Remote meter reading system using electric power lines

• US 3,914,757 A
• Filed: 03/06/1974
• Issued: 10/21/1975
• Est. Priority Date: 03/01/1972
• Status: Expired due to Term

• Current Assignee: Alexander Finlay Jr, Robert E. Dyer, William D. Kessler
• Original Assignee: Alexander Finlay Jr, Robert E. Dyer, William D. Kessler
• Inventors: Finlay, Alexander Jr., Dyer, Robert E., Kessler, William D.
• Primary Examiner(s): Habecker, Thomas B.
• Application Number:
  US05/448,703
• Time in Patent Office: 594 Days
• Field of Search: 340/27P,31R,31A 179/15A,15AL 325/308,320
• US Class Current: 340/870.02
• CPC Class Codes: H02J 13/00007 using the power network as support for the transmission
• 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 remote meter reading system in which transmitters provide data signals over electric power line conductors to indicate the measurements of each of a plurality of meters to associated receivers at a remote location. The meter transmitters are divided into groups, the transmitters of each group being operative to generate different frequency signals in a given frequency band assigned to such group. The transmitters of each group are further divided into subgroups, each subgroup of transmitters being connected to a correspondingly different pair of the power line conductors. A receiver unit is provided for each subgroup of transmitters, the receiver for a subgroup being tunable to the frequencies in the band assigned to the group, and being connected to the same pair of line conductors as the transmitters of its associated subgroup. Each transmitter provides signals at a preassigned frequency as determined by the group and subgroup to which the transmitter is assigned, the signals being of a first and second phase to represent the meter measurement by logic 1 and logic 0 signals. The signal input to each receiver is sampled for phase and converted to digital signals which are stored in discrete storage circuits for each of the transmitters.

Claims

1. In a system for use with the transmission lines of an alternating current, electric power distribution system, a plurality of meter transmitters, each of which is aSsociated with a discrete meter, and each of which is operative to transmit a correspondingly different carrier signal, said carrier signals at each transmitter being at times modulated by a first set of one half cycle pulses derived from a first phase of the power on said transmission lines and being modulated at other times by a second set of one half cycle pulses derived from a second phase of the power on said transmission lines, receiver means having a receiver circuit connected to said transmission lines, adjustable tuning means operable to selectively tune said receiver circuit to receive the different carrier frequency signals on said transmission line in a predetermined pattern, phase detector means for detecting the phase of the received signals, means connected to said phase detector means for providing digital output signals representative of said received signals, a plurality of storage means, each of which is connected to store the signals which represent the information received from a different transmitter, selector means for transmitting said output signals to the assigned storage means for storage purposes, and program means for selectively operating said tuning means in the adjustment of said receiver circuit to receive the carrier signal output of each of said transmitters in said predetermined pattern, and simultaneously operating said selector means to transmit said output signals to the one of the storage means which is preassigned to store the signal output for the transmitter which is transmitting the selected carrier frequency.

2. In a system as set forth in claim 1 in which said tuning means includes a first circuit including at least one inductance and one capacitor connected in parallel, a further capacitor for each one of said preassigned frequencies to be selected by said receiver, and means for selectively connecting an additional one of said capacitors in parallel with said one capacitor to thereby adjust the receiving circuit to receive correspondingly different ones of said preassigned frequencies.

3. In a system as set forth in claim 1 in which said receiver circuit includes a beat oscillator, and means controlled by said program means for adjusting the frequency output of said beat oscillator to different frequency values with each adjustment of said tuning means to receive a different frequency, the difference frequency values being selected so as to maintain a constant IF frequency output from said receiver circuit for all received frequencies.

4. In a system as set forth in claim 1 in which said phase detector means includes an input circuit connected to said transmission line to derive a phase reference signal for use in detecting the phase of the received signals.

5. In a system as set forth in claim 4 in which said means for providing digital output signals includes means for deriving an analog signal for each signal output from said phase detector means, and means for converting the analog output signals to digital signals.

6. A system as set forth in claim 1 in which said means for providing output signals representative of said receiver means includes a first output means for providing an output signal indicating the receipt of a signal of said first phase by said phase detector means and a second output means for indicating the receipt of a signal of a second phase, envelope filter means connected to said first and second outputs to provide analog signals indicating the receipt of signals of said first and second phases, differential amplifier means connected to the output of said envelope filter means for providing signals of different values in response to receipt of the signals of said first and second phase, and analog to digital converter means for converting each of the signals to digital signals for storage purposes.

7. A system as set forth in claim 1 in which a separate input channel is provided for each storage means, each of which channels includes means for selectively providing a logic 1 or a logic 0 output in response to the receipt of said output signals from said selector means.

8. In an automatic meter reading system for use with the transmission lines of an AC electric power distribution system, a meter transmitter circuit for each meter device which includes signal generator means for generating signals which represent the measurements made by the associated meter device including encoder means continually operated by said meter device to provide a first output signal of a first phase as reference to the AC power on said transmission lines to represent the period of measurement of a first quantum of energy measured by said meter device and to provide an output signal of a second phase as reference to the power on said transmission line to represent the period of measurement of a second quantum of energy by said meter device, said encoder means being operative to shift its signal output with each measurement of a different quantum by said meter device, oscillator means including an input circuit connected to the output of said encoder means operable in response to said first output signal to provide signals at a predetermined carrier frequency during only one half cycle of the power on said transmission lines to represent said first quantum of measured energy, and operative in response to said second output signal to provide said signals of said predetermined carrier frequency only during the other half cycle of the power on said transmission lines, said oscillator means for different meter transmitter circuits being operative to generate a correspondingly different carrier frequency, and output means including a series resonant circuit for modulating the power on said transmission lines with the phase-oriented frequency signals output from said oscillator means to provide a coded indication of the different measurements by said meter device, and receiver means connected to said transmission lines for receiving the carrier frequency signals as modulated by the one half cycle, phase oriented pulses which are derived from the power on said transmission line.

9. A system as set forth in claim 8 in which said output means includes amplifier means coupled to the output of said oscillator means, a further tank circuit connected in the output of said amplifier means including a parallel-connected capacitor, resistor and inductance tuned to the same frequency as the tank circuit for said oscillator circuit, and means connecting the output of said amplifier to said series resonant circuit.

10. A system as set forth in claim 8 which includes at least one receiver tuned to receive the predetermined frequency output of said one transmitter circuit, phase detector means operable to detect the phase of the received signals including first means for providing a first output signal in response to detection of a signal of said first phase, and second means for providing a second output signal in response to detection of a signal of said second phase, envelope filter means connected to said first and second means respectively, means connected to said envelope filter means for providing a first output in response to the signal output by said envelope filter means in response to detection of a signal of a first phase, and a second output in response to the signal output by said envelope filter means in response to detection of a signal of a second phase, and means for converting said signals to digital signals.