A wavelength modulation spectroscopy (WMS) setup for long-range methane measurements in the atmosphere over distances of kilometers was developed. To overcome the influence on the signal from noise, random factors and air turbulence, we applied denoising processing methods, which were analyzed and compared. The real-time digital Kalman filter was selected and utilized, improving the detection limit for methane sensing from 60 ppb with integration time of 60 s to 2 ppb with integration time of 1 s. To our knowledge, this is the first realization of such highly sensitive and yet simple sensor by combining the real-time filter and WMS. This approach opens the possibility to replace much more complicated instruments in sensitive measurements of trace gases when evaluating the experimental data with the Kalman filter.

开发了一种波长调制光谱（WMS）装置，用于在几千米的距离内对大气中的甲烷进行远距离测量。为了克服噪声，随机因素和空气湍流对信号的影响，我们采用了降噪处理方法，对其进行了分析和比较。选择并使用了实时数字卡尔曼滤波器，将甲烷感测的检测限从60 ppb（积分时间为60 s）提高到2 ppb（积分时间为1 s）。据我们所知，这是通过结合实时滤波器和WMS首次实现这种高灵敏度且简单的传感器。当使用卡尔曼滤波器评估实验数据时，这种方法为在痕量气体的灵敏测量中替代更复杂的仪器提供了可能性。