Study On Robust Direction Of Arrival For Coherent Signal Technique

Array signal processing includes direction of arrival estimation is widely used in telecommunication and target detection fields because of its precise angle estimation capacity. After introducing the traditional DOA algorithms, DOA algorithms for coherent signal, fast DOA algorithm and DOA algorhtms for wideband signal are studied. Effects of channel inequality on DOA estimation and the way to mitigate it are studied. The main work in this thesis is listed below:1. The basic array signal model is given. The classical MUSIC and ESPRIT algorithms are introduced and detailed principle are given. The charictertistic of the algorithms are given respectively. After that, simulation results are given in this paper and the angle detection ability against the input SINR is given by the simulation results.2. Traditional DOA algorithms cannot work encountering coherent signal. In order to solve this problem, several methods are proposed. First, Toeplitze technology is involved and the new toeplitzed covariance matrix is applied to classical DOA as a mitigation. Second, virtual smooth technology is used to make the coherent signals uncoherent and then the DOA estimation can be carried out. The effectivness and accuracy of the proposed algorithm are verified by the simulation results.3. In order to solve the heavy computational burden caused by tradional DOA, GS-DOA and MSWF-DOA are proposed, which acquire approximately signal subspace and save a lot of time. The proposed methods are compared with the traditional DOA methods by simulation results. It can be seen that the proposed methods are really time saving. This kind of method is useful to practical situation.4. In order to solve the DOA problem in wideband signal situation, the global focusing based DOA algorithm is introduced after the focusing based DOA algorithms are given. It is not necessary for this method to get any knowledge prior and the direction of arrival of the signal can be achieved precisely. The operation after focusing is just the same as the DOA algorithm for narrow band signal. The effectivness and correctness of the proposed algorithm are verified by the simulation results.5. In order to solve the problem caused by the channel inequality, the effects of it on DOA is studied and the simulation results are given. It is shown that the amplitude inequality affects the amplitudes and the phase inequality also affects the peak location. To solve this problem, a channel calibration method is given. The results after the calibration are significantly improved.