Weight measurement apparatus, method of eliminating noise and method of designing digital filter

摘要

A filtering technique which makes it possible to easily and appropriately eliminate a noise without increasing a scale of a circuit necessary for a filtering process even if a noise frequency is liable to be changed is provided. A filter coefficient calculator (6) of a weight measurement apparatus calculates filter coefficients using a predetermined arithmetic expression and outputs them to a signal processor (5). The signal processor (5) carries out a filtering process on a weighing signal (Ds) using the filter coefficients. The arithmetic expression includes a parameter specifying a band position of an attenuation band where attenuation must be locally enhanced. A user can input a value of the parameter via a data entry part (7). In this manner, the filter coefficients can be changed by using a parameter specifying the band position of the attenuation band which is physical and thus easy to grasp. Accordingly, it is possible to easily move the attenuation band, and thus noise can be eliminated easily and appropriately.