation (MHZ) Oscillation (MHZ)0 902.7584 782.3360 792.16641 903.7824 783.3600 793.19042 904.8064 784.3840 794.21443 905.8304 785.4080 795.23844 906.8544 786.4320 796.26245 907.8784 787.4560 797.28646 908.9024 788.4800 798.31047 910.1312 789.7088 799.53928 911.1552 790.7328 800.56329 912.1792 791.7568 801.587210 913.2032 792.7808 802.611211 914.2272 793.8048 803.635212 915.2512 794.8288 804.659213 916.2752 795.8528 805.683214 917.2992 796.8768 806.707215 918.3232 797.9008 807.731216 919.9616 799.5392 809.369617 920.9856 800.5632 810.393618 922.0096 801.5872 811.417619 923.2384 802.8160 812.646420 924.2624 803.8400 813.670421 925.2864 804.8640 814.694422 926.3104 805.8880 815.718423 927.3344 806.9120 816.7424A third signal, which is fixed at 120.4224 MHz, is alsosupplied by the dual frequency synthesizer. This signal issupplied to conductor 106 and may be referred to as the intermedi-ate frequency (IF) local oscillation signal.RF receiver section 78 of RF transceiver 62 includes lownoise amplifier 108, the input of which is connected to transmit-receive switch 84. The output of low noise amplifier 108 isconnected to intermediate frequency (IF) signal mixer 110. Theother input to signal mixer' 110 is the output fron1 frequencysynthesizer 72 in conductor 104. The output of signal mixer 110 isan intermediate frequency signal which is passed through band pass-15-101520253035CA 02264796 1999-03-03W0 98/ 10394 PCT/US97/15570The otherinput to intermediate frequency signal mixer 114 is the 120.4224filter 112 to intermediate frequency signal mixer 114.MHz fixed frequency signal from frequency synthesizer 72 inconductor 106. Intermediate frequency signal mixer 114 convertsthe received signals to a final intermediate frequency of, forexample, 9.8304 MHz.The intermediate frequency from intermediatefrequency signal mixer 114 is passed through band pass limitingcircuitry comprising band pass filter 116, amplifier 118, band passfilter 120, and amplifier 122.signalThe signal from amplifier 122 is provided to quadraturefrequency discriminator 124 comprised of band pass filter 126 andsignal mixer 128. The output of frequency discriminator 124 isprovided to a linear phase low pass filter 130 and a voltagecomparator 132. The output of voltage comparator 132 in conductor134 comprises the received baseband data signal for interfacemanagement unit 22. The signal in conductor 134 is provided tospread spectrum processor 60, and in turn, to communicationmicrocontroller 58.In transmission mode, frequency synthesizer 72 providesa signal having a frequency in the 782-807 MHz range in conductor102, modulated with the data to be transmitted.section 76 includes signal mixer 136 which mixes the signal inRF transmitterconductor 102 with the fixed frequency IF local oscillator signalin conductor 106. This results in an RF signal which rangesbetween 902 MHz and 928 MHz.filter 138 to reduce harmonics and out of band signals, amplifiedThe signal is filtered by bandpassby a medium power amplifier 138 and supplied to transmit/receiveswitch 84.Operation of Interface Management UnitSystem timing and power management within the interfacemanagement unit 22 are controlled by supervisory microcontroller56. The communications hardware of the unit is periodicallypowered. up frou1 a sleep mode to test for the presence of anFigs. 11Aâ11C is a flowdiagram of the power management and system communication of theinterrogating signal from gateway node 24.interface management unit 22 in accordance with the presentinvention.-17-101520253035CA 02264796 1999-03-03WO 98/10394 PCT/US97/15570Referring now to Figs. 7 and 11A-C, a request communica-tions episode comprises three different phases: a wake-up intervalof the communications hardware of the interface management unit,sometimes called "blinking"; the polling data from the gatewaynode; and a response by the interface management unit. Theresponse may include the meter count indicative of the amount ofcommodity consumed.Because of the need to conserve battery power, theinterface management unit is operated in a pulsed mode where itwakes up from a sleep mode periodically, typically 2-8 seconds.The interface management unit starts off in sleep mode as shown inFig. 