A Fast Algorithm of Running Fourier Transform.

A short-time Fourier transform can be derived by low-pass filtering of the product of an input signal and exp(j2πft). According to this method, called the Running Fourier Transform (RFT) in this paper, running power spectra with arbitrary center frequencies and arbitrary Q values can be obtained. This paper proposes a fast algorithm of discrete RFT (FRFT). In the FRFT, a first-order lag system is adopted as the low-pass filter (LPF), and by approximating the impulse response of the LPF with a step function, the amount of multiplications is reduced. The calculation of the complex exponentials is omitted by referring to a table of sin(2πk/K) (k = 0, …, K). [ABSTRACT FROM AUTHOR]