
A signal-processing apparatus has a digital filter for processing input data from a knock-sensor. The digital filter is designed as an FIR filter characterized by filter coefficients that are equal to values of mince points 0 to 16 obtained based on a reference waveform. The reference waveform is created by concatenating half waves of a first sinusoidal waveform with half waves of a second sinusoidal waveform with peak values equal to half the peak value of the first sinusoidal waveform. The val...










