Research On Implementation Technologies Of 5GHZ Radar And Communication Integrated System Based On OFDM

For a long time,the integrated platform has received extensive attention in both military and civil radio fields,for its high functional integration characteristics meeting the needs of miniaturization and integration.However,there are some problems to be solved.First of all,how does the system generate a waveform signal that combines radar information and communication information? Secondly,unlike the communication signal,the radar signal is not sensitive to the waveform distortion caused by non-linear character,while the communication information is very sensitive to all kinds of nonlinear distortion in the transmission channel.In order to ensure higher detection resolution,radar systems often need to have high radio frequency bandwidth,while communication systems often use narrowband communication in order to avoid channel fading.In order to solve the above problems,a fusion waveform scheme based on OFDM is studied.This scheme is designed to ensure a low output peak-toaverage ratio(PAPR),and the high-precision ranging algorithm in the case of small bandwidth.Combined with the integrated hardware platform,the corresponding measurement verification is carried out.Based on the above points,the main work and innovation of this paper are as follows.Firstly,the design requirements of integrated hardware platform under OFDM system are analyzed,and a high sensitivity transceiver hardware implementation scheme based on zero intermediate frequency architecture is given.Aiming at the problems of orthogonal amplitude and phase balance,carrier leakage suppression and low noise amplifier stability in transceiver hardware,the corresponding solutions and measured results are given in this paper.A new calibration method for carrier leakage suppression at the transmitter is proposed in this paper.the test results based on the AD9361 verification platform show that the carrier suppression performance of the calibration method is more than 5d B,which can effectively improve the reliability of the hardware platform.Secondly,a technical scheme of direct sequence spread spectrum processing for sources is proposed,which solves the problem of peak-to-average ratio of OFDM radar signals with integrated communication information.The research results show that the scheme can effectively reduce the fusion signal peak-to-average ratio(up to 8d B)under the condition of better communication performance,and obtain the desired pushpin signal ambiguity map of the radar system.In addition,this paper puts forward the implementation method of IFFT/FFT and RRC algorithm based on FPGA,which solves the problems of large amount of data calculation and poor real-time performance of the system.Thirdly,combined with the integrated software and hardware platform,the experimental verification of the system performance of many scenarios such as cable loop and antenna OTA is carried out,and the test results confirm the effectiveness of the integrated design method and hardware platform implementation scheme.