基于经典小波变换的布里渊光时域反射计光信号处理

布里渊光时域反射计结构的布里渊散射分布式光纤传感器检测的是自发散射光,信号非常微弱,而且频带在几十兆赫兹以上,难以应用普通相干解调方法。针对传感散射光信号特点,提出基于经典(Morlet)小波变换的光相干检测方法。首先采用微波电光调制产生频移参考光和自发布里渊散射光进行相干检测,再应用经典小波变换进行散射光信号的幅度解调,得到信噪比改善的布里渊散射传感光信号。给出了数值模拟和实验数据处理结果,表明经典小波变换能较好地处理布里渊光时域反射计检测信号。并和基于希尔伯特(Hilbert)变换的传感信号处理方法进行了对比,发现此方法优于基于希尔伯特变换的信号处理。

Optical Signal Processing in Brillouin Optical Time Domain Reflector Based Morlet Wavelet Transform

It is spontaneous scattering light that the optical time domain reflector(OTDR) based on Brillouin scattering distributed optical fiber sensor detects,which is very weak,and has a frequency width of several decades megahertz,so it is difficult to perform traditional coherent demodulation.A novel optical coherent detection based on Morlet wavelet transform is presented according to the signal's characteristic.Firstly,the spontaneous Brillouin back-scattering light is coherently detected with the frequency-shifted light modulated by a microwave electric optical modulator as the reference light.Secondly,the detected photocurrent signal is processed with amplitude demodulation by Morlet wavelet transform.Finally,the distributed sensing signal with improved signal-noise ratio is gained.The simulation and experimental results of the detection method are given,and the proposed method can process the Brillouin optical time domain reflector signal quite well.The methods based on Morlet wavelet transform and Hilbert transform respectively are compared,and it is found that the former is better for Brillouin optical time domain reflector.