| 摘要 |
PURPOSE:To simplify a circuit so facilely, by calculating a noise level according to output pulse number of a comparing device at a noise gate section, while finding a knocking judging level on the basis of this calculation. CONSTITUTION:An output signal out of a knocking sensor 21 enters a comparator 23 after its noise component is eliminated by a band-pass filter 22. On the other hand, a noise calculating device 30 outputs the noise level calculated at the previous ignition to the comparator 23 via a digital-to-analog converter 24 at a noise gate section by a noise gate generating device 32, and when output of the part of the filter 22 is larger, an output pulse is generated there so that the noise level is calculated from this output pulse number, and it is set down to the noise level of the next ignition. And, with this output pulse number, a knocking judging device 28 judges the knocking, and gives a command to a delay timing controlling device 35. Thus, a rectifier, an integrator, an analog switch, etc., are all become useless whereby constitution is well simplified. |
