基于平均周期图法提高光纤光栅微弱振动信号检测能力的研究

High Sensitive Fiber Bragg Grating Vibration Sensor Based on Averaged Periodogram Method

光纤布拉格光栅(FBG)用于微弱振动检测时,当被测振动太微弱时系统输出传感信号的信噪比小于1,从时域采集的数据很难直接测得到信号的幅度和频率信息。提出一种信号处理方法,即将传感器在时域测量获得的连续数据分段后,对每段数据分别进行快速傅里叶变换获得其对应的功率谱信号,然后将频域信号做叠加平均得到新的数据。实验结果表明,采用这种频域叠加平均的方法处理后,FBG传感信号在频域内的信噪比提高了15.6dB,明显提升了微弱信号的检测能力。初步实验表明:该系统对FBG波长变化的检测灵敏度可提高到1.5fm。该信号处理方法特别适合噪声环境恶劣、被测信号以一定频率持续存在的工程应用领域,对实际环境下微小振动的识别与检测具有较大的意义。

Fiber Bragg grating （FBG） sensor monRor the micro-vibration in harsh environment is adopted. The micro-vibration cannot be detected when FBG sensor signal has low signal noise ratio （SNR） （less than 1）. The averaged periodogram method is used to improve the sensitive. It divides the signal into N segments, fast Fourier transform （FFT） is performed on each data segments, then averaging the N power spectrum to get the new power evaluation. The primary results show, SNR is improved by 15.6 dB in frequency domain after the treatment with averaged periodogram method, and the FBG detection sensitivity is up to 1.5 fro. This high-accuracy sensor can be used in sustained vibration detection in structural health monitoring. It is important to increase the detection accuracy of the micro-vibration.