Abstract: Fractional Fourier transform can be considered as generalization of the Fourier transform. Four basic quadratic signal representations, i.e., signal correlation function, spectral correlation function, Wigner distribution, and ambiguity function, can be interpreted with Fourier transform. A new timefrequency distribution function based on 2D fractional Fourier transform is presented. The distributions have partial time/frequency-lag and partial frequency/time-lag characteristics of signals. Main properties of the distribution function are discussed. Simulations show that the described distribution can detect chirp signal.

Key words: ambiguity function
, fractional Fourier transform, Wigner distribution, timefrequency analysis