CA1314338C - Remote meter reading method and apparatus - Google Patents
Remote meter reading method and apparatusInfo
- Publication number
- CA1314338C CA1314338C CA000601232A CA601232A CA1314338C CA 1314338 C CA1314338 C CA 1314338C CA 000601232 A CA000601232 A CA 000601232A CA 601232 A CA601232 A CA 601232A CA 1314338 C CA1314338 C CA 1314338C
- Authority
- CA
- Canada
- Prior art keywords
- meter
- microprocessor
- pulse
- coupled
- switching
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M11/00—Telephonic communication systems specially adapted for combination with other electrical systems
- H04M11/002—Telephonic communication systems specially adapted for combination with other electrical systems with telemetering systems
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D4/00—Tariff metering apparatus
- G01D4/002—Remote reading of utility meters
- G01D4/004—Remote reading of utility meters to a fixed location
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02B90/20—Smart grids as enabling technology in buildings sector
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
- Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
- Y04S20/00—Management or operation of end-user stationary applications or the last stages of power distribution; Controlling, monitoring or operating thereof
- Y04S20/30—Smart metering, e.g. specially adapted for remote reading
Abstract
REMOTE METER READING METHOD AND APPARATUS
ABSTRACT OF THE DISCLOSURE
A remote meter reading system has equipment at a telephone company office coupled by modems to a utility company computer which issues requests for customer data. Telephone test trunks are used to access individual meter sites and initiate meter readings using a number of single freguency bursts.
Meter sending units emit a pulse for each unit of consumption and a microprocessor counts the pulses in RAM to derive separate meter readings. When interrogated, the microprocessor outputs the readings in a binary coded decimal format to a DTMF tone generator which emits each decimal number as a tone pair which is transmitted via the telephone line and is detected at the telephone company, translated into ASCII code and transmitted by modem to the utility computer.
ABSTRACT OF THE DISCLOSURE
A remote meter reading system has equipment at a telephone company office coupled by modems to a utility company computer which issues requests for customer data. Telephone test trunks are used to access individual meter sites and initiate meter readings using a number of single freguency bursts.
Meter sending units emit a pulse for each unit of consumption and a microprocessor counts the pulses in RAM to derive separate meter readings. When interrogated, the microprocessor outputs the readings in a binary coded decimal format to a DTMF tone generator which emits each decimal number as a tone pair which is transmitted via the telephone line and is detected at the telephone company, translated into ASCII code and transmitted by modem to the utility computer.
Description
1 31 ~33'~
P 3~3 - 1 -REMOT~ ER R~ADI~ N~OD A~D APPARAT~S
FIELD OF T~ I~V~TION
This invention relates to the method and apparatus for automatic mater reading by telephone and particularly ~o meter d~ta encoding methocl and apparatus for remote meter reading.
BAC~G~o~ND OF ~E I~VE~TION
It is generally desirable for utility companies to collect meter reading information from homes or commercial esta~lishments without visually inspecting every meter at its resident location. The traditional labor intensive collection system is too expensive to be maintained and the accuracy of the data collected is subiect to considerable error. A
number of proposals ~or remote meter reading have ` 20 been made and some have been put into operation. One system which has been tried uses a radio link with the meter an~ a mobile radio unit which is driven around selected neighborhoods ~o collect data from local meters. This reguires manned operation of the mobile units and thus is a compromise which uses less labor than the traditional data collection method.
Still another system for remote meter reading uses telephone communica~ian between the utility company and the meters to be read. The present invention pertains to this category.
131~338 Telephonic meter reading systems have long been proposed without commercial success although in recent times there has been a renewal of commercial atte~pts which seek to capitali.ze on improving telephone communication ~echnology. In general, the~e systems incorporate a modem in each residential unit to receive interrogation signals from the telephone line and to formulate and transmit meter readings via the telephone line to the utility company. Such modems have come into widespread use for telephone communication an~ are characterized by two traits: they are expensive and unreliable as communication devicPs. Even though a modem might accurately produce signals representing the data to be transmitted, the signals are in such a form that, due to noise interference or limited system fidelity, they are not faithfully transmitted over normal telephone lines. Some systems use communication devices which may not be recognized as modems, yet the transmission reliability i5 questionable. Some r presentative patented systems are described below.
m e U.S. Patent No. 3,842,21~ to De~uca et al describes a sys~em for remote meter reading by telephone ~hich uses a modem (FIGURE S) at the meter : site for initiating the interrogation of meters upon receiving a command signal and generating a series of tones to communicate the meter consumption information. The meters have decades supplying signals on ten lines to ~he tone generator which yields data in decimal form.
131~33~
P-363 - 3 ~
The U.S. Patent No. 3,868,640 to Binnie et al discloses a remote meter read;.ng system using telephony. In one version using a frequency division m~ltiplex basis, a unit at the meter site has four tone decoders and an interrogation signal comprising up to four simultaneous frequencies is evaluated by the unit for prompting a response. In another version using a time division multiplex basis, single tone decoder is used and the interrogation signal comprises a binary code made up of a series o~
single frequency tones each representing a '1" or NO~. In either version the unit responds by transmitting the meter readings in the form of a series of tones of the same frequency.
~ The U.S. Patent No. 3,842,206 to Barselotti et : al shows a remote meter reading system having a meter unit which transmits meter readings as a serial binary pulse train. Each bit in the pulse train comprises either of two fre~uencies representing a ~l n or a ~On.
:The U.S. Patent NoO Re.26,331 to Brothman et al discloses a remote meter reading system having a unit at the meter site for transmitting a coded meter reading in the ~orm o~ a modulated AC signal in one : version or in the form of ~erial binary pulses interspersed with synchronization pulses in another version.
U.5. Patent 4,587,536 to Oliver et al granted March 25, 1986, discloses a meter reading system ; including interface means ~etween the meter and 1 31 ~338 P-363 _ 4 _ telephone line for sending AC signals to the central office in response to an interrogation signal.
Plural multiplexers are provided at the central office for multiplexing the signals between a group of telephone lines and central office. A computer selects a multiplexer and one of the telephone lines and a continuous DC and AC coupling is established to the telephone line during on-hook conditions. The interface means generates DTMF signals corresponding to the meter reading value which are transmitted over the telephone line to the central office.
*
The Lumsden patent 4,3~8,690 granted June 14, 1983, discloses an automatic meter reading transponder. The transponder includes a CPU
connected to a receiver and transmitter and a real time clock is connected to the CPU. The CPU receives the input pulses representative of electric power consumption. The RAM o~ the CPU has a plurality of addressable registers wherein the CPU equates each register sequentially with a predetermined time period. Each register contains a count which is representative of the power consumed during the associated time period.
8~MKARY OF T~ I~VE~TION
Accordin~ly the invention seeks to provide an inexpensive meter reading and data transmitting apparatus for a telephonic automatic meter reading system.
* U . S . PATENT NUMBER
. . ~ , 13 1 a,338 P~3~3 - 5 -Still further the invention seeks to provide an exceptionally reliable method of meter reading and telephonic data transmission.
The invention is also carried out in a remote meter reading system having telephone co~munication of meter data by a meter telephone unit comprising;
terminals for connection to a telephone line, means coupled to the terminals for initiating a meter reading operation, control means for acquiring data and furnishing data in response to initiation of meter reading, and a DTMF tone generator coupled to the terminals and to the control means for receiving the data ~rom the control means and for producing a set of tone pairs representing the data or transmission over the line.
In accordance with this invention, an improved transponder is provided for use in an automatic meter reading system of the type which utilizes the telephone system for transmission of meter readings.
The transponder comprises a microprocessor including a read/write memory. A meter pulse generating means is coupled with a meter and produces a meter pulse corresponding to a unit of measurement. The microprocessor is normally in a quiescent mode and is switched to an active mode in response to a meter pulse. The microprocessor is programmed to count pulses and to store the pulse count in the read/write memory and to switch ~he microprocessor to the quiescent mode after the pulse count is stored. A
detecting means detects a con~rol signal on the telephone line and the microprocessor is switched , ... ... .
from the quiescent mode to an active mode in response to the control signal. The microprocessor is programmed to produce a tone generator signal for a DTMF tone ~enerator in response to receipt of a control signal. The tone generator produces a sequence of tone pairs representing a pulse count stored in the read/write memory and the microprocessor is switched to the quiescent mode after the sequence of tone pairs is produced.
Further, in accordance with the invention, the transducer is powered by supply voltage on the telephone line except when a fault occurs on the line or the telephone i5 off hook and then it is powered by a battery in the transducer which supplies an auxiliary supply voltage. Battery power is conserved and yet the integrity of pulse counting is assured by maintain:ing the microprocessor in the quiescent state except when a meter pulse is generated. Further, battery power is conserved by utilizing for meter pulse generation a Wiegand sensor which requires no power supply.
The invention in one aspect as claimed provides a transponder for use in a meter reading system using a telephone line for communication of meter data, the transponder comprising detecting means for detecting a control signal on the telephone line, a microprocessor including a read/write memory, and a meter pulse generating means coupled with the meter for producing an electrical meter pulse corresponding to a predetermined meter event, with first coupling means for coupling the meter pulse generating means to the microprocessor. Means provide for switching the microprocessor from a quiescent mode to an active mode in response to a meter pulse and the microprocessor is programmed to count puls~s from the meter pulse generating means and for storing the pulse count in the read/write memory, and for switching the microprocessor to the quiescent mode after the pulse count is stored. A data signal generator is coupled with the microprocessor. Second coupling means couples the detecting means to the microprocessor, and there is means for switching the microprocessor from a quiescent to an active mode in response ~o a control signal, the microprocessor being programmed to cause `~ ,, - 6a - 1 31 4338 the data signal generator to transmit encoded data representing the pulse count stored in the read/write memory in response to a predetermined control signal and for switching the microprocessor to the quiescent mode after the encoded data signal is transmitted.
