DOA estimation of LFM sources based on time-frequency interferometer in UCA

Based on the time-frequency (t-f) interferometer of the uniform circular array (UCA), a new direction of arrival (DOA) estimation algorithm of multiple linear frequency modulation (LFM) sources is proposed. Firstly, the cross smoothed pseudo Wigner-Ville distribution (SPWVD) of the elements' output is calculated and the single source t-f points are selected by using a "noise threshold" procedure and cluster based algorithm. Then, by selecting different groups of sensor pairs, the proposed algorithm can solve the phase ambiguity of the t-f points by using a focusing based algorithm. And a lookup table based ambiguity resolution algorithm is also presented to reduce the computational complexity. The simulation results illustrate that the proposed t-f interferometer can be applied to multiple wideband LFM sources and it also can improve the DOA estimation precision compared with the traditional phase interferometer and sub-band interferometer. Especially in the low signal to noise ratio (SNR) and limited snapshots situations, the estimation root mean square errors (RMSEs) of the proposed algorithm are also within 3 degrees. (C) 2019 Elsevier GmbH. All rights reserved.