Study On Beamforming Algorithm Of Array With Virtual Elements

Beamforming is the significant research problem in Array Signal Processing. The aperture of acoustic array should be increased to get high resolution of conventional beamforming(CBF) algorithm at a certain frequency, which is often not allowed in practical applications. In this dissertation, beamforming algorithm of array with virtual elements has been investigated systematically. The main works are as follows:1. Basic theory of array signal processing had been studied, mathematical models of the signal arriving at the array are analyzed, the narrowband and broadband expressions of the output data of array with arbitrary geometry are given, and the typical array manifold is deduced.2. Conventional beamforming algorithm is analyzed. The principle and character of the narrowband beamforming and broadband beamforming are studied respectively. The multiplication theorem and MVDR beamforming are introduced. Various broadband beamforming methods and methods of broadband constant beamwidth beamforming are studied.3. The necessity and the importance to introduce beamforming of array with virtual elements had been analyzed, the main ideas and principle are studied deeply. A beamforming algorithm of array with virtual elements based on linear prediction is proposed. A beamforming algorithm of array with virtual based on least squares estimator is presented, and the modified algorithm is proposed further. In this thesis, we also study the beamforming algorithm of array with virtual elements based on time delay and summation. For the first two methods broadband constant beamwidth for broadband signal had also been achieved by using different number of virtual elements in array processing technology. The output data of virtual sensors are estimated from the output of physical array using linear prediction. The aperture of total array is broadened in the virtual sense, and high directivity narrow beam is realized for a small size physical array. The effectiveness of this new algorithm was verified via computer simulations. And the approach to realize broadband constant beamwidth beamforming is viable.4. The effects of beamforming algorithm of array with virtual elements based on linear prediction, on modified least squares estimator, and on time delay and summation are thoroughly studied via 1998's Songhua Lake experiment. The...