scholarly journals Distributed Sensing Based on Interferometry and Polarization Methods for Use in Fibre Infrastructure Protection

Sensors ◽  
2019 ◽  
Vol 19 (8) ◽  
pp. 1810
Author(s):  
Petr Munster ◽  
Tomas Horvath ◽  
Josef Vojtech
Keyword(s):  
Direct Detection ◽  
Average Power ◽  
Distributed Sensing ◽  
Acoustic Vibrations ◽  
Fibre Optic ◽  
Laboratory Measurements ◽  
Unexpected Events ◽  
Infrastructure Protection ◽  
Sensing Systems

Fibre optic infrastructures are very important, and therefore, it is necessary to protect them from fibre cuts. Most fibre cuts are caused by digging activity, and many network operators seek appropriate solutions enabling detection of possible unexpected events (predict these cuts) and subsequent network outages. In most cases, there is no need to locate events, and only information regarding the occurrence of the event is sufficient. Direct detection-based distributed fibre optic sensing systems appear to be an appropriate solution, allowing digging to be detected before the fibre breaks. The average power of such signals is relatively small, and there is no interference with other signals in the fibre. We performed laboratory measurements to compare the sensitivity and accuracy of interferometric and polarization systems for acoustic vibrations. In the case of interferometric systems, the reference and sensing arms were in the same cable, and both were subjected to acoustic vibrations.

A ten channel fibre-optic device for distributed sensing of underground hydrocarbon leakage

2000 ◽  
Vol 2 (6) ◽  
pp. 670-673 ◽  
Author(s):  
Laurie J. Ritchie ◽  
Clive P. Ferguson ◽  
Conrad Bessant ◽  
Selwayan Saini
Keyword(s):  
Distributed Sensing ◽  
Fibre Optic

A novel fitting algorithm for Brillouin scattering spectrum of distributed sensing systems based on RBFN networks

Optik ◽  
2013 ◽  
Vol 124 (8) ◽  
pp. 718-721 ◽  
Author(s):  
Yanjun Zhang ◽  
Guangwei Fu ◽  
Yin Liu ◽  
Weihong Bi ◽  
Da Li
Keyword(s):  
Brillouin Scattering ◽  
Distributed Sensing ◽  
Sensing Systems ◽  
Scattering Spectrum ◽  
Fitting Algorithm

scholarly journals Cooperative Spectrum Sensing Algorithm to Overcome Noise Fluctuations Based on Energy Detection in Sensing Systems

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Guicai Yu ◽  
Han Wang ◽  
Wencai Du
Keyword(s):  
Spectrum Sensing ◽  
Cooperative Spectrum Sensing ◽  
Signal To Noise Ratio ◽  
Average Power ◽  
Energy Detection ◽  
Detection Algorithm ◽  
Detection Sensitivity ◽  
Power Fluctuation ◽  
Sensing Systems ◽  
Noisy Signals

In sensing systems, nodes must be able to rapidly detect whether a signal from a primary transmitter is present in a certain spectrum. However, traditional energy-detection algorithms are poorly adapted to treating noisy signals. In this paper, we investigate how rapid energy detection and detection sensitivity are related to detection duration and average power fluctuation in noise. The results indicate that detection performance and detection sensitivity decrease quickly with increasing average power fluctuation in noise and are worse in situations with low signal-to-noise ratio. First, we present a dynamic threshold algorithm based on energy detection to suppress the influence of noise fluctuation and improve the sensing sensitivity. Then, we present a new energy-detection algorithm based on cooperation between nodes. Simulations show that the proposed scheme improves the resistance to average power fluctuation in noise for short detection timescales and provides sensitive detection that improves with increasing numbers of cooperative detectors. In other words, the proposed scheme enhances the ability to overcome noise and improves spectrum sensing performance.

PAPR Reduction for O-OFDM UOWC System

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Jurong Bai ◽  
Hang Dai ◽  
Feng Zhao ◽  
Yi Yang ◽  
Yanben Wang
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Direct Detection ◽  
Optical Transition ◽  
Average Power ◽  
Maximum Amplitude ◽  
Ofdm System ◽  
Wireless Optical Communication ◽  
Speed Up ◽  
Optical Ofdm ◽  
Papr Performance

AbstractIn this paper, a combination of Tone Reservation-Signal to Clipping noise Ratio (TR-SCR) and Companding schemes is proposed for underwater wireless optical communication (UOWC), in order to solve the problem of high peak-to-average power ratio (PAPR) of underwater Optical-Orthogonal Frequency Division Multiplexing (O-OFDM) system. Two optical modulation schemes, namely Direct Current-biased Optical OFDM (DCO-OFDM) and Asymmetrically Clipped Optical OFDM (ACO-OFDM), are adopted separately to achieve intensity modulation/direct detection over the seawater channel, with a distance of 100 meters of wireless optical transition to obtain the system bit error rate (BER). In the TR-SCR scheme, only the maximum amplitude signal is selected to reduce the complexity of the algorithm. The LSA method is introduced in the TR-SCR scheme for iteratively updating the signal to speed up the convergence. Finally, with the combination of the Companding scheme, the PAPR performance is significantly improved. The PAPR of the underwater optical OFDM system is reduced to 3.85 dB with its BER still satisfying the UOWC system requirements.

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