Research On High Resolution Vehicle Frequency Modulated Continuous Wave Synthetic Aperture Imaging Method

As a cutting-edge radar imaging technology,SAR imaging plays an important role in aviation,aerospace,remote sensing and other fields.The traditional SAR imaging technology uses pulse wave as the transmitting signal.Pulse radar transmits narrow-pulse signals,which have high peak power,so the range of pulse radar will be very long.However,high peak power will also bring high power consumption and large volume.Compared with pulse wave,FMCW has the advantages of light weight,low power consumption,small size and high resolution.Therefore,FMCW SAR technology has the greatest research significance.Nowadays,FMCW SAR imaging technology is widely used in environmental protection,disaster monitoring,agricultural development,military exploration,geology,literature,oceanography and other fields.With the development of science and technology,more and more people begin to use cars.The invention of cars not only brings convenience to people’s life,but also brings frequent traffic accidents.In order to reduce or avoid traffic accidents,this paper studies vehiclemounted FMCW SAR,and realizes high-resolution imaging of vehicle-mounted scenes by relying on the all-weather and all-day working characteristics of SAR,so as to improve the platform’s ability to obtain road information around the vehicle body in extreme weather such as fog,night,rainstorm and snowstorm.The main research work of this paper is as follows:According to the characteristics of vehicle-mounted FMCW SAR system,the imaging geometric model of vehicle-mounted FMCW SAR system was established,and the echo signal model of vehicle-mounted FMCW SAR system was deduced according to the geometric model of vehicle-mounted FMCW SAR system and the characteristics of FMCW signal.The characteristics of the vehicle-mounted FMCW SAR system were analyzed,and the key problems faced by the vehicle-mounted FMCW SAR system were proposed.Based on the key problems,this paper modified the traditional RDA algorithm and RMA algorithm,and deduced the RDA algorithm and RMA algorithm suitable for the vehicle-mounted FMCW SAR system.Verify whether RDA algorithm and RMA algorithm can be applied to FMCW SAR system.In the actual process of vehicle platform non-ideal movement,radar instability,uneven road surface caused by vehicle bumps and other phenomena will make the actual car body track deviated from the ideal track,resulting in the data is not ideal and resulting in the image focusing quality decline.In this paper,compared with the characteristics of the traditional airborne motion error,the motion error expression based on the vehicle is deduced,and the Mo Co algorithm is proposed,and the Mo Co algorithm is used to correct the errors caused by speed and direction.Based on traditional MD algorithm,proposed by distance unit to evaluate,the method of using the improved MD algorithm to estimate doppler rate,the PGA algorithm is adopted to distortion after image error estimation and compensation,the motion compensation algorithm was combined with RDA algorithm,the whole process of algorithm is derived,and by spoil derivative according to the simulation experiment,Verify the effectiveness of motion compensation algorithm in vehicle-mounted FMCW SAR system.Finally,the measured data are used to verify the correctness of RDA algorithm,RMA algorithm and motion compensation algorithm.