Diagnosis and recognition of vibration interference in distributed laser methane detection system

In order to eliminate influences of external vibration on distributed laser methane detection system, based on analysis of frequency characteristics of vibration waveform and influences of vibration on physical properties of fiber and methane detection, a vibration waveform recognition algorithm based on real-time sampling signal and set frequency signal was proposed. The algorithm can effectively identify external vibration waveforms with different frequencies by steps including Fourier transform, cross-correlation operation, maximum similarity coefficient judgment and methane concentration calculation, and then the vibration waveform can be accurately deleted and the influences of external vibration on methane concentration measurement can be eliminated. The laboratory test and industrial test results show that the algorithm can effectively identify the vibration interference with different frequencies and avoid measurement error introduced by vibration signal.