Analog signal processor
First Claim
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1. Apparatus for an analog signal processing system comprising:
- an analog input circuit having means for controllably selecting an incoming process signal or at least one reference voltage as an input voltage;
means for sampling said input voltage to obtain a sampled value and for producing a digital signal equivalent to said sampled value;
means for digitally filtering said sampled value to yield an actual filtered value of said process signal and a separate actual filtered value of said reference voltage;
means, responsive to said actual filtered reference voltage value and to an expected value of said filtered reference voltage, for calculating at least one coefficient appearing in a pre-defined model of said analog input circuitry to determine an error component injected by said analog input circuitry and existing in the filtered value of said reference voltage; and
means for compensating said actual filtered value of the process signal, in accordance with said model and using said calculated coefficient therein, to yield a calibrated value therefor.
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Abstract
Apparatus and a method for use therein are disclosed for an analog signal processor, particularly one suited for use in nuclear power plant applications, which converts analog process signals to digital form and employs continuous on-line automatic calibration in order to accurately compensate for gain and bias errors occurring in its input analog circuitry.
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Citations
27 Claims
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1. Apparatus for an analog signal processing system comprising:
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an analog input circuit having means for controllably selecting an incoming process signal or at least one reference voltage as an input voltage; means for sampling said input voltage to obtain a sampled value and for producing a digital signal equivalent to said sampled value; means for digitally filtering said sampled value to yield an actual filtered value of said process signal and a separate actual filtered value of said reference voltage; means, responsive to said actual filtered reference voltage value and to an expected value of said filtered reference voltage, for calculating at least one coefficient appearing in a pre-defined model of said analog input circuitry to determine an error component injected by said analog input circuitry and existing in the filtered value of said reference voltage; and means for compensating said actual filtered value of the process signal, in accordance with said model and using said calculated coefficient therein, to yield a calibrated value therefor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. Apparatus for an analog signal processing system comprising:
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an analog input circuit having means for controllably selecting an incoming process signal, a first reference voltage or a second reference voltage as an input voltage; means for sampling said input voltage to obtain a sampled value and for producing a digital signal equivalent to said sampled value; means for digitally filtering said sampled value to yield an actual filtered value of said process signal and a separate actual filtered value of each of said first and second reference voltages; means, responsive to said actual filtered values for said first and second reference voltages and to expected values therefor, for linearly estimating gain and bias values of said analog input circuit, wherein said gain value is estimated as the ratio of the difference between the actual filtered values for both of said reference voltages to the difference between the expected filtered values for both of said reference voltages, and said bias value is estimated as the actual filtered value of one of said reference voltages less that gain value times the expected filtered value for said one of the reference voltages; and means for compensating the actual filtered value of the process signal, in accordance with a pre-defined relationship using said calculated gain and bias values, to yield a calibrated value for said process signal. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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19. A method for use in an analog signal processing system comprising the steps of:
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controllably selecting an incoming process signal or at least one reference voltage to be applied as an input voltage to an analog input circuit; sampling said input voltage to obtain a sampled value and for producing a digital signal equivalent to said sampled value; digitally filtering said sampled value to yield an actual filtered value of said process signal and a separate actual filtered value of said reference voltage; calculating, in response to said actual filtered reference voltage value and to an expected value of said filtered reference voltage, at least one coefficient appearing in a pre-defined model of said analog input circuitry to determine an error component injected by said analog input circuitry and existing in the filtered value of said reference voltage; and compensating said actual filtered value of the process signal, in accordance with said model and using said calculated coefficient therein, to yield a calibrated value therefor. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27)
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Specification