Design And Implementation Of Radar Altimeter Simulator Based On FPGA

In the research and manufacture of radar altimeters,performance test is an import-ant part of work,and radar altimeter simulator play an important role in this process.Compared to out-field test,the radar simulator can be used in repeative test of radar per-formance under indoor condition,which greatly improving the radar test efficiency and saving the test cost.An aircraft radar altimeter simulator is proposed in this thesis,which is used to si-mulate the actual radar targets and noise,and achieve the purpose of testing radar perf-ormance.In this thesis,we proposed a new radar altimeter simulator system based on research of a lot of references on radar altimeter and radar simulator.The system can simultaneously receive and send three radar signals at the RF front-end and back-end.In the digital part the three channel signals with target characteristics can be seperately si-mulated,especially in high precision distance delay and zero delay.This thesis mainly made the following aspects of research work:This radar altimeter simulator is based on high-speed real-time paralleled signal processing structure,Firstly,we have analyzed the theory of high broadband digital down conversion and digital up-conversion,and improved the traditional parallel signal proce-ssing structure.Secondly,we have studied the target amplitude delay characteris-tic.The amplitude characteristic part analyzes three common RCS fluctuation statistical models: chisquare mode,rice mode and lognormal distribu-tion mode,emphasizely anal-ysis the target fluctuation character of sweriling I type and sweriling III type under the chisquare mode.In target delay characteristic part,we have researched a lot of high precision delay method,including SVD-FIR,Maximum flatness,WLS-VDF,SVD-VFD and so on,and we have worked out a detailed theory derivation based on WLS-VDF and farrow structure method.Lastly,we have introduced a new way to generate pseudo-random Gaussian white noise.On the basis of theoretical research,this thesis analyzes and designs the various functional modules of the system according to the requirements of practical system.After a lot of simulation work with Matlab,Vivado and Modesim,we have designed a radar altimeter simulator based on FPGA hardware,400 M signal bandwith,pulse wid-th from 10 ns to 1us,pulse period from 100 ns to 10 us,2ns precision of digital delay,10 Hz precision of doppler modulation,and the output power between-100 dBm to-10 dBm.This radar simulator has already tested with a radar altimeter,satisfies the system requirements.