Wavelet coefficients for window width and subsequent harmonics estimation – Case study

This paper is an extended version of the original author’s work presented during XIV IMEKO TC-4 Symposium [T. Tarasiuk, Estimation of measurement window width by interpolation based on wavelet coefficients – case study, in: Proceedings of 14th IMEKO TC-4 International Symposium, Poland, Gdynia/Jurata 2005, pp. 352–357]. Especially, new results have been added. This paper deals with the problem of reliable width estimation of a measurement window and its impact on harmonic analysis of chosen signals. The simple method of window width estimation is detection of a zero-crossing instant of a given signal by the analysis of sample polarisation changes. But the method is sensitive to waveform distortions, especially analysed signal multiple zero-crossings. So, the idea of implementing a discrete wavelet transform for risk reduction of measurement results corruption by the higher frequency phenomena has been proposed and preliminarily tested [T. Tarasiuk, Interpolation based on wavelet coefficients for frequency measurement, in: Proceedings of XVII IMEKO World Congress, June 22–27, 2003, Dubrovnik, Croatia, pp. 895–898]. In this paper, the concept has been further developed, especially the analysis of real voltages with multiple zero-crossing has been carried out. Then, the consequences of the chosen methods for the subsequent harmonics analysis have been laid and discussed.