相位敏感光时域反射计(Phase-sensitive Optical Time Domain Reflectometer,Φ-OTDR)是一种新型的分布式光纤传感技术,在周界安防入侵和建筑结构健康监测等领域具有广泛应用.针对Φ-OTDR的传感原理,根据其系统结构及信号处理,总结了Φ-...相位敏感光时域反射计(Phase-sensitive Optical Time Domain Reflectometer,Φ-OTDR)是一种新型的分布式光纤传感技术,在周界安防入侵和建筑结构健康监测等领域具有广泛应用.针对Φ-OTDR的传感原理,根据其系统结构及信号处理,总结了Φ-OTDR系统在光源技术、传感头技术、探测技术、复用技术和信号处理技术方面的进展,并对其进行了简要分析.展开更多
Overlapped time domain multiplexing(OvTDM)is an innovative encoding scheme that can obtain high spectral efficiency.However,the intentional inter-symbol interference(ISI)caused by OvTDM will make the decoding process ...Overlapped time domain multiplexing(OvTDM)is an innovative encoding scheme that can obtain high spectral efficiency.However,the intentional inter-symbol interference(ISI)caused by OvTDM will make the decoding process more complex.The computational complexity of maximum likelihood sequence detection increases exponentially with the growth of spectral efficiency in OvTDM.As a consequence of high complexity,the decoding effort for a given spectral efficiency may occasionally exceed the physical limitations of the decoder,leading inevitably to buffer overflows and information erasures.In this paper,we propose a bidirectional Viterbi algorithm(BVA)based on the bidirectional sequence decoding for OvTDM.With the BVA,the decoding operation starts simultaneously from the both ends of the corresponding trellis and stops at the middle of trellis.The simulation results show that compared with Viterbi algorithm(VA),the decoding time of BVA can be reduced by about half.And the memory space of two decoders in BVA are about half of that in VA,which means that the BVA has lower memory requirements for decoder.And the decoding performance of BVA is almost the same as VA.展开更多
光栅定位是大规模超弱光纤光栅阵列制备及铺设质量检测的关键技术之一。针对传统光时域反射仪定位超弱光栅时存在的问题,提出了一种超弱光栅阵列的相位-强度二维定位方法。该方法采用光栅时域反射技术查询阵列中的单体光栅,通过调节选...光栅定位是大规模超弱光纤光栅阵列制备及铺设质量检测的关键技术之一。针对传统光时域反射仪定位超弱光栅时存在的问题,提出了一种超弱光栅阵列的相位-强度二维定位方法。该方法采用光栅时域反射技术查询阵列中的单体光栅,通过调节选择脉冲和入射脉冲之间的相位差,捕捉反射信号的光强峰值,实现对目标光栅的准确定位。构建了超弱光栅阵列的定位系统,对1009个平均反射率-34 d B、间隔2.5 m的超弱光栅阵列进行了定位实验,定位误差小于10 cm。展开更多
文摘相位敏感光时域反射计(Phase-sensitive Optical Time Domain Reflectometer,Φ-OTDR)是一种新型的分布式光纤传感技术,在周界安防入侵和建筑结构健康监测等领域具有广泛应用.针对Φ-OTDR的传感原理,根据其系统结构及信号处理,总结了Φ-OTDR系统在光源技术、传感头技术、探测技术、复用技术和信号处理技术方面的进展,并对其进行了简要分析.
文摘Overlapped time domain multiplexing(OvTDM)is an innovative encoding scheme that can obtain high spectral efficiency.However,the intentional inter-symbol interference(ISI)caused by OvTDM will make the decoding process more complex.The computational complexity of maximum likelihood sequence detection increases exponentially with the growth of spectral efficiency in OvTDM.As a consequence of high complexity,the decoding effort for a given spectral efficiency may occasionally exceed the physical limitations of the decoder,leading inevitably to buffer overflows and information erasures.In this paper,we propose a bidirectional Viterbi algorithm(BVA)based on the bidirectional sequence decoding for OvTDM.With the BVA,the decoding operation starts simultaneously from the both ends of the corresponding trellis and stops at the middle of trellis.The simulation results show that compared with Viterbi algorithm(VA),the decoding time of BVA can be reduced by about half.And the memory space of two decoders in BVA are about half of that in VA,which means that the BVA has lower memory requirements for decoder.And the decoding performance of BVA is almost the same as VA.
文摘光栅定位是大规模超弱光纤光栅阵列制备及铺设质量检测的关键技术之一。针对传统光时域反射仪定位超弱光栅时存在的问题,提出了一种超弱光栅阵列的相位-强度二维定位方法。该方法采用光栅时域反射技术查询阵列中的单体光栅,通过调节选择脉冲和入射脉冲之间的相位差,捕捉反射信号的光强峰值,实现对目标光栅的准确定位。构建了超弱光栅阵列的定位系统,对1009个平均反射率-34 d B、间隔2.5 m的超弱光栅阵列进行了定位实验,定位误差小于10 cm。