In a preferred aspect, the transponder includes a movable magnetic member carried by the met0r and it is cyclically movable along a path having a length corresponding to a predetermined unit of mea~urement, and a Wiegand sensor having an output coil 0 i5 coupled therewith for producing an output voltage pulse when the magnetic state of the Wiegand sensor is switched from one polarity to the other, the sensor being disposed adjacent to the path for generating a voltage pulse in response to movement of the magnetic member past the sensor.
The invention as claimed also pertains to an automatic meter reading system of the type which utilizes a telephone system having a central office, multiple subscriber lines each having a subscriber telephone connected therewith at a subscriber station, the subscriber lines being coupled to a switch in the central office for selective connection of any one of the subscriber lines to another line. Voltage supply means supplies electrical power from the central office to the subscriber lines and a test trunk is provided for selectively accessing the subscriber lines without ringing the telephone of the selected line. A subscriber line access means is coupled with the test trunk for accessing a selected line and a transpondèr at the subscriber station is coupled with the subscriber line and with one or more utility meters. Control signal means is coupled with the subscriber access means for generating a control signal for the transponder at a selected subscriber station. The transponder is of the above type and preferably includes a DTMF
tone generator coupled with the microprocessor, the microprocessor being programmed to produce a tone generator signal for the tone generator in response to a predetermined control signal for producing a sequence of tone pairs representing the pulse count stored in the read/write memory and ~, - 6b - I 3 1 4338 for switching the microprocessor to the quiescent mode after the sequence of tone pairs is produced.
In a preferred embodiment of the system, a voltage regulator :~ i5 provided for energi~ing the transponder and has an input coupled with the subscriber line for receiving a supply voltage.
A battery produces an auxiliary supply voltage, and means is provided for switching the auxiliary supply voltage to the input of the voltage regulator when the supply voltage on the subscriber line falls below a predetermined value due to a fault on the subscriber line or due to the telephone going off-hook wher`eby the transponder continues to accumulate the pulse count from the meter.
A more complete understanding of the invention may be obtained from the detailed description that follows taken with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a block diagram of an automatic meter reading system incorporating a meter unit according to the invention;
131~33~3 ~-363 - 7 -FIG~RE 2 is a schematic CirCllit diagram o~ the meter unit according to the inven~ion;
FIG~E 3 is a diagra~matic s,howîng of a meter sending unit;
FIG~E 4 is a represen~ation of a Wiegand type sensor in the sending unit;
10FIG~R$ 5 is a flow chart representing a part of the control program of the microprocessor, and FIG~RE 6 depicts storage registers in the RAM
of tha microprocessor; shown with FIGURE 3.
D~8CRIP~ION OF T~B ~EF~RED E~BODI~T
A remote meter reading system is intended to provide the various utility companies with a cost effective and timely method of collecting billing ~ info~mation. Integrity of ~he collected info~mation : is of paramount importance. By using telephony as the data collection medium, a system i~ available for nearly every utility customer, The utility company : 25 needs ~special equipment at itæ central office for ; interfa~ing with the telephone company equipment as well as equipment a~ each home, business or other ~eter site for automatically collecting meter data.
By pxoviding suitable flexibility in the equip~ent, other ~unctions such as tamper detection and remote : disconnect can be provided.
P 363 - a Referring now to the drawings, there is shown an illustrative embodiment of the i~vention in an automatic meter reading system wherein the transmission of meter reading data from the meter site is initiated by an interrogat:ion signal from the telephone company. It will be appreciated, as the description proceeds; t~at the invention is also applicable in a meter reading system wherein the transmission of meter reading data is initiated by a suitable unit at the meter site. It will ~come apparent to those skilled in the art that the invention may be practiced in many different forms and may be utilized in a variety of applications.
As indicated in FIG~RE 1, the system is distributed ~mong the utility company, the telephone company and the customers of ~he utility company.
The customar has an incoming telephone line 10 connected to a conventional telephone 12 and to a transponder comprising a residential sexvices unit 14 (RSU) and one or more sending units 17. Each sending unit i~ coupled with a utility meter 16. The telephone 12 may be the same telephone used by the telephnne company subscriber for conventional voice 2S communication over the telephone system. The telephone company has a test trunk 18 which is provided for the purpose of accessing individual telephone lines without ringing the phones to test line xesistance and other aspects of the telephone equipment. This same test trunk is used to access the individual RSU's 14 to carry out meter reading and related functions. The test trunk 18 is connected to the customer lines 10 through a switch s 1 3 1 l~338 P--~63 9 -22 and a main distribution frame 24. The telephone company also houses a utility access unit (UAU) 26 which is connec~ed to ~he tes~ t~nk 18 through a subscriber access unit (SAU) 2~ and is connected to the utility company through a mode:m 30. The UAU 26 accepts requests ~rom th~ utility, obtains ~ata, and transmits the data to the utility. The (SAU) 28 accesses customer RSU's 14 over the test trunk 18 when commanded by the utility access unit 26. The utility has a computer or terminal 32 coupled through a modem 36 to the telep~one company modem 30.
The meter reading system interrogates the RSU
14 at each meter site and communicates meter data to the utility company computer for billing purposes without interfering in any way with the customer's ~;~ service. The utility computer 32 requests meter readings using account numbers or telephone numbers;
this communication is over the dial-up network using commercial modems 36, 30. In response ~o the re~uest the UA~ 26 instruc~s the SAU 28 to access the customer RSU 14 via ~he test trunk 18 (i.e., without ringing). The S~U 28 will not access the customer's telephone line if i~ is in use ~busy). Also the RSU
14 incorporates a nbusy de~ct~ function that causes the system to release the line whenever the customer picks up the telephone. The SAU 28 commands the RSU
14 to transmit meter readings, reset registers, etc., by sending a control signal including a command signal comprising a sequence of single freguency tone bursts on the ~e}ephone line. The RSU 14 responds with DTMF (dual tone multifrequency or /'touchtone"
signalling) to the SAU 28. Data communicated from 1 31 ~338 ~-363 - 10 -the RSU to the S~U is checksummed to ensure data integrity. Following com~and execution, the RSU
automatically assumes a quiescent mode~ The SAU has a digit receiver with frequency s~lective ~ilters to detect the DTMF tones. The DTMF data received from the RSU is translated into ASCII and sent to the UAU
which forwards it to ~he utili~y computer 32. The SAU communica~es with the UAU in ASCII format using serial RS232C protocol.
The system is designed to work with co~monly used meters of the ordinary unencoded type or the encoded type. Appropriate meter inter~aces or sending units are provided as separate assemblies to provide flexibility in packaging as well as the ability to accommodate a large number and variety of ~; meters. Unencoded meters may have magnetic pickups . added. The sending units make all meters compatible with the RSU 14 and all meters are read in the same manner. In par~icular, the sending unit issues a voltage pulse to ~he RSU for each unit of consumption. In accordance with this invention, a special sending unit is provided, as will be described subsequently.
2s The RSU 14 shown in FIGURE 2 has a line interface comprising tip and ring terminals for connection to the telephone line 10 and a diode bridge 40 having its input connected to the terminals and its outpu~ connected to ground and a positive line 44. ~ 2sa volt zener diode 46 is connected across ground and line 44 for transient suppression, The bridge assures ~hat the voltage output is 1 ~ 1 4338 P--3~
independent of the telephone line 10 polarity. The nominal voltage into the terminals is 48 volts. The line 10 furnishes power to the RSU.
A voltage regulator 48 and power switch circuitry furnish a regulated vol~age Vcc~ A 24 volt zener diode 50 and a resistor 51 couple the positive line 44 to the collector and base of a transistor 52 while the emitter is coupled to the collector and base of a transistor 53 which is configured as a 14 volt zener diode connected at one side to ground. A
pair of Darlington connected transistors 54, 55 have the input base connected to the resistor 51, their collectors connected to the anode of the diode 50 and their output emitter connected through four serially connected diodes 56, 57, 58 and 60 to the input of the regulator 48. The regulator has a terminal connected to ground and capacitors 61 and 62 are connected between the regulator 48 input and output, respectively, and ground. The elements 50 through 60 drop the 48 volt input ~oltage to approximately 11.5 voIts for input to the voltage regulator which maintains an output Vcc of a constant 5 volts.
A tone selective filter, comprising a capacitor 63 and an inductor 64, is serially connected between the line 44 and ground have a junction point connected to the base of a transistor 68. The filter is tuned to the control signal frequency of 1633Kh.
For backup purposes a 9 volt lithium battery 70 maintains continued operation of the RSU when telephone line power is not available to the input of 1 3 1 ~38 the voltage regulator 48. This occurs when there is a failure o~ voltage supply on ~he telephone line and also when the telephone is of-hook as will be described subsequently. The batte~y 70 is connerted between ground and the input of the regulator 48 :through a dioda 7~. As long as there is power from the telephone line 10, the voltage at the regulator 48 input is highex than the voltage at the anode of the diode 74 and all power will be supplied by the line 10. When ~he telephone line is removed or the voltage drops below 24 volts the diode 74 will conduct to supply battery power to the regulator 48.
A low battery detect circuit includes an operational amplifier 80; it also provides a voltage divid~r 82 and a transistor ~4 serially coupled between the battery 70 and ground. A zener diode 86 is connected between an input of the operational ~amplifier ~0 and the collector of the transistor 84 :~20 to provide a reference voltage at the operational amplifier when the transistor 84 is turned on. The transistQr 84 is normally ~urned off, creating approximately the same voltage on all inputs of the operational a~pli~ier 80 keeping it turned off.
Power is turned on to the operational amplifier only when the transistor 84 is turned on to obtain a reading and then a reference voltage is placed on one input of the operational amplifier. The voltage on the other input (derived from battery voltage) is :~30 compared to the re~erence voltage and when the :battery voltage is low the output of the operational amplifier is low.
