Digital Beamforming And DOA Estimation Algorithm Used For Reconnaissance Array Receiver

Considering the angle ambiguity in estimating the direction of arrival (DOA), the feasibility of ambiguity solving with virtual arrays, based on basic virtual array theories, is analyzed in this thesis. The conclusion, virtual array theories can not be used to solve angle ambiguity problem, is obtained at last. Computer simulations and performance analysis are presented to confirm the conclusion. Combined with some type airborne reconnaissance array receiver, the hardware implementation of high resolution DOA estimation and multiple digital beamforming (DBF) is studied in the thesis. Algorithm scheme and the overall framework of the hardware platform according to the system are given firstly. MUSIC algorithm is choosed as the DOA estimation algorithm of the project, furthermore, projection matrix is constructed for DOA estimation when weak and strong signals exist at the same time, and spatial smoothing algorithm is exploited to decorrelate possibly correlated sources. With the directions of desired signals, the adaptive anti-jamming DBF algorithm based on linear constraint minimal variance is employed to strengthen desired signals and to suppress jams. Then, the structure of the signal processing circuit board is introduced. Finally, the hardware design of the system is described in detail, including the FPGA logic design, the coordination of FPGA together with DSP processor, high speed LVDS technology used for data transmission, etc. Supported by the high speed signal processing system, theoretical algorithms on high resolution DOA estimation and multiple DBF are realized in the hardware platform, which is of great significance in practice.