Abstract: An adaptive knock control for a spark ignited, internal combustion engine is disclosed in which a signal indicating sensed knock induced and other bursts of engine vibrations is passed through a bandpass filter effective to tune the apparatus to a characteristic knock frequency which is variable with engine speed. The filter tuned frequency may be varied directly with engine speed to follow the characteristic knock frequency. Additionally or alternatively, it may be varied, at a particular engine speed, in a first direction away from the knock frequency avoid a strong engine noise component in the opposite direction from the knock frequency.

Abstract: An adaptive knock control for a spark ignited, internal combustion engine is disclosed in which a signal representing sensed knock induced and other bursts of engine vibrations is demodulated to generate pulses corresponding to the envelopes of such knock induced and other burst of engine vibrations. Discrimination apparatus responsive to pulses duration compares each to a discrimination reference and selectively discriminates in favor of those having a longer duration characteristic of knock induced bursts. The discrimination apparatus is responsive to engine speed to vary the discrimination reference therewith in the direction of shorter time durations with increased engine speed and longer time durations with slower engine speed. If the discrimination apparatus is a low pass filter, its corner frequency is varied directly with engine speed. If the discrimination apparatus is an ignore timer, the ignore time is varied inversely with engine speed.