Research And Implementation Of Time Domain Delay Wideband Beamforming And Channel Equalization Techniques

Due to the characteristics of the flexible pattern synthesis ability and the strong adaptive anti-jamming capability in space domain,the array antenna with digital beamforming technology has been widely applicated in lots of fields.With the increase of the signal bandwidth,phase-shifting method used in narrowband beamforming is not suitable for the reason of beam pointing spatial dispersion.When the aperture transit time is longer than or close to the reciprocal of the signal bandwidth,the beamforming performance will be severely degraded.The main works of this paper are focused on time domain wideband beamforming and channel equalization,which are listed as follows:Firstly,true time delay wideband beamforming and channel equalization algorithms are researched.The controllable delay with picosecond level precision is realized by the flip-flop of digital circuit and the Farrow based variable fractional delay filter.To solve the influence of channel mismatch on wideband beamforming,channel equalization algorithm of frequency domain and the improved equalization algorithm are studied.The theoretical analysis,algorithm optimization and simulation experiments verify the feasibility and validity of the Farrow based variable fractional delay filter and the improved channel equalization algorithm of frequency domain for wideband beamforming system.Then,a new realization scheme of the true time delay wideband beamforming and the channel equalization is proposed.The Farrow based wideband beamformer and channel equalizer are transplanted and realized in the K7 series FPGA on 8-channel wideband intermediate frequency digital beamforming processing circuit verification platform.In order to verify and test the performance of the designed scheme,a wideband 8-channel intermediate frequency signal emulation system is also constructed.The related indexes are tested in this experimental system.The testing results show that the time delay mean square error is less than 6ps;the residual amplitude and phase mismatch mean square errors of the channel are less than 0.4dB and 1.5° respectively within the 60%relative bandwidth.Wideband beam scanning is accurately realized with less than 1° pointing errors in whole bandwidth.The research and experimental results of this paper lay a solid foundation for the practical application of true time delay wideband beamforming technique.