11A by reference numeral 300.Referring now to Figs. 11Aâ1lC, responsive to a signalfrom supervisory microcontroller 56, communication microcontroller58 will activate RF receiver 78 periodically for a short time, or"blink"gateway node 24 on the RF channel established for the interfacemanagement unit.interval, to determine the presence of a signal fromSee step 302. The signal from gateway node 24comprises spreadspectrum PN data recognizable by interfacemanagement unit 22 as a valid interrogator signal. If no spreadspectrum PN data is seen, or the data which is there is determinedto be invalid, receiver 78 shuts down or goes back to "sleep." Ifthe PN sequence is recognized as valid, receiver 78 will remain onuntil the communication episode is complete.Since the interface management unit 22 is not listeningcontinuously for data it is necessary for gateway node 24 to "wakeup" the interface management unit before sending data to it.Polling or commissioning data will be sent only after the interfacemanagement unit has had sufficient time to wake up. It willrespond with the requested information shortly after polling hasOnce the finished theinterface management unit will resume its normal behavior ofterminated. communication episode isblinking to test for the presence of aa signal from the datainterrogator in the RF channel.A blink cycle begins with supervisory microcontroller 56asserting the power control line low which applies power to spreadspectrum processor 60 and starts all oscillators in the interfacestep 304.troller has allowed time for the oscillators to start and stabi-management unit 22, After the supervisory microcon--13-101520253035CA 02264796 1999-03-03W0 98/ 10394 PCT/U S97/ 15570lize, it provides a pulse on wake up line 142 to activate communi-cation microcontroller 58, step 306. Communication microcontroller58 generates a "keep alive" signal to supervisory microcontroller56 in line 144 to indicate to supervisory microcontroller 56 thatit has activities in progress and that supervisory microcontroller56 must continue to maintain the components of interface managementunit 22 in the operations condition. This occurs in step 308.The next step, step 310 in the communication process ispolling by gateway node 24. For any meaningful data interchange tooccur it is necessary to load spread spectrum processor 60 with itsPN codes and mode control data. In this code, every pair of serialdata bits, termed a "dibit", is represented by a unique 32 bit PNIt is also necessary to load MSK frequency synthesizer72 with the proper channel programming data via control bus 100.data issequence.communicationmicrocontrollerâ 58 and spread spectrunt processor 60 via. 8 bitSpread spectrum transferred betweencontrol bus 146.After frequency synthesizer 72 is programmed to thecorrect RF channel, it is time to sample the RF channel for validSee steps 312 and 314.spread spectrum serial data is transferred at a rate of 2400 bitsspread spectrum data. Direct sequenceper second for all communication episodes.When RF transceiver 62demodulated dataprocessor 60.there will bespreadis stabilized,available at the input of spectrumIn the event that valid codes are received, spreadspectrum processor 60 will assert the "lock detect" signal 148 toIf a lock detectsignal is not asserted in conductor 148 within a predefined timecommunication microcontroller 58 at step 316.period, interface management unit 22 will revert back to its sleepmode. Assuming, however, that lock detect did occur, there will beserial data present at the input of communication microcontroller58. See step 318. When gateway node 24 has finished sending itspacket of data it will cease transmitting over the RF channel,causing a loss of the lock detect signal at some random time afterthe end of the transmission. Once lock detect is lost, power to RFreceiver 78 is removed. See step 320.The serial data at the input to communication microcon-troller S8 is decoded by the communication microcontroller and thevalidity of the received message is determined. If the message is-19..101520253035CA 02264796 1999-03-03WO 98/10394 PCT/US97/ 15570correctly formatted and the serial number data contained in themessage matches the serial number of the interface management unitthat received it, then data is interchanged with the supervisorymicrocontroller 56 via serial data conductors 150, 152, and 154,with communication microcontroller 58 acting as the master. Amessage is sent from communication microcontroller 58 to superviso-Whenthe direction of the master/slavery microcontroller 56. supervisory microcontroller S6responds, it will reverserelationship on the serial interface system by a asserting theslave enable signal in conductor 156. Data is then sent back usingthe supervisory microcontroller as the serial interface clock. Theslave enable signal is removed when the message is completed. Seesteps 322, 324, 326, and 328.This data interchange will occur for every receivedmessage except a valve actuation message and a requestâfor serialnumberâ message. If there is In: data interchange required, aresponse to that effect is sent.After the requested data (if any) is returned fromsupervisory