Remote meter reading method and apparatus

• US 5,010,568 A
• Filed: 04/04/1989
• Issued: 04/23/1991
• Est. Priority Date: 04/04/1989
• Status: Expired due to Fees

• Current Assignee: Sparton Corporation (Elbit Systems Limited)
• Original Assignee: Sparton Corporation (Elbit Systems Limited)
• Inventors: Scott, Dale L., Merriam, David P., Scott, Bryan F.
• Primary Examiner(s): Ng, Jin F.
• Assistant Examiner(s): Woo, Stella L.
• Application Number:
  US07/333,117
• Time in Patent Office: 749 Days
• Field of Search: 379/107, 379/106, 379/413
• US Class Current: 379/106.07
• CPC Class Codes: G01D 4/004 Remote reading of utility meters to a fixed location
• CPC Class Codes: H04M 11/002 with telemetering systems telemetering in general G08C
• CPC Class Codes: Y02B 90/20 Smart grids as enabling technology in buildings sector smart grids supporting the management or operation of end-user stationary applications in general, or like technologies with no associated climate change mitigation effect Y04S20/00
• CPC Class Codes: Y04S 20/30 Smart metering, e.g. specially adapted for remote reading

Abstract

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 frequency 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.

Claims

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 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.

2. The invention as defined in claim 1 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.

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.

4. The invention as defined in claim 1 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.

5. The invention as defined in claim 1 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.

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 offhook whereby said transponder continues to accumulate the pulse count from said meter.

7. The invention as defined in claim 1 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.

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,

a 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.