Aiming at the quadrature unbalance phenomenon in the phase-sensitive optical time domain reflectometry ( Φ\Phi -OTDR) system, a method of quadrature unbalance compensation for the Φ\Phi -OTDR system based on the recursive least square (RLS) algorithm is studied and demonstrated to improve the accuracy of the demodulated phase waveform. Firstly, the DC residual term of the quadrature imbalance is eliminated by calculating the mean value of the envelope. Further, the cyclic symmetry of the AC orthogonal unbalance is tracked to complete parameter estimation, and then the orthogonal unbalance correction is completed through an adaptive filtering method. The experimental results show that under the condition of the detection light pulse with a repetition frequency of 5 KHz and a pulse width of 100 ns, the RLS compensation algorithm greatly improves the demodulation characteristics of the system and suppresses the quadrature imbalance. It is of great significance to the practical process of the Φ\Phi -OTDR system.

中文翻译：

---

基于RLS算法的朵-OTDR系统正交不平衡补偿方法


针对相敏光时域反射仪( Φ\Phi -OTDR)系统中的正交不平衡现象，研究了一种基于递归最小二乘(RLS)算法的Φ\Phi -OTDR系统正交不平衡补偿方法并证明可以提高解调相位波​​形的精度。首先，通过计算包络均值来消除正交不平衡的直流残差项。进一步跟踪交流正交不平衡的循环对称性，完成参数估计，然后通过自适应滤波方法完成正交不平衡校正。实验结果表明，在探测光脉冲重复频率为5 KHz、脉冲宽度为100 ns的条件下，RLS补偿算法极大地改善了系统的解调特性，抑制了正交不平衡。这对于Φ\Phi-OTDR系统的实用化进程具有重要意义。