High stability time-frequency transmission over optical fiber

2012 ◽  
Author(s):  
Jianping Chen ◽  
Weiwen Zou ◽  
Guiling Wu
Keyword(s):  
Optical Fiber ◽  
High Stability ◽  
Time Frequency ◽  
Stability Time

scholarly journals Long-Distance Time Transfer in Optical Fiber Networks Using a Cascaded Taming Technology

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Ding Chen ◽  
Jiangning Xu ◽  
Yifeng Liang ◽  
Shan Jiang ◽  
Hongyang He
Keyword(s):  
Optical Fiber ◽  
High Precision ◽  
Wavelength Division Multiplexing ◽  
Time Synchronization ◽  
Atomic Clock ◽  
Process Time ◽  
Long Distance ◽  
Time Service ◽  
Time Frequency ◽  
Fiber Link

In order to meet the time service needs of high-precision, long-distance, and multinode optical network, this paper proposes a new time synchronization solution, which combines the wavelength division multiplexing (WDM) technology with cascaded taming clock technology. The WDM technology is used for time synchronization between each pair of master-slave nodes. In the system, there are two wavelengths on the fiber link between the master node and the slave node for transmitting signals. 1 plus per second (PPS) signal, time code signal, and 10 MHz signal are, respectively, and successively, sent to the optical fiber link. By solving the one-way delay through analysis of error contribution and link characteristics of the time transmission process, time synchronization of the master-slave nodes pair is achieved. Furthermore, the authors adopt cascaded taming clock technology to ensure accurate time synchronization of each node. A 700 km long-distance time-frequency synchronization system is constructed in the laboratory. The system uses a cesium atomic clock as the reference clock source and transmits the signals through 8 small rubidium atomic clocks (RB clocks) hierarchically. Results from the experiment show that the long-term time stability is 47.5 ps/104 s. The system’s structural characteristics and the experiment results meet the requirements to allow practical use of high-precision time synchronization in networks. This proposed solution can be applied in various civil, commercial, and military fields.

Event Discrimination Method for Distributed Optical Fiber Intrusion Sensing System Based on Integrated Time/Frequency Domain Feature Extraction

2019 ◽  
Vol 39 (6) ◽  
pp. 0628002 ◽  
Author(s):  
彭宽 Kuan Peng ◽  
冯诚 Cheng Feng ◽  
王森懋 Senmao Wang ◽  
艾凡 Fan Ai ◽  
李豪 Hao Li ◽  
...  
Keyword(s):  
Feature Extraction ◽  
Optical Fiber ◽  
Frequency Domain ◽  
Time Frequency ◽  
Sensing System ◽  
Distributed Optical Fiber ◽  
Discrimination Method

Numerical Analysis of Thermal Dependence of the Spectral Response of Polymer Optical Fiber Bragg Gratings

2016 ◽  
Vol 12 (1) ◽  
pp. 85-95 ◽  
Author(s):  
Hisham Hisham
Keyword(s):  
Optical Fiber ◽  
High Stability ◽  
Spectral Response ◽  
Fiber Bragg Gratings ◽  
Bragg Gratings ◽  
Bragg Reflector ◽  
Polymer Optical Fiber ◽  
Thermal Dependence ◽  
Silica Optical Fiber ◽  
Index Modulation

The thermal dependence of the spectral response (i.e. transmission, reflection and time delay ( r) responses) of uniform polymer optical fiber (POF) Bragg gratings has been investigated. In addition to the temperature dependence, the effects of grating strength (kLg) and fiber index modulation ( n) have been investigated. Besides high capability of tunable wavelength due to the unique large and negative thermo-optic coefficient of POF, the spectral response for POF Bragg gratings show high stability and larger spectrum bandwidth with temperature variation compare with the silica optical fiber (SOF) Bragg gratings, especially with the increase of the kLg value. It was found that by increasing kLg, the peak reflectance value increases and the bandwidth of the Bragg reflector become narrower. Also it’s shown by increasing the kLg value, r deceasing significantly and reach its minimum value at the designed wavelength ( B). Furthermore, the r for POF Bragg gratings is less than that for SOF Bragg gratings at the same value of kLg. Also it’s found that the peak reflectivity value increases to around 60% when the n value increases from 1*10-4 to 5*10-4.