microcontroller 56 to communication.microcontroller 58,a return message to gateway node 24 is formulated at step 330.When communication microcontroller 58 is ready to transmit, it mustreprogram frequency synthesizer 72 to change its frequency offset.The RF transmitter 76and spread spectrum processor 60 are then enabled to transmit aThis is accomplished over control bus 100.response by the interface management unit 22. After spreadspectrum processor 60 has had time to stabilize, the return messageis sent. This message is terminated by disabling spread spectrumSee steps 332 through 340.Following completion of transmission, RF receiver 78 isprocessor 60 and RF transmitter 76.activated once again to check for more incoming data as at step342. This is done to allow multiple messages to be interchangedonce interface management unit 22 has been awakened without theneed to complete a wake up cycle for each message. If communi-cation Inicrocontroller' 58 does not detect the presence of anyincoming messages within a given time period it will causeinterface management unit 22 to return to its sleep mode. Step344. Frequency synthesizer 72 is commanded to revert to its lowpower mode by a message on control bus 100 and the keep alivesignal in conductor 144 to supervisory microcontroller 56 is-20-l01520253035W0 98/ 10394CA 02264796 1999-03-03PCT/U S97/ 15570released to tell the supervisory microcontroller that communicationhas ended. Step 346. Supervisory microcontroller 56 then removespower to the remaining portions of interface management unit 22.Step 348.Communication between supervisory microcontroller 56 andthe communication microcontroller S8 is accomplished via the serialinterface bus comprised of signals 150, 152 and 154. All interproâcessor communication consists of a control code byte, a data byte,and a check sum byte. Messages that request information consist ofonly the control code byte and the check sum byte. The check sumis a twos complement check sum.An example communications episode can be described asfollows:The RF receiver 78 of interface management unit 22 wakesThe second time the RFreceiver wakes up it sees the spread spectrum PN sequence fromup, sees no data, and goes back to sleep.gateway node 24, recognizes it, and waits for polling data toemerge from spread spectrum processor 60. Once the unit is awake,it will receive and decode the polling message from gateway node 24and formulate an appropriate response.During the wake up interval, gateway node 24 transmits acontinuous idle condition to allow spread spectrum processor 60 tosynchronize and to assure that the interface management unit blinkwindow is open long enough to see the incoming PN sequences. Oncecode lock is achieved the listen interval will extend to accommo-date the incoming data, because the wake up is deemed successful ifcode lock is achieved. If code lock occurs but a message fails tobe recognized or no data is seen within the specified time window,then the communication microcontroller 58 will go back to sleep.After the unit 22 has been successfully awakened, thegateway node 24 must command it to perform one of many predefinedfunctions. When the unit responds to a message, it echoes thecontrol word back with the highest order bit cleared along with themeter serial number as a confirmation of the origin of the returnmessage. This scheme should assure that gateway node 24 will notrespond to any return data which did not originate from theintended interface management unit 22.Each data message starts with a predefined control codefollowed by the necessary data and a check sum of all bytes up to-21..101520253035CA 02264796 1999-03-03W0 98/10394 PCT/US97I 15570the check sum byte. The check sum is calculated by taking the twoscomplement of the sum of all bytes preceding the check sum byte.This allows testing the check sum by adding all of the messagebytes, including the check sum, and testing for a result of zero.Data types used for data interchange include the following: metercount, utility serial number, RF channel, unit of measure, metertype, conversion factor, error code, actuator port, transmit count,company identifier, software version and manufacturer serialnumber.Circuitry of Gateway NodeFig. 