Signal Processing Technology In FMCW Laser Distance Measurement System Based On DSP

This article has developed the signal processing technology in Frequency Modulated Continuous Wave(FMCW) laser distance measurement system and designed hardware electric circuits and programmed the software algorithm based on the embedded processor of DSP.Firstly, according to the ranging principle of triangular wave frequency modulation, the scheme for system has designed. The frequency spectrum refinement algorithm is selected to improve the range accuracy after the simulation and comparsion of Time domain method of zero padding and Chirp-Z transform. And the decision method with normalized spatial spectrum has been designed to distinguish the smoke interference of laser. Then the signal processing algorithm is realized based on TMS320F28335 DSP which is the main processor in the system with the main function of changing the time domain signal to frequency domain signal.The article has produced the circuit of signal processing minimum system of FMCW laser distance measurement: the power module, clock module and reset module of DSP, the external memory module, ADC onditioning circuit and SCI communication module. Then the signal processing algorithm has been designed and programmed on the DSP hardware platform. The algorithm procedure consists of ADC, FIR, FFT, the decision method of smoke interference, Chirp-Z transform and SCI.Finally, the paper has completed the test of TMS320F28335 minimum system and FMCW Laser Distance Measurement principle prototype. Through the ranging experiment of different target, different intersection angles and smoke interference, the FMCW Laser Distance Measurement principle prototype can measure the distance of diffusely target between 3m to 13 m. The results showed that the maximum error of distance is ?0.26 m and the mean square error is 0.158 m by the spectrum zooming algorithm.