| 摘要 |
An analog signal processing circuit for detecting engine knock is disclosed. A sensor mechanically resonant at characteristic engine knock frequencies provides an analog signal related to engine knock and engine background noise. An envelope detector provides the signal envelope of the sensor signal. An integrator means provides an average signal related to the average of the envelope signal while an attenuator and subsequent filter (integrator) provide an integrated and attenuated signal which responds faster to amplitude changes in the envelope signal than the average signal. The integrated and attenuated signal level is set below the average signal level for conditions of no-knock. A comparator receives both the average signal and the integrated and attenuated signal and provides an output signal indicating knock detection in response to the amplitude of the integrated and attenuated signal exceeding the amplitude of the average signal. Preferably the knock detection output of the comparator is latched and the comparator is reset by periodic engine pulses.
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