Research On High Resolution DBF Direction Finding Algorithms

High resolution direction finding technology is developed a new spatial signal processing technology in nearly 40 years and its main objective is to enhance the angle estimation accuracy, the angle resolution and improve the operation speed. High resolution direction finding techniques has excellent estimate performance and shows a good prospect in radar, communications, sonar, and other fields. The excellent performance is based on that the array meets a series of assumptions. If in the complex signal environment and the model error exists, the performance will be greatly decreased. Based on the above problems, the dissertation researches on the key technologies of high resolution direction finding. 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:Research on high resolution measurement to the theory of high resolution, as well as an ideal model of basic assumptions. This dissertation establishes the mathematical model of array and makes comparison of the pattern characteristics of ULA, UCA and IUCA. DOA estimation methods for narrowband coherent signals have bad performance. So we can use forward-backward spatial smoothing method in the linear array and use virtual array translation method in the IUCA array which has good performance in the UCA array. Through the computer simulation result, it has proved this kind of method is valid.In the paper, error in model of array direction finding system is analyzed and regulated. Firstly, the factors that caused the error in model are analyzed. And two main factors are found and regulated through proposed algorithms with building mathematical modeling respectively. Further, the two proposed algorithms are applied to Uniform Circular Array with 1+N units. Simulation shows that the problem that the channel's uncertainty and antenna coupling are regulated effectually with the proposed algorithms.The DOA valuation are studied in this paper too. At the present time, the main methods of DOA valuation are the ISM and CSM methods. However, the ISM method can only do help with the un-correlated wideband signals and the CSM method can deal with the correlated signals with some disadvantages, for example, the performance are easily affected with the choice of the initial value, and the total computational complexity are too huge for real-time processing, For these questions, a improved ISM algorithm, with which, the problem first mention above are resolved totally, based on translating of virtual array is proposed. The DOA of wideband correlated signals are valuated preferably with a superior resolving power and a lower computational complexity by using the improved algorithm. The validity of the improved ISM algorithm are verified through the analysis and simulation .