Abstract: A knock control system for internal combustion engines comprising a knock sensor and a knock detection circuit that uses an electronic engine controller. The knock sensor creates an electrical output signal indicating the presence of engine structure vibrations resulting from engine combustion characteristics. The circuit filters the knock sensor signal, time gated at independent crankshaft angles, and transfers it to a noise channel and to a knock channel. A comparator distinguishes between background vibration and vibrations during the combustion event that are due to knock. The knock detection function, along with the crankshaft angle position reference signal, develops time gated "snapshot" signals indicating the magnitudes for both the background noise and the vibrations created by denotation and distinguishes between them.