Time-frequency DOA Estimation And Application Comprehensived Polarization Information

Spatial spectrum estimation technology has always been the focused research project in array signal processing of High Frequency Surface Wave Radar(HFSWR). In recent years, as the coastal area of space gets smaller to make HFSWR array antenna sperture get smaller too, using signal processing technology to improve the precision of the direction of arrival(DOA) estimation algorithm has also become a research hotspot. The time-frequency analysis method has unique advantages in dealing with non-stationary signals, and the polarization sensitive array is sensitive to the polarization information of electromagnetic signals. Therefore, this thesis takes the polarization sensitive array for the model, and combine with time-frequency analysis method for DOA estimation of HFSWR echo signals, which can make full use of the spatial, time-frequency and polarized domain information of signals.This paper introduces the principle of modern spatial spectrum estimation technologies, including Multiple Signal Classification(MUSIC) algorithm, Estimation of Signal Parameters Via Rotational In-variance Techniques(ESPRIT) as well as their improved algorithms. In addition, these algorithms are verified with simulation experiments and real data in MATLAB platform.In order to improve the accuracy of DOA estimated value, this paper introduces the method of time-frequency analysis. Time-frequency MUSIC algorithm and time-frequency ESPRIT algorithm can be realized when the spatial time-frequency matrix substitude the covariance matrix of traditional DOA estimation algorithms. The principles of both algorithms are analyzed in detail, and their performance as well as respective advantages and disadvantages are analyzed by computer simulation. On this basis, some improvements are made on the algorithm. Finally the improved algorithm is verified with the real data.To take full advantage of polarization information of electromagnetic signals, double polarization orthogonal dipole array is established. On this basis the polarized MUSIC algorithm and polarized ESPRIT algorithm are introduced, and their performance is analyzed through simulations. Then time-frequency MUSIC and ESPRIT algorithms of integrated polarization information are studied, and the improved algorithm is proposed based on the advantages and disadvantages of both algorithms. The improved algorithm first estimate the azimuth angles of signals roughly with the polarized time-frequency ESPRIT algorithm, and then determine a small scope centered on each azimuth. Within the scope a more accurate DOA estimated value is got by spectral peak search with MUSIC algorithm, so it can save computation time on the basis of accuracy of the DOA estimation. Finally, the polarized parameters influence on DOA estimation is studied, including the polarized parameter estimation error influence on DOA estimation and what kind of polarization state will make higher accuracy of DOA estimates for different signals.