digitalfilter for an electronic musical instrument

摘要

An elementary digital filter comprising an arithmetic logic unit with associated registers and timing circuits, simulates a current and a voltage in a corresponding elementary analog filter. The frequency response character of this elementary digital filter is changed when a coefficient used in the simulation or the sampling period used as the data renovation cycle of the simulation is changed. A digital filter circuit is composed of such an elementary digital filter or a combination of such elementary digital filters. A time function is passed through this composed digital filter circuit, and the output of the digital filter circuit is converted to an analog voltage to produce a musical tone. The tone quality of the produced musical tone is determined by the original waveform of the time function and the frequency response character of the composed digital filter circuit.