1 3 I ~ 3 3 ~
;
A processor 100 such as a COP840C
microprocessor is coupled to the circuitry described above. It is also coupled to meters 16 and other inputs throu~h a ~ulkiplexer 102 (MUX) such as a CM 512B multiplexer and to a DTMF tone generator 104 such as a TP508~ generator which transmits the RSU
;~output data. The processor 100 includes a RAM, i.e., a read/write memory, and is operated under control of a program stored in its ROM. The processor lOO ha~
ports GND and Vcc for power supply connection, clock ports CXI and CKO connected to a crystal 106 for clock input, a port Gl connected to the base of transistor 84 to turn on the low battery detect circuit, and a port I3 connected to the output of -15 operational amplifier 80 to receive the low battery signal. Processor ports LO through L4 are connected to inputs of the tone generator 104. Ports LO, Ll and L2 are also connected to the selector ports A, B
and C of the m~ltiple~er 102. The m~ltiplexer has one data ou~put port which is coupled to port Il. A
RESET port activates the processor when a voltage is applied to the port thxough a transistor 120. A
latching port DO coupled to the base of the transistor 120 can be energized by the processor to latch the RESET on. A port I2 is connected to a voltage divider 121 which is connected to the junction of diodes 58 and 60 to sense the presence of voltage at that point. The normal voltage is 4.2 volts and is limited to 5.7 volts maximum by a clamping circuit including a diode. The voltage is lost if the line voltage goes below the 24 volt level of the zener diode 50. When the telephone is off-hook, i.e. in use, the reduced voltage on the 1 31 ~338 P-363 - lg -telephone line will be blocked by zener diode 50 and the voltage at poxt I2 will be at logic low and this prevents port D3 from going high. This in turn, prevents any tone generator output.
A~ shown in Figure 2, there are four meter sending units 17 in the illustrative meter reading sy~tem. Each sending unit 17 i~ associated w.ith a different me~er, the meters being numbered 1, 2, 3 and 4. Each of the meter sending units is of a special type which requires no power supply and has no moving parts. It is well adapted for retro fitting on existing meters, especially the conventional water meker and gas meter which use a separate rotary hand indicator or number wheel indicator ~or each decimal digit in the reading. The ; sending unit uses a Wiegand sensor which is co~mercially a~ailable from the Sensor Engine2ring Co~pany of Hamden, Connecticut. The principles and structure of ~he Wiegan sensor are disclosed in Wiegand patent 3,820,090 granted June 25, 1974 and Wiegand patent 4,247,601 granted January 27, 1981.
The Wiegand sensor utili2es a bistable feromagnetic wire of generally uniform composition having a central magnetically soft core portion and an outer ~agnetical}y hard shell portion ~ith relatively low and high coercivity respec~ively. The shell portion ~ is permanently magnetized and operates to magnetize ; the core portion in a first direction (the ~confluent state~) in the absence of an external magnetic field.
The magnetization of the core portion is reversible by the application of an external magnetic field so that the core and shell have opposi~e polari~y (the * U. S . PATENT NUMBER`
1 31 ~33~
;revexse state~) when the external field is removed the magnatization of the core is changed to the first ~-~direction by the effect of the shell portion. Thus, by manipulating ths external magnetic field excursions, the shell and core can be switched to the con~luent or reverse states of ma~netic polarity.
~The polarity switching occurs abruptly. For use as a :pulse generator, a sensing coil is wrapped around the Wiegand wire and the sensor comprises a two wire device that requires no power. The sensing coil develops signal pulses of two or three volts in :magnitude and twenty microseconds in duration and can operate with a pulse rate up to twenty KHz. It is suita~le for very low speed operation as well and is operable over a wide range of temperature.
A meter sending unit 17 is shown ;diagrammatically in FIGURES 3 and 4. FIGURE 3 shows a typical meter such as a gas meter with a panel 130 having five different dial indicators of the rotary hand type, each dif~erent hand representing a :different digit in the meter reading. The hand representing the least significant digit is replaced with a rotary two-pole permanent magnet 134 and a Wiegand sensor 136 is disposed adjacent the rotary magnet. The Wiegand sensor 136 and the rotary magnet 134 are shown in FI~URE 4. The ~iegand wire 138 is wrapped with a sensing coil 142. The rotaxy magnet wheel 134 is located so that its magnetic field is :~30 effective to switch Wiegand wire from the confluent state to the reverse state and allows it to switch back to the con~luent state as it rotates through one~
~ 31 4338 revolution. Accordingly, meter pulses of alternate polarity are generated in the coil 142 as shown in the waveform diagram of FIGURE 4.
The sensor of each meter sending unit 17 is coupled through a meter in~erface circuit with the input of the multiplexer 102, as shown in FIGURE 2.
The interface circuit comprises a transistor 110 having its base connected through a resistor to the output terminal of the Wiegand wire sensor. The diode across thE~ base bypasses the negative pulses and the positive pulses are effective to turn on the transistor llO. The collector of the transistor is connected with one oî the input ports Xl, X2, X3 or X4 of the multiplexer 102. The collectors are also coupled through a large resistor lll to the base of : ~ the transistor 120 so tha~ as a pulse, at ground potential, is applied to the multiplexer by a meter :: sending unit, a similar pulse turns on the transistor 20 120 to activate the processor 100.
The data input ports of the multiplexer }02 are selectively coupled to the port I1 of the processor.
The ~our meter sending units 17 are coupled through 25 individual signal conditioning circuits 108, as discussed above, to one oi~ the input ports Xl "~2, X3 or X4 of the multiplexer 10~, Th~ command signal : issued by the SAU is transmitted~ over the telephone line as a sequence of tone burs~s at 1633Hz. This signal is derived from the filter capacitor 63 and inductor 64 and applied through transistor 68 to the input port X0 of the multiplexer. The input at port X0 is at logic low during each tone burst. A tamper 1 31 $;~38 P-363 ~ 17 detector terminal is coupled throuqh a transistor 122 to the data input port X6 of ~he multiplexer. When the terminal is grounded, the input at port X6 is at logic high. DTR terminals DTR 1, 2 and 3 are provided for connection to an installer5 portable field unit to initialize registers in the processor and perform tes~s at the tim~ of installation. The ter~inals DTR 2 and 3 are conn~cted to input ports Io and G0 respectively on the processor for receiving and transmitting data, respectively. The terminal ; DTR 1 is coupled through a resistor and conductor 124 to the port X5 of the multiplexer. These other inputs, like the meter sending units 17, are coupled to the base of the transistor 120 through resistors 111 to activate the RESET when a pulse occurs. The ~ultiplexer 102 operates under control of the processor 100 to provide the input signals to the processor as they occur and, if more than one occurs simultaneously, to present them in a prescribed ordex. When a pulse occurs it is applied to a ; multiplexer input and aleo through the transistor 120 to activate the processor. The processor t~en sweeps through a series of seven 3 bit codes, one for each MUX input, applying them to the multiplexer via ports ~5 L0, Ll and L2. When the code matches a MUX input at ground potential an outpu~ pulse is sent to the port I1 o~ the processor. The processor acts on the pulse according to its source.
The processor 100 has a por~ D3 coupled to the b~se of a tr~nsistor 112 which connects Vcc to the tone generator 104 ~o supply power thereto. To supply data to the tone generator the processor . .
1 31 ~338 P-363 - 18 ~
energizes a tone enable output port L4 and a four bit data output at the ports L0 through L3. The tone generator, in turn has an output port coupled to the b~e of a transistor 114 whicll is connected to modulate the lsad current on the transistors 54 and 55.
In operation the RSU is powered by the telephone line 10 but the power requirements are extremely small. The RSU has a very high input impedance ~at least 5 megohms) during idle state.
Except when receiving inputs or when in~errogated by the SA~, the processor 100 remains in the quiescent or halt mode and draws less than 1 microamp. Wh~n a pulse is emitted by a sender 17, the multiplexer 102 receives the pulse on input port X0, Xl, X2 or X3 and the RESET port of the processor receives a logic high input to activate the processor. Similarly when a command signal, ~2~per signal or DTR signal is received on input ports X0, X5 or X6, the processor is activated. The processor sends a sequence of 3 bit codes to the ~UX which operates to serially couple to the processor poxt Il any input pulses which are present on the inputs of the MUX when their corresponding codes are received from the processor o~ the MUX ports A, B and C. When a meter pulse is emitted by a sender 17, the processor responds to the pulse by incrementing a coun~ in RAM at an address re~erved as a register for the meter identified by the particular code. The registers in RAM are depicted in FIGURE 6 as Rl, R2, R3 and R4, corresponding to meters 1, 2, 3 and 4, respectively.
Then the processor returns ~o the halt mode and 1 3 1 ~33~
~363 _ ~9 _ awaits anoth0r event. Information is stored in a similar manner for th~- tamper detection or installation input. Thu~ the proce.ssor itself serves as the data storage medium f or the meter reading and S other data. When it is time to report the data to the utility company no search or interrogation of the sources of the data, suc:h as the meters, is r~quired.
The command signal tones received from the t01ephone line are presented to the processor in the same way.
10 The operation as described above is performed by the processor under control of the program stored in ROM.
The relevant part of the control program is represented by the f low chart of FIGURE 5 .
When the SAU issues a control signal via the telephone line, it does so by a series of tone bursts at a frequency of 1633 Hz. The initial tone signal is an alert signal. The initial or alert signal, if acknowledged, is followed hy command signal which 20 iden~ifies the meter number. The number of tone bursts in each signal is the code for a particular function. The filter 63, 64 passes that tone to the transistors 68 and 120 which, in turn, pass it to the multiplexer 102 and to the RESET port of the 25 processor. The multiplexer 102 passes the tone to the processor port Il as described above. After determining that a tone is present the processor will keep itself activated by supplying the latching ; signal ~ro~ the port D0. The processor verifies the frequency by monitoring the level transitions of the tone. The frequency verification is performed by the ; processor under program ~ontrol as represented by the flow chart o~ FIGURE 5~ If the frequency is , 1 31 433~
P-363 - 2~ ;
incorrect, the processor will turn off, otherwisa, the processor will turn on the tone generator 104 through transistor 112 by resetting port D3. Then the generator outputs an acknowledge burst in the form o~ a DTMF tone pair which is a~ mix o~ two preset ~re~uencies. The tone pair modulates the load current drawn by the RSU via the ~ransistors 114, 55 and 54 and that modulation is sensed by the SAU and decoded. Then a command signal of 1, 2, 3 or 4 requests the reading of the corresponding meter~
When a meter reading is requested the processor outputs a series of digits to the tone generator 104.
