METER INTERROGATION SYSTEM HAVING STROBE LOGIC CONTROL

• US 3,733,586 A
• Filed: 03/14/1972
• Issued: 05/15/1973
• Est. Priority Date: 03/14/1972
• Status: Expired due to Term

• Current Assignee: Herbert L. Feldman, Joe F. Lusk, William H. Rood
• Original Assignee: Herbert L. Feldman, Joe F. Lusk, William H. Rood
• Inventors: Lusk, Joe F., Rood, William H., Feldman, Herbert L.
• Primary Examiner(s): Pitts, Harold I.
• Application Number:
  US05/234,670
• Time in Patent Office: 427 Days
• Field of Search: 340/151R,31R
• US Class Current: 340/870.03
• CPC Class Codes: H02J 13/00007 using the power network as support for the transmission
• CPC Class Codes: H02J 13/00028 involving the use of Internet protocols
• CPC Class Codes: H02J 13/00034 the elements or equipment being or involving an electric power substation
• CPC Class Codes: H04Q 9/14 Calling by using pulses
• CPC Class Codes: Y02E 60/00 Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• CPC Class Codes: Y04S 40/121 using the power network as support for the transmission

Abstract

A system adapted for connection to a polyphase power distribution network to interrogate a plurality of separate watt meters and store respective readings from the watt meters. The system comprises a central control unit coupled to the power distribution network for storing a plurality of separate meter identification codes each including a group of binary coded bits and means for serially sending the bits including means for modulating a signal on said power distribution network of fixed time duration and indicative of the binary state of each bit of said group. A plurality of meter transponder units are each coupled respectively to the plurality of watt meters for demodulating the signal impressed on the power distribution network and identifying the transmitted group of binary codes bits as its own predetermined identity code. In one embodiment of the invention, the transmitted identity code is sequentially stored in a register and a variable strobe logic unit is provided for entering each received bit into this register at a time dependent upon the maximum delay of a particular power distribution network. The strobe logic includes means for determining the time difference between the receipt of the beginning of the bit over the shortest path, and the termination of the same transmitted bit over the maximum path. In a preferred embodiment, the strobe logic also includes means for strobing the bit of data at about the middle of the determined time difference, and means for preventing the subsequent bit from being strobed until after the determined time difference has elapsed, thus preventing an erroneous bit sensing due to system delay variations. Similar strobe logic can also be provided to compensate for system delay variations when transmitting the binary coded reading from the identified transponder unit to the central control unit.

Claims

1. A system adapted for connection to a communications link to interrogate a plurality of separate meters and store respective readings therefrom, comprising:

a central control unit coupled to the communications link; and

a plurality of transponder units each coupled to a meter and the communications link;

said central control unit comprising;

means for storing a plurality of meter identification codes, each of said codes comprising a plurality of bits, and means for sequentially sending said meter identification codes to said plurality of transponder units including means for impressing a signal of predetermined duration on said communications link indicative of the state of each of said bits of said identification code, each of said transponder units comprising;

means for storing each bit of a transmitted identification code, means for identifying its own predetermined identification code, means for registering the reading of said meter, and means for transmitting a meter reading code to said central control unit, said means for storing each bit of a transmitted identification code comprising demodulating means coupled from the communications link, an identification code store and strobe logic means having an output coupled to the identification code store, said strobe logic means being responsive to the duration of each received bit of the identification code for generating an output pulse which enters each bit into the identification code store, said strobe logic means including means for varying the time of occurrence of the output pulse from the strobe logic means depending upon the duration of the received bit signal which duration is in turn a function of the maximum delay path of the communications link.

2. A system as set forth in claim 1 wherein said communication link includes a multipath power distribution network.

3. A system as set forth in claim 1 wherein said central control unit comprises means for storing a meter reading code transmitted from each of said transponder units, comprising a meter reading store and second strobe logic means for entering each bit of said reading code into said meter reading store, said second strobe logic means including means for varying the time of occurrence of the output from said second strobe logic means depending upon the duration of the bit signal received from the transponder unit.

