Digital filtering method, digital filtering equipment, digital filtering program, and recording medium and recorded device which are readable on computer

Digital filtering equipment for extracting a feature quantity based on an inputted signal waveform, the equipment comprising:

• an amplitude determining section for obtaining an amplitude of an inputted signal waveform and quantizing said amplitude;
• a division value operating section for summing an amplitude value in a data in a prescribed adjoining region to divide the amplitude value by the number of summed data, with respect to a data quantized at each point by said amplitude determining section, so that a division value is obtained with said data being centered;
• a subtraction means for obtaining a difference by subtraction between the division value calculated by said division value operating section and the amplitude value calculated by said amplitude operating section, with respect to each data;
• a storage device for retaining at least one of a summation value, a subtraction value and a division value;
• and
• a filter for effecting a low-pass filtering based on said division value obtained by said division value operating section, while effecting a high-pass filtering based on said subtraction value obtained by said subtraction means,
• wherein the number of data to be summed in the prescribed region by the division value operating section is a power of two.

A digital filtering program stored on a non-transitory recording medium or recorded device that is readable by a computer, said digital filtering program being for extracting a feature quantity based on an inputted signal waveform, wherein the computer is enabled by said digital filtering program to carry out:

• a function of inputting a signal waveform and quantizing the signal waveform;
• a function of summing the quantized signal data in a prescribed adjoining region to divide the summation value by the number of data in the prescribed region, so that a division value is obtained with said data being centered, with respect to the quantized data at each point;
• a function of calculating a difference between the quantized signal data and the corresponding division value;
• a function of retaining at least one of the calculated summation value, subtraction value and division value in a storage device as well as subjecting an inputted signal waveform to a digital filtering based on at least one value of the summation value, subtraction value and division value, and
• a function of effecting a low-pass filtering based on said division value, while effecting a high-pass filtering based on said subtraction value
• wherein the number of data to be summed in the prescribed region is a power of two.