Research On Robust Broadband Beamforming Technology And Its Realization

With the development of communication technology, broadband signal is widely applied for its good comprehensive properties. Consequently, the subject of broadband beamforming is proposed. With important theoretical significance and practical value, the research on robustness of broadband beamforming technology has been considered as one of the focal point of study. This paper focuses on robust broadband beamforming technology, and implements part of them on chip ADSP-TS201. The main content is as following:1. Being the basis of wideband processing, narrowband beamforming technology has been deeply studied. Aiming at the limitations of Covariance Matrix Taper technique on array shape, we propose a Covariance Matrix Taper technique applicable to arbitrary arrat shape. Then we combine the technique with constant modulus algorithm and optimal diagonally loading technique, and put forward a constant modulus algorithm with trough widening. Being capable of avoiding the shortcoming or miss convergence existing in the constant modulus algorithm and robust to array amplitude and phase errors, signal steering errors and the problem of the weight mismatching the data of the measurement2. In the aspect of the time-domain broadband beamforming technique, the emphasis is laid on the broadband beamforming algorithms based on the Frost broadband array structure. Conventional Frost broadband array is sensitive to pre-steering errors, although its length of the Tapped-delay-lines is short. So a novel adaptive broadband beamforming algorithm is proposed. The proposed broadband beamforming algorithm which is based on second-order cone programming, have robustness to the pre-steering errors. Simulation results show that the algorithm has a good performance in the case of big pre-steering errors, meanwhile have good robustness to array amplitude and phase errors , signal steering errors.3. A broadband beam forming algorithm based on spatial structure is discussed. Being a completely new structure, spatial broadband structure can easily implement its physical structure. In view that the performance of the broadband beamspace algorithm will degrade if signal steering errors exist, we propose a blind beamforming algorithm based on the spatial broadband beamspace. The algorithm has good robustness to the signal steering errors. Then we study the conditions for to calculate frequency invariance weight, and present a broadband spatial algorithm based on constant modulus criterion. Simulation results show that the algorithm has a good performance in the case of array amplitude and phase errors, signal steering errors.4. The optimal diagonally loading technique based constant modulus algorithm with trough widening, and the robust spatial broadband beamforming algorithm, are implemented on chip ADSP-TS201. According to the system requirements, we carry out a series of program optimization, and then the robust narrowband/broadband beamforming algorithms are implemented efficiently.