4. A system as set forth in claim 1 wherein said strobe logic means includes means for determining the time difference between the receipt of the beginning of each bit over the shortest path of the communication link and the termination of the same transmitted bit over the maximum path.

5. A system as set forth in claim 4 wherein said strobe logic means includes means for storing an indication of about the middle of the determined time difference and for strobing the next bit at that stored indication time.

6. A system as set forth in claim 5 wherein said strobe logic means includes means for preventing the next bit from being strobed until after the determined time difference.

7. A system adapted for connection to a communications link to interrogate a plurality of separate meters and store respective readings therefrom comprising:

a central control unit coupled to the communications link, and a plurality of transponder units each coupled to a meter and the communications link, said central control unit comprising, means for storing a plurality of meter identification codes, each of said codes comprising a plurality of bits, and means for sequentially sending said meter identification codes to said plurality of transponder units including means for impressing a signal of predetermined duration on said communications link indicative of the state of each of said bits of said identification code, each of said transponder uNits comprising, means for storing each bit of a transmitted identification code, means for identifying its own predetermined identification code, means for registering the reading of said meter, and means for transmitting a meter reading code to said central control unit, wherein said central control unit further comprises means for storing a meter reading code transmitted from each of said transponder units, said means for storing a meter reading code comprising demodulating means coupled from the communications link, a meter code store and strobe logic means having an output coupled to the meter code store, said strobe logic means being responsive to the duration of each received bit of the meter reading code for generating an output pulse which enters each bit into the meter code store, said strobe logic means including means for varying the time of occurrence of the output pulse from the strobe logic means depending upon the duration of the received bit signal which duration is in turn a function of the maximum delay path of the communications link.

8. In a power distribution network having a multiplicity of transmission line paths coupled to a plurality of meters and a central control unit adapted to store and send meter identification codes, a plurality of transponder units each comprising:

means for storing and identifying its own predetermined identification code, means for registering the reading of one of said meters, means for transmitting a meter reading code to said central control unit, said means for storing and identifying its own predetermined identification code comprising an identification code store and strobe means having an output coupled to the identification code store, said strobe means being responsive to the duration of each received bit of the identification code for generating an output pulse which enters each bit into the identification code store, said strobe means including means for time varying the output pulse from the strobe means depending upon the duration of the received bit signal, and means coupled from said means for storing to said means for transmitting responsive to the duration of each bit received from the central control unit for varying the rate at which the bits of the meter reading code are transmitted.

9. A system as set forth in claim 4 wherein said means for determining the time difference includes a monostable multivibrator.

10. A system as set forth in claim 1 wherein said means for varying the time of occurrence of the output pulse includes a comparator having an output coupled to the strobe logic output, a differentiator at the input of said strobe logic means, a counter having an input coupled from the differentiator and having a plurality of outputs coupled to a first set of inputs of the comparator, a register having a plurality of outputs coupled to a second set of inputs of the comparator and a plurality of inputs coupled from the counter, and a monostable multivibrator for determining the time difference between the receipt of the beginning of each bit over the shortest path of the communications link and the termination of the said bit over the maximum path, said multivibrator having an output coupled to said counter for resetting the counter after the termination of the bit over the maximum path and an output coupled to the register for causing a transfer of a part of the count in the counter to the register prior to resetting of the register.

11. A system as set forth in claim 10 including an initial condition circuit coupled to the register for initially setting a preselected count into the register.

12. A system as set forth in claim 10 including delay means coupled between the multivibrator and the counter for delaying the resetting of the counter until after the part of the count therein has been transferred to the register.

13. A system as set forth in claim 10 wherein one-half the count is transferred from the counter to the register.

14. A system as set forth in claim 1 wherein said demodulating means includes a filter means, squaring circuit and frequency to binary converter.

15. A system as set forth in claim 3 including means located in said central control unit coupled from said means for storing a meter reading code to said means for sequentially sending said meter identification codes responsive to the duration of each bit received from the transponder unit for varying the rate at which the bits of the meter identification code are transmitted.

