New method for scalar miss distance measurement based on the fractional Fourier transform

Since the hypothesis of constant amplitude and constant frequency, adopted by the conventional miss distance measurement method using Doppler information, leads to notable estimation error of Doppler frequency around the closest point approaching the target, a quasi real-time method of scalar miss distance measurement is proposed based on the assumption of constant amplitude chirp signal. Through increasing the fitted segment time used for Doppler frequency, the integration duration is prolonged effectively. What's more, the proposed method is realized via the fast discrete algorithm of the fractional Fourier transform. The simulation results show that, compared with the real-time method of scalar miss distance measurement based on the FFT, this method can obtain higher accuracy and better robustness, particularly when the signal-noise-ratio is low relatively. However, the computation complexity rises slightly.