全相位FFT频率测量在调频激光测距技术中的应用

调频连续波激光测距技术在常见的非合作目标激光测距技术中,目前具有最高的测量精度,其原理是对激光的光频进行线性调制,通过测量发射信号和回波信号的频率差反推目标的距离。因此频率测量精度对于距离测量精度具有决定性影响。传统FFT由于存在频谱泄露,且频谱细化方法从根本上受限于FFT的精度,导致测量精度低。全相位FFT较好的解决了频谱泄露的问题,具有相位不变性。本文提出将全相位FFT方法应用于调频激光测距,采用时移相位差法对频率进行测量,在MATLAB环境下对试验获取的数据进行频率解算并计算目标距离。试验证明,全相位FFT应用于调频激光测距数字信号处理时,在大于50m距离处测距误差小于0.3mm,达到了良好的应用效果。

Application of All Phase FFT Frequency Measurement in FMCW Laser Ranging Technology

The Frequency-Modulated-Continuous-Wave laser ranging technology has the highest measurement accuracy in the common non-cooperative target laser ranging technology. The principle is to linearly modulate the optical frequency of the emitted laser. Calculate the distance of the target by measuring the frequency difference between the transmitted signal and the echo signal. Therefore, the accuracy of frequency measurement has a decisive influence on the accuracy of distance measurement. Due to the spectral leakage of the conventional FFT, the measurement accuracy is low, and the spectrum refinement method is fundamentally limited by the accuracy of the FFT. The all-phase FFT solves the problem of spectrum leakage and has the property of phase invariance. In this paper, the all-phase FFT method is applied to the frequency measurement of FMCW laser ranging. The frequency is measured by the time-shift phase difference method. The actual measured data is solved the MATLAB environment to calculate the target distance. Experiment shows that when the full-phase FFT is applied to the frequency modulation laser ranging digital signal processing, the ranging error is less than 0.3mm at a distance greater than 50 m, which achieves a good application effect.