| 摘要 |
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 values of mince points 4, 8 and 12 are 0. Each value of mince points 1, 3, 13 and 15 is equal to corresponding value of mince points 5, 7, 9 and 11. The digital filter effectively reduces a filter-processing load.
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