Design Method of Effective Passband Flat Variable FIR Filters for Weight Measurement

In order to efficiently eliminate noise in the mass measurement of objects, design methods of FIR filters with high attenuation in a part of the stopband and variable characteristics in the stopband have been proposed. Recently, we have proposed a design method for variable FIR filters with a flat amplitude in the passband and equiripple in the stopband, where the magnitude of the high attenuation can be specified in dB to improve measurement accuracy. In this paper, we present a design method for a variable linear phase-variable FIR filter with a specified attenuation in a part of the stopband. The proposed design method produces a variable filter whose magnitude is greater than or equal to the specified attenuation even if the position of the specified attenuation changes. Finally, we confirm the effectiveness of the proposed method by actually designing a variable filter using the method.