Design And Research Of A Tree Structure Broadband Beamforming

Beam-forming, a sensor array signal processing technology used for directional signal transmitted or received, has been used in communication and navigation systems widely. It has been applied to the sonar, communication, radar, earthquake, sound and the microphone array, and other fields. The objective of beam-forming is to improve the SINR(Signal-to-interfere and noise ratio) of system by enhancement of the desired signal gain and the inhibition of other signals and background noise to wave direction. In practical application, there are many advantages of the broadband signal,of which the higher resolution can improve the communication and detection performance of system and so on. So the broadband signals are usually used in radar, sonar and communication systems. Therefore, there is rather important practical significance to research the design and methods of the broadband signal beam shaper.In this paper, the main research content is broadband signal beam-forming. Firstly, the current common broadband beam-forming—Frost broadband beam-forming has been discussed. With the increase of signal bandwidth,the sampling signal increases correspondingly, which increases the number of filter taps. This will increase the amount of calculation, which leads to slow down the speed of the weight convergence, and the adaptive adjustment ability of system will fall. In order to solve these problems, we study the following several aspects of content.1、We propose two new structures to realize broadband beam-forming: tree structure and the improved tree structure of broadband beam-forming in order to solve these problems. The new structures are cascaded with basic blocks which are formed by Frost beam-formers with the smaller number of channels and tapped delays. We design the algorithm process of the tree structure, also the amount of calculation and the theory output SINR of the algorithm have been discussed.2、We propose two iterative methods to update the new beam-former weights: the layer-iteration and the iteration step by step. There are several advantages and disadvantages for two iterations each. The former can obtain the higher SINR, and the latter will spend update time shorter. It is shown that the new structures reduce the computational loads significantly by comparing with the computational complexity of the tree structures and the equivalent Frost beam-former. Furthermore, the parallel updating of the basic blocks will be feasible, which is favorable for instantaneity of the system.3、The system robustness and effectiveness also have been researched in the existing steering vector errors and interferences cases. Such as a single narrowband source, a single broadband source, and double broadband source interferences have been simulated. The simulation results of computer are confirmed the validity of the proposed structures. The new structures are essentially sub-optimal, so the mentioned advantages of the proposed structures are gained at the expense of the loss of output SINR. However, the sacrifice is very worthy because the real time and robustness of the system are very important.