Digital filter device, digital filtering method and control program for the digital filter device

A digital filtering method, comprising:

• setting a filter coefficient of a first distortion compensation filter unit based on an amount of compensation for an inputted signal;
• compensating distortion of first waveform distortion included in the inputted signal;
• setting a filter coefficient of a second distortion compensation filter unit based on the filter coefficient of the first distortion compensation filter unit, the filter coefficient of the second distortion compensation filter unit being set independently from an amount of waveform distortion of the inputted signal;
• and
• compensating second waveform distortion included in a signal outputted from the first distortion compensation filter unit.

A non-transitory computer-readable recording medium storing a control program configured to enable a processor of a digital filter device to implement:

• a first distortion compensation filter unit configured to conduct distortion compensation of first waveform distortion, included in an inputted signal, through digital signal processing;
• a first filter coefficient setting unit configured to set a filter coefficient of the first distortion compensation filter unit based on an amount of compensation for the inputted signal;
• a second distortion compensation filter unit configured to compensate second waveform distortion included in a signal outputted from the first distortion compensation filter unit;
• and
• a second filter coefficient setting unit configured to set a filter coefficient of the second distortion compensation filter unit based on the filter coefficient set by the first filter coefficient setting unit, the filter coefficient of the second distortion compensation filter unit being set independently from an amount of waveform distortion of the inputted signal.