The DTMF protocol provides 8 fixed frequencies combined in 16 tone pairs representing the decimal digits and six other characters. The meter reading, : as accumulated in the corresponding register in the processor ~AM, is output in a binary coded decimal . : format. Each decimal digit is represented by a four bit code whi~h is translated by the tone generator into a tone pair unique to the digit value. The meter reading is accompanied by other data which .is output as a series of DTMF tones representing decimal digits. Tones representing o~her characters are used for the message header and terminator. The complete response is typically as ~ollows: message header (1 ; digit), meter type (2 digits), customer account number (8 digits), wake command echo (3 digits), meter reading (lO digits), tamper indication ~1 digit), error code indication (2 digits), checksum 1 3 1 ~33~
; value (3 digits), and a message terminator (1 digit).
The tones are 70 to 90 msec long and are separated by pauses of the same length.
A busy detection function is provided by the 24 volt zener diode 50. When a telephone is taken off-hook, the voltage across the tip and ring terminals drops to 24 volts or le~s. At this level the diode 50 inhibits input current and no voltage is present at the port I2 of the processor which prevents any tone output.
Tamper indication is used to recognize an event such as opening the RSU housing or disconnecting the :~ 15 wires. When such an event is detected an appropriate flag is set in the processor and is read out along with the meter reading.
It will thus be seen that the invantion provides an inexpensive rPmote meter reader which produces data outputs for telephone transmission with the highest integrity, operates at extremsly low power levels, and is flexible to perform auxiliary functions as well.
Although the description of this invention has been given with reference to a particular embodiment, it is not to be cons~rued in a limiting sense. Many variations and modifications of the invention will now occur to those skilled in the art. For a definition of the invention reference is made to the appended claims.
P 3~3 - 1 -REMOT~ ER R~ADI~ N~OD A~D APPARAT~S
FIELD OF T~ I~V~TION
This invention relates to the method and apparatus for automatic mater reading by telephone and particularly ~o meter d~ta encoding methocl and apparatus for remote meter reading.
BAC~G~o~ND OF ~E I~VE~TION
It is generally desirable for utility companies to collect meter reading information from homes or commercial esta~lishments without visually inspecting every meter at its resident location. The traditional labor intensive collection system is too expensive to be maintained and the accuracy of the data collected is subiect to considerable error. A
number of proposals ~or remote meter reading have ` 20 been made and some have been put into operation. One system which has been tried uses a radio link with the meter an~ a mobile radio unit which is driven around selected neighborhoods ~o collect data from local meters. This reguires manned operation of the mobile units and thus is a compromise which uses less labor than the traditional data collection method.
Still another system for remote meter reading uses telephone communica~ian between the utility company and the meters to be read. The present invention pertains to this category.
131~338 Telephonic meter reading systems have long been proposed without commercial success although in recent times there has been a renewal of commercial atte~pts which seek to capitali.ze on improving telephone communication ~echnology. In general, the~e systems incorporate a modem in each residential unit to receive interrogation signals from the telephone line and to formulate and transmit meter readings via the telephone line to the utility company. Such modems have come into widespread use for telephone communication an~ are characterized by two traits: they are expensive and unreliable as communication devicPs. Even though a modem might accurately produce signals representing the data to be transmitted, the signals are in such a form that, due to noise interference or limited system fidelity, they are not faithfully transmitted over normal telephone lines. Some systems use communication devices which may not be recognized as modems, yet the transmission reliability i5 questionable. Some r presentative patented systems are described below.
m e U.S. Patent No. 3,842,21~ to De~uca et al describes a sys~em for remote meter reading by telephone ~hich uses a modem (FIGURE S) at the meter : site for initiating the interrogation of meters upon receiving a command signal and generating a series of tones to communicate the meter consumption information. The meters have decades supplying signals on ten lines to ~he tone generator which yields data in decimal form.
131~33~
P-363 - 3 ~
The U.S. Patent No. 3,868,640 to Binnie et al discloses a remote meter read;.ng system using telephony. In one version using a frequency division m~ltiplex basis, a unit at the meter site has four tone decoders and an interrogation signal comprising up to four simultaneous frequencies is evaluated by the unit for prompting a response. In another version using a time division multiplex basis, single tone decoder is used and the interrogation signal comprises a binary code made up of a series o~
single frequency tones each representing a '1" or NO~. In either version the unit responds by transmitting the meter readings in the form of a series of tones of the same frequency.
~ The U.S. Patent No. 3,842,206 to Barselotti et : al shows a remote meter reading system having a meter unit which transmits meter readings as a serial binary pulse train. Each bit in the pulse train comprises either of two fre~uencies representing a ~l n or a ~On.
:The U.S. Patent NoO Re.26,331 to Brothman et al discloses a remote meter reading system having a unit at the meter site for transmitting a coded meter reading in the ~orm o~ a modulated AC signal in one : version or in the form of ~erial binary pulses interspersed with synchronization pulses in another version.
U.5. Patent 4,587,536 to Oliver et al granted March 25, 1986, discloses a meter reading system ; including interface means ~etween the meter and 1 31 ~338 P-363 _ 4 _ telephone line for sending AC signals to the central office in response to an interrogation signal.
Plural multiplexers are provided at the central office for multiplexing the signals between a group of telephone lines and central office. A computer selects a multiplexer and one of the telephone lines and a continuous DC and AC coupling is established to the telephone line during on-hook conditions. The interface means generates DTMF signals corresponding to the meter reading value which are transmitted over the telephone line to the central office.
*
The Lumsden patent 4,3~8,690 granted June 14, 1983, discloses an automatic meter reading transponder. The transponder includes a CPU
connected to a receiver and transmitter and a real time clock is connected to the CPU. The CPU receives the input pulses representative of electric power consumption. The RAM o~ the CPU has a plurality of addressable registers wherein the CPU equates each register sequentially with a predetermined time period. Each register contains a count which is representative of the power consumed during the associated time period.
8~MKARY OF T~ I~VE~TION
Accordin~ly the invention seeks to provide an inexpensive meter reading and data transmitting apparatus for a telephonic automatic meter reading system.
* U . S . PATENT NUMBER
. . ~ , 13 1 a,338 P~3~3 - 5 -Still further the invention seeks to provide an exceptionally reliable method of meter reading and telephonic data transmission.
The invention is also carried out in a remote meter reading system having telephone co~munication of meter data by a meter telephone unit comprising;
terminals for connection to a telephone line, means coupled to the terminals for initiating a meter reading operation, control means for acquiring data and furnishing data in response to initiation of meter reading, and a DTMF tone generator coupled to the terminals and to the control means for receiving the data ~rom the control means and for producing a set of tone pairs representing the data or transmission over the line.
In accordance with this invention, an improved transponder is provided for use in an automatic meter reading system of the type which utilizes the telephone system for transmission of meter readings.
The transponder comprises a microprocessor including a read/write memory. A meter pulse generating means is coupled with a meter and produces a meter pulse corresponding to a unit of measurement. The microprocessor is normally in a quiescent mode and is switched to an active mode in response to a meter pulse. The microprocessor is programmed to count pulses and to store the pulse count in the read/write memory and to switch ~he microprocessor to the quiescent mode after the pulse count is stored. A
detecting means detects a con~rol signal on the telephone line and the microprocessor is switched , ... ... .
from the quiescent mode to an active mode in response to the control signal. The microprocessor is programmed to produce a tone generator signal for a DTMF tone ~enerator in response to receipt of a control signal. The tone generator produces a sequence of tone pairs representing a pulse count stored in the read/write memory and the microprocessor is switched to the quiescent mode after the sequence of tone pairs is produced.
Further, in accordance with the invention, the transducer is powered by supply voltage on the telephone line except when a fault occurs on the line or the telephone i5 off hook and then it is powered by a battery in the transducer which supplies an auxiliary supply voltage. Battery power is conserved and yet the integrity of pulse counting is assured by maintain:ing the microprocessor in the quiescent state except when a meter pulse is generated. Further, battery power is conserved by utilizing for meter pulse generation a Wiegand sensor which requires no power supply.
The invention in one aspect as claimed provides a transponder for use in a meter reading system using a telephone line for communication of meter data, the transponder comprising detecting means for detecting a control signal on the telephone line, a microprocessor including a read/write memory, and a meter pulse generating means coupled with the meter for producing an electrical meter pulse corresponding to a predetermined meter event, with first coupling means for coupling the meter pulse generating means to the microprocessor. Means provide for switching the microprocessor from a quiescent mode to an active mode in response to a meter pulse and the microprocessor is programmed to count puls~s from the meter pulse generating means and for storing the pulse count in the read/write memory, and for switching the microprocessor to the quiescent mode after the pulse count is stored. A data signal generator is coupled with the microprocessor. Second coupling means couples the detecting means to the microprocessor, and there is means for switching the microprocessor from a quiescent to an active mode in response ~o a control signal, the microprocessor being programmed to cause `~ ,, - 6a - 1 31 4338 the data signal generator to transmit encoded data representing the pulse count stored in the read/write memory in response to a predetermined control signal and for switching the microprocessor to the quiescent mode after the encoded data signal is transmitted.
In a preferred aspect, the transponder includes a movable magnetic member carried by the met0r and it is cyclically movable along a path having a length corresponding to a predetermined unit of mea~urement, and a Wiegand sensor having an output coil 0 i5 coupled therewith for producing an output voltage pulse when the magnetic state of the Wiegand sensor is switched from one polarity to the other, the sensor being disposed adjacent to the path for generating a voltage pulse in response to movement of the magnetic member past the sensor.
