Wideband digital array real-time delay technology
|School||University of Electronic Science and Technology|
|Course||Signal and Information Processing|
|Keywords||Fractional delay Digital beamforming Wideband Digital Array Radar ADSP21161|
In order to obtain a more subtle information to meet the target recognition, or the need for precise positioning of the target, the radar often use high range resolution signal, i.e., a wideband signal. When all-digital array antenna using broadband signal, the transmit and receive digital beamforming technology called wideband digital array radar. Wideband digital array radar in recent years by a growing number of researchers concern, has become a hot research. Broadband radar, however, bring a lot of technical problems, one question is: broadband signal is still used traditional narrowband beamforming technology because of the aperture effect so that the beam pointing offset and are not allowed to scan. To solve this problem, this paper analysis and study. First broadband signal beam pointing brief frequency broadband beamformer and time domain beamformer, proposed to compensate for the array of digital delay lines and fractional delay filter combination structure for of Time Domain broadband beam intersymbol time difference. Secondly, the design of the FIR type, and all pass type two categories fractional delay filter, the two design approaches performance, complexity, stability, flatness compared. General, the design of the same fraction of the delay filter, the all-pass filter than the FIR filter order is less, but the stability of the all-pass filter is better. In addition, in the actual design of fractional delay filter, first select the Lagrange method and group delay maximally flat, because the filter coefficients of these two methods has a simple and clear form data update soon, the drawback is the passband bandwidth with the the order of the filter increases more slowly. However, the fractional delay filter selection method of least squares is designed with greater flexibility, to facilitate the choice of the bandwidth of the pass band. On this basis, further study of the FIR and all-pass type variable fractional delay filter design and the realization of structural and simulation analysis. Again, the design fractional delay filter applications in the broadband digital array beamforming MATLAB simulation verify the validity and correctness of the design of the filter. Finally, select two representative fractional delay filter design algorithm, written based on the ADSP21161 the broadband beamforming DSP software module, Visual DSP environment development and simulation, and simple optimization.