Comparison of selected methods for spectral analysis of non-stationary signals

In this paper we present a comparison of selected methods that are suitable for the spectral analysis of non-stationary signals. The first selected method is the Wavelet Transform (WT), often used in practical applications for analysing and pre-processing electrocardiograph signals (ECG). The second method is an adaptive modification of the widely-used Short-Time Fourier Transform (STFT). It achieves satisfactory results for multispectral analysis of non-stationary signals. The last selected method is our Short-Time Approximated Discrete Zolotarev Transform (STADZT), which exploits the unique spectral properties of selective Zolotarev polynomials and achieves better time and frequency resolution than STFT.