Electromagnetic Interference (EMI) as Spark-Ignited Combustion Engines Diagnostic Parameter and Its Wireless Measurement and Wavelet Analysis

This paper reveals that the ignition and combustion process of Spark-ignited Engine (SIE) inspires electromagnetic interference (EMI) that bears some inner information from SIE. The EMI conducted measurement and radiated measurement methods are experimented upon and both obtain correct signals while conducted measurement gets higher signal/noise ratio than radiated measurement. Because most signals are found in irregular structures and transient forms, the traditional frequency analysis tool Fourier Transform fails to deal with; and because during the combustion process the signals are mixed with environment noise; we use wavelet decomposition and Lipschitz signal singularity identification algorithm to confirm that among EMI signals, there are significant signals generated by SIE, thus offering an effective approach to further unveil the relationship between combustion process and EMI. Considering that the measurement is wireless completely, it is possible to develop a potable instrument for SIE diagnostic and research purpose.