Remote meter reading method and apparatus

• US 5,311,581 A
• Filed: 11/02/1992
• Issued: 05/10/1994
• 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: Merriam, David P., Scott, Bryan F., Scott, Dale L.
• Primary Examiner(s): Kuntz, Curtis
• Assistant Examiner(s): Woo, Stella L.
• Application Number:
  US07/970,265
• Time in Patent Office: 554 Days
• Field of Search: 379/107, 379/106, 379/102, 379/104, 379/105, 379/97, 340/870.02, 340/870.03
• 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. 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, said control signal being comprised of a tone frequency,

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 said 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 the quiescent to the active mode in response to said control signal which is comprised of said tone frequency, said microprocessor being programmed to determine whether said tone frequency is equal to a predetermined frequency and, if it is not, to switch said microprocessor to said quiescent mode, and if it is, to cause said data signal generator to transmit encoded data representing the pulse count stored in the read/write memory in response to a command signal and for switching the microprocessor to the quiescent mode after the encoded data signal is transmitted.

2. The invention as defined by claim 1 wherein said data signal generator is a DTMF tone generator.

3. The invention as defined in claim 2 wherein:

the pulse count stored in said read/write memory is formatted as sequence of binary coded decimal numbers,

and the DTMF tone generator generates a unique tone pair for each of said numbers 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 the quiescent mode to the active mode in response to said meter pulse and for switching it to the quiescent mode after the occurrence of said meter pulse,

and means responsive to said pulse for incrementing a pulse count register in the read/write memory.

5. 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, 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 said meter pulse and for switching it to the quiescent mode after the occurrence of said meter pulse,

a tamper detector coupled with an input of said multiplexer for applying a logic signal thereto in response to tampering with a circuit of said transponder,

means for switching the microprocessor from the quiescent mode to the active mode in response to said meter pulse,

a data signal generator coupled with the microprocessor,

said microprocessor having means for interrogating said multiplexer when in an active mode to increment a pulse count register in the read/write memory and to set a tamper flag in said read/write memory,

second coupling means for coupling said detecting means to said microprocessor, and

means for switching the microprocessor from the quiescent to the active mode in response to said control signal, said microprocessor being programmed to cause said data signal generator to transmit encoded data representing the pulse count and said tamper flag stored in the read/write memory in response to a command signal and for switching the microprocessor to the quiescent mode after the encoded data signal is transmitted.

6. The invention as claimed in claim 5 wherein:

said tamper detector has a tamper responsive circuit with a terminal for producing said logic signal in response to said tampering,

said multiplexer circuit and said reset circuit each having an input coupled with said terminal,

whereby said microprocessor is switched from the quiescent mode to the active mode in response to said logic signal from said tamper detector and is switched to the quiescent mode after the occurrence of said logic signal.