A novel in-service measurement technique using the same wavelength band as SCM signals

This paper proposes a new technique for measuring in-service optical fibers, that uses an optical time domain reflectometer (OTDR). The feature of the proposed technique is that the OTDR light is in the same wavelength band as the video signal, which is distributed by using the subcarrier multiplexing (SCM) technique. In a 40-channel SCM system operating at a signal wavelength of 1.558 /spl mu/m, we show that the required video quality can be maintained, by using the proposed OTDR operating in the 1.55 /spl mu/m band, even though the measured fiber is in service and the OTDR light enters an optical receiver. Moreover, we clarify the conditions for undertaking measurements, without the need for optical filters designed to prevent OTDR light from degrading the SCM signal quality.     

A new modal power distribution measurement for high-speed short-reach optical systems

We propose a pair of related new techniques for measuring the modal power distribution (MPD) of light launched into a multimode fiber (MMF). For modern applications involving laser launches, our method has several potential advantages over ray optics-based methods such as and recent extensions of them . Instead of relying on a time-averaged measurement of near-field intensity with a CCD camera to spatially resolve the launched power, our method uses a specially designed probe fiber to temporally resolve the launched power. If the source can be modulated fast enough (as is necessary for 10 Gbps serial transmission, for instance), the measurement is straightforward and the calculation of the MPD is trivial. For slower sources, a more involved measurement and inversion algorithm are required.     

Coherent self-heterodyne Brillouin OTDR for measurement ofBrillouin frequency shift distribution in optical fibers

Time domain reflectometry of spontaneously Brillouin scattered lightwaves in a single-mode optical fiber is demonstrated with a coherent self-heterodyne detection system employing a recently proposed frequency translator, a DFB laser diode, and erbium-doped fiber amplifiers. Since the probe pulse frequency is up-converted by the translator by an amount approximately equal to the Brillouin frequency shift, the self-heterodyne beat frequency can be reduced to a sufficiently low frequency in the IF band. The system enables one-end measurement of the Brillouin frequency shift distribution in optical fibers with a single way dynamic range (SWDR) of 16 dB and a frequency resolution of 5 MHz for a spatial resolution of 100 m     

A novel in-service surveillance scheme for optically amplified transmission systems

We propose here a novel surveillance scheme for an optically amplified transmission system which allows simultaneous in-service fault identification for fiber and optical amplifiers. While requiring additional fiber Bragg gratings of designated wavelengths to be integrated with optical amplifiers, the monitoring light source is derived from the unused spectra of ASE and no dedicated light source is needed as in conventional OTDR technique. We have further demonstrated the scheme's feasibility with a 100-km, three-EDFA optical transmission system.     

激光照明LCCD测量系统的光源功率选择方法

分析了LCCD成像的影响因素和被测目标的反射规律,分别建立了LCCD成像能力和目标反射能量模型,进一步推导了LCCD成像系统激光光源的功率选择公式。最后利用LCCD相机和激光线光源对被测目标进行了成像实验,证明了所建立的激光功率选择模型的有效性。     

Reliability growth modeling for in-service electronic systems considering latent failure modes

A latent failure mode is a type of failure that may not occur until the system has operated in the field for a certain period of time. Predicting latent failures is often difficult, but it has a great importance for reliability management in terms of system maintenance and warranty services. This paper proposes a stochastic model to predict the reliability growth for field or in-service electronic systems considering latent failures. The proposed model can be applied to electronics industries where extended in-house reliability testing cannot be implemented due to the tight design schedule. Based on the new method, the product management can proactively implement corrective actions against key failure modes using relevant engineering resources. A discussion between the effectiveness of corrective actions and the associated cost is also provided. Finally, field failure data collected from a fleet of automatic test equipment are used to demonstrate the applicability and performance of the model.     

New simple one-end splice loss measurement method using an OTDR for single-mode optical fibre

The letter presents a new simple method using an optical time-domain reflectometer for measuring the real splice loss of single-mode optical fibres from one end of the fibre. Importantly, the method eliminates the difference in backscattering properties of the spliced fibres by subtracting two discontinuities obtained at different wavelengths in the received backscattered power.     

Hybrid systems modeling for power systems

In this work a framework for modeling power systems using hybrid input/output automata (HIOA) is proposed. The system is assumed to consist of several distinct components. Some of them drive the continuous dynamics while others exhibit event-driven discrete dynamics. Such behavior is characterized by interactions between continuous dynamics and discrete events. Therefore the power systems are an important example of hybrid systems. This hybrid modeling process is applied to a simple power system.     

Spectral filtering criteria for U-band test light for in-service line monitoring in optical fiber networks

In the fiber-to-the-home era, thousands of optical fibers will have to be accommodated in the central offices of optical access networks. To reduce maintenance costs and improve the service reliability of optical fiber networks, the authors must develop an optical fiber line testing system with a function for in-service line monitoring that uses a test light with a wavelength different from the communication light wavelength. To monitor an in-service line in an optical network, the effective rejection ratio of the test light must be taken into account. This ratio depends on the spectrum of the test light from the optical time-domain reflectometer and the rejection band of the filter in front of the optical network unit. The dependence of the effective rejection ratio as a function of the sideband suppression ratio (SBSR) and of the ratio of the rejection band to the bandwidth of the sideband noise d/D is clarified. When d/D=0.1 and the target effective rejection ratio of the filter is -40 dB, the SBSR and the filter loss of the termination cable must be -70 and -43 dB, respectively, or the SBSR must be -80 dB. When d/D<0.5 and the target effective rejection ratio of the filter is -40 dB, the SBSR is also required to be -80 dB. In-service line monitoring for a 10-Gb/s transmission using a 1650-nm test light with an SBSR of -80 dB is also demonstrated.     

