NOISE ELIMINATOR FOR GRAVIMETRY AND NOISE ELIMINATION METHOD FOR GRAVIMETRY

摘要

PROBLEM TO BE SOLVED: To damp a constant-period oscillating noise whose frequency changes with high precision, by causing filter characteristics to follow and change with respect to the frequency variation of the constant-period oscillating noise.;SOLUTION: A noise eliminator 1 is provided with an amplifier 10 which amplifies a measured signal ms outputted from a weighting apparatus 3, an analog filter 11, an ADC 12, a digital filter 14, a coefficient control unit 13, and a data input unit 15. The digital filter 14 is a notch filter which damps the frequency components of a weighed signal D_(n) outputted from the ADC 12 by a plurality of notches (blocking regions). The transfer function of this digital filter 14 is represented by the product of a plurality of factors having roots which correspond to the notches. The control unit 13 changes the frequency component of a root corresponding to a notch designated from among the notches, develops the transfer function of the re-formed digital filter 14 into a polynomial after that, and computes a new series of filter coefficients on the basis of the polynomial.;COPYRIGHT: (C)2004,JPO