Reduced cost automatic meter reading system and method using locally communicating utility meters
First Claim
Patent Images
1. An LCD driver having an inverter signal line, at least one bit line, and an LCD driver line, said LCD driver comprising:
- at least one exclusive OR gate coupled to said inverter line and coupled to said at least one bit line, wherein said exclusive OR gate is adapted to generate a voltage signal in correspondence with the logical status of said inverter line and said at least one bit line;
a respective voltage level capacitor coupled to said at least one exclusive OR gate, wherein said respective voltage level capacitor has a capacitance value that is proportional to the numerical significance of said at least one bit line coupled to said at least one exclusive OR gate, and wherein said respective voltage level capacitor is adapted to generate a voltage level proportional to the respective capacitance value and the voltage signal generated by said at least one exclusive OR gate; and
a summing amplifier coupled to each respective voltage level capacitor, wherein said summing amplifier is adapted to sum the voltage level across each respective voltage level capacitor so as to generate a plurality of LCD driving voltage levels.
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Abstract
A low cost and easy to assemble communicating utility meter provides selectable measurement, calibration, display, and communications means so as to be re-configurable based on several factors including; harmonic content of the power signal measured, LCD display alternatives, time of use measurements, bandpass filter settings, power quality measurements, PLC communications alternatives, radio frequency communications alternatives, optical communications alternatives, and hard wire communications alternatives.
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Citations
42 Claims
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1. An LCD driver having an inverter signal line, at least one bit line, and an LCD driver line, said LCD driver comprising:
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at least one exclusive OR gate coupled to said inverter line and coupled to said at least one bit line, wherein said exclusive OR gate is adapted to generate a voltage signal in correspondence with the logical status of said inverter line and said at least one bit line;
a respective voltage level capacitor coupled to said at least one exclusive OR gate, wherein said respective voltage level capacitor has a capacitance value that is proportional to the numerical significance of said at least one bit line coupled to said at least one exclusive OR gate, and wherein said respective voltage level capacitor is adapted to generate a voltage level proportional to the respective capacitance value and the voltage signal generated by said at least one exclusive OR gate; and
a summing amplifier coupled to each respective voltage level capacitor, wherein said summing amplifier is adapted to sum the voltage level across each respective voltage level capacitor so as to generate a plurality of LCD driving voltage levels. - View Dependent Claims (2)
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3. A method of responding to a reduction in power supply voltage in a communicating utility meter having non-volatile memory, said power supply having three voltage thresholds, said method comprising the steps of:
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first removing power from non-critical functions when the power supply voltage is less than said first threshold;
second, saving critical values in non-volatile memory when the power supply voltage is less than said first threshold and less than said second threshold;
third, taking no action when the power supply voltage is greater than said second threshold and less than said third threshold;
fourth, restarting said communicating utility meter when the power supply voltage is greater than said third threshold. - View Dependent Claims (4, 5, 6, 7)
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8. A method of responding to a reduction in power supply voltage in a communicating utility meter having non-volatile memory, said power supply having a voltage threshold, said method comprising the steps of:
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removing power from non-critical functions when the power supply voltage is less than said voltage threshold for a time duration of one voltage cycle; and
saving critical functions in non-volatile memory when the power supply voltage has been below said voltage threshold for four voltage cycles.