The invention as claimed also pertains to an automatic meter reading system of the type which utilizes a telephone system having a central office, multiple subscriber lines each having a subscriber telephone connected therewith at a subscriber station, the subscriber lines being coupled to a switch in the central office for selective connection of any one of the subscriber lines to another line. Voltage supply means supplies electrical power from the central office to the subscriber lines and a test trunk is provided for selectively accessing the subscriber lines without ringing the telephone of the selected line. A subscriber line access means is coupled with the test trunk for accessing a selected line and a transpondèr at the subscriber station is coupled with the subscriber line and with one or more utility meters. Control signal means is coupled with the subscriber access means for generating a control signal for the transponder at a selected subscriber station. The transponder is of the above type and preferably includes a DTMF
tone generator coupled with the microprocessor, the microprocessor being programmed to produce a tone generator signal for the tone generator in response to a predetermined control signal for producing a sequence of tone pairs representing the pulse count stored in the read/write memory and ~, - 6b - I 3 1 4338 for switching the microprocessor to the quiescent mode after the sequence of tone pairs is produced.
In a preferred embodiment of the system, a voltage regulator :~ i5 provided for energi~ing the transponder and has an input coupled with the subscriber line for receiving a supply voltage.
A battery produces an auxiliary supply voltage, and means is provided for switching the auxiliary supply voltage to the input of the voltage regulator when the supply voltage on the subscriber line falls below a predetermined value due to a fault on the subscriber line or due to the telephone going off-hook wher`eby the transponder continues to accumulate the pulse count from the meter.
A more complete understanding of the invention may be obtained from the detailed description that follows taken with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a block diagram of an automatic meter reading system incorporating a meter unit according to the invention;
131~33~3 ~-363 - 7 -FIG~RE 2 is a schematic CirCllit diagram o~ the meter unit according to the inven~ion;
FIG~E 3 is a diagra~matic s,howîng of a meter sending unit;
FIG~E 4 is a represen~ation of a Wiegand type sensor in the sending unit;
10FIG~R$ 5 is a flow chart representing a part of the control program of the microprocessor, and FIG~RE 6 depicts storage registers in the RAM
of tha microprocessor; shown with FIGURE 3.
D~8CRIP~ION OF T~B ~EF~RED E~BODI~T
A remote meter reading system is intended to provide the various utility companies with a cost effective and timely method of collecting billing ~ info~mation. Integrity of ~he collected info~mation : is of paramount importance. By using telephony as the data collection medium, a system i~ available for nearly every utility customer, The utility company : 25 needs ~special equipment at itæ central office for ; interfa~ing with the telephone company equipment as well as equipment a~ each home, business or other ~eter site for automatically collecting meter data.
By pxoviding suitable flexibility in the equip~ent, other ~unctions such as tamper detection and remote : disconnect can be provided.
P 363 - a Referring now to the drawings, there is shown an illustrative embodiment of the i~vention in an automatic meter reading system wherein the transmission of meter reading data from the meter site is initiated by an interrogat:ion signal from the telephone company. It will be appreciated, as the description proceeds; t~at the invention is also applicable in a meter reading system wherein the transmission of meter reading data is initiated by a suitable unit at the meter site. It will ~come apparent to those skilled in the art that the invention may be practiced in many different forms and may be utilized in a variety of applications.
As indicated in FIG~RE 1, the system is distributed ~mong the utility company, the telephone company and the customers of ~he utility company.
The customar has an incoming telephone line 10 connected to a conventional telephone 12 and to a transponder comprising a residential sexvices unit 14 (RSU) and one or more sending units 17. Each sending unit i~ coupled with a utility meter 16. The telephone 12 may be the same telephone used by the telephnne company subscriber for conventional voice 2S communication over the telephone system. The telephone company has a test trunk 18 which is provided for the purpose of accessing individual telephone lines without ringing the phones to test line xesistance and other aspects of the telephone equipment. This same test trunk is used to access the individual RSU's 14 to carry out meter reading and related functions. The test trunk 18 is connected to the customer lines 10 through a switch s 1 3 1 l~338 P--~63 9 -22 and a main distribution frame 24. The telephone company also houses a utility access unit (UAU) 26 which is connec~ed to ~he tes~ t~nk 18 through a subscriber access unit (SAU) 2~ and is connected to the utility company through a mode:m 30. The UAU 26 accepts requests ~rom th~ utility, obtains ~ata, and transmits the data to the utility. The (SAU) 28 accesses customer RSU's 14 over the test trunk 18 when commanded by the utility access unit 26. The utility has a computer or terminal 32 coupled through a modem 36 to the telep~one company modem 30.
The meter reading system interrogates the RSU
14 at each meter site and communicates meter data to the utility company computer for billing purposes without interfering in any way with the customer's ~;~ service. The utility computer 32 requests meter readings using account numbers or telephone numbers;
this communication is over the dial-up network using commercial modems 36, 30. In response ~o the re~uest the UA~ 26 instruc~s the SAU 28 to access the customer RSU 14 via ~he test trunk 18 (i.e., without ringing). The S~U 28 will not access the customer's telephone line if i~ is in use ~busy). Also the RSU
14 incorporates a nbusy de~ct~ function that causes the system to release the line whenever the customer picks up the telephone. The SAU 28 commands the RSU
14 to transmit meter readings, reset registers, etc., by sending a control signal including a command signal comprising a sequence of single freguency tone bursts on the ~e}ephone line. The RSU 14 responds with DTMF (dual tone multifrequency or /'touchtone"
signalling) to the SAU 28. Data communicated from 1 31 ~338 ~-363 - 10 -the RSU to the S~U is checksummed to ensure data integrity. Following com~and execution, the RSU
automatically assumes a quiescent mode~ The SAU has a digit receiver with frequency s~lective ~ilters to detect the DTMF tones. The DTMF data received from the RSU is translated into ASCII and sent to the UAU
which forwards it to ~he utili~y computer 32. The SAU communica~es with the UAU in ASCII format using serial RS232C protocol.
The system is designed to work with co~monly used meters of the ordinary unencoded type or the encoded type. Appropriate meter inter~aces or sending units are provided as separate assemblies to provide flexibility in packaging as well as the ability to accommodate a large number and variety of ~; meters. Unencoded meters may have magnetic pickups . added. The sending units make all meters compatible with the RSU 14 and all meters are read in the same manner. In par~icular, the sending unit issues a voltage pulse to ~he RSU for each unit of consumption. In accordance with this invention, a special sending unit is provided, as will be described subsequently.
2s The RSU 14 shown in FIGURE 2 has a line interface comprising tip and ring terminals for connection to the telephone line 10 and a diode bridge 40 having its input connected to the terminals and its outpu~ connected to ground and a positive line 44. ~ 2sa volt zener diode 46 is connected across ground and line 44 for transient suppression, The bridge assures ~hat the voltage output is 1 ~ 1 4338 P--3~
independent of the telephone line 10 polarity. The nominal voltage into the terminals is 48 volts. The line 10 furnishes power to the RSU.
A voltage regulator 48 and power switch circuitry furnish a regulated vol~age Vcc~ A 24 volt zener diode 50 and a resistor 51 couple the positive line 44 to the collector and base of a transistor 52 while the emitter is coupled to the collector and base of a transistor 53 which is configured as a 14 volt zener diode connected at one side to ground. A
pair of Darlington connected transistors 54, 55 have the input base connected to the resistor 51, their collectors connected to the anode of the diode 50 and their output emitter connected through four serially connected diodes 56, 57, 58 and 60 to the input of the regulator 48. The regulator has a terminal connected to ground and capacitors 61 and 62 are connected between the regulator 48 input and output, respectively, and ground. The elements 50 through 60 drop the 48 volt input ~oltage to approximately 11.5 voIts for input to the voltage regulator which maintains an output Vcc of a constant 5 volts.
A tone selective filter, comprising a capacitor 63 and an inductor 64, is serially connected between the line 44 and ground have a junction point connected to the base of a transistor 68. The filter is tuned to the control signal frequency of 1633Kh.
For backup purposes a 9 volt lithium battery 70 maintains continued operation of the RSU when telephone line power is not available to the input of 1 3 1 ~38 the voltage regulator 48. This occurs when there is a failure o~ voltage supply on ~he telephone line and also when the telephone is of-hook as will be described subsequently. The batte~y 70 is connerted between ground and the input of the regulator 48 :through a dioda 7~. As long as there is power from the telephone line 10, the voltage at the regulator 48 input is highex than the voltage at the anode of the diode 74 and all power will be supplied by the line 10. When ~he telephone line is removed or the voltage drops below 24 volts the diode 74 will conduct to supply battery power to the regulator 48.
A low battery detect circuit includes an operational amplifier 80; it also provides a voltage divid~r 82 and a transistor ~4 serially coupled between the battery 70 and ground. A zener diode 86 is connected between an input of the operational ~amplifier ~0 and the collector of the transistor 84 :~20 to provide a reference voltage at the operational amplifier when the transistor 84 is turned on. The transistQr 84 is normally ~urned off, creating approximately the same voltage on all inputs of the operational a~pli~ier 80 keeping it turned off.
Power is turned on to the operational amplifier only when the transistor 84 is turned on to obtain a reading and then a reference voltage is placed on one input of the operational amplifier. The voltage on the other input (derived from battery voltage) is :~30 compared to the re~erence voltage and when the :battery voltage is low the output of the operational amplifier is low.
