Research of Daubechies Wavelet spectrum of vibroacoustic signals for diagnostic of diesel engines of combine harvesters

The authors have researched the practice of diesel engines vibration diagnostics of combine harvesters and established the existence of non-stationary signals dissemination, whose statistical properties evolve over time. It was determined that they consist of short-term high-frequency elements, which are supported by low-frequency components are imposed on the first. The short-term Fourier transform was used to analysis such signals, which showed the appropriateness of the frequency distribution in concert with the differ time allocation. The authors have used the wavelets in cases where the certain signal analysis result should contain not only a simple enumeration of its typical frequencies, scales (spectrum analysis), but also local coordinates data under which these frequencies manifest themselves. This is an issue to identify the aspects when defects in the diesel engines of combine harvester's connections arise.