DOA Estimation of Wideband LFM Signals Based on Zoom-FRFT

摘要

The conventional direction of arrival (DOA) estimation methods of wideband linear frequency modulated (LFM) signals based on fractional Fourier transform (FRFT) have good performance, in which LFM signals are changed into narrowband stationary ones and time-variant steering vector is converted to time-invariant one. However, the accuracy of peak estimation is greatly reduced under the condition of low SNR and insufficient snapshots, which seriously affects the accuracy of DOA estimation. Thus, a method for the DOA estimation based on Zoom-FRFT is proposed which can improve the estimation accuracy without increasing the sample sizes and sampling rate, especially at the low signal-noise ratio (SNR). Through Zoom-FRFT, the algorithm extracts all peaks of the LFM signals and construct the fractional autocorrelation matrix in Zoom-FRF domain. Thereafter, the DOAs of coherent and uncorrelated LFM signals are estimated by the multiple signal classification technique (MUSIC). The effectiveness of the proposed algorithm was verified by theoretical analysis and Monte-Carlo simulation trials.