1 3 I ~ 3 3 ~
;
A processor 100 such as a COP840C
microprocessor is coupled to the circuitry described above. It is also coupled to meters 16 and other inputs throu~h a ~ulkiplexer 102 (MUX) such as a CM 512B multiplexer and to a DTMF tone generator 104 such as a TP508~ generator which transmits the RSU
;~output data. The processor 100 includes a RAM, i.e., a read/write memory, and is operated under control of a program stored in its ROM. The processor lOO ha~
ports GND and Vcc for power supply connection, clock ports CXI and CKO connected to a crystal 106 for clock input, a port Gl connected to the base of transistor 84 to turn on the low battery detect circuit, and a port I3 connected to the output of -15 operational amplifier 80 to receive the low battery signal. Processor ports LO through L4 are connected to inputs of the tone generator 104. Ports LO, Ll and L2 are also connected to the selector ports A, B
and C of the m~ltiple~er 102. The m~ltiplexer has one data ou~put port which is coupled to port Il. A
RESET port activates the processor when a voltage is applied to the port thxough a transistor 120. A
latching port DO coupled to the base of the transistor 120 can be energized by the processor to latch the RESET on. A port I2 is connected to a voltage divider 121 which is connected to the junction of diodes 58 and 60 to sense the presence of voltage at that point. The normal voltage is 4.2 volts and is limited to 5.7 volts maximum by a clamping circuit including a diode. The voltage is lost if the line voltage goes below the 24 volt level of the zener diode 50. When the telephone is off-hook, i.e. in use, the reduced voltage on the 1 31 ~338 P-363 - lg -telephone line will be blocked by zener diode 50 and the voltage at poxt I2 will be at logic low and this prevents port D3 from going high. This in turn, prevents any tone generator output.
A~ shown in Figure 2, there are four meter sending units 17 in the illustrative meter reading sy~tem. Each sending unit 17 i~ associated w.ith a different me~er, the meters being numbered 1, 2, 3 and 4. Each of the meter sending units is of a special type which requires no power supply and has no moving parts. It is well adapted for retro fitting on existing meters, especially the conventional water meker and gas meter which use a separate rotary hand indicator or number wheel indicator ~or each decimal digit in the reading. The ; sending unit uses a Wiegand sensor which is co~mercially a~ailable from the Sensor Engine2ring Co~pany of Hamden, Connecticut. The principles and structure of ~he Wiegan sensor are disclosed in Wiegand patent 3,820,090 granted June 25, 1974 and Wiegand patent 4,247,601 granted January 27, 1981.
The Wiegand sensor utili2es a bistable feromagnetic wire of generally uniform composition having a central magnetically soft core portion and an outer ~agnetical}y hard shell portion ~ith relatively low and high coercivity respec~ively. The shell portion ~ is permanently magnetized and operates to magnetize ; the core portion in a first direction (the ~confluent state~) in the absence of an external magnetic field.
The magnetization of the core portion is reversible by the application of an external magnetic field so that the core and shell have opposi~e polari~y (the * U. S . PATENT NUMBER`
1 31 ~33~
;revexse state~) when the external field is removed the magnatization of the core is changed to the first ~-~direction by the effect of the shell portion. Thus, by manipulating ths external magnetic field excursions, the shell and core can be switched to the con~luent or reverse states of ma~netic polarity.
~The polarity switching occurs abruptly. For use as a :pulse generator, a sensing coil is wrapped around the Wiegand wire and the sensor comprises a two wire device that requires no power. The sensing coil develops signal pulses of two or three volts in :magnitude and twenty microseconds in duration and can operate with a pulse rate up to twenty KHz. It is suita~le for very low speed operation as well and is operable over a wide range of temperature.
A meter sending unit 17 is shown ;diagrammatically in FIGURES 3 and 4. FIGURE 3 shows a typical meter such as a gas meter with a panel 130 having five different dial indicators of the rotary hand type, each dif~erent hand representing a :different digit in the meter reading. The hand representing the least significant digit is replaced with a rotary two-pole permanent magnet 134 and a Wiegand sensor 136 is disposed adjacent the rotary magnet. The Wiegand sensor 136 and the rotary magnet 134 are shown in FI~URE 4. The ~iegand wire 138 is wrapped with a sensing coil 142. The rotaxy magnet wheel 134 is located so that its magnetic field is :~30 effective to switch Wiegand wire from the confluent state to the reverse state and allows it to switch back to the con~luent state as it rotates through one~
~ 31 4338 revolution. Accordingly, meter pulses of alternate polarity are generated in the coil 142 as shown in the waveform diagram of FIGURE 4.
The sensor of each meter sending unit 17 is coupled through a meter in~erface circuit with the input of the multiplexer 102, as shown in FIGURE 2.
The interface circuit comprises a transistor 110 having its base connected through a resistor to the output terminal of the Wiegand wire sensor. The diode across thE~ base bypasses the negative pulses and the positive pulses are effective to turn on the transistor llO. The collector of the transistor is connected with one oî the input ports Xl, X2, X3 or X4 of the multiplexer 102. The collectors are also coupled through a large resistor lll to the base of : ~ the transistor 120 so tha~ as a pulse, at ground potential, is applied to the multiplexer by a meter :: sending unit, a similar pulse turns on the transistor 20 120 to activate the processor 100.
The data input ports of the multiplexer }02 are selectively coupled to the port I1 of the processor.
The ~our meter sending units 17 are coupled through 25 individual signal conditioning circuits 108, as discussed above, to one oi~ the input ports Xl "~2, X3 or X4 of the multiplexer 10~, Th~ command signal : issued by the SAU is transmitted~ over the telephone line as a sequence of tone burs~s at 1633Hz. This signal is derived from the filter capacitor 63 and inductor 64 and applied through transistor 68 to the input port X0 of the multiplexer. The input at port X0 is at logic low during each tone burst. A tamper 1 31 $;~38 P-363 ~ 17 detector terminal is coupled throuqh a transistor 122 to the data input port X6 of ~he multiplexer. When the terminal is grounded, the input at port X6 is at logic high. DTR terminals DTR 1, 2 and 3 are provided for connection to an installer5 portable field unit to initialize registers in the processor and perform tes~s at the tim~ of installation. The ter~inals DTR 2 and 3 are conn~cted to input ports Io and G0 respectively on the processor for receiving and transmitting data, respectively. The terminal ; DTR 1 is coupled through a resistor and conductor 124 to the port X5 of the multiplexer. These other inputs, like the meter sending units 17, are coupled to the base of the transistor 120 through resistors 111 to activate the RESET when a pulse occurs. The ~ultiplexer 102 operates under control of the processor 100 to provide the input signals to the processor as they occur and, if more than one occurs simultaneously, to present them in a prescribed ordex. When a pulse occurs it is applied to a ; multiplexer input and aleo through the transistor 120 to activate the processor. The processor t~en sweeps through a series of seven 3 bit codes, one for each MUX input, applying them to the multiplexer via ports ~5 L0, Ll and L2. When the code matches a MUX input at ground potential an outpu~ pulse is sent to the port I1 o~ the processor. The processor acts on the pulse according to its source.
The processor 100 has a por~ D3 coupled to the b~se of a tr~nsistor 112 which connects Vcc to the tone generator 104 ~o supply power thereto. To supply data to the tone generator the processor . .
1 31 ~338 P-363 - 18 ~
energizes a tone enable output port L4 and a four bit data output at the ports L0 through L3. The tone generator, in turn has an output port coupled to the b~e of a transistor 114 whicll is connected to modulate the lsad current on the transistors 54 and 55.
In operation the RSU is powered by the telephone line 10 but the power requirements are extremely small. The RSU has a very high input impedance ~at least 5 megohms) during idle state.
Except when receiving inputs or when in~errogated by the SA~, the processor 100 remains in the quiescent or halt mode and draws less than 1 microamp. Wh~n a pulse is emitted by a sender 17, the multiplexer 102 receives the pulse on input port X0, Xl, X2 or X3 and the RESET port of the processor receives a logic high input to activate the processor. Similarly when a command signal, ~2~per signal or DTR signal is received on input ports X0, X5 or X6, the processor is activated. The processor sends a sequence of 3 bit codes to the ~UX which operates to serially couple to the processor poxt Il any input pulses which are present on the inputs of the MUX when their corresponding codes are received from the processor o~ the MUX ports A, B and C. When a meter pulse is emitted by a sender 17, the processor responds to the pulse by incrementing a coun~ in RAM at an address re~erved as a register for the meter identified by the particular code. The registers in RAM are depicted in FIGURE 6 as Rl, R2, R3 and R4, corresponding to meters 1, 2, 3 and 4, respectively.
Then the processor returns ~o the halt mode and 1 3 1 ~33~
~363 _ ~9 _ awaits anoth0r event. Information is stored in a similar manner for th~- tamper detection or installation input. Thu~ the proce.ssor itself serves as the data storage medium f or the meter reading and S other data. When it is time to report the data to the utility company no search or interrogation of the sources of the data, suc:h as the meters, is r~quired.
The command signal tones received from the t01ephone line are presented to the processor in the same way.
10 The operation as described above is performed by the processor under control of the program stored in ROM.
The relevant part of the control program is represented by the f low chart of FIGURE 5 .
When the SAU issues a control signal via the telephone line, it does so by a series of tone bursts at a frequency of 1633 Hz. The initial tone signal is an alert signal. The initial or alert signal, if acknowledged, is followed hy command signal which 20 iden~ifies the meter number. The number of tone bursts in each signal is the code for a particular function. The filter 63, 64 passes that tone to the transistors 68 and 120 which, in turn, pass it to the multiplexer 102 and to the RESET port of the 25 processor. The multiplexer 102 passes the tone to the processor port Il as described above. After determining that a tone is present the processor will keep itself activated by supplying the latching ; signal ~ro~ the port D0. The processor verifies the frequency by monitoring the level transitions of the tone. The frequency verification is performed by the ; processor under program ~ontrol as represented by the flow chart o~ FIGURE 5~ If the frequency is , 1 31 433~
P-363 - 2~ ;
incorrect, the processor will turn off, otherwisa, the processor will turn on the tone generator 104 through transistor 112 by resetting port D3. Then the generator outputs an acknowledge burst in the form o~ a DTMF tone pair which is a~ mix o~ two preset ~re~uencies. The tone pair modulates the load current drawn by the RSU via the ~ransistors 114, 55 and 54 and that modulation is sensed by the SAU and decoded. Then a command signal of 1, 2, 3 or 4 requests the reading of the corresponding meter~
When a meter reading is requested the processor outputs a series of digits to the tone generator 104.
