The new measurement algorithm of the engine speed base on the basic frequency of vibration signal

To get the engine speed information fast and accurately for the automotive fault diagnosis is of great significance. In view of the shortcomings and inconvenience of the traditional rotate speed measurements of engine, the mathematical relationship between the basic frequency of vibration signal and the rotate speed has been analyzed. And the basic frequency extraction principle and specific approaches have been discussed. Based on LabVIEW, the data acquisition system employs the short-time signal processing technique to pick the basic frequency of vibration signal. A highly precise and less expensive new algorithm which is easy to implement is proposed. It combines wavelet transform, Fourier technology and autocorrelation function, and testified by experiment. The results show that the error rate of the algorithm is less than 1% and the accuracy and robustness of the algorithm meet the measurement requirements. Therefore, the algorithm is of great practical value.