相位法激光测距的测量精度与鉴相环节密切相关,实现高精度的距离测量要求鉴相器能够准确测量高频率调制信号之间的相位差。研究了使用正交解调的方法测量相位差,通过对测量信号和参考信号进行正交解调处理获得与相位差相关的直流偏置电平,采样并计算即可得到相位差测量结果。使用移相器配合两个正交解调模块,综合两个模块的测量结果,可以保证测量精度并分辨两路信号之间的超前滞后关系。通过实验验证,当信号频率为100 MHz,信号幅度为80 dBμV时,相位差的测量误差在-1°～1°。

The precision of phase measurement method is closely related to phase-shift laser-ranging. It is required that high precision phase-shift measurement between high frequency modulated signals for laser-ranging. In this paper, the I/Q demodulation method is used to measure the phase-shift, and the DC bias level obtained by I/Q demodulation of the measured signal and the reference signal is related to the phase-shift. The phase-shift measurement result can be obtained by sampling and calculating. With the phase shifter and two I/Q demodulation module, measurement accuracy can guaranteed and the lead lag relationship between the two signals can be distinguished by combining the two groups of measurement results. Experiments results show that when the signal frequency is 100 MHz, the signal amplitude is 80 dBμV, the phase difference measurement error within ±1 °.