| 摘要 |
PURPOSE:To provide a digital filter which is seasoned with the tone distortion peculiar to analog filter and usable as tone color adjusting filter giving a rich sound quality by means of the connection of a nonlinear conversion means applying desired nonlinear conversion to an input or output signal. CONSTITUTION:A ROM 3y storing a table of a nonlinear function is interposed between an adder 3a and a one-sampling period delay circuit 3b being components of the digital filter. Then the output (x) of the adder 3a is supplied as an address, a value (y) corresponding thereto is read from the ROM 3y and supplied to a delay circuit 3b, the output (x) of the adder 3a is subject to nonlinear conversion is fed back and accumulated to the adder 3a via the circuit 3b. As a result, when a transmission quantity frequency characteristic as a primary low pass filter is disturbed, an output signal comprising a signal and many harmonic components resulting from band-limiting an input signal with the transmission quantity frequency characteristic is outputted from the adder 3a, a tone color processing means having the distortion obtained from an analog filter is realized and rich sound quality is obtained in the case of using the filter as a tone color adjustment filter. |
