Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – Self-calibration
Patent
1987-05-19
1989-08-22
Eisenzopf, Reinhard J.
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
Self-calibration
324 74, 324 73AT, 324 73R, G01R 3500, G01R 102
Patent
active
048599360
ABSTRACT:
Calibrating errors of a variable gain amplifier used in an AC calibrator or a meter for measuring AC is determined for a gamut of frequencies. The gain of the variable gain amplifier is varied by adjusting the value of a variable resistor in discrete steps. A variable amplitude signal is applied to the amplifier while the resistor is adjusted in discrete steps so the amplifier derives a gamut of variable amplitude signals that are supposed to have predetermined values. The amplitudes of the gamut of variable amplitude signals derived by the amplifier are detected and compared with the values that the signals are supposed to have to derive a calibrating error signal of the amplifier for each variable resistor value. A gamut of variable frequency, constant amplitude signals is applied to the amplifier while the amplifier gain is constant. The amplifier has a tendency to derive an AC output signal having a different amplitude in response to different ones of the frequencies. The amplitude of the amplifier output for each frequency in the gamut of frequencies applied to the amplifier is detected and compared with the output signal of the amplifier while each frequency in the gamut of frequencies is applied to the amplifier with the amplitude of the amplifier output for one frequency in the gamut to derive an amplitude versus frequency response indication of the amplifier. The amplitude versus frequency response indication is modified by the derived calibrating error signal. The calibrated amplifier is used in a voltmeter or AC calibrator to that the amplifier output is modified as a function of input frequency and gain setting.
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Becker Stephen
Eisenzopf Reinhard J.
Ishimaru Mikio
John Fluke Mfg. Co. Inc.
Nguyen Vinh P.
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