Abstract: A system for detecting the presence of a knock condition by interpreting a broadband spectra signal as measured from an internal combustion engine is described. The system includes a spectra measurement device, preferably an accelerometer (101) mounted to an engine for providing a broadband spectra signal (103) to a knock detector (105). Preferably the knock detector (105) is based on a digital signal processor. The signal (103) is provided simultaneously to knock discrimination elements (405, 409, and 413), that provide a knock spectra signal (415) representative of the average energy within a predetermined knock spectra, and noise discrimination elements (417, 421, and 425), that provide a noise spectra signal (427) representative of average energy within a predetermined noise spectra. The knock spectra signal (415) is combined with the noise spectra signal (427) to provide a knock signal (431) when an engine knocking condition is detected.