Parameter Estimation Of Wideband LFM Signals Based On MP Decomposition

Nonstationary signals whose frequency contents evolve with time widely exist in our real life, such as audio, radar and sonar signals. When dealing with these signals, the performance of traditional methods in array signal processing may degrade heavily because of the narrowband and stationary signals assumptions. Currently, this widely used method obtain direction-of-arrival (DOA) in time-frequency domain, via establishing the spatial time frequency distribution (STFD) matrix and then combining the traditional methods of array signal processing. However, obtaining DOA using STFD will be affected by the selection of the correct time-frequency points and the performance cross-terms impact. And only under the condition of higher signal-to-noise ratio (SNR) would be a better estimation.Sparse decomposition of signals is emerging as a signal processing method, which has many excellent features. This paper applies sparse decomposition to wideband array signal processing, and presents a new method for frequency and DOA estimation of wideband linear frequency modulation (LFM) signals based on matching pursuit (MP) decomposition. The main work and contributions of the dissertation are in the several aspects as follows:1. Time domain, frequency domain characteristic of LFM and the typical time-frequency analysis method — Wigner-Ville distribution (WVD) are studied. DOA estimation algorithm for wideband LFM signals based on the subspace method under time-frequency analysis is presented. Orthogonal signal decomposition of the traditional methods and adaptive signal--MP decomposition algorithm are discussed.2. A new method based on MP decomposition is presented to estimate the parameters of LFM signals in wideband array signal processing. The parameters of frequency and DOA of sources can be found by MP decomposition of the array output, over an adaptive over-complete matrix dictionary, the atoms of which are established according to the LFM signals' frequency parameter and the array geometry. Numerical simulations of the resolution of overlapping echos are shown to be much higher than conventional STFD based methods, especially in the case of...