一种基于微波光子信号正交锁定的测距方法

Ranging method based on orthogonal phase-locked microwave photonic signal

提出了一种基于微波光子信号正交锁定的测距方法,首先通过对目标反射回来的调制激光信号拍频获得电信号,然后和同频参考信号混频来提取携带距离信息的相位差。为提高测距精度,实验中使用信号源扫频,找到微波光子信号和射频参考信号的相位正交点,此时混频器输出直流信号功率最小,通过测量相邻两个正交点间的频差即可计算出测量距离。实验中对两种长度的光纤进行了多次测量,验证了测距方案且取得了相对误差小于3e-4的较高精度。

A ranging method based on orthogonal phase-locked microwave photonic signal is proposed in this paper.A RF signal is first obtained from a modulated optical signal that is reflected by the target,and then mixed with the reference RF signal of the same frequency to extract their phase difference, which contains the ranging information.To improve the ranging accuracy, the frequency of the RF signal is swept to seek out the phase quadrature point between the microwave photonic signal and the reference signal, where the DC output of the mixer is minimum. In this way,the distance measurement can be achieved by calculating the frequency difference between two adjacent phage quadrature points.The ranging method is verified by measuring two lengths of fiber reDeatedlv and achieved a high precision with a relative error less than 3e-4.