10 shows a block diagram of the gateway nodecircuitry. The RF transceiver section 156 of gateway node 24 isthe same as the RF transceiver section 62 ofunit 22.spectrum processor 60 in interface management unit 22interface managementSpread spectrum processor 158 is also the same as spreadso thatfrequency synthesis, modulation, demodulation, and spread spectrumcontrol in gateway node 24 are equivalent to that found ininterface management unit 22.The communication and supervisory microcontrollers S8, 56in interface management unit 22 are replaced by an initializationmicrocontroller 160 and WAN interface module 162, respectively.WAN interface module 162 may incorporate electronic circuitry fora two-way pager, power line carrier (PLC), satellite, cellulartelephone, fiber optics, cellular digital packet data (CDPD)system, personal communication services (PCS), or other fixed widearea network (WAN) The construction of WAN interfacemodule 162 anddepending on the desired WAN interface.system.initialization microcontroller 160 may changeRF channel selection isaccomplished through an RF channel select bus 164 which interfacesdirectly with the initialization microcontroller 160.Initialization microcontroller 160 controls all nodefunctions including programming spread spectrum processor 158, RFchannel selection in frequency synthesizer 166 of RF transceiver156,interface module 162.transmit/receive switching, and detecting failures in WANUpon power up, initialization microcon-troller 160 will program the internal registers of spread spectrumprocessor 158, read the RF channel selection from the interfacemanagement unit 22, and set the system for communication at the-22-l01520253035WO 98/10394CA 02264796 1999-03-03PCT/US97/15570frequency corresponding to the channel selected by the interfacemanagement unit 22.Selection of the RF channel used for transmission andreception is accomplished via the RF channel select bus 164 toinitialization microcontroller 160. Valid channel numbers rangefrom 0 to 23. In order to minimize a possibility of noise on theinput to initialization microcontroller 160 causing false channelswitching, the inputs have been debounced through software.Channel selection data must be present and stable on the inputs toinitialization microcontroller 160 for approximately 250 ps beforethe initialization microcontroller will accept it and initiate achannel change. After the channel change has been initiated, ittakes about 600 us for frequency synthesizer 166 of RF transceiver156 to receive the programming data and for the oscillators in thefrequency synthesizer to settle to the changed frequency. Channelselection may only be completed while gateway node 24 is in thereceive mode. If the RF channel select lines are changed duringthe transmit mode the change will not take effect until after thegateway node has been returned to the receive mode.Once initial parameters are established, initializationmicrocontroller 160 begins its monitoring functions. When gatewaynode 24 is in the receive mode, the initialization microcontroller160 continuously monitors RF channel select bus 164 to determine ifa channel change is to be implemented.For receiving data, gateway node 24 monitors theinterface management unit 22 to determine the presence of data.some additional handshaking hardware may be required to sense thepresence of a spread spectrum signal.An alarnx message is sent automatically by interfacemanagement unit 22 in the event of a tamper or alarm condition ofmeter 28. The message is sent periodically until the error hascleared. Gateway node 24 must know how many bytes of data it isexpecting to see and count them as they come in. When the propernumber of bytes is received, reception is deemed complete and themessage is processed. Any deviation from the anticipated number ofreceived bytes may be assumed to be an erroneous message.During the transmit mode of gateway node 24, initializa-tion microcontroller 160 monitors the data line to detect idleconditions, start bits, and stop bits. This is done to prevent-23..101520253035W0 98/ 10394CA 02264796 1999-03-03PCT/U S97/ 15570gateway node 24 from continuously transmitting meaninglessinformation in the event a failure of WAN interface module 162occurs and also to prevent erroneous trailing edge data from beingsent which cannot terminate transmissions in a timely fashion. Theinitialization microcontroller 160 will not enable RF transmitter168 of RF transceiver 156 unless the data line is in the invalididle state when communication is initiated.A second watchdog function of initialization micro-controller 160 when gateway node 24 is in the transmit mode is totest for valid start and stop bits in the serial data stream beingThe firststart bit is defined as the first falling edge of serial data aftertransmitted. This ensures that data is read correctly.it has entered the idle stage. All further timing during thatcommunication episode is referenced from that start bit. Timingfor the location of a stop bit is measured from the leading edge ofa start bit for that particular byte of data. Initializationmicrocontroller 160 measures an interval which is 9.5 bit