Research On High Resolution Array DF Technology Of Passive Signal

High resolution array direction finding techniques have shown the bright future applications in many fields for their excellent resolution and estimation performance. Nevertheless, many algorithms are based on an ideal mathematical model, which couldn't often be satisfied in practical applications, for example, wide frequency band, complicated signal environment and real system model error and so on. These cases will degrade the performance of the methods extremely and restrict their applications.In this dissertation, we study some key techniques of high resolution array direction finding with considering the problems mentioned above. Several applicable algorithms are proposed and their corresponding theoretical analyses are given. The algorithms and conclusions in the dissertation are verified by a plenty of computer simulations. The main work of this dissertation is in the several aspects as follows:The two-dimension direction finding ambiguity of planer array in the wide band direction finding system is studied. The sufficient and necessary condition for arbitrary planer array that doesn't exist two-dimension direction finding ambiguity is proposed. Thus we can design the array properly in order not to occur ambiguity. The uniform circular arrays are analyzed according to the condition, and several planer arrays are provided which don't occur two-dimension direction finding ambiguity.The decorrelation methods of being able to resolving the coherent signals are presented. The reason why high resolution array direction finding algorithms are disabled for coherent signals is analyzed. Some different methods are put forward for different planer array. For the linear array, we can use forward-backwardspatial smoothing method and modified spatial smoothing method. For arbitrary planer array, we may adopt a kind of array interpolation method that can estimate azimuth of the signals in multisectors. This method is basically feasible, but it's efficiency and feasibility will further analyzed and proved.The model error of direction finding system is analyzed and calibrated. We present some factors of model error, compare the influence with these factors.Two primary factors in model error------the channel's uncertainty and antennacoupling are found, establish the mathematical model with model error and the calibration methods of these two model errors are proposed. We give a good method that can calibrate the channel's uncertainty well. This method is suitable for uniform circular array and shows good performance of estimating the channel's uncertainty and directions of signals.