Noise cancelling apparatus and method for weight measurement

摘要

A noise canceling apparatus (1) comprises an amplifier (10), an analog filter (11), an ADC (12), a digital filter (14), a coefficient control section (13), and a data input section (15). The digital filter (14) is a notch filter for attenuating a frequency component of a quantitative signal D(n) outputted from the ADC (12) at a plurality of notches. A transfer function of the digital filter (14) 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 (13) 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 (14). On the basis of the polynomial thereby obtained, a new series of filter coefficients is calculated. <IMAGE>