timesfrom that start bit edge and then looks for a stop bit. Similarly,a timer of 1 bit interval is started from the 9.5 bit point to lookfor the next start bit. If the following start bit does not assertitself within 1 bit time of a 9.5 bit time marker a failure isdeclared. The response to a failure condition is to disable RFtransmitter 168.Commissioning of Interface Management Unitwhen an interface management unit is initially installedit does not contain any utility serial number, meter scaling, or RFchannel information. These constants must be programmed duringinstallation and commissioning to allow the interface managementunit to interface with the utility billing software and the metertype. A flow diagram of the interface management unit commission-ing is shown in Fig. 12.When an interface management unit is manufactured it willdefault to the first RF channel in its internal frequency list.This known channel will be used to speed production line testingand interface management unit commissioning. When an interfacemanagement unit is installed, a commissioning device will programthe interface management unit with a utility serial number, meterscaling characteristics, and RF channel selection data. See step-24-101520253035W0 98/ 10394CA 02264796 1999-03-03PCT/U S97/ 15570360. It will then try to obtain a response on the default RFchannel first. If there is no response from the default channel,the commissioning device will move to the next channel on thefrequency list and repeat the process until the interface manage-ment unit responds. This allows a commissioning device to set upnew meters as well as to recommission meters which are already inthe field .In order for the interface management unit to function asa part of the network and to co-exist with other interfacemanagement units in the area it may be necessary to coordinateThis taskinterface management unittheir operating frequencies to minimize data collisions.must be performed at the time ofcommissioning and will be the responsibility of the commissioningdevice. In a fixed local area network setting all interfacemanagement units could occupy the same frequency since they areaccessed one at a time by serial number.Each interface management unit has a finite distance overwhich it can transmit and receive RF signals, typically 400 feet.In order for a gateway node to establish successful communicationwith an interface management unit it must be within that finitedistance over which it can transmit and receive RF signals,otherwise it is necessary to install a relay node to boost the RFsignal. As mentioned earlier, it is possible to have all interfacemanagement units on the same channel in a network setting sincethere will be unique serial number requests as part of the pollingprocedure by the interfacegateway node. Even if multiplemanagement units hear the polling message, only the designatedserial numbered unit will respond.Assignment of interface management unit frequencies willbe performed by the commissioning device at the time of installa-tion. This will be accomplished through the use of an RF survey todetermine the presence of interfering interface management units orother conflicting RF signals. See step 362.Upon survey initiation the commissioning device willperform a send serial numbers message on the first or default RFchannel, at step 364. An interface management unit within range ofthe commissioning device should respond since this is a serialnumber independent message. If the commissioning device does notget a response on this channel, it will label it as okay for use-25-10152025303540CA 02264796 1999-03-03WO 98/10394 PCT/US97/15570and the survey will stop. However, should the channel be occupied,the commissioning device will move on to the next channel in thelist as shown in step 366. This process will repeat itself untilan unoccupied channel is located or all 24 channels have beenSee step 368.exhausted. Once an unoccupied RF channel islocated, the commissioning device programs the utility serialnumber, the operating RF channel, and all remaining meter parame-ters into the interface management unit's memory.and 372.parameters may be changed at any time by a "set serial numbers"message from the commissioning device as outlined in step 374.See steps 370The utility serial number, RF channel and other meterThe same RF frequencies may be used over and over again.When the installer moves out of the range of an interface manage-ment unit on channel 1, for example, this channel becomes availablefor use again by another interface management unit. This plan ispreferable to a preassigned frequency plan since it takes intoaccount actual radio propagation conditions in the area and doesnot require extensive preplanning or a complicated map of channels.Operation of Interface Management UnitVirtual shut-off FunctionFig. 