Study On Waveform Design And Signal Processing Technology For Dual Polarization Weather Radar

Ground clutter recognition and filtering,the range-velocity dealiasing under the range-Doppler Dilemma and accurate moment characteristics estimation of weather echoes are regarded as three key technical issues in the field of Doppler weather radar signal processing.In terms of ground clutter suppression,this paper analyzes the adaptive clutter filtering technique of single pulse repetition frequency(PRF)radar waveform and applies it to dual-PRF radar signal processing.In terms of the range-velocity dealiasing,radar waveform based on frequency diversity is proposed to compress the volume scan period and increase the spatial observation data rate.In terms of polarization characteristics estimation,this paper applies the complex-domain phase difference technique to estimate specific differential phase,and compares with the real-domain differential phase estimation algorithm using the measured data from the operational radar.The main work of the paper includes:Firstly,in the aspect of ground clutter suppression,the performance of Clutter Environment Analysis using Adaptive Processing(CLEAN-AP)is analyzed,and based on that,it is applied to clutter suppression of dual-PRF signals with meteorological channel applications of dual polarization multi-phase phased array weather radar and terminal aircraft surveillance radar as background.Simulation analysis and the measured data prove this method has good ground clutter suppression performance and can provide high-quality filtered signals for spectral moment estimation.Secondly,with respect to dual polarization weather radar waveform design,a dealiasing waveform design method based on frequency diversity is proposed under different conditions of bands and scaning elevations.This method combines the range and the velocity measuring signals using frequency diversity.Compared with the continuous surveillance/continuous Doppler and alternating grouping(Batch mode)waveforms widely used in the existing operational radar system,it can reduce spatial scanning time effectively on the basis of ensuring the same degree as the maximum unambiguous velocity and the maximum dealiasing range.Besides,this waveform can effectively avoid inherent time asynchrony problem of continuous surveillance/continuous Doppler waveform and inherent spatial resolution bin asynchrony of Batch measuring,improving the estimation accuracy of base data of dual polarization weather radars.Thirdly,when the differential propagation phase crosses the principal phase or there is random measurement fluctuation,specific differential phase estimation will produce a bias,which affects weather characteristics estimation such as rainfall intensity.For this issue,the paper first introduces the radar polarization estimation technology;on this basis,nonlinear fitting method of differential phase in the complex domain is studied,and specific differential phase estimation experiment is carried out by simulation analysis and measured data calculation method.The results show that the proposed method has better estimation performance than fitting method of differential phase in the real-domain in the regions of differential phase with large spatial gradient and random fluctuation.The paper's work on ground clutter suppression can be applied to existing operational radar systems and developing dual polarization multi-function phased array weather radars;proposed range-velocity dealiasing radar waveform design method based on frequency diversity is especially suitable for solid-state dual polarization radar system and phased array weather radar system,which can effectively enhance spatial scanning capability and provide potential waveform design scheme for disastrous weather observation radar design such as short-time heavy rainfall and squall line;the proposed specific differential phase provides a more accurate method for polarization characteristics estimation in the regions of large spatial rainfall gradients.