Research On Signal Processing Method Of Laser Doppler Velocimetry

Laser Doppler velocimetry technology has the advantages of non-contact,fast dynamic response,high precision and is widely used in aerospace,medical equipment,industrial measurement and other fields.However,there are few related products in China,and many related products have been produced abroad.The extraction of Doppler shift largely determines the accuracy of Doppler velocity measurement.Therefore,the Doppler velocimetry signal processing method is studied in this paper.The main contents of this paper include:The laser Doppler dual beam double scattering optical path is adopted.Selection of optical elements is completed.The structure design of Doppler velocimetry is completed,and the optical path and circuit are encapsulated.A digital signal processing algorithm based on FFT is designed.The adaptive filtering band algorithm is used to filter out the basal signal of Doppler signal.An adaptive sampling frequency algorithm is proposed,which realizes the adaptive conversion of sampling frequency and enhances the speed range of the system.FFT is combined with the spectrum thinning algorithm and the ratio spectrum correction algorithm to realize accurate frequency extraction of the Doppler signal.The design of signal processing circuit is completed with FPGA as the core.The amplification and filtering circuit are designed,which realized the amplification and filtering of Doppler signal.The AD conversion circuit is designed,which realized the conversion of analog signal to digital signal.The UDP communication circuit is designed and PC software is designed.The communication between FPGA and PC is realized,and the real-time display of object speed and length information is realized.Under laboratory conditions,the calibration of system parameters is completed.Through the accuracy verification experiment,the feasibility of the Doppler signal processing algorithm designed in this paper is verified,and the measurement accuracy of the whole system is verified.The experimental results show that the system can measure the speed and length information in real-time,and the accuracy of the length measurement is better than 0.1%.