Investigation of the effect of an increased supervisory signal power in a high-loss loopback monitoring system

We present experimental results for the effect of an increased supervisory signal power in a high-loss loopback supervisory system in an optically amplified wavelength division multiplexing (WDM) transmission line. The study focuses on the investigation of increasing the input power for the supervisory signal and the effect on the co-propagating WDM data signals using different channel spacing. This investigation is useful for determining the power limitation of the supervisory signal if extra power is needed to improve the monitoring. The study also shows the effect of spacing on the quality of the supervisory signal itself because of interaction with adjacent data signals

High efficiency, character-oriented, local area networks

Imperial Users onl

A tunable-channel multi-access wavelength division multiplexed network and surveillance schemes for optical cross-connects.

by Eddie Ting Pong Kong.Thesis (M.Phil.)--Chinese University of Hong Kong, 1999.Includes bibliographical references (leaves 61-68).Abstracts in English and Chinese.Chapter 1 --- Introduction --- p.1Chapter 1.1 --- Optical Network Architecture --- p.1Chapter 1.2 --- High-Speed All-Optical Tunable-Channel Multi-Access Networks --- p.3Chapter 1.3 --- Fault Surveillance of Optical Cross-Connects in Wavelength Routing Network --- p.3Chapter 1.4 --- Outline of the Thesis --- p.5Chapter 2 --- Optical Multi-Access Networks --- p.6Chapter 2.1 --- All-Optical Networks --- p.6Chapter 2.2 --- Optical Multi-Access Schemes --- p.8Chapter 2.2.1 --- Wavelength-Division Multi-Access (WDMA) --- p.9Chapter 2.2.2 --- Time-Division Multi-Access (TDMA) --- p.12Chapter 2.2.3 --- Subcarrier Multi-Access (SCMA) --- p.14Chapter 2.3 --- Design Considerations --- p.14Chapter 3 --- All-Optical Tunable-Channel Multi-Access Networks --- p.18Chapter 3.1 --- Tunable-Channel Multi-Access Networks --- p.19Chapter 3.2 --- Protocols for TCMA Networks --- p.20Chapter 3.3 --- Photonic Implementation of a Wavelength Division TCMA Network with Time- Slot Access --- p.23Chapter 3.3.1 --- Proposed Network Architecture --- p.25Chapter 3.3.2 --- Experimental Results --- p.30Chapter 3.3.3 --- Discussion --- p.34Chapter 3.3.4 --- Summary --- p.35Chapter 4 --- Fault Surveillance for Optical Cross-Connects in Wavelength Routing Networks --- p.36Chapter 4.1 --- Wavelength Routing Networks --- p.37Chapter 4.2 --- Options in Fault Surveillance --- p.39Chapter 4.3 --- Optical Path Surveillance of Optical Cross-Connects in Wavelength Routing Networks --- p.41Chapter 4.3.1 --- Scanning Amplified Spontaneous Emission Identification Surveillance Scheme --- p.43Chapter 4.3.2 --- Pilot-Tone Based Surveillance and Removal Scheme --- p.49Chapter 4.4 --- Summary --- p.55Chapter 5 --- Conclusion --- p.57Chapter 5.1 --- Summary of the Thesis --- p.57Chapter 5.2 --- Future Work --- p.60Bibliography --- p.61Publication List --- p.5

Optical fiber sensors in physical intrusion detection systems: A review

Fiber optic sensors have become a mainstream sensing technology within a large array of applications due to their inherent benefits. They are now used significantly in structural health monitoring, and are an essential solution for monitoring harsh environments. Since their first development over 30 years ago, they have also found promise in security applications. This paper reviews all of the optical fiber-based techniques used in physical intrusion detection systems. It details the different approaches used for sensing, interrogation, and networking, by research groups, attempting to secure both commercial and residential premises from physical security breaches. The advantages and the disadvantages of the systems are discussed, and each of the different perimeter protection methods is outlined, namely, in-ground, perimeter fence, and window and door protection. This paper reviews the progress in optical fiber-based intrusion detection techniques from the past through to the current state-of-the-art systems and identifies areas, which may provide opportunities for improvement, as well as proposing future directions in this field

