| 摘要 |
PURPOSE:To remove noises so as to detect nothing but knockings accurately by a method wherein the knocking decision level is kept under feedback control by the detection of producing states of knocking signals. CONSTITUTION:There is provided a knocking signal detecting circuit 3 composed of a counter circuit 32 and a knocking decision level circuit 31 which keep a knocking decision level under feedback control by detecting the producing states of knocking signals. To take an example, when a valve noise or the like exceeds a knocking decision level, it is detected by a knocking decision and controlling circuit 5 and the knocking decision is controlled under such a state as B. As a result, the output signal of a monostable multivibrator equipped in the count circuit 32 take a form like (g) and valve noises and the like are not detected. |
