scholarly journals Novel Model for the Angle and Skewness Dependent Transmission Behavior of Step-Index Polymer Optical Fiber

Fibers ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 65 ◽  
Author(s):  
Thomas Becker ◽  
Rainer Engelbrecht ◽  
Bernhard Schmauss
Keyword(s):  
Measurement Error ◽  
Optical Fibers ◽  
Optical Transmission ◽  
Real Data ◽  
Transmission System ◽  
Phase Response ◽  
Polymer Optical Fiber ◽  
Step Index ◽  
The Impact ◽  
Novel Model

Step-index polymer optical fibers (SI-POFs) are deployed in both sensing and data transmission systems. The optical transmission behavior of these fibers is complex and affected by intrinsic influences like modal dispersion, scattering and attenuation as well as extrinsic influences like the launching condition and the angular sensitivity of the receiver. Since a proper modeling of the transmission behavior is important in order to evaluate the suitability of the fiber for a specific application, we present a novel model for step-index multi-mode fibers (SI-MMFs) which considers all the previously mentioned impacts. Furthermore, the model differentiates scattering and attenuation for propagating rays not only by their propagating angle θ z but also by the skewness θ ϕ . It is therefore possible to distinguish between guided, tunneling and refracted modes. The model uses scatter and attenuation data from previously published measurements of an SI-POF and computes the impulse response of the transmission system which is transferred to the frequency domain to derive the amplitude and phase response. A possible application for SI-POF is the length or strain measurement of the fiber by measuring the phase of a harmonically modulated signal. These sensors rely on a linear relation between the length of the fiber and the phase of the modulated signal. We demonstrate the application of the model by simulating the length measurement error that occurs for these sensors by obtaining the phase response for the corresponding optical transmission system. Furthermore, we will demonstrate the flexibility of the model by varying several influences including the excitation of different mode categories and evaluate the impact on the measurement error. Finally, we compare the simulated length error derived from the model to real data obtained from a cutback measurement. An implementation of the model, which was used for all simulations in this paper, is publicly available.

scholarly journals Optical Strain Measurement with Step-Index Polymer Optical Fiber Based on the Phase Measurement of an Intensity-Modulated Signal

Sensors ◽  
2018 ◽  
Vol 18 (7) ◽  
pp. 2319 ◽  
Author(s):  
Thomas Becker ◽  
Olaf Ziemann ◽  
Rainer Engelbrecht ◽  
Bernhard Schmauss
Keyword(s):  
Refractive Index ◽  
Optical Fiber ◽  
Optical Fibers ◽  
Phase Measurement ◽  
Polymer Optical Fiber ◽  
Step Index ◽  
Intensity Modulated ◽  
Optical Strain ◽  
The Impact ◽  
Multi Mode

Polymer optical fibers (POFs) have been proposed for optical strain sensors due to their large elastic strain range compared to glass optical fibers (GOFs). The phase response of a single-mode polymer optical fiber (SM-POF) is well-known in the literature, and depends on the physical deformation of the fiber as well as the impact on the refractive index of the core. In this paper, we investigate the impact of strain on a step-index polymer optical fiber (SI-POF). In particular, we discuss the responsivity of an optical strain sensor which is based on the phase measurement of an intensity-modulated signal. In comparison to the phase response of an SM-POF, we must take additional influences into account. Firstly, the SI-POF is a multi-mode fiber (MMF). Consequently, we not only consider the strain dependence of the refractive index, but also its dependency on the propagation angle θz. Second, we investigate the phase of an intensity-modulated signal. The development of this modulation phase along the fiber is influenced by modal dispersion, scattering, and attenuation. The modulation phase therefore has no linear dependency on the length of the fiber, even in the unstrained state. For the proper consideration of these effects, we rely on a novel model for step-index multi-mode fibers (SI-MMFs). We expand the model to consider the strain-induced effects, simulate the strain responsivity of the sensor, and compare it to experimental results. This led to the conclusion that the scattering behavior of a SI-POF is strain-dependent, which was further proven by measuring the far field at the end of a SI-POF under different strain conditions.

scholarly journals Performance Analysis of Subcarrier Multiplexed Optical Transmission System for QPSK Data

