Broadband Digital Beamforming Technology And Research

Digital array radar transmits wideband signal, for the need of improving anti-interference ability, improving identification, recognition of the target, and solving the problem of radar imaging. With the development of high-speed sampling technology and high-speed digital processors, wideband radar signal can be dealed in all-digital, and then wideband digital array radar is concerned more and more. Wideband digital array radar is fully digitized array antenna radar, employs wide signal waveform, and uses digital beamforming technology in transmitting and receiving. Wideband digital beamforming (DBF) is one of the critical technologies, and becomes an important research direction for wideband digital array radar.First of all, this article introduces the basic theory of wideband DBF including the digital beam forming system and wideband radar signals. Besides, wideband DBF methods in frequency-domain is introduced, the idea is to transform receive signals by FFT, and then do DBF in the frequency domain using incoherent signal-subspace method(ISM) and coherent signal-subspace method(CSM). Validity of the two methods is proved by simulation.Then, wideband DBF method in frequency domain is studied deeply. DBF in the context of coherent sources is considered, giving the coherent source model. The analysis shows frequency domain smoothing algorithm can distinguish coherent signal sources, so as to overcome the phenomenon of extinction effectively. Wideband DBF at subarray level combines the theory of subarray division and DBF technology, reduces the computation and system complexity to a certain extent. The technology of widening notch is studied to enhance the robustness of the algorithm.Taking into account the special frequency modulation characteristics of LFM signals, this article introduces stretching processing theory into wideband DBF. The bandwidth of target signal after stretch processing and narrowband filtering, the data sample ratio is reduced greatly, so that DBF can be carried out in a small bandwidth and the method is easy for engineering implementation.Finally, the implementation of MVDR algorithm and ISM based on ADSP TS201S is explored in the thesis initially. Using the soft environment of Visual DSP++, Soft simulation of the two DBF algorithms is done by assembly language. Simulation results show that the process be able to achieve the desired results, achieve beamforming performance.In this dissertation, it is in-depth analyzed and researched that wideband DBF algorithm. Some conclusions of practical significance have been drawn through a lot of simulation and comparison, to be the reference for practical implementation of wideband digital array radar.