Research And Implementation Of Multi-target Ranging And Positioning System Based On FMCW Radar

Wireless positioning and identification technology are widely used in positioning,navigation,logistics management and other fields,occupying an important position in people's daily life and industrial production.Because of its advantages of high accuracy,low cost,small size,easy implementation and strong concealment,Frequency Modulated Continuous Wave Radar(FMCW)is widely used in ranging and positioning,radar imaging,unmanned driving,missile guidance and other fields among the current ranging technologies that can realize wireless positioning.This paper studies the working principle of the traditional FMCW radar.An improved method is proposed to solve the problem that the FMCW radar cannot implement identity recognition.This method adds an active tag to the measured object based on the linear FMCW radar,realizing the user identification through code division multiple access technology,and uses the characteristics that spread spectrum code has different autocorrelation values at different frequency offsets to achieve distance measuring.Besides,a fast algorithm of identity recognition and ranging is designed.The algorithm uses a two-dimensional search synchronization method,by superimposing signals at different frequency points to reduce the times of searches,and then uses FFT to achieve fast correlation operations to complete identification,and finally iterates through the dichotomy method to improve the accuracy of the ranging.The algorithm shortens time required for measurement.This paper designs and implements a hardware platform which can verify the method on the basis of MATLAB system simulation,implementing the identification and ranging algorithm based on FPGA,developing the data processing and the control system through MCU.Simulation and test results show that the method can measure the distance of multiple targets and obtain their identities at the same time.At 200 MHz of the radar sweep bandwidth,163.84 us of the sweep period,30 dB of the spreading gain,and-15 dB of the signal-to-noise ratio,the average absolute error of the ranging is 1.12 cm,the probability of the error within 1cm is 52.58%,the probability of being within 10 cm is 99.73%.