Research On The Signal Real-time Processing Method Of Frequency-agility Radar Based On FPGA

Pulse Doppler system radar signal processing method is simple,easy to implement,and has a good real-time signal processing,so it is also a common target detection method for radar.However,when placed in an increasingly complex electromagnetic environment,PD(Pulse Doppler)radars are stretched to cope with a wide variety of interferences.In recent years,the emerging frequency-agile radar has shown a clear advantage over the PD radar in combating deceptive and transmissive interference.However,in order to solve the problem of coherent processing of radar signals under the new system,the complexity of signal processing algorithms also increases.Traditional signal processing uses the framework of "FPGA + DSP" as the core.FPGA only performs simple front-end preprocessing engineering in the whole signal processing flow,and complex radar signal processing algorithms are implemented by DSP.Because the algorithm for realizing the radar signal coherent processing under the new system is more complicated than the traditional PD radar,the DSP alone cannot meet the real-time requirements of the system.In response to this problem,the paper has carried out the following research:Firstly,comparing the two kinds of radars of pulse Doppler and frequency-agile,this paper analyzes the nonlinear variation of the echo phase of the inter-pulse carrier frequency agile system radar in a CPI(Coherent Processing Interval,CPI).The impact of processing.In this paper,a signal processing method based on sparse theory is proposed,and the high resolution distance information of the target is extracted.The feasibility of the method is verified by simulation.Secondly,the computational complexity of the reconstruction process of the orthogonal matching pursuit algorithm is analyzed,and the redundant information in the cross-correlation matrix of the atomic support set is removed by the principal component analysis method,and only the part containing the largest amount of target information is retained.The dimensionality reduction processing of the cross-correlation matrix simplifies the process of the final target sparse solution and improves the real-time performance of the algorithm signal processing.Finally,based on vivado HLS,the various functional modules of the agile radar signal processing algorithm are quickly realized,and the problem of long iteration period of the QR decomposition module is achieved.By reducing the register bit width,although the calculation accuracy is lost,the real-time performance of the signal processing is improved..It is verified by simulation that the loss of precision will not affect the reconstruction of the main target.And by adjusting the pipeline structure in the sparse reconstruction process,the data throughput rate of the module is improved,and the real-time effect of the overall signal processing is improved.