Design And Implementation Of Millimeter Wave Synthetic Aperture Radiometer Data Processing System

Millimeter-wave imaging technology has all-weather operation and item penetration capability,so it has high application value in remote sensing,medical,security,military and other fields.Among many passive millimeter wave imaging systems,synthetic aperture radiometer has a high technical advantage by equating small-aperture array antennas into large-aperture antennas with the help of synthetic aperture technology.However,the large number of receiving channels and data processing operations,resulting in a large data throughput and high complexity of computing,limit the real-time imaging applications of synthetic aperture radiometer.In order to realize the synthetic aperture imaging inversion with good real-time,we need to design and implement the synthetic aperture data processing system with a special data computing platform to accelerate the imaging process by parallel computing.Field programmable gate array(FPGA),as a hardware programmable special integrated circuit,can be relied on to accelerate the computational speed of the data processing system,and its programmable feature also enables flexible iterative design.Therefore,this paper intends to study the synthetic aperture data processing system based on FPGA platform and existing data processing system,and realize the synthetic aperture data processing system with high definition and good real-time performance by using FPGA for complex correlation and imaging inversion operation.The specific research of this paper includes:(1)Designing a synthetic aperture data processing system for millimeter wave signal acquisition and computing.The system acquires the orthogonal downconverted signals from the synchronous interference receiver through a high-speed data acquisition card,obtains the visibility function of the target scene through the complex correlation operation on the data computing platform,and inverse the millimeter wave image of the target scene from the visibility function with the help of the corresponding imaging algorithm.(2)Parallel acceleration design for synthetic aperture data operation based on FPGA platform.According to the synthetic aperture imaging inversion process and the characteristics of FPGA operations,the accelerated design and implementation of synthetic aperture complex correlation,MFFT imaging inversion and MP generalized inverse operations are carried out.The experimental results show that the FPGA-based data processing algorithm has high inversion accuracy and fast imaging speed,and its operation results are basically the same as the MATLAB fixed-point operation results,which can meet the demand for real-time synthetic aperture imaging inversion.(3)To address the problem of high sensitivity of the distance parameter of the imaging model in the near-field synthetic aperture imaging inversion,a self-correcting imaging method based on error evaluation is proposed.According to the synthetic aperture near-field imaging characteristics of the imaging target for sharpness correction,to achieve a more accurate reconstruction of the target scene inversion.The experimental results show that the error-evaluated self-corrected imaging method can effectively correct the actual millimeter-wave images,and the imaging inversion results have higher definition.