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The Performance Analysis of DOA Estimation Algorithm for Troposcatter Signal based on Time Frequency Diffusion Modification

DOA estimation is the main task in troposcatter passive reconnaissance over-the-horizon (OTH). In the previous modeling for signal characteristics, the received troposcatter signals show low signal-to-noise ratio (SNR) and fading diffusion characteristics in the time-frequency domain. The classical MUSIC algorithm for direction-of-arrival (DOA) becomes invalid. Drawing lessons from strong energy aggregation features of time-frequency analysis, the spatial time-frequency distribution (STFD) matrix modified by fading diffusion in the time-frequency domain is constructed, which is used to replace the data covariance matrix in classical MUSIC algorithm. It's the SNR improvement, subspace estimation error and angle estimation variance that are deduced and analyzed for the modified algorithm. By means of the simulation experiments, the spatial spectral estimation and angle estimation accuracy are compared and analyzed in the modification before and after. The formula derivation and simulation results both verify the superiority of the time-frequency MUSIC (T-F MUSIC) performance modified by time-frequency diffusion.