Fiber media converter

Monday, 15 January 2007

A media converter is used in data networks to convert signal transmission from one media, such as twisted pair copper, to another media such as fiber optics. The speed of computers and the data transfer between them is ever increasing. Optical data transmission techniques have been developed to provide high capacity signal transmission without many of the physical limitations for electrical cables. While the information transmission typically uses transmission media, such as a cable, an optical fiber cable among them has multipurpose utility because it may effectively transmit data over a long distance at a much higher speed than those of conventional pair lines or coaxial metallic cables. Optical fiber communication systems are beginning to achieve their great potential for the rapid transmission of vast amounts of information. In essence, an optical fiber system comprises a light source, a modulator for impressing information on the light, an optical transmission waveguide for carrying the optical signals, and a receiver for detecting the signals and for demodulating the information they carry. Unlike its metallic cables (e.g., coaxial and twisted pair topologies), fiber optics does not have the astringent speed and distance limitations. Because fiber optics utilizes light pulses to send the signal, it is free of radiated noise, which renders it safe to install in sensitive environment. A typical fiber optic cable comprises a core, a cladding, a coating, a strengthener, and a protective jacket. The core is the center of the cable and is the medium of propagation for an optical signal. Cores can be made of glass (e.g., silica) and/or plastic, configured as hollow or solid, and with a high refractive index. Glass based cores provide longer distances and greater bandwidth, whereas plastic provides a more affordable cable that is easier to install and splice.

A media converter is configured to convert a signal propagating through a first transmission medium to a signal for propagation through a second transmission medium, different from the first transmission medium. The transmission media can include, for example, an unshielded twisted pair (UTP) cable, and an optical fiber cable (single mode or multimode), where an electrical signal from the UTP cable is converted by the media converter to an optical signal for propagation in the optical fiber cable. There has been a lot of development of FTTH (fiber to the home) allowing high-speed transmission of multimedia data such as music, moving picture, and medical data by the installation of optical fiber directly to the home. It is often desirable to transmit the data between a source and a receiver using light generated by a laser and transmitted through an optical fiber. The benefits achieved by transmitting the data optically include electrical isolation between transmitter and receiver, as well as the ability to transmit the data at a greater distance by avoiding the electrical loss typically associated with transmission over copper wire. In an era of FTTH, a fiber media converter is an indispensable communication device to connect a fiber-optic line to a computer in the home or office. A fiber media converter has a pair of ports that are to be connected to a fiber-optic cable and a UTP cable, respectively. For each of the ports, a physical-layer device is provided, which supports MII (media independent interface) conforming to IEEE802.3 standards. Media converter systems include a power supply and one or more media converters. The fiber media converter performs the conversion of signal transmission. Typically, at an office or the home, many media converters for performing media conversion between an optical fiber and a UTP cable are used in order to connect the optical fibers to interconnecting devices, such as routers, terminals and the like. In a building having a plurality of offices or apartments, repeaters are often used in order to extend the lines in the building. A plurality of media converters having a small number of ports are often used instead of one media converter having many ports for exchange, operation, and wire configuration purposes. For instance, when each media converter is assigned to a different area, an area affected by an exchange of one faulty media converter can be limited to the area assigned to the broken media converter. Media converters receive the data signal through one media and output the data signal through another. The media converter is an active device and requires a supply voltage.

Media converters provide not only a LAN Ethernet with signal transmissions using an optical fiber cable of several kilometers, but also FTTH (fiber to the home). In addition, the rapid development of optical fiber cables and LANs (local area networks) /WANs (wide area networks) has demanded use of scores of media converters. Computer users can use a high-speed network in homes, owing to progress of FTTH (fiber to the home) techniques which provides various communication services such as telephone, ISDN, and the like through optical fiber cables extended to homes. In those networks in which optical fibers extend to the desk, a conversion must take place to allow a computer or other electronic device to communicate with the optical network since computers are typically designed to transmit and receive electrical signals. Most computers include a network interface card through which the computer transmits and receives electrical signals. External media converters are utilized to convert between electrical and optical signals. Media converters typically reside between the wall outlet and the computer. The optical network can extend to the wall outlet and can then be optically connected to the media converter by means of a fiber optic jumper. On the other hand, the computer can be connected to the media converter by means of an electrical cable or the like. The media converter then serves to convert optical signals to electrical signals for presentation to the computer and, conversely, to convert electrical signals provided by the computer to optical signals for transmission via the optical network.

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