Customer premise service study for 30/20 GHz satellite system

Satellite systems in which the space segment operates in the 30/20 GHz frequency band are defined and compared as to their potential for providing various types of communications services to customer premises and the economic and technical feasibility of doing so. Technical tasks performed include: market postulation, definition of the ground segment, definition of the space segment, definition of the integrated satellite system, service costs for satellite systems, sensitivity analysis, and critical technology. Based on an analysis of market data, a sufficiently large market for services is projected so as to make the system economically viable. A large market, and hence a high capacity satellite system, is found to be necessary to minimize service costs, i.e., economy of scale is found to hold. The wide bandwidth expected to be available in the 30/20 GHz band, along with frequency reuse which further increases the effective system bandwidth, makes possible the high capacity system. Extensive ground networking is required in most systems to both connect users into the system and to interconnect Earth stations to provide spatial diversity. Earth station spatial diversity is found to be a cost effective means of compensating the large fading encountered in the 30/20 GHz operating band

Advanced Communications Technology Satellite (ACTS): Design and on-orbit performance measurements

The Advanced Communications Technology Satellite (ACTS), developed and built by Lockheed Martin Astro space for the NASA Lewis Research Center, was launched in September 1993 on the shuttle STS 51 mission. ACTS is a digital experimental communications test bed that incorporates gigahertz bandwidth transponders operating at Ka band, hopping spot beams, on-board storage and switching, and dynamic rain fade compensation. This paper describes the ACTS enabling technologies, the design of the communications payload, the constraints imposed on the spacecraft bus, and the measurements conducted to verify the performance of the system in orbit

Intensity based interrogation of optical fibre sensors for industrial automation and intrusion detection systems

In this study, the use of optical fibre sensors for intrusion detection and industrial automation systems has been demonstrated, with a particular focus on low cost, intensity-based, interrogation techniques. The use of optical fibre sensors for intrusion detection systems to secure residential, commercial, and industrial premises against potential security breaches has been extensively reviewed in this thesis. Fibre Bragg grating (FBG) sensing is one form of optical fibre sensing that has been underutilised in applications such as in-ground, in-fence, and window and door monitoring, and addressing that opportunity has been a major goal of this thesis. Both security and industrial sensor systems must include some centralised intelligence (electronic controller) and ideally both automation and security sensor systems would be controlled and monitored by the same centralised system. Optical fibre sensor systems that could be used for either application have been designed, developed, and tested in this study, and optoelectronic interfaces for integrating these sensors with electronic controllers have been demonstrated. The versatility of FBG sensors means that they are also ideal for certain mainstream industrial applications. Two novel transducers have been developed in this work; a highly sensitive low pressure FBG diaphragm transducer and a FBG load cell transducer. Both have been designed to allow interrogation of the optical signal could occur within the housing of the individual sensors themselves. This is achieved in a simple and low cost manner that enables the output of the transducers to be easily connected to standard electronic controllers, such as programmable logic controllers. Furthermore, some of the nonlinear characteristics of FBG sensors have been explored with the aim of developing transducers that are inherently decoupled from strain and temperature interference. One of the major advantages of optical fibre sensors is their ability to be both time division and wavelength division multiplexed. The intensity-based interrogation techniques used here complement this attribute and are a major consideration when developing the transducers and optoelectronic circuits. A time division multiplexing technique, using transmit-reflect detection and incorporating a dual bus, has also been developed. This system architecture enables all the different optical fibre transducers on the network to have the same Bragg wavelength and hence the number of spare replacement transducers required is minimal. Moreover, sensors can be replaced in an online control system without disrupting the network. In addition, by analysing both the transmitted and reflected signals, problems associated with optical power fluctuations are eliminated and the intensity of the sensor signals is increased through differential amplification. Overall, the research addresses the limitations of conventional electrical sensors, such as susceptibility to corrosive damage in wet and corrosive environments, and risk of causing an explosion in hazardous environments, as well as the limitations of current stand-alone optical fibre sensor systems. This thesis supports more alert, reliable, affordable, and coordinated, control and monitoring systems in an on-line environment