Application Study On Constant Beamwidth Beamformer And Broadband DOA Estimation

As an important part of the modern signal processing, high-resolution direction of arrival estimation technique has a promising perspective in many fields such as radar and sonar, with the development of the microelectronic and digital techniques. The analysis of wideband signals will improve the resolution capability and accuracy of estimation, for more frequency components can be synthetically used. Constant beam-width beam-former and direction of arrival of sources for wideband signals are the important parts of wideband array signal processing. Aiming at the practical applications on engineering, the dissertation studies the theories and application technologies of constant beam-width beam-former and DOA estimation for wideband signals. The main results and achievements are summarized as follows:1. The fundamental concepts and theories of array signal processing are discussed summarily, and the model of wideband array signal processing is set up.2. The two thoughts of designing constant beam-width beam-former are studied, and the least square method and spatial resample method to calculate the weighting coefficients of the array elements are analyzed and compared, and the constant beam-width beam-former is designed, both in frequency and time domains.3. The typical wideband high-resolution method-the coherent signal subspace method (CSSM) is studied. We analyzed its nature of resolving coherent sources and compared the influence of different focusing matrices. Simulations are conducted to test the performance of these focusing matrices.4. The wideband beam-space high-resolution technique is studied. The differences on resolution capability and the performance of estimation between beam-space processing and element-space processing are analyzed. Transforming matrices are designed for the consideration of depressing the resolution threshold and estimation variance.A method is proposed to make for the loss of the orthogonal converting matrix's performance on constant beam-width, that is giving different frequency components different weighing values during orthogonal process, which is called weighted orthogonal converting matrix. Simulation results show that the weighted orthogonal converting matrix not only has good performance on constantbeam-width, but also has the same performance on resolution and estimation as those of common orthogonal converting matrix.5. The constant beam-width beam-former and wideband DOA estimation algorithms are realized in the DSP hardware systems. The system hardware architecture is analyzed, and the properties of ADSP2116x and the methodology of software development are presented. The system software is developed and debugged in modularization. Reasonable designing scenarios are proposed for the key modules, for the consideration of algorithms' being performed in real time. The simulation results based on the target board show that the system running properly.