Research On Wideband Radar Transmitter Technology Based On SDR

With the increasing complexity of the battlefield electromagnetic environment,the electronic warfare systems often require transmitter systems to transmit signals with multiple parameters and configurable software,and have the function of transmitting wideband signals.For example,in order to verify the function of a signal recognition system in a radar reconnaissance system,it is necessary to simulate complex electromagnetic environment test,or to jam multiple radar devices in jammer system.To meet the above requirements,this paper researched a wideband radar transmitter system based on Software Defined Radio(SDR).Firstly,this paper introduced the related theoretical basis of wideband channelized transmitter of software radio.The structure of channelized transmitter with complex signal output and real signal output were deduced mathematically and theoretically.The transmitter had simple structure and high computational efficiency.Then the Peak to Average Power Ratio(PAPR)problem in channelized transmitter was studied,It was concluded that PAPR is affected by the number of channelization.The PAPR suppressed by the amplitude limit method,which can effectively reduce PAR,but it also brings spectrum distortion.Secondly,to solve the problems of low spectrum utilization and high hardware implementation complexity caused by the transition band of filter in the poly-phase channelized transmitter system,this paper improved and optimized the system by Frequency Response Masking(FRM)technique.The complex exponential modulation FRM design methods were deduced.The structure of channelized transmitter whose output was real signal based on complex exponential modulation FRM was deduced,and two different structure models were given.The correctness of the transmitter structure was verified by simulation.The complexity of each structure model and the system delay index of the novel structure were compared with other channelized transmitter structures,it is concluded that the two structures deduced in this paper have their own advantages and disadvantages and their respective application occasions.Finally,the architecture was designed and implied on Field-Programmable Gate Array(FPGA).A flexible and real-time configurable Linear Frequency-Modulated(LFM)signal generator system was designed and implemented by Direct Digital Synthesy(DDS).Then a wideband LFM signal generator system based on multi-channel DDS was designed and implemented by using the method of poly-phase decomposition.The design and implementation of poly-phase structure channelized transmitter system and complex exponential modulation FRM-based channelized transmitter system based on FPGA were completed by System Generator.The resource consumption ratio of the two structures was carefully analyzed and compared,it was proved that the channel transmitter structure based on complex exponential modulation FRM can reduce the hardware multiplier resources from the hardware implementation point of view.