Abstract: A method and system (10) are provided for monitoring an operating state of an engine (12). Data are measured (84) from the engine (12). The data are indicative of the operating state of the engine (12). The data are processed (86, 90, 92) according to a discrete Fourier transform. The operating state of the engine is monitored by processing (96-114) the discrete Fourier transform.

Abstract: A method is provided for decoding a composite signal which includes receiving a composite signal including a pilot signal at a pilot signal frequency, and first and second information modulated with a subcarrier at a harmonic of the pilot frequency. The composite signal is sampled at a preselected sampling frequency. The sampled composite signal is mixed down with a reference signal of approximately the same frequency. The mixed down pilot signal is extracted from the mixed down composite signal, the amplitude and sign of the mixed down pilot signal proportional to the phase difference between the pilot signal and the reference signal. The phase of the reference signal is adjusted as a function of the amplitude and sign of the mixed down pilot signal such that the reference signal is approximately 90.degree. out of phase with the received pilot signal. The sample of the composite signal taken closest to the start of a period of the pilot signal is identified.

Abstract: An engine timing chain snubber comprises a pair of guide shoes fixedly supported on the engine block and extending in line-to-line nondeflecting contact with the inner sides of unsupported chain portions between drive and driven sprockets. The guide shoes prevent movement of the chain runs inwardly of their tensioned positions and thus prevent chain oscillation or vibration.