Study On Signal Processing Method In Frequency Modulated Continuous Wave Laser Ranging Technology

Frequency-Modulated Continuous Wave(FMCW)laser ranging is a medium-to-high-range high-precision ranging technology,which has the advantages of fast measuring speed,high measurement accuracy,non-cooperation,etc.The measurement accuracy can reach the order of several tens of micrometers,and the current non-cooperative target laser measurement The field has the highest measurement accuracy.According to the ranging principle of the FMCW laser ranging technology,the measurement of the distance is actually the measurement of the frequency of the echo intermediate frequency signal.In this paper,the signal processing algorithms of FMCW laser ranging technology are studied,including digital filtering,error compensation and frequency solving.At the same time,the signal acquisition and processing circuits are realized.The research and main achievements of this paper are as follows:A brief and concise analysis of the principle of FMCW laser ranging technology is given,and the factors affecting the ranging accuracy and ranging resolution are pointed out.According to the characteristics of the measurement signal,the corresponding digital filter is designed.Combined with the specific application of the project,the general flow and design points of the filter design are given.Finally,it is implemented on the FPGA,and the corresponding verification method is given.The source and characteristics of the nonlinear phase error of the measured signal are analyzed theoretically.Based on this,the time domain phase difference amplification compensation algorithm is proposed to compensate the nonlinear phase error.The effectiveness of the time domain phase difference amplification compensation algorithm to compensate the phase error is proved theoretically and experimentally.The hardware implementation method of time domain phase difference amplification compensation algorithm is studied and the specific process of implementation is designed.The dual-window all-phase FFT spectrum correction algorithm is applied to FMCW laser ranging.The algorithm principle of frequency measurement based on all-phase FFT time-lapse phase difference spectrum correction method is introduced.The effect of the setting of the all-phase FFT calculation parameters on the frequency measurement is discussed.The corresponding frequency-modulated continuous wave laser ranging experiment is designed to verify the time domain phase difference amplification compensation algorithm and the all-phase FFT spectrum correction algorithm.The uncertainty of the measurement results after the new algorithm is analyzed,and then the measurement accuracy is The improvement was verified.The experimental results show that the frequency-modulated continuous wave laser ranging system can effectively improve the measurement accuracy and measurement repeatability by using the algorithm studied in this paper.At the same time,the anti-interference ability of the algorithm is also improved.At the time of writing this paper,the signal processing method in the paper has been applied to the FMCW laser radar and tested at the National Institute of Metrology.The test procedure and test data are given in the appendix.