Tuesday, April 17, 2007

Digital Fiber Optic Multichannel V/A/D Transport Systems

Fiber optics is now the dominant medium for terrestrial transmission of digital signals, and digital fiber optic systems are well established for transporting high quality video, audio, and data signals. Systems must make efficient use of optical fiber by transporting multiple channels of video and audio on a single fiber. A digital system working within a digital domain should be capable of expanding, inserting, routing, and switching signals within a network in such a way that video and audio performance is not affected. Of growing importance is the ability of these networks to accept a variety of signal formats and to interface with public television communication networks. Signal formats for transmission of video might include video encoding at various levels of digitizing accuracy, compressed video, advanced or high definition video, as well as digital high speed data. Understanding aspects of multiplexing, modulation schemes, and digital systems are important to implementing a multichannel transmission system.

All video/audio/data transport systems share a number of elements in common that form the basic system building blocks for any v/a/d system. These include: transmitters, receivers, signal regenerators, repeaters, coders, decoders, switches, modulators, amplifiers, A/D and D/A converters, splitters, combiners, signal fanouts, which allow signals to be added and dropped from a network or utilize smaller system components for the signal distribution, A/B switching for redundant circuit protection, network control data interfaces, and synchronizing clock interfaces.

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