13 shows a flow diagram of the virtual shut-offfunction of the interface management unit in accordance with thepresent invention.The virtual shut-off function of the interface managementunit is used for situations such as a change of ownership where autility service is to be temporarily inactive. When a residence isvacated there should not be any significant consumption ofutilities at that location. If there is anyâ meter movement,indicating either a leak or unauthorized usage, the utility needsto be notified. This tamper mode condition provides a means offlagging and reporting meter movement beyond a preset thresholdvalue.Activation of the virtual shut-off mode is accomplishedthrough thecount which the interface management unit is not to exceed. Inâset virtual threshold" defined as a metermessage,order to know where to set the threshold it is necessary to knowthe present meter count. The relay node, gateway node, commission-ing device, or other interface management unit communication devicemust read the meter count, steps 376 and 378,add whatever offset-26-101520253035CA 02204790 1999-03-03W0 98/ 10394 PCTIUS97/15570is deemed appropriate, step 380, send the result to the interfacemanagement unit as a "set virtual shut-off" message at step 382.The interface management unit will then enable the virtual shutâoffmode at step 384. The interface management unit then accumulatesthe meter counts at step 386. If the meter count is greater thanthe preset threshold value then the interface management unit sendsa "send alarm" message to the gateway node until a "clear errorcode" message is issued in response by the gateway node as detailedin steps 388 and 390. However, if the meter count is not greaterthan the preset threshold value then the interface management unitcontinues to monitor the meter count at step 392. The virtualshutâoff mode may be canceled at any time by a "clear error code"message from the gateway node at step 394.If the meter count in the interface management unit doesnot exceed the preset threshold value at any given sampling time,the unit continues to count (step 392) until the preset thresholdcount is attained or until operation in the virtual shut-off modeis canceled (step 394).Automatic Meter Reading Data Communication SystemFig. 14 shows a functional flow diagram of the automaticmeter reading data communication system of the present invention inA flowdiagram includes the main functional components of the gateway notewhich the components are described as functional blocks.24 which include a message dispatcher 200, an RF handler 202, a WANhandler 204, a data stores component 206 and a scheduler component208.is preprogrammed into the gateway node's memory.The data stores and scheduler components comprise data thatThe gateway nodeinterfaces with an interface management unit or a relay node 210over the twoâway wireless LAN. A gateway node 24 also interfaceswith a utility service provider over the fixed common carrier WAN.Fig. 15A is a detailed functional diagram of the WANhandler 204 of Fig. 14.utility 212 may initiate a request for data from the interfaceThe WANhandler of the gateway node receives the WAN data stream, createsIn a typical communication episode, themanagement unit 210 by sending a data stream over the WAN.a WAN message, verifies the utility ID of the sender from the datastores 206 and routes the WAN message to the message dispatcher 200in the gateway node.-27..101520253035CA 02264796 1999-03-03WO 98/10394 PCT/US97/15570Referring now to Fig. 15B, the message dispatcher 200receives the WAN message from the WAN handler and determines therequest from the utility 212. The message dispatcher 200 deter-mines that the end recipient or target is the interface managementunit or relay node 210. The message dispatcher then verifies theinterface management unit ID from the data stores 206, creates anRF message and routes the RF message to the RF handler 202.Referring now to Fig. 15C, the RF handler receives the RFmessage from the message dispatcher 200, selects a proper RFchannel, converts the RF message to an RF data stream, sends the RFdata stream to the interface management unit or relay node 210 overthe LAN and waits for a response. The interface management unitthen responds by sending an RF data stream over the LAN to the RFhandler 202 of the gateway node 24. The RF handler 202 receivesthe RF data stream, creates an RF message from the RF data streamand routes the RF message to the message dispatcher 200.in Fig. 153,determines the target utility for response