Non-Stationary Signal Analysis A Modified Time Frequency Approach
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Abstract
Fourier investigation becomes invaluable when the signal contains non-stationary characteristics or transitory characteristics like transients and patterns that vary with time. As time domain and frequency domain representations are inadequate to give all the information possessed by the non-stationary signal. Therefore time-Frequency methods (TFMs) are used to analyze a signal in time and frequency domains simultaneously. This paper deals with the analysis of non-stationary signals by using short time Fourier transform; fractional Fourier transform to analyze the time frequency behavior of the non-stationary signal. A combination method is known as Short time fractional Fourier transform (STFRFT) also proposed here, which provides unique properties of the non-stationary signal. By using different windows like the rectangular window, Hamming window, Hanning window and Blackman window, the fractional Fourier transform of the chirp signal has been plotted. The MATLAB simulations were made to show the STFRFT of the signal
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