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9. A re-configurable utility meter, having a current signal and having a voltage signal, said utility meter comprising:
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a current sensor;
a voltage sensor;
a DSP coupled to said current sensor and coupled to said voltage sensor, said DSP comprising;
a high pass filter, wherein said high pass filter is adapted to eliminate the DC component and noise from the current sensor signal;
a phase corrector coupled to said high pass filter, wherein said phase corrector is adapted to correct phase error in the current sensor signal;
a gain corrector coupled to said phase corrector, wherein said gain corrector is adapted to correct for gain error in the current sensor signal; and
a power measurement block coupled to said DSP and coupled to said power signal, wherein said power measurement block is adapted to be re-configurable so as to compute real power, reactive power, or apparent power. - View Dependent Claims (11, 12, 13, 14, 24, 25)
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10. A re-configurable utility meter, having a voltage signal and having a current signal, said utility meter comprising:
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a current sensor;
a voltage sensor;
a DSP coupled to said current sensor and coupled to said voltage sensor, said DSP comprising;
a high pass filter, wherein said high pass filter is adapted to eliminate the DC component and noise from the voltage sensor signal;
a phase corrector coupled to said high pass filter, wherein said phase corrector is adapted to correct phase error in the voltage sensor signal;
a gain corrector coupled to said phase corrector, wherein said gain corrector is adapted to correct for gain error in the voltage sensor signal; and
a power measurement block coupled to said DSP and coupled to said power signal, wherein said power measurement block is adapted to be re-configurable so as to compute real power, reactive power, or apparent power. - View Dependent Claims (15, 16, 17, 18)
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19. A re-configurable utility meter, having a current signal and having a voltage signal, said utility meter comprising:
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a current sensor;
a voltage sensor;
a DSP coupled to said current sensor and coupled to said voltage sensor, said DSP comprising;
a current high pass filter, wherein said high pass filter is adapted to eliminate the DC component and noise from the current sensor signal;
a current phase corrector coupled to said current high pass filter, wherein said phase corrector is adapted to correct phase error in the current sensor signal;
a current gain corrector coupled to said current phase corrector, wherein said current gain corrector is adapted to correct for gain error in the current sensor signal;
a voltage high pass filter, wherein said voltage high pass filter is adapted to eliminate the DC component and noise from the voltage sensor signal;
a voltage phase corrector coupled to said voltage high pass filter, wherein said voltage phase corrector is adapted to correct phase error in the voltage sensor signal;
a voltage gain corrector coupled to said voltage phase corrector, wherein said voltage gain corrector is adapted to correct for gain error in the voltage sensor signal; and
a power measurement block coupled to said DSP and coupled to said power signal, wherein said power measurement block is adapted to be re-configurable so as to compute real power, reactive power, or apparent power. - View Dependent Claims (20, 21, 22, 23, 26, 27)
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28. A circuit for filtering a current sensor signal comprising a second order infinite impulse response (IIR) filter, said IIR filter having a z domain response defined by:
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wherein c is a normalization constant, and wherein k is approximately equal to 1, and wherein {circumflex over (k)} is approximately equal to k. - View Dependent Claims (29)
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30. A method of selecting IIR filter constants k and {circumflex over (k)} within a circuit for filtering a current sensor signal, said method comprising the steps of:
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selecting a first zero at z=1;
selecting a second zero at z=−
1; and
selecting a pair of poles at the roots of equation z2−
2k+{circumflex over (k)}2 sufficiently close to said first zero such that said pair of poles and said first zero appear as a single pole at z=1 for frequencies within a selected pass band. - View Dependent Claims (31, 32)
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33. A method of calculating calibration constants used to calibrate a utility meter, said method comprising the steps of:
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connecting the voltage signal of a precision voltage supply to the utility meter;
connecting the current signal of a precision current supply to the utility meter;
collecting a plurality of un-calibrated voltage samples and un-calibrated current samples generated by said precision voltage supply and said precision current supply;
performing a Fourier Transform of the voltage samples and a Fourier Transform of the current samples, wherein the amplitude and phase of the respective voltage and current signals is generated; and
calculating calibration constants based on the amplitude and phase of the respective voltage and current signals.
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34. A utility meter having pre-selectable communication protocols selectable by the use of “
- soft-keys”
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a CPU; and
a communication hardware module coupled to said CPU and coupled to an external device, wherein said communications hardware module is adapted to be reconfigured via software to communicate using a standard radio frequency protocol, and alternatively to communicate using a standard serial wire-line protocol, and alternatively to communicate using a standard optical protocol, and alternatively to communicate using a power line carrier protocol. - View Dependent Claims (35, 36)
- soft-keys”
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37. A set of utility meter hardware having a base, at least one current sensor, and at least one printed wiring board (PWB), for improved assembly of a utility meter, said utility meter hardware comprising:
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a sensor shield adapted to house said current sensor;
said base having a locating pin, wherein said pin is adapted to align said sensor shield to said base so as to provide registration to couple said sensor shield to said base;
at least one snap connector respectively coupled to said at least one PWB, wherein said at least one snap connector is adapted to provide a repeatable electrical connection between said at least one PWB and said at least one current sensor; and
wherein said sensor shield and said base and said at least one PWB is adapted to snap together to form a utility meter housing. - View Dependent Claims (38, 39, 40, 41, 42)
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Specification