from the data stores206, creates a WAN message and routes the WAN message to the WANhandler 204. The WAN handler 204 receives the WAN message from themessage dispatcher, converts the WAN message to a WAN data streamAs shownthe message dispatcher receives the RF message,and sends the WAN data stream to the utility over the fixed commoncarrier WAN, as shown in Fig. 15A to complete the communicationepisode.A communication episode can also be initiated byscheduled readings preprogrammed into the scheduler 208 of thegateway node as shown in Fig. 15D. A list of scheduled readingtimes is preprogrammed into memory within the gateway node 24. Thescheduler 208 runs periodically when a scheduled reading is due.When it scheduler 208retrieves interface management unit or relay node information fromthe data stores 206,message to the RF handler 202, receives the RF message, selects ais time for a scheduled reading, thecreates an. RF message and routes the RFproper RF channel, converts the RF message to an RF data stream,sends the RF data stream to the interface management unit or relaynode 210 and waits for a response. The interface management unitThe RFhandler 202 receives the RF data stream, creates an RF message fromthen responds with an RF data stream to the RF handler 202.the RF data stream and routes the RF message to the message-28-101520253035CA 02264796 1999-03-03W0 98/ 10394 PCT/U S97/ 15570dispatcher 202. The message dispatcher receives the RF message,determines the target utility for response from the data stores206, creates a WAN message and routes the WAN message to the WANhandler 204. The WAN handler receives the WAN message, convertsthe WAN message to a WAN data stream and sends the WAN data streamto the utility 212.Occasionally, the utility may request data that is storedwithin the gateway node's memory. the utilityinitiates the communication episode by sending a WAN data stream tothe WAN handler 204. The WAN handler receives the WAN data stream,creates a WAN message, verifies the utility ID of the sender in theIn this case,data stores 206 and routes the WAN message to the message dispatch-er 200.the WAN message and determines the request from the utility 212.the target of theIf the data requested is stored in the gateway nodethen the requested task,determines that the requesting utility is the target utility for aAs shown in Fig. 15B, the message dispatcher 200 receivesThe message dispatcher 200 then determinesmessage.memory, gateway node performs theresponse, creates a WAN message and routes the WAN message to theWAN handler 204. The WAN handler 204 receives the WAN message,converts the WAN message to a WAN data stream and sends the WANdata stream to the utility 212.The last type of communication episode is one which isinitiated by the interface management unit. In this case, theinterface management unit detects an alarm or tamper condition andsends an RF data stream to the RF handler 202 of the gateway node24. The RF handler 202 receives the RF data stream, creates an RFmessage from the RF data stream and routes the RF message to themessage dispatcher 200. The message dispatcher 200 receives the RFmessage, determines the target utility for response from the datastores 206, creates a WAN message and routes the WAN message to theWAN handler 204.converts the WAN message to a WAN data stream and sends the WANdata stream to the utility.The WAN handler receives the WAN message,There are thus three different types of communicationepisodes that can be accomplished within the automatic meterreading data communication system shown in Figs. 14 and 15A-E.Fig. 15D represents information or data that is prepro-grammed into the gateway node's memory. Included within the memory-29-..,.........,.....w......â......u.â._.......... ~~~~~~ ~ ~1015CA 02264796 1999-03-03W0 98/10394 PCT/US97/15570is a list of scheduled reading times to be performed by theinterface management unit. These reading times may correspond tomonthly or weekly usage readings, etc.Fig. 15E represents data or information stored in thegateway node's memory dealing with registered utility informationThis dataincludes the utility identification numbers of registered utili-and registered interface management unit information.ties, interface management unit identification numbers of regis-tered interface management units, and other information forspecific utilities and specific interface management units, so thatthe gateway node may communicate directly with the desired utilityor correct interface management unit.It is recognized that other equivalents, alternatives,and modifications aside from those expressly stated, are possibleand within the scope of the appended claims.-30-