The DTMF protocol provides 8 fixed frequencies combined in 16 tone pairs representing the decimal digits and six other characters. The meter reading, : as accumulated in the corresponding register in the processor ~AM, is output in a binary coded decimal . : format. Each decimal digit is represented by a four bit code whi~h is translated by the tone generator into a tone pair unique to the digit value. The meter reading is accompanied by other data which .is output as a series of DTMF tones representing decimal digits. Tones representing o~her characters are used for the message header and terminator. The complete response is typically as ~ollows: message header (1 ; digit), meter type (2 digits), customer account number (8 digits), wake command echo (3 digits), meter reading (lO digits), tamper indication ~1 digit), error code indication (2 digits), checksum 1 3 1 ~33~
; value (3 digits), and a message terminator (1 digit).
The tones are 70 to 90 msec long and are separated by pauses of the same length.
A busy detection function is provided by the 24 volt zener diode 50. When a telephone is taken off-hook, the voltage across the tip and ring terminals drops to 24 volts or le~s. At this level the diode 50 inhibits input current and no voltage is present at the port I2 of the processor which prevents any tone output.
Tamper indication is used to recognize an event such as opening the RSU housing or disconnecting the :~ 15 wires. When such an event is detected an appropriate flag is set in the processor and is read out along with the meter reading.
It will thus be seen that the invantion provides an inexpensive rPmote meter reader which produces data outputs for telephone transmission with the highest integrity, operates at extremsly low power levels, and is flexible to perform auxiliary functions as well.
Although the description of this invention has been given with reference to a particular embodiment, it is not to be cons~rued in a limiting sense. Many variations and modifications of the invention will now occur to those skilled in the art. For a definition of the invention reference is made to the appended claims.
Claims (13)
1. In an automatic meter reading system of the type which utilizes a telephone system having a central office, multiple subscriber lines each having a subscriber telephone connected therewith at a subscriber station, said subscriber lines being coupled to a switch in the central office for selective connection of any one of the subscriber lines to another line, voltage supply means for supplying electrical power from the central office to the subscriber lines, a test trunk for selectively accessing said subscriber lines without ringing the telephone of the selected line, a subscriber line access means coupled with the test trunk for accessing a selected line, a transponder at the subscriber station coupled with said subscriber line and with one or more utility meters, and control signal means coupled with the subscriber access means for generating a control signal for a transponder at a selected subscriber station, the improvement wherein said transponder comprises:
detecting means for detecting a control signal on the telephone line, a microprocessor including a read/write memory, a meter pulse generating means coupled with said meter for producing an electrical meter pulse corresponding to a predetermined meter event, first coupling means for coupling the meter pulse generating means to the microprocessor, means for switching the microprocessor from a quiescent mode to an active mode in response to a meter pulse, the microprocessor being programmed to count pulses from said mater pulse generating means and for storing the pulse count in said read/write memory, and for switching the microprocessor to the quiescent mode after the pulse count is stored, a DTMF tone generator coupled with the microprocessor, second coupling means for coupling said detecting means to said microprocessor, and means for switching the microprocessor from a quiescent mode to an active mode in response to a control signal, said microprocessor being programmed to produce a tone generator signal for said tone generator in response to a predetermined control signal for producing a sequence of tone pairs representing said pulse count stored in the read/write memory and for switching the microprocessor to the quiescent mode after the sequence of tone pairs is produced.
detecting means for detecting a control signal on the telephone line, a microprocessor including a read/write memory, a meter pulse generating means coupled with said meter for producing an electrical meter pulse corresponding to a predetermined meter event, first coupling means for coupling the meter pulse generating means to the microprocessor, means for switching the microprocessor from a quiescent mode to an active mode in response to a meter pulse, the microprocessor being programmed to count pulses from said mater pulse generating means and for storing the pulse count in said read/write memory, and for switching the microprocessor to the quiescent mode after the pulse count is stored, a DTMF tone generator coupled with the microprocessor, second coupling means for coupling said detecting means to said microprocessor, and means for switching the microprocessor from a quiescent mode to an active mode in response to a control signal, said microprocessor being programmed to produce a tone generator signal for said tone generator in response to a predetermined control signal for producing a sequence of tone pairs representing said pulse count stored in the read/write memory and for switching the microprocessor to the quiescent mode after the sequence of tone pairs is produced.
2. The invention as defined in Claim wherein:
said transponder has a pair of terminals connected respectively with the tip and ring conductors of said telephone line whereby said transponder is normally energized from said voltage supply means from the central office, and modulating means for modulating the current on said telephone line, said DTMF tone generator has an output coupled with said modulating means for modulating the current in said telephone line at the frequencies of the tone pairs.
said transponder has a pair of terminals connected respectively with the tip and ring conductors of said telephone line whereby said transponder is normally energized from said voltage supply means from the central office, and modulating means for modulating the current on said telephone line, said DTMF tone generator has an output coupled with said modulating means for modulating the current in said telephone line at the frequencies of the tone pairs.
3. The invention as defined in Claim 2 wherein:
the pulse count stored in said read/write memory is formatted as a sequence of binary coded decimal numbers, and the DTMF tone generator generates a unique tone pair for each number, whereby the pulse count is transmitted as a sequence of tone pairs.
the pulse count stored in said read/write memory is formatted as a sequence of binary coded decimal numbers, and the DTMF tone generator generates a unique tone pair for each number, whereby the pulse count is transmitted as a sequence of tone pairs.
4. The invention as defined in Claim wherein:
said first coupling means comprises a multiplexer circuit and a reset circuit each having an input coupled with the meter pulse generating means, the reset circuit having an output coupled to a reset input of the microprocessor for switching the microprocessor from a quiescent mode to an active mode in response to a meter pulse and for switching it to a quiescent mode after the occurrence of a mater pulse, the microprocessor has means for interrogating a multiplexer when in an active mode to identify which meter issued said pulse, and means responsive to said pulse for incrementing a pulse count register in the read/write memory corresponding to the identified meter.
said first coupling means comprises a multiplexer circuit and a reset circuit each having an input coupled with the meter pulse generating means, the reset circuit having an output coupled to a reset input of the microprocessor for switching the microprocessor from a quiescent mode to an active mode in response to a meter pulse and for switching it to a quiescent mode after the occurrence of a mater pulse, the microprocessor has means for interrogating a multiplexer when in an active mode to identify which meter issued said pulse, and means responsive to said pulse for incrementing a pulse count register in the read/write memory corresponding to the identified meter.
5. The invention as defined in Claim including:
a movable magnetic member carried by said meter and which is cyclically movable along a path having a length corresponding to a predetermined unit of measurement, and a Wiegand sensor having an output coil coupled therewith for producing an output voltage pulse when the magnetic state of the Wiegand sensor is switched from one polarity to the other, said sensor being disposed adjacent to said path for generating a voltage pulse in response to movement of said magnetic member past said sensor.
a movable magnetic member carried by said meter and which is cyclically movable along a path having a length corresponding to a predetermined unit of measurement, and a Wiegand sensor having an output coil coupled therewith for producing an output voltage pulse when the magnetic state of the Wiegand sensor is switched from one polarity to the other, said sensor being disposed adjacent to said path for generating a voltage pulse in response to movement of said magnetic member past said sensor.
6. The invention as defined in Claim 5 wherein said transponder further comprises:
a voltage regulator for energizing said transponder and having an input coupled with the subscriber line for receiving a supply voltage, a battery for producing an auxiliary supply voltage, and means for switching the auxiliary supply voltage to the input of the voltage regulator when the supply voltage on the subscriber line falls below a predetermined value due to a fault on said subscriber line or due to said telephone going off-hook whereby said transponder continues to accumulate the pulse count from said meter.
a voltage regulator for energizing said transponder and having an input coupled with the subscriber line for receiving a supply voltage, a battery for producing an auxiliary supply voltage, and means for switching the auxiliary supply voltage to the input of the voltage regulator when the supply voltage on the subscriber line falls below a predetermined value due to a fault on said subscriber line or due to said telephone going off-hook whereby said transponder continues to accumulate the pulse count from said meter.
7. The invention as defined in Claim wherein:
said control signal is comprised of a tone of predetermined frequency, and said processor is programmed for determining whether the frequency of the control signal is equal to said predetermined frequency, and to switch the processor to the quiescent mode if it is not said predetermined frequency.
said control signal is comprised of a tone of predetermined frequency, and said processor is programmed for determining whether the frequency of the control signal is equal to said predetermined frequency, and to switch the processor to the quiescent mode if it is not said predetermined frequency.
8. For use in a meter reading system using a telephone line for communication of meter data, a transponder comprising:
detecting means for detecting a control signal on the telephone line, a microprocessor including a read/write memory, a meter pulse generating means coupled with said meter for producing an electrical meter pulse corresponding to a predetermined meter event, first coupling means for coupling the meter pulse generating means to the microprocessor, means for switching the microprocessor from a quiescent mode to an active mode in response to a meter pulse, the microprocessor being programmed to count pulses from said meter pulse generating means and for storing the pulse count in said read/write memory, and for switching the microprocessor to the quiescent mode after the pulse count is stored, a data signal generator coupled with the microprocessor, second coupling means for coupling said detecting means to said microprocessor, and means for switching the microprocessor from a quiescent to an active mode in response to a control signal, said microprocessor being programmed to cause said data signal generator to transmit encoded data representing the pulse count stored in the read/write memory in response to a predetermined control signal and for switching the microprocessor to the quiescent mode after the encoded data signal is transmitted.
detecting means for detecting a control signal on the telephone line, a microprocessor including a read/write memory, a meter pulse generating means coupled with said meter for producing an electrical meter pulse corresponding to a predetermined meter event, first coupling means for coupling the meter pulse generating means to the microprocessor, means for switching the microprocessor from a quiescent mode to an active mode in response to a meter pulse, the microprocessor being programmed to count pulses from said meter pulse generating means and for storing the pulse count in said read/write memory, and for switching the microprocessor to the quiescent mode after the pulse count is stored, a data signal generator coupled with the microprocessor, second coupling means for coupling said detecting means to said microprocessor, and means for switching the microprocessor from a quiescent to an active mode in response to a control signal, said microprocessor being programmed to cause said data signal generator to transmit encoded data representing the pulse count stored in the read/write memory in response to a predetermined control signal and for switching the microprocessor to the quiescent mode after the encoded data signal is transmitted.
