Noise canceling apparatus for weight measurement, and noise canceling method for weight measurement

Abstract

A noise canceling apparatus () comprises an amplifier () for amplifying a measured signal (ms) outputted from a measuring device (), an analog filter (), an ADC (), a digital filter (), a coefficient control section (), and a data input section (). The digital filter () is a notch filter for attenuating a frequency component of a quantitative signal D(n) outputted from the ADC () at a plurality of notches (stop bands). A transfer function of the digital filter () is expressed by the product of a plurality of factors each having a root that corresponds to each one of the plurality of notches. The coefficient control section () changes a frequency component of a root corresponding to a notch selected from the plurality of notches, and thereafter, expands in a polynomial the transfer function of the reconstructed digital filter (). On the basis of the polynomial thereby obtained, a new series of filter coefficients is calculated. A filter characteristic is controlled in such a manner that it conforms to a frequency variation of a fixed-period vibration noise, whereby the fixed-period vibration noise that varies in frequency is attenuated with a high degree of precision.