2020 ◽  
Vol 9 (2) ◽  
pp. 466-476
Keyword(s):  
Optical Transmission ◽  
Dispersion Compensation ◽  
Chromatic Dispersion ◽  
Transmission System ◽  
Laser Source ◽  
Radio Link ◽  
Link Distance ◽  
Performance Results ◽  
The Impact ◽  
Dispersion And Attenuation

This paper focuses on the impact of different parameters on the performance of the Subcarrier Multiplexed Optical Transmission System for the application on radio link via optical fiber. Performance results are evaluated for QPSK data format for ODSB and OSSB modulation of Microwave subcarriers with digital NRZ coded random data patterns. The four subsystems of QPSK modulators are at 400, 500, 600, 700 MHz subcarrier frequencies with frequency spacing of 100 MHz. The power of subcarriers is decreasing with increasing the link distance due to dispersion and attenuation. By using dispersion compensation fiber, the link distance has been enhanced from 100 km to 240 km successfully. The impact of chromatic dispersion has been reduced in OSSB by using dual-electrode MZM. The constellation diagram also confirms that the phase of the signal after traveling through the link is changing due to dispersion. The phase is the same for subcarrier 600 MHz & 700 MHz for ODSB and OSSB in QPSK SCM. The impact of linewidth and responsivity on SNR has also analyzed to evaluate the performance. It is concluded that the maximum SNR is decreasing with increase in the linewidth of laser source and increasing with the increase in responsivity of PIN diode for the same fiber length in SCM transmission.

scholarly journals Compound Bias due to Measurement Error When Comparing Regression Coefficients

2019 ◽  
Vol 80 (3) ◽  
pp. 548-577
Author(s):  
William M. Murrah
Keyword(s):  
Measurement Error ◽  
Multiple Regression ◽  
Simulation Study ◽  
Type I Error ◽  
Real Data ◽  
Error Rates ◽  
Regression Coefficients ◽  
Type I ◽  
Type I Error Rates ◽  
The Impact

Multiple regression is often used to compare the importance of two or more predictors. When the predictors being compared are measured with error, the estimated coefficients can be biased and Type I error rates can be inflated. This study explores the impact of measurement error on comparing predictors when one is measured with error, followed by a simulation study to help quantify the bias and Type I error rates for common research situations. Two methods used to adjust for measurement error are demonstrated using a real data example. This study adds to the literature documenting the impact of measurement error on regression modeling, identifying issues particular to the use of multiple regression for comparing predictors, and offers recommendations for researchers conducting such studies.

scholarly journals Experimental Assessment of the Transmission Performance of Step Index Polymer Optical Fibers Using a Green Laser Diode

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3397
Author(s):  
María Ángeles Losada ◽  
María Mazo ◽  
Alicia López ◽  
Candela Muzás ◽  
Javier Mateo
Keyword(s):  
Optical Fibers ◽  
Green Light ◽  
Green Laser ◽  
Polymer Optical Fiber ◽  
Modal Dispersion ◽  
Step Index ◽  
Polymer Optical Fibers ◽  
Dispersion And Attenuation ◽  
Potential Use ◽  
Distribution Frequency

Large-core polymer optical fiber (POF) links have limitations in capacity and reach due to the fibers’ high modal dispersion and attenuation. Most of these links use red laser diodes, even though the attenuation spectrum of poly(methyl methacrylate) (PMMA), the basic polymer used to manufacture these fibers, has a lower minimum in the green region. Therefore, we set out to explore the potential use of green light in transmission systems, comparing the performances of three step-index polymer optical fibers (SI-POFs) with different numerical apertures. We obtained measurements of intensity distribution, frequency response and bit error rate (BER), as functions of fiber length. We have also compared the fibers’ frequency responses with red and green light for a few selected lengths. Our results confirm that SI-POFs attenuate less in response to green light, which can increase their length. This advantage is partially counterbalanced by a slightly higher dispersion that limits the capacity of the high-aperture fibers, particularly at relatively short lengths. Our conclusions are critical to understanding SI-POF behavior and to designing thorough SI-POF models that can aid the design of POF-based links for different scenarios.

