Powertrain noise is broadly classified into two main categories - Mechanical Noise and Combustion Noise. Mechanical noise, because of its periodicity in time scale, can be easily characterized using customary spectral analysis methods. However, combustion noise which is controlled by the cylinder pressure profile has more periodicity in crank angle scale. Hence, the standard spectral analysis is often not sufficient for combustion NVH assessment.
Combustion noise can be better characterized with time-frequency analysis. In this paper, results obtained with the time-frequency analysis are presented. Also a brief portrayal of advanced signal processing tools for combustion noise analysis has been provided.