Method and apparatus for calibrating transducer/amplifier systems
First Claim
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1. A method for calibrating a measuring system comprising the steps of:
- (a) storing a plurality of correction tables with respect to a range of frequencies in the frequency domain each table having a plurality of values for a given parameter;
(b) sensing a time domain signal;
(c) transforming the time domain signal into a plurality of uncalibrated frequency domain signals;
(d) comparing each of the uncalibrated frequency domain signals to an appropriate value for a corresponding one of the plurality of corrections tables for forming a plurality of calibration signals;
(e) operating on each of the uncalibrated frequency domain signals with an appropriate calibration signal to form a plurality of calibrated frequency domain signals; and
(f) converting the plurality of calibrated frequency domain signals into a calibrated time domain signal.
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Abstract
The present invention improves the accuracy of waveshape measurements and transducers. Specifically, it is a method and apparatus which calibrates a system, which comprises transducers, amplifiers, filters and analog-to-digital converters, by digitally removing phase and amplitude errors over a frequency spectrum.
92 Citations
14 Claims
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1. A method for calibrating a measuring system comprising the steps of:
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(a) storing a plurality of correction tables with respect to a range of frequencies in the frequency domain each table having a plurality of values for a given parameter; (b) sensing a time domain signal; (c) transforming the time domain signal into a plurality of uncalibrated frequency domain signals; (d) comparing each of the uncalibrated frequency domain signals to an appropriate value for a corresponding one of the plurality of corrections tables for forming a plurality of calibration signals; (e) operating on each of the uncalibrated frequency domain signals with an appropriate calibration signal to form a plurality of calibrated frequency domain signals; and (f) converting the plurality of calibrated frequency domain signals into a calibrated time domain signal. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for calibrating a measuring system comprising the steps of:
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(a) storing a plurality of amplitude correction tables with respect to a range of frequencies in the frequency domain for a plurality of frequencies; (b) storing a plurality of phase correction tables with respect to a range of frequencies in the frequency domain for a plurality of frequencies; (c) measuring a physical value; (d) forming a measured signal from said physical value; (e) converting said measured signal to form an uncalibrated digital signal; (f) performing a Fourier transform on said uncalibrated digital signal to form a plurality of uncalibrated frequency domain signals; (g) comparing each of said frequency domain signals to an appropriate one of said plurality of amplitude correction tables and to one of said plurality of phase correction tables to form a plurality of calibrated frequency domain signals; (h) performing a reverse Fourier transform to said calibrated frequency domain signals to form a calibrated digital signal.
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8. An apparatus for calibrating a measuring system comprising:
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(a) means for storing a plurality of correction tables with respect to a range of frequencies in the frequency domain each table having a plurality of values for a given parameter; (b) means for sensing a time domain signal; (c) means for transforming the time domain signal into a plurality of uncalibrated frequency domain signals; (d) means for comparing each of the uncalibrated frequency domain signals to an appropriate value for a corresponding one of the plurality of correction tables for forming a plurality of calibration signals; (e) means for operating on each of the uncalibrated frequency domain signals with an appropriate calibration signal to form a plurality of calibrated frequency domain signals; and (f) means for converting the plurality of calibrated frequency domain signals into a calibrated time domain signal. - View Dependent Claims (9, 10, 11, 12, 13)
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14. An apparatus for calibrating a measuring system comprising:
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(a) means for storing a plurality of amplitude correction tables with respect to a range of frequencies in the frequency domain for a plurality of frequencies; (b) means for storing a plurality of phase correction tables with respect to a range of frequencies in the frequency domain for a plurality of frequencies; (c) means for measuring a physical value; (d) means for forming a measured signal from said physical value; (e) means for converting said measured signal to form an uncalibrated digital signal; (f) means for performing a Fourier transform on said uncalibrated digital signal to form a plurality of uncalibrated frequency domain signals; (g) means for comparing each of said frequency domain signals to an appropriate one of said plurality of amplitude to frequency correction tables and to one of said plurality of phase to frequency correction tables to form a plurality of calibrated frequency domain signals; (h) means for performing a reverse Fourier transform to said calibrated frequency domain signals to form a calibrated digital signal.
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Specification