Resolution ability of fractional Fourier transform in multi-component Chirp signal center frequency

The resolution ability of fractional Fourier transform (FRFT) in the center frequency was studied, when multi-component Chirp signal had only one Chirp-rate. From the estimation sector of the center frequency in the FRFT's numerical calculation, the center frequency's resolution ability expression was deduced. Based on partial differential equation, the influence of the sampling time, sampling frequency and Chirp-rate upon the resolution ability were analyzed further. The computer simulation results indicate that the smallest resolution ability of center frequency has the cave parabola relationship about with Chirp-rate and is greater than 2 MHz, when the sampling frequency is 400 MHz, sampling time is 2μs and the value of Chirp-rate is no more than 100 MHz/μs.