Study Of Laser Doppler Vibration Measurement Based On FPGA

In the process of the application and development of modern engineering,it is necessary to carry out high-precision non-contact measurement of the vibrating object.At the same time,the rapid development of computer science,optical devices and chip manufacturing has enabled this measurement technology to be realized.FPGA relies on its advantages of high integration and high speed to become the core of the whole system design and the ideal choice of signal processing.In this paper,the SPARTAN-6 of Xilinx company is used as the signal processing core of the control box of the whole system.The whole system is divided into three parts: vibration signal acquisition module,weak signal conditioning module,and vibration signal digital processing module.The vibration signal acquisition module completes the 80 MHz heterodyne design of the optical system based on the laser Doppler technology,and achieves the information acquisition of the vibrating object through the optical system.The weak signal conditioning module performs the processing of amplification,high pass filtering,demodulation,low pass filtering and A/D conversion for the electrical signals collected by the photodetector.The digital signal processing module of FFT operation on the digital signal,and other modulo operations using CORDIC and DDR3 to SDRAM core board verification,real-time reading of data,all data processing is completed by USB to PC for subsequent processing and verification.Among them,ADC chip,demodulation chip,DDR3 SDRAM chip and USB chip have FPGA control.In addition,the system also includes peripheral circuits,such as clock,power supply,FPGA downloading configuration circuit and so on.Finally,we introduce the construction of optical system,get the experimental results of vibration signal through optical system,and further analyze the cause of the error.The test results show that the performance of the design is within the target requirements,and meets the design requirements.