Multiple target localization using wideband echo chirp signals

Active target detection and localization is a classical signal processing problem that arises in various military and biomedical applications. A novel method for the detection and estimation of the range, velocity and direction of arrival (DOA) of multiple far-field targets using wideband chirp signals is proposed in this paper. Using the plane wave representation of the signals reflected from far-field targets, a modal preprocessing procedure is designed for the echo signals received at a concentric circular array. Following that, the parameter estimation method for the multiple targets present is developed based on (i) the fractional Fourier transform which projects a signal onto an orthonormal basis formed by chirps and (ii) the Root-MUSIC algorithm which is a high resolution DOA estimation method originally proposed for narrowband signals received at a uniform linear array. There is no limit on the number of targets detectable by the proposed method as long as the echo signals are separable in the chosen fractional Fourier domain. Simulation results show that the proposed method demonstrates good performance, with low root-mean-square errors in the parameters estimated under difficult conditions such as closely spaced targets and low signal-to-noise ratio.