A theoretical/numerical study on ultrasound wave coupling from structure to remotely bonded fiber Bragg grating (FBG) ultrasound sensor

2020 ◽  
pp. 1-31
Author(s):  
Haiying Huang ◽  
Kranthi Balusu
Keyword(s):  
Optical Fiber ◽  
Numerical Study ◽  
Longitudinal Mode ◽  
Propagation Speed ◽  
Ultrasound Wave ◽  
Ultrasound Waves ◽  
Time Frequency ◽  
Bonding Parameters ◽  
Ultrasound Sensor ◽  
Fbg Sensors

Abstract Recent published experimental works on remotely bonded FBG ultrasound sensors show that they display some unique characteristics that are not observed with directly bonded FBG sensors. These studies suggest that the bonding of the optical fiber strongly influences how the ultrasound waves are coupled from the structure to the FBG sensor. In this paper, the analytical model of the structure-adhesive-optical fiber section, treated as an ultrasound coupler, is derived and analyzed to explain the observed experimental phenomena. The resulting dispersion curve shows that the ultrasound coupler possesses a cut-off frequency, above which a dispersive longitudinal mode exists. The low propagation speed of the dispersive longitudinal mode leads to multiple resonances at and above the cut-off frequency. To characterize the resonant characteristics of the ultrasound coupler, a semi-analytical numerical model is implemented and the scattering parameters (S-parameters) are introduced for broadband time-frequency analysis. The simulation was able to reproduce the experiment observations reported by other researchers. Parametric studies conducted on the bonding parameters demonstrated that the behaviors of the remotely bonded FBG sensors can be explained based on its resonant characteristics.

Postural Control Profiles of Typically Developing Children From 6 to 12 Years old: An Approach Using Self-Organizing Maps

2020 ◽  
Vol 8 (1) ◽  
pp. 52-66 ◽  
Author(s):  
Xavier García-Massó ◽  
Isaac Estevan ◽  
Roberto Izquierdo-Herrera ◽  
Israel Villarrasa-Sapiña ◽  
Luis-Millan Gonzalez
Keyword(s):  
Postural Control ◽  
Visual Information ◽  
High Stability ◽  
Center Of Pressure ◽  
Standing Position ◽  
Self Organizing Map ◽  
Typically Developing ◽  
Typically Developing Children ◽  
Time Frequency ◽  
Self Organizing

The purposes of the present study were a) to establish postural control profiles for individuals 6–12 years of age, b) to analyze the participants’ characteristics (age, sex, weight, height, and physical activity) in those profiles, and c) to analyze the influence of visual information in the profiles found. Two hundred and eight typically developing children aged 6–12 years performed two trials in bipedal standing position with eyes open and closed. Feature extraction involved time, frequency, and sway-density plot variables using signals from the center of pressure. A Self-Organizing Map was used to classify and visualize the values of the participants in all the postural control variables tested. A k-means cluster analysis was applied to generate a small number of postural control profiles. The results determined six postural control profiles; three with participants denoting high stability and three considered as low stability profiles. Age, sex, and height were related to the postural control profiles. Boys were more frequently allocated in high stability clusters than girls, while the other factors yielded unclear difference between high and low stability profiles. The analysis of children’s profiles reflecting postural stability should therefore involve more than one factor including the individuals’ age, sex, and height.

Orbits of Geostationary TV Satellites

1997 ◽  
Vol 165 ◽  
pp. 347-350
Author(s):  
Andrzej Drożyner
Keyword(s):  
Orbit Determination ◽  
Software Package ◽  
High Stability ◽  
Arrival Times ◽  
European Cooperation ◽  
Dynamical State ◽  
Observational Technique ◽  
San Fernando ◽  
Stability Time

AbstractIn the frame of European cooperation among some stations (Brussels, Praha, Cagliari, Torino, Penc, Borowiec, Teddington, Metsahovi, Besançon and San Fernando) the method of time comparisons by a TV link has been used for orbit determination of the Eutelsat-F2 satellite. Observational stations are equipped with commercial TV receivers and high stability time services. The technique of observations is based on the registration of arrival times of synchronous pulses broadcast by the satellite. For this type of observations a special orbital software package (TOP-COGEOS) has been developed, which allows the determination of the dynamical state of the satellite and some additional parameters connected to applied observational technique.

scholarly journals A High Stability Time Difference Readout Technique of RTD-Fluxgate Sensors

Sensors ◽  
2017 ◽  
Vol 17 (10) ◽  
pp. 2325 ◽  
Author(s):  
Na Pang ◽  
Defu Cheng ◽  
Yanzhang Wang
Keyword(s):  
High Stability ◽  
Time Difference ◽  
Stability Time

High-stability optical fiber sensor system

1991 ◽  
Author(s):  
Yu-Feng Chen ◽  
Yue-kun Liang ◽  
Hong Bian
Keyword(s):  
Optical Fiber ◽  
High Stability ◽  
Optical Fiber Sensor ◽  
Sensor System ◽  
Fiber Sensor
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