Separation of HFM and NLFM signals for radar using fractional fourier transform

Abstract

The Hyperbolic Frequency Modulated (HFM) and Nonlinear Frequency Modulated (NLFM) signals have been gradually used in new radar systems. These signals excitation when combined with pulse compression provides an increase in SNR at the receiver. These signals are of longer duration as compared to pulse signals of same bandwidth. Separation of echoes becomes impossible in some practical situations when these signals are used for transmission. In this paper a new method is explored to separate the time overlapping HFM and NLFM signals using the fractional fourier transform. The motivation behind using this method is because some of the techniques like time windowing and frequency domain filtering are unable to separate these signals overlapping in time and spectra. Simulation results show that using FrFT desirable outputs are obtained.