提出一种基于硬件的等光频间隔采样消除调频连续波(FMCW)激光测距系统调频非线性的改进措施。改进后的等光频间隔采样通过硬件数据采集即可一步实现, 无需再进行后续繁杂的软件处理过程, 极大地节省了内存空间和数据处理时间, 并且较之基于软件的等光频间隔重采样方法采样位置更准确。研究了调频非线性对调频连续波激光测距系统测距精度的影响以及等光频间隔采样消除调频非线性的原理。在此基础上, 针对等光频间隔采样方法在时域上为非均匀采样, 传统频谱分析方法不再适用的问题, 对其进行新的频谱分析, 并推导出了重采样之后频谱峰值频率计算公式以及测距系统的距离求取公式, 通过仿真验证了新的频谱分析公式的正确性。实验结果表明, 基于硬件的等光频间隔采样方法比基于软件的等光频间隔重采样方法更简单并且具有更好的非线性消除效果、更高的测距分辨力和稳定性。

An improved nonlinearity correction algorithm by hardware-based equispaced-phase resampling for frequency modulated continuous wave (FMCW) ranging system was proposed. After improvement, equispaced-phase resampling method could be realized in one step by hardware data acquisition. No subsequent complex data processing is needed any more, which will save much memory space and data processing time. Moreover, compared with software-based equispaced-phase resampling method, the improved method had higher sampling accuracy. The effect of nonlinear frequency modulation on ranging precision of FMCW ranging system and the principle of equispaced-phase resampling for nonlinearity correction were explored. On this basis, a new spectral analysis method was presented for the reason that the equispaced-phase resampled data was not equally spaced in time domain and the traditional spectral analysis method is no longer applicable. The computational formulas of peak spectral frequency and object distance were deduced. Their correctness was verified by simulation. Experimental results show that equispaced-phase resampling based on hardware has higher ranging precision and resolution than equispaced-phase resampling based on software, and the former is simpler.