9, The invention as defined in Claim 8 wherein:
said first coupling means comprises a multiplexer circuit and a reset circuit each having an input coupled with the meter pulse generating means, the reset circuit having an output coupled to a reset input of the microprocessor for switching the microprocessor from a quiescent mode to an active mode in response to a meter pulse and for switching it to a quiescent mode after the occurrence of a meter pulse, the microprocessor has means for interrogating a multiplexer when in an active mode to identify which meter issued said pulse, and means responsive to said pulse for incrementing a pulse count register in the read/write memory corresponding to the identified meter.
said first coupling means comprises a multiplexer circuit and a reset circuit each having an input coupled with the meter pulse generating means, the reset circuit having an output coupled to a reset input of the microprocessor for switching the microprocessor from a quiescent mode to an active mode in response to a meter pulse and for switching it to a quiescent mode after the occurrence of a meter pulse, the microprocessor has means for interrogating a multiplexer when in an active mode to identify which meter issued said pulse, and means responsive to said pulse for incrementing a pulse count register in the read/write memory corresponding to the identified meter.
10. For use in a meter reading system using a telephone line for communication of meter data, a transponder comprising:
detecting means for detecting a control signal on the telephone line;
a microprocessor including a read/write memory;
a meter pulse generating means coupled with said meter for producing an electrical meter pulse corresponding to a predetermined meter event, first coupling means for coupling the meter pulse generating means to the microprocessor:
means for switching the microprocessor from a quiescent mode to an active mode in response to a meter pulse;
the microprocessor being programmed to count pulses from said meter pulse generating means and for storing the pulse count in said read/write memory and for switching the microprocessor to the quiescent mode after the pulse count is stored, a data signal generator coupled with the microprocessor;
second coupling means for coupling said detecting means to said microprocessor and means for switching the microprocessor from a quiescent to an active mode in response to a control signal, said microprocessor being programmed to cause said data signal generator to transmit encoded data representing the pulse count stored in the read/write memory in response to a predetermined control signal and for switching the microprocessor to the quiescent mode after the encoded data signal is transmitted;
a movable magnetic member carried by said meter and which is cyclically movable along a path having a length corresponding to a predetermined unit of measurement;
and a Wiegand sensor having an output coil coupled therewith for producing an output voltage pulse when the magnetic state of the Wiegand sensor is switched from one polarity to the other, said sensor being disposed adjacent to said path for generating a voltage pulse in response to movement of said magnetic member past said sensor.
detecting means for detecting a control signal on the telephone line;
a microprocessor including a read/write memory;
a meter pulse generating means coupled with said meter for producing an electrical meter pulse corresponding to a predetermined meter event, first coupling means for coupling the meter pulse generating means to the microprocessor:
means for switching the microprocessor from a quiescent mode to an active mode in response to a meter pulse;
the microprocessor being programmed to count pulses from said meter pulse generating means and for storing the pulse count in said read/write memory and for switching the microprocessor to the quiescent mode after the pulse count is stored, a data signal generator coupled with the microprocessor;
second coupling means for coupling said detecting means to said microprocessor and means for switching the microprocessor from a quiescent to an active mode in response to a control signal, said microprocessor being programmed to cause said data signal generator to transmit encoded data representing the pulse count stored in the read/write memory in response to a predetermined control signal and for switching the microprocessor to the quiescent mode after the encoded data signal is transmitted;
a movable magnetic member carried by said meter and which is cyclically movable along a path having a length corresponding to a predetermined unit of measurement;
and a Wiegand sensor having an output coil coupled therewith for producing an output voltage pulse when the magnetic state of the Wiegand sensor is switched from one polarity to the other, said sensor being disposed adjacent to said path for generating a voltage pulse in response to movement of said magnetic member past said sensor.
11. The invention as defined in Claim 10 including:
a voltage regulator for energizing said transponder and having an input coupled with the subscriber line for receiving a supply voltage;
a battery for producing an auxiliary supply voltage;
and means for switching the auxiliary supply voltage to the input of the voltage regulator when the supply voltage on the subscriber line falls below a predetermined value due to a fault on said subscriber line or due to said telephone going off-hook whereby said transponder continues to accumulate the pulse count from said meter.
a voltage regulator for energizing said transponder and having an input coupled with the subscriber line for receiving a supply voltage;
a battery for producing an auxiliary supply voltage;
and means for switching the auxiliary supply voltage to the input of the voltage regulator when the supply voltage on the subscriber line falls below a predetermined value due to a fault on said subscriber line or due to said telephone going off-hook whereby said transponder continues to accumulate the pulse count from said meter.
12. The invention as defined in Claim 10 wherein:
said control signal is comprised of a tone of predetermined frequency;
and said microprocessor is programmed for determining whether the frequency of the control signal is equal to said predetermined frequency and to switch the microprocessor to the quiescent mode if it is not said predetermined frequency.
said control signal is comprised of a tone of predetermined frequency;
and said microprocessor is programmed for determining whether the frequency of the control signal is equal to said predetermined frequency and to switch the microprocessor to the quiescent mode if it is not said predetermined frequency.
13. In an automatic meter reading system of the type which utilizes a telephone system having a central office, multiple subscriber lines each having a subscriber telephone connected therewith at a subscriber station, said subscriber lines being coupled to a switch in the central office for selective connection of any one of the subscriber lines to another line, voltage supply means for supplying electrical power from the central office to the subscriber lines, a test trunk for selectively accessing said subscriber lines without ringing the telephone of the selected line, a subscriber line access means coupled with said subscriber line and with one or more utility meters and control signal means coupled with the subscriber access means for generating a control signal for a transponder at a selected subscriber station, the improvement wherein said transponder comprises:
detecting means for detecting a control signal on the telephone line;
a microprocessor including a read/write memory;
a meter pulse generating means coupled with said meter for producing an electrical meter pulse corresponding to a predetermined meter event;
first coupling means for coupling the meter pulse generating means to the microprocessor;
means for switching the microprocessor from a quiescent mode to an active mode in response to a meter pulse;
the microprocessor being programmed to count pulses from said meter pulse generating means and for storing the pulse count in said read/write memory and for switching the microprocessor to the quiescent mode after the pulse count is stored;
a DTMF tone generator coupled with the microprocessor;
second coupling means for coupling said detecting means to said microprocessor;
and means for switching the microprocessor from a quiescent mode to an active mode in response to a control signal, said microprocessor being programmed to produce a tone generator signal for said tone generator in response to a predetermined control signal for producing a sequence of tone pairs representing said pulse count stored in the read/write memory and for switching the microprocessor to the quiescent mode after the sequence of tone pairs is produced;
a voltage regulator for energizing said transponder and having an input coupled with the subscriber line for receiving a supply voltage;
a battery for producing an auxiliary supply voltage;
and means for switching the auxiliary supply voltage to the input of the voltage regulator when the supply voltage on the subscriber line falls below a predetermined value due to a fault on said subscriber line or due to said telephone going off-hook whereby said transponder continues to accumulate the pulse count from said meter.
detecting means for detecting a control signal on the telephone line;
a microprocessor including a read/write memory;
a meter pulse generating means coupled with said meter for producing an electrical meter pulse corresponding to a predetermined meter event;
first coupling means for coupling the meter pulse generating means to the microprocessor;
means for switching the microprocessor from a quiescent mode to an active mode in response to a meter pulse;
the microprocessor being programmed to count pulses from said meter pulse generating means and for storing the pulse count in said read/write memory and for switching the microprocessor to the quiescent mode after the pulse count is stored;
a DTMF tone generator coupled with the microprocessor;
second coupling means for coupling said detecting means to said microprocessor;
and means for switching the microprocessor from a quiescent mode to an active mode in response to a control signal, said microprocessor being programmed to produce a tone generator signal for said tone generator in response to a predetermined control signal for producing a sequence of tone pairs representing said pulse count stored in the read/write memory and for switching the microprocessor to the quiescent mode after the sequence of tone pairs is produced;
a voltage regulator for energizing said transponder and having an input coupled with the subscriber line for receiving a supply voltage;
a battery for producing an auxiliary supply voltage;
and means for switching the auxiliary supply voltage to the input of the voltage regulator when the supply voltage on the subscriber line falls below a predetermined value due to a fault on said subscriber line or due to said telephone going off-hook whereby said transponder continues to accumulate the pulse count from said meter.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US333,117 | 1989-04-04 | ||
| US07/333,117 US5010568A (en) | 1989-04-04 | 1989-04-04 | Remote meter reading method and apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1314338C true CA1314338C (en) | 1993-03-09 |
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ID=23301350
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000601232A Expired - Fee Related CA1314338C (en) | 1989-04-04 | 1989-05-31 | Remote meter reading method and apparatus |
Country Status (3)
| Country | Link |
|---|---|
| US (2) | US5010568A (en) |
| CA (1) | CA1314338C (en) |
| GB (1) | GB2230161B (en) |
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-
1989
- 1989-04-04 US US07/333,117 patent/US5010568A/en not_active Expired - Fee Related
- 1989-05-31 CA CA000601232A patent/CA1314338C/en not_active Expired - Fee Related
- 1989-06-02 GB GB8912690A patent/GB2230161B/en not_active Expired - Fee Related
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1992
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Also Published As
| Publication number | Publication date |
|---|---|
| US5010568A (en) | 1991-04-23 |
| GB2230161B (en) | 1994-04-13 |
| GB2230161A (en) | 1990-10-10 |
| GB8912690D0 (en) | 1989-07-19 |
| US5311581A (en) | 1994-05-10 |
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