16. A system as set forth in claim 15 wherein said central control unit includes demodulating means.

17. A system as set forth in claim 16 wherein said means for sequentially sending said meter identification codes includes a parallel to serial register, and said means for storing a plurality of meter identification codes includes a storage memory and means for transferring data into and out of said storage memory.

18. A system as set forth in claim 17 wherein said means for varying the rate at which the bits of the meter identification code is transmitted includes a charging circuit coupled from the demodulating means of the central control unit, a voltage controlled oscillator coupled from the charging circuit, and a shift register having an input coupled from the voltage controlled oscillator and a plurality of outputs coupled to the parallel to serial register for controlling the serial transmission of data bits from the parallel to serial register.

19. A system as set forth in claim 18 wherein the parallel to serial register includes a plurality of AND gates and an OR gate.

20. A system as set forth in claim 1 wherein said central control unit comprises a computer, and control means for transferring identification codes from said computer to said means for storing a plurality of meter identification codes during a first time interval and for transferring meter reading codes to said computer during a second time interval.

21. A system as set forth in claim 1 wherein said transponder unit comprises means coupled from said means for storing each bit of a transmitted identification code to said means for transmitting a meter reading code responsive to the duration of each bit received from the central control unit for varying the rate at which the bits of the meter reading code are transmitted.

22. A system as set forth in claim 7 wherein said transponder unit comprises an identification code store and strobe logic means for entering each bit of the identification code into said identification code store, said strobe logic means of said transponder unit including means for varying the time of occurrence of the output from the said strobe logic means of said transponder depending upon the duration of the bit signal received from the central control unit.

23. A system as set forth in claim 7 wherein said strobe logic means includes means for determining the time difference between the receipt of the beginning of each bit over the shortest path of the communication link and the termination of the same transmitted bit over the maximum path.

24. A system as set forth in claim 23 wherein said strobe logic means includes means for storing an indication of about the middle of the determined time difference and for strobing the subsequent bit at that stored indication time.

25. A system as set forth in claim 7 wherein said central control unit includes means coupled from said means for storing a meter reading code to said means for sequentially sending said meter identification code responsive to the duration of each bit received from the transponder unit for varying the rate at which the bits of the meter identification code are transmitted.

26. In a power distribution network having a multiplicity of transmission line paths coupled to a plurality of meters and a plurality of transponder units adapted to store and send meter reading codes, a central control unit comprising;

means for storing a pluralIty of meter identification codes each said code comprising a plurality of bits, means for sequentially sending said meter identification codes to said plurality of transponder units, means for storing a meter reading code from a responding transponder unit, said means for storing a meter reading code comprising a meter code store and strobe means having an output coupled to the meter code store, said strobe means being responsive to the duration of each received bit of the meter reading code for generating an output pulse which enters each bit into the meter code store, said strobe means including means for time varying the output pulse from the strobe means depending upon the duration of the received bit signal, and means coupled from said means for storing to said means for sequentially sending responsive to the duration of each bit received from the transponder unit for varying the rate at which the bits of the meter identification code are transmitted.

27. Apparatus for automatically reading, from a remote location, a plurality of utility meters respectively metering the consumption of a utility by a plurality of users, each meter being connected to said remote location by a plurality of paths of an electrical power distribution network, comprising means for determining the maximum delay of information signals transmitted over said network between said remote location and said meters and for generating a control signal which is a function of said maximum delay and means responsive to said control signal for decreasing the rate of transmission of said information signals as said maximum delay increases and for increasing the rate of transmission of said signals as said maximum delay decreases.

28. A method of automatically reading, from a remote location, a plurality of utility meters respectively metering the consumption of a utility by a plurality of users, each meter being connected to said remote location by a plurality of paths of an electrical power distribution network, comprising the steps of determining the maximum delay of information signals transmitted over said network between said remote location and said meter, generating a control signal which is a function of said maximum delay, and, in response to said control signal, decreasing the rate of transmission of said information signals as said maximum delay increases and increasing the rate of transmission of said signals as said maximum delay decreases.