predates optical fiber and has its roots in wartime efforts to develop secure communication systems that did not require cable and could withstand radio jamming. FSO has been around for more than a decade‚ but it is only recently that interest in this technology has started to grow. Free Space Optics (FSO) communications‚ also called Free Space Photonics (FSP) or Optical Wireless‚ refers to the transmission of modulated visible or infrared (IR) beams through the atmosphere to obtain optical communications
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Chapter 1 Introduction 1.1 History of Free Space Optics Even though fibre-optic communications gained worldwide acceptance in the telecommunication industry‚ FSO communications is still considered relatively new. But optical communication‚ in various forms‚ has been used for thousands of years. The Ancient Greeks polished their shields to send signals during battle. In the modern era‚ semaphores and wireless solar telegraphs called heliographs were developed‚ using coded signals to communicate
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Technology Devices to Overcome the Limitations of Sight and Hearing Humans have sight and hearing limitation. Without any devices‚ our sight and hearing was limited. Most of the limitation of sight can be overcome with the help of certain optical instruments such as magnifying glass‚ microscope‚ binoculars and others. The range of frequency of hearing in human 20 Hz to 20 000 Hz. It was different according to the age of a person. Hearing limitations can be overcome by using devices such as
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surrounded by a twisted braid‚ foil or both and bound in a single plastic sheath containing balanced twisted-pair conductors that are individually shielded. Fiber-optic Cable- is a cable made up of optical fibers that can transmit large amounts of information at the speed of light. Dark Fiber- is an unused optical fiber available for use in fiber-optic communication. Coaxial Cable- a cable that consists of a center wire surrounded by insulation and then a grounded shield of braided wire. Plenum- a compartment
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RAM RAM is an acronym for Random Access Memory that is also known as volatile memory‚ because the data it holds is lost when the desktop PC or laptop/notebook computer using it is switched off. Briefly‚ RAM memory is used by the system to store data in the form of files for processing by a computer’s central processing unit (CPU)‚ also known as the processor. The amount of RAM memory used in modern desktop and laptop computers is expressed in megabytes (MB) and gigabytes(GB). A gigabyte (1GB)
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considered noise or interference and is expressed in decibels. 2. Waveguides – A structure that guides electromagnetic waves along their length. The core fiber in an optical-fiber cable is an optical waveguide. 3. FTTH – (fiber-to-the-home): Fiber reaches the boundary of the living space‚ such as a box on the outside wall of a home. Passive optical networks and point-to-point Ethernet are architectures that deliver triple-play services over FTTH networks directly from an operator’s central office. 4. Simplex
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Optical Distortion‚ Inc (ODI) is a company that has developed special contact lenses to harmful impact the eyesight of egg-laying chickens. The reduced vision from the contact lenses helps preserve the life of chickens‚ increase the productivity of egg laying and reduce costs for farmers using the lenses for their flocks. At the end of 1974‚ ODI’s owners and management were finalizing a strategic marketing plan to introduce the lenses commercially early in 1975 and work towards nationwide penetration
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unit 4 for NT 1310Cabling -Definitions 1. Horizontal cable: The wiring/cabling between the telecommunications outlet/connector and the horizontal cross-connect. 2. Backbone Cable: Backbone Cabling is the inter-building and intra-building cable connections in structured cabling between entrances. 3. Patch Cords: Insulated cord with a plug at each end‚ for use with a patch panel. 4. Connectors: Cable connectors are devices for keeping two parts of an electric circuit in contact. 5
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meeting standards on each task they are being evaluated on. They don ’t want to provide documentation when the employee is not performing to expectations. They don ’t want to be the "bad guy" and choose to not "upset" the employee with negative feedback. (Neely‚ G.) Ø The "pitchfork effect" is evaluating the employee on a recent event whether positive or negative‚ rather than evaluating them for the entire time of the evaluation. (San Joaquin County Human Resources Division‚ 2002) Ø The "labeling
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Fiber Optics Definitions 1. Crosstalk – The coupling or transfer of unwanted signals from one pair within a cable to another pair. 2. Waveguides – A structure that guides electromagnetic waves along their length. The core fiber in an optical-fiber cable is an optical waveguide. 3. FTTH – Fiber-to-the-home 4. Simplex – a. A link that can only carry a signal in one direction. b. A fiber-optic cable or cord carrying a single fiber. Simplex cordage is mainly used for patch cords and temporary installations
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