The Signal Generation, Acquisition And Transmission System Of The Security Inspection Radar Is Realized

The millimeter wave imaging security system has the characteristics of high resolution,strong recognition ability,high security,fast scanning imaging and privacy protection.It is a major trend in future security inspection systems.The quality of the millimeter wave transmitted signal,the effect of the echo signal acquisition,and the accuracy of the acquired data transmission will directly or indirectly affect the final imaging.This paper will design and implement its signal generation and data acquisition and transmission system with the millimeter wave imaging security radar as the background.This paper first analyzes the performance requirements and indicators proposed by the signal generation and data acquisition and transmission system of millimeter wave security radar,designs the software and hardware implementation scheme of the system,gives the system structure block diagram and workflow.On the basis of the design scheme,dividing the system into different modules according to the logic function,and the specific modular design is carried out.Aiming at the limitation of DDS output signal frequency,the scheme of parallel DDS technology to generate wideband signal is proposed.The synthesis process of sinusoidal signal,chirp signal and step frequency signal is analyzed.The correctness of signal synthesis theory is verified by MATLAB.Then based on the FPGA platform,the wideband chirp signal,step frequency signal and point frequency signal are generated by the high-speed digital-to-analog converter AD9739.The echo signal is acquired by the high-speed analog-to-digital converter ADS5474.Analyze the implementation logic of AXI4 protocol,realize the conversion of streaming data to AXI4 data based on Verilog language.The DDR3 read/write control logic is designed,and the collected data is buffered to the DDR3 memory through the AXI4 interface.After that,the DMA controller is implemented,and controls data to upload from the DDR3 memory to the host computer memory through the PCIE3.0 interface.Using 8 solid-state hard disks to form a disk array in RAID0 as a storage solution solves the problem that the disk read/write speed is lower than the data collection speed.Finally,the system is tested for function.Firstly,each module is tested separately.Then the system is adjusted,and the data collected by PCIE to the host computer is analyzed.The integrity and accuracy of the data are verified,which proves the reliability of the system implemented in this paper.After testing,the system can generate stable wideband signals according to predetermined indicators.The acquired waveforms have no burrs,and the achieved PCIE3.0 data transmission interface rate can reach 4.5 GB/s,which meets the requirements of imaging systems and can be applied to most high-speed acquisition transmission scenarios.