A distributed acoustic sensing with digital differential coherent optical time-domain reflectometry based on heterogeneous dual-sideband linear frequency-modulated (LFM) pulse is proposed. The positive and negative LFM signals are loaded on the upper and lower optical sidebands respectively. The loaded signals with the same spectrum width but opposite slope chirps will result in an opposite interference pattern movement. By performing the digital difference on the phase demodulation results of the two sidebands, the sensitivity at 1 kHz is doubled at least and the suppression of 27.26 dB in the low-frequency common-mode phase drift noise is obtained at 10 Hz.

中文翻译：

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基于异质双边带LFM脉冲的相干OTDR感测的相移噪声抑制

提出了一种基于异质双边带线性调频脉冲的数字差分相干光时域反射法分布式声学传感技术。正和负LFM信号分别加载在上部和下部光学边带上。具有相同频谱宽度但反向斜率rp的加载信号将导致相反的干扰方向图运动。通过对两个边带的相位解调结果进行数字差分，可以将1 kHz的灵敏度至少提高一倍，并在10 Hz的频率下获得27.26 dB的低频共模相位漂移噪声抑制。