| 摘要 |
<p>A knocking signal detection circuit includes threshold device (104) which has a threshold level which is raised when background noise and/or the level of knocking signals increases. The knocking signals are supplied to an amplifier (102) controlled by a loop (123, 120, 108). The threshold level of the threshold device (104) is determined by a control input (181) which receives (i) an output (B) of the loop representing actual background noise, and/or (ii) an engine-speed dependent signal (Px.y) representing expected background noise, and/or (iii) an average knocking or K-factor signal (K) representing expected knocking signal level.</p> |
