为了对西藏人烟稀少地区和单跨段传输距离很长的光纤链路进行检测，文章提出一种用于提高线性调频（LFM）光时域反射仪（OTDR）空间分辨率和测量距离的方法。该方法通过产生一个调频范围为200 MHz、脉冲宽度为20 μs的强度调制模拟LFM信号来实现高的空间分辨率和大的探测距离。使用该方法在西藏地区的实际光纤传输链路中进行了实验测试，实验结果表明，该方法能够在长度为240 km的光纤链路上实现0.000 53 km的空间分辨率，与相同测量参数的单脉冲OTDR相比，动态范围提高了8.5 dB。

In order to monitor the fiber-optic links in Tibet, which are sparsely populated and have long transmission distances. This paper presents a method of improving the spatial resolution and measuring the distance of a Linear Frequency Modulated (LFM) Optical Time Domain Reflectometry (OTDR). The method achieves high spatial resolution and large detection distance by generating an intensity modulated analog chirp signal with a frequency range of 200 MHz and a pulse width of 20 μs. Experiments are carried out on the actual fiber-optic transmission link in Tibet using this method. The experiment results show that the method can achieve a spatial resolution of 0.000 53 km on a fiber link with a length of 240 km. And compared with the single pulse OTDR with the same measurement parameters, the dynamic range is improved by 8.5 dB.