COVID-19: Time-Dependent Effective Reproduction Number and Sub-notification Effect Estimation Modeling (Preprint)

2020 ◽  
Author(s):  
Eduardo Atem De Carvalho ◽  
Rogerio Atem De Carvalho
Keyword(s):  
New York ◽  
Reproduction Number ◽  
Moving Average ◽  
Real Data ◽  
Time Dependent ◽  
Initial Value ◽  
Health Authorities ◽  
Reproduction Numbers ◽  
Effect Estimation ◽  
The Impact

BACKGROUND Since the beginning of the COVID-19 pandemic, researchers and health authorities have sought to identify the different parameters that govern their infection and death cycles, in order to be able to make better decisions. In particular, a series of reproduction number estimation models have been presented, with different practical results. OBJECTIVE This article aims to present an effective and efficient model for estimating the Reproduction Number and to discuss the impacts of sub-notification on these calculations. METHODS The concept of Moving Average Method with Initial value (MAMI) is used, as well as a model for Rt, the Reproduction Number, is derived from experimental data. The models are applied to real data and their performance is presented. RESULTS Analyses on Rt and sub-notification effects for Germany, Italy, Sweden, United Kingdom, South Korea, and the State of New York are presented to show the performance of the methods here introduced. CONCLUSIONS We show that, with relatively simple mathematical tools, it is possible to obtain reliable values for time-dependent, incubation period-independent Reproduction Numbers (Rt). We also demonstrate that the impact of sub-notification is relatively low, after the initial phase of the epidemic cycle has passed.

Jitter accumulation in a simulated 591.2 Mbit/s, 6000 km optical transmission system

1988 ◽  
Vol 24 (11) ◽  
pp. 676-678
Author(s):  
B.I. McNally ◽  
S.F. Carter ◽  
S.D. Walker
Keyword(s):  
Optical Transmission ◽  
Transmission System

Automatic polarisation mode dispersion compensation in 40 Gbit/s optical transmission system

1998 ◽  
Vol 34 (23) ◽  
pp. 2258 ◽  
Author(s):  
D. Sandel ◽  
M. Yoshida-Dierolf ◽  
R. Noé ◽  
A. Schöpflin ◽  
E. Gottwald ◽  
...  
Keyword(s):  
Optical Transmission ◽  
Dispersion Compensation ◽  
Transmission System ◽  
Mode Dispersion ◽  
Polarisation Mode Dispersion

scholarly journals Robust Filtering Techniques for RTK Positioning in Harsh Propagation Environments

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1250
Author(s):  
Daniel Medina ◽  
Haoqing Li ◽  
Jordi Vilà-Valls ◽  
Pau Closas
Keyword(s):  
Intelligent Transportation Systems ◽  
Robust Statistics ◽  
Real Data ◽  
Transportation Systems ◽  
Global Navigation Satellite Systems ◽  
Mixed Integer ◽  
Robust Filtering ◽  
Precise Positioning ◽  
The Impact ◽  
Filtering Techniques

Global navigation satellite systems (GNSSs) play a key role in intelligent transportation systems such as autonomous driving or unmanned systems navigation. In such applications, it is fundamental to ensure a reliable precise positioning solution able to operate in harsh propagation conditions such as urban environments and under multipath and other disturbances. Exploiting carrier phase observations allows for precise positioning solutions at the complexity cost of resolving integer phase ambiguities, a procedure that is particularly affected by non-nominal conditions. This limits the applicability of conventional filtering techniques in challenging scenarios, and new robust solutions must be accounted for. This contribution deals with real-time kinematic (RTK) positioning and the design of robust filtering solutions for the associated mixed integer- and real-valued estimation problem. Families of Kalman filter (KF) approaches based on robust statistics and variational inference are explored, such as the generalized M-based KF or the variational-based KF, aiming to mitigate the impact of outliers or non-nominal measurement behaviors. The performance assessment under harsh propagation conditions is realized using a simulated scenario and real data from a measurement campaign. The proposed robust filtering solutions are shown to offer excellent resilience against outlying observations, with the variational-based KF showcasing the overall best performance in terms of Gaussian efficiency and robustness.

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