| 摘要 |
PROBLEM TO BE SOLVED: To reduce a filter processing load in a signal processing unit used for a knocking detector used to detect the generation of a knock by analyzing a knock sensor signal. SOLUTION: The signal processing unit is provided with a digital filter to which data on the knock sensor signal to be A/D-converted at each definite cycle T by an A/D converter is input sequentially so as to be processed. The filter is constituted as an FIR filter in which the values of respective points 0 to 16 formed by engraving reference waveforms in a reversely symmetric shape formed by connecting a waveform as half waves of sine waves to a waveform by halving a height of the waveform from an end at each cycle T are identical to filter factors. Consequently, when from among the filter factors, a sign of an (m-1)st factor is different from a sign of an (m+1)st factor, an m-th factor (a factor corresponding to the points 4, 8 and 12) becomes 0, and four or more factors having the same absolute value exist (factors corresponding to a set of the points 1, 3, 13 and 15 and a set of the points 5, 7, 9 and 11). COPYRIGHT: (C)2004,JPO
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