A solid-state instrument for the measurement of frequency and phase angle in power systems

This paper describes the development of an instrument, using electronic switching circuits for the measurement of frequency and phase angles in power systems. The phase angle and frequency are indicated on a meter with linear scale. The instrument responds to changes in system frequency and the phase-angle measurement is inherently lead-lag sensitive.     

现代通信系统电源设计

通信设备使用的电源器件有很多种,从前端的功率因数校正(PFC)AC／DC电源到后端的高效DC／DC模块和负载点(POL)转换器,不一而足。从需要很高效率的中间总线转换器(IBC),到那些日趋细小轻巧的VoIP数字电话,以及要求多路紧密调节电压(7～13路输出)的数字用户线(xDSL)电源等,DC／DC电源在现代通信中获得了广泛应用。     

Projection systems for light valves

This paper classifies schlieren projection systems for light valves (LV's) into three groups according to the type of illumination. The requirements for uniform illumination and the tradeoffs between brightness, contrast, and resolution are discussed for different systems. Consideration is given to transmissive versus reflective LV's, black-on-white versus white-on-black, image overlay, color, and luminous efficiency.     

Expert systems for power applications

The author briefly discusses expert systems and the incentives for producing them. He then goes on to discuss applications in the power industry including an energy management system for control of power generation, power transmission, and distribution networks. They are also used for power system security, voltage and transient stability, decisionmaking in design, and for planning scenarios. They are also used for process plant control     

Phase-orthogonal FIR filter based reactive power measurement for power meters

Analog Integrated Circuits and Signal Processing - In filter based reactive power measurements, the voltage is phase shifted by $$90^circ$$ relative to the current. This paper presents a technique...     

基于单片机的液压动力钳检测系统研究与实现

针对油田修井使用的多种液压动力钳系统没有使用扭矩力限定装置,容易因人为因素产生过大转矩,对油管螺纹造成永久性的损坏;过小转矩,对油管密封不好或脱落的问题,本文采用单片机设计液压管钳检测系统,系统包括液压动力钳扭矩检测传感器、数据采集通信仪表及检测上位机软件,能够实时记录及检测扭矩力值,并提供多点力矩超限声光报警。成功的减少施工和运行维护费用,提高作业安全和工作效率。     

PON系统测试用光功率计

文章介绍了一种无源光网络(PON)系统中测试用的光功率计,该功率计通过特殊设计的光路和电路结构来实现PON系统中对信号光功率测试的特殊要求,即要满足线路上3种光信号波长的同时测试、在线测试和1 310 nm信号的突发测试功能,从而大大方便PON系统的安装、管理和维护.     

Probability of false power control command in CDMA systems subject to measurement errors

In this letter we introduce a new performance measurement, the probability of false power control command (P/sub FC/), to evaluate the impact of measurement errors on the closed-loop power control in code division multiple access systems. We derive a closed-form expression for P/sub FC/. As compared to the variable-step-sized power control, we find that the fixed-step-sized CLPC scheme, thanks to its nonlinear operation in the up/down control scheme, is less sensitive to the measurement error.     

Tighter controls for busier systems [power systems]

A variety of new technologies are becoming available that will help utilities maintain power system reliability while handling the larger volume of transactions. For example, power electronic systems can provide unprecedented control over electricity flow on transmission networks, preventing or containing cascading disturbances. In addition, new sensor technology, faster communications between control centers, and advanced software tools can enable utilities to monitor system conditions in real time, letting them respond more quickly to disturbances and minimize their impact. Over the next decade, these technologies will facilitate increased power transfers through power delivery systems that are presently constrained, providing power at lower cost to a greater number of customers. It is a question of how to optimize power flow through an entire network by integrating multiple technologies and coordinating control over wide areas. Such integration and coordination will be necessary for deregulation to proceed smoothly toward its twin goals: reducing electricity costs to US consumers, while maintaining the high levels of reliability they have come to expect. The authors discuss the following technologies to help achieve these goals including: flexible AC transmission systems (FACTS), the next generation of FACTS controllers, hierarchical control of FACTS, on-line power systems analysis, control centre communications, and wide area measurement system     

Computer-aided dispatch for electric power systems

This paper provides a review of the subject of electric power dispatching. In Section I we show where dispatching fits into the hierarchy of power system operating and planning problems. Section II provides an overview of the issues, concerns and practices of dispatching. Sections III-V are devoted to the algorithmic aspects of dispatching. Finally, in Section VI we highlight the conclusions reached in the proceeding sections and identify a number of research needs.     

用于倍频激光测量的能量计

本文叙述了用于倍频激光测量的能量计原理、结构。给出的工作参数满足神光装置中短波长、短脉冲激光能量测量的